Report

Separation of Binary Mixture By Using Pervaporation Chapter 1

INTRODUCTION TO PERVAPORATION 1.1 BACKGROUND: Most industrial scale separation processes are based on energy intensive methods such as distillation, evaporation, and freeze crystallization. Membrane separations offer significant advantages over existing separation processes. Current membrane separation technologies can offer energy savings, low-cost modular construction, high selectivity of separated materials, and processing of temperature- sensitive products [1-5]. Membranes separate mixtures by discriminating the components on the basis of physical or chemical attributes, such as molecular size, charge, or solubility [6]. By passing water and retaining salts, membranes are used to produce over half of the world's desalinized potable water. Membranes can also separate oxygen and nitrogen from air as well as hazardous organics from contaminated water in applications such as groundwater remediation. The need for membrane separation technology increases as environmental requirements tighten, water circuits close, the recycling of wastes increases and the purity requirements for foodstuff and pharmaceuticals increase Six major membrane processes (microfiltration, ultrafiltration, reverse osmosis, electrodialysis, gas separation and pervaporation) have found use in such application areas as water purification, chemical and food processing, drug delivery, bioseparations, and medical treatment [1-6]. Compared with traditional separation processes, such as distillation, extraction and filtration, membrane technology is a relatively new method that has been developed in the past few decades, but it has been widely adopted in many industries. The membrane processes have the following distinguishing characteristics [Mulder 1991]: 1) Continuity and simplicity of the processes, 2) Adjustability of the separation properties, 3) Feasibility of incorporation into hybrid processes, 4) Low energy consumption and moderate operating conditions. Developments in membrane formation techniques and materials science accelerate the research and applications of membrane technology. Now commercial membrane applications have successfully 1

Separation of Binary Mixture By Using Pervaporation displaced some conventional processes, and membrane technology has become an indispensable component in many industrial fields and our daily life.

Figure 1.1 Schematic membrane separation processes Figure 1.1 shows a schematic membrane process [Mulder 1991; Baker 2004]. Separation membranes are located between the feed side and the permeate side. In most membrane processes, such as gas separation, reverse osmosis and ultra filtration, both the feed and the permeate sides are in the same phases, gas or liquid, while in pervaporation, the liquid feed is separated into vaporous permeates with the aid of vacuum or a purge gas in the downstream side. Pervaporation has become a very important technique to separate azeotropes, closeboiling mixtures, and recover volatile organic chemicals from liquid mixtures, and now it has emerged as a good choice for separating heat sensitive products. The phenomenon of pervaporation was first discovered in 1917 by Kober [1995], but no extensive research was carried out until in the 1950s by Binning et al. [1961]. In pervaporation processes with functional polymer membranes, the non-porous dense membranes are essential. By choosing proper membranes, pervaporation has great advantages as an alternative separation method in the following separation tasks: 1) Dehydration of organic solvents, 2) Removal of organics from water, 3) Separation of organic liquids.

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Separation of Binary Mixture By Using Pervaporation Non-porous dense membranes can also be applied in other separation processes such as gas separation. Furthermore, both gas separation and pervaporation can be interpreted with the solution diffusion mechanism for mass transport in membranes. Membrane-based pervaporation or vapor permeation is a promising alternative to distillation since it is an energy-saving one-step separation process. If the proper membrane material is selected, pervaporation can separate azeotropic

mixtures and close boiling

mixtures that traditional

distillation has difficulties in processing [3]. Membrane

Feed phase /

Process

Permeate phase

Pervaporation Liquid / vapor

Driving Force

Membrane

Main application

Chemical

dense,liophilic

Separation of liquid

potential gradient Vapor

Vapor / vapor

permeation

Chemical potential

mixture dense,liophilic

gradient

Separation of liquid mixtures or vapors from

Pertraction

Liquid / liquid

Concentration

dense,liophilic

gases Separation of organic

Gas separation

Gas/gas

gradient Hydrostatic pressure

Porous or dense

solutions Separation of gaseous

Liquid/vapor

gradient Vapor pressure

Porous,liophilic

mixture Ultrapure water,

Membrane Distillation

gradient

concentration of solutions

Table 1.1.Overview of chosen membrane separation processes 1.2 MEMBRANE BASED PERVAPORATION SEPARATION: 1.2.1

Pervaporation Process Pervaporation is recognized as a separation process in which a binary or

multicomponent liquid mixture is separated by partial vaporization through a dense nonporous membrane. During pervaporation, the feed mixture is in direct contact with one side of the liophilic membrane whereas the permeate is removed in a vapor state from the opposite side into a vacuum or sweeping gas and then condense. Pervaporation is unique 3

Separation of Binary Mixture By Using Pervaporation among membrane separations, involving the liquid-vapor phase change to achieve the separation [7, 8]. In Pervaporation (PV), components of a volatile liquid feed will permeate through a nonporous permselective membrane and evaporate into the permeate space (Figure 1.2.1). The feed components undergo a phase change, making PV a unique membrane processes (Néel, 1991; Villaluenga and Tabe-Mohammadi, 2000).

Figure 1.2.1 The pervaporation process (Schleiffelder and Claudia, 2001). Liquid feed flows along one side of the membrane and various feed components selectively permeate into and through the membrane. In laboratory-scale batch-PV, liquid retentate is returned to the feed tank, depleted in preferentially permeating components. The enriched permeate vapour is swept from the membranes downstream surface under vacuum conditions or by an inert sweep gas, and is collected in a condenser (Feng and Huang, 1997; Schleiffelder and Claudia, 2001). Pervaporation, in its simplest form, is an energy efficient combination of membrane permeation and evaporation. Liquid mixtures can be separated by partial vaporization through a non-porus permselective membrane. This technique, which was originally called “Liquid permeation” has subsequently been termed “pervaporation” in order to emphasized the fact that permeate undergoes a phase change, from liquid to vapor, during the transport through the barrier.

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Separation of Binary Mixture By Using Pervaporation It's considered an attractive alternative to other separation methods for a variety of processes. For example, with the low temperatures and pressures involved in pervaporation, it often has cost and performance advantages for the separation of constant-boiling azeotropes. Pervaporation is also used for the dehydration of organic solvents and the removal of organics from aqueous streams. Additionally, pervaporation has emerged as a good choice for separation heat sensitive products. Pervaporation involves the separation of two or more components across a membrane by differing rates of diffusion through a thin polymer and an evaporative phase change comparable to a simple flash step. A concentrate and vapor pressure gradient is used to allow one component to preferentially permeate across the membrane. A vacuum applied to the permeate side is coupled with the immediate condensation of the permeated vapors. Pervaporation is typically suited to separating a minor component of a liquid mixture, thus high selectivity through the membrane is essential. In addition, a pervaporation unit can be integrated into a bioreactor to improve bioconversion rate and reduce downstream processing costs, if membranes can selectively remove volatile inhibitory substances from fermentation broths [7]. Compared to the relatively easy separation of non-aggressive chemicals from water in industry, very few commercial systems have been developed to separate aggressive organics-water systems [8-11]. The most significant opportunity to use pervaporation is in splitting an azeotrope or a close boiling-temperature mixture, where distillation is less efficient due to the huge amount of energy consumption. Theoretically, if a liquid feed contacts a nonporous membrane with vacuum downstream, the vaporization rate of each component in the liquid is limited by the membrane permeability. In other words, the concentration distribution of each component in the liquid and vapor is not only controlled by the thermodynamic equilibrium [12], but also is governed by the membrane permeability. In this case, the membrane is sometimes referred to as a “mass separating agent”. Nevertheless,

the

membrane-mediated

evaporation

is

generally

regarded

as

pervaporation. In order to maximize the driving force, i.e. an activity difference between a feed liquid and permeate vapor, heating the feed liquid at the boiling temperature on one side of the membrane and pulling a vacuum or cooling the permeate vapor to condense on the other side are generally applied in the pervaporation process [3].

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Separation of Binary Mixture By Using Pervaporation

Figure 1.2.2: Membrane-based pervaporation separation processes Vacuum Operation Pervaporation can used for breaking azeotropes, dehydration of solvents and other volatile organics, organic/organic separations such as ethanol or methanol removal, and wastewater purification. 1.2.2

Possible modes of Pervaporation Pervaporation units can operate either in the straight-forward or batch mode (Fig.

1.2.3). The straightforward mode is best applied to continuous feed streams, a relatively small amount of the component to be removed and systems for which concentration polarization is not a major problem (Fig. 1.2.3(A)). For small streams with large amounts of one component to separate, or with many different operating conditions, it may be advantageous to design a batch plant (Fig. 1.2.3(B)) with one or several modules, and a large feed circulation rate. The product is recycled to the feed tank until the required concentration is reached. This process simplifies plant design and offers maximum flexibility, however, with increased utility requirements.

Fig.1.2.3 (A) Continuous Pervaporation

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Separation of Binary Mixture By Using Pervaporation

Fig.1.2.3 (B) Batch Pervaporation

Fig.1.2.3 Possible modes of Pervaporation Batch pervaporation is a simple system with great flexibility; however a buffer tank is required for batch operation. Continuous pervaporation consumes very little energy, operates best with low impurities in the feed, and is best for larger capacities. Vapor phase permeation is preferred for direct feeds from distillation columns or for streams with dissolved solids. Characteristics of the Pervaporation process include: 1. Low energy consumption 2. No entrainer required, no contamination 3. Permeate must be volatile at operating conditions 4. Functions independent of vapor/liquid equilibrium 1.2.3

Pervaporation for Separation Liquid transport in pervaporation is described by various solution-diffusion

models1. The steps included are the sorption of the permeate at the interface of the solution feed and the membrane, diffusion across the membrane due to concentration gradients (rate determining steps), and finally desorption into a vapor phase at the permeate side of the membrane. The first two steps are primarily responsible for the permselectivity1. As material passes through the membrane a "swelling" effect makes the membrane more permeable, but less selective, until a point of unacceptable selectivity is reached and the membrane must be regenerated. The other driving force for separation is

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Separation of Binary Mixture By Using Pervaporation the difference in partial pressures across the membrane. By reducing the pressure on the permeate side of the membrane, a driving force is created. Another method of inducing a partial pressure gradient is to sweep an inert gas over the permeate side of the membrane. 1.2.4 Pervaporation applications There are three common applications of pervaporation (Koops and Smolders, 1991; Feng and Huang, 1997): • Dehydrating organic solvents using hydrophilic membranes (i.e., water-alcohol, -ethers, -ketones, -carboxylic acids), • Removing organic compounds from aqueous solutions using hydrophobic Membranes (i.e., water-chlorinated hydrocarbons, -phenol), and • Separating anhydrous organic mixtures using organo-selective membranes (i.e., MTBE/methanol). 1.2.5Alternative techniques The requirements for technological or economic operation of the most common processing techniques for separating organic-organic mixtures are given in Table 2:01. Separating close boiling organic-organic solvent mixtures by distillation or liquid-liquid extraction is difficult, as the components have very similar physical and chemical properties (Young, 1973). Process

Requirements for basic or economical operation

Azeotropic distillation

Requires high aromatic content (>90%)

Extractive distillation

Requires medium aromatic content (65–90%)

Liquid-liquid extraction

Requires low aromatic content (20–65%)

Crystallization

Distillative pre-separation (e.g., o-xylene and ethylbenzene separated from C8 aromatic fractions)

Adsorption on solids

Continuous, reversible and selective adsorption

Table 1.2.5 Processes for aromatic recovery (Villaluenga and Tabe-Mohammadi, 2000; Porter, 2001). 8

Separation of Binary Mixture By Using Pervaporation Because PV is based on sorption and diffusion properties of the feed components and membrane permselectivity rather than relative volatility, this process is especially attractive for azeotropes and close boiling point mixtures, if close boiling point mixture is challenging process in the chemical industry. Conventional distillation produces a low purity product (85–98%), so azeotropic distillation and extractive distillation are commonly used. However, these processes require addition of a third component, which increases the process complexity and cost (Villaluenga and Tabe- Mohammadi, 2000). Adsorption is primarily used for aqueous-organic separations. However, PV is a better process when the organic components concentration is relatively high. The organic can be removed continuously so the process is not limited by adsorber capacity (Shao, 2003). Systems

combining

PV

membranes

with

traditional

techniques

(e.g.,

PV/distillation) have been used (Ishida and Nakagawa, 1985; Hömmerich and Rautenbach, 1998; Ferreira et al., 2002). However, membrane performance is still the key factor limiting PV efficiency (Smitha et al., 2004). 1.3 MEMBRANE STRUCTURE Work on membrane separations began in the early 1960s, using membrane materials such as dense metals, zeolites, polymers, ceramics and biological materials. Of these, polymers are the most widely used material (Smitha et al., 2004). Several different polymer membrane structures are commonly used today, including porous, dense and asymmetric membranes. Selecting a good membrane requires a sound knowledge of membrane structures. Much of the following discussion is based on the excellent review by Smitha et al. (2004). 1.3.1 Membrane The membranes used in pervaporation processes are classified according to the nature of the separation being performed. Hydrophilic membranes are used to remove water from organic solutions. These types of membranes are typical made of polymers with glass transition temperatures above room temperatures. Polyvinyl alcohol is an example of a hydrophilic membrane material. Organophilic membranes are used to

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Separation of Binary Mixture By Using Pervaporation recover organics from solutions. These membranes are typically made up of elastomeric materials (polymers with glass transition temperatures below room temperature). The flexible nature of these polymers makes them ideal for allowing organic to pass through. Examples include nitrile, butadiene rubber, and styrene butadiene rubber. Synthetic membranes are thin, solid-phase barriers that allow preferential passage of certain substances under the influence of a driving force. Both the chemical and the physical nature of the membrane material control membrane separation. Membrane separation occurs because of differences in size, shape, chemical properties, or electrical charge of the substances to be separated. Microporous membranes control separation by size, shape and charge discrimination, whereas nonporous membranes depend on sorption and diffusion. The performance of the membrane is determined by the degree of separation of fluid mixtures and permeation rate (flux). (3, 33) Three general categories of inorganic membranes are ceramics, metals and glass. Because they are so rigid, ceramic microfilters accommodate fluxes five to ten times greater than those of asymmetric polymeric membranes. They can be backwashed frequently without damaging the membrane skin layer. Ceramic membranes are highly resistant to cleaning chemicals and can be sterilized repeatedly by high pressurized steam. Their life span is up to ten years compared to the typical life spans for polymer membranes, which are about one year for hydrophobic membranes and up to four years for fluoropolymers. Ceramic membranes are brittle and are more expensive than polymeric membranes. (3,34) Pervaporation membranes are typically composites. The first layer is a porous, polymeric support coated with a second polymer, the "active" or "permselective" layer, which is engineered to preferentially absorb the chemical species of interest. The membranes’ separation characteristics can be further refined by varying the thickness of the permselective layer. (4,88)

For example, asymmetric composite hydrophilic membranes such as composite PVA-

PS (Poly(vinyl alcohol)-Polysulfone) are used for pervaporation. Pervaporation separation plants contain between ten and one hundred m2 of membrane area, which must be packaged efficiently and economically into units called membrane modules. Flat-sheet and spiral-wound modules are commonly used.(3,41) Silicon rubber membranes are also used in pervaporation. Spiral wound configuration offers a high membrane surface area per module and allows for relatively high feed flow rates which are common for 10

Separation of Binary Mixture By Using Pervaporation pervaporation. Silicone rubber pervaporation modules are remarkably effective at separating organic solutes from dilute aqueous solutions.(2,35) Spiral wound modules are available in 2, 4 and 8 inch diameters to accommodate a variety of feed flow requirements and to allow for economical system design.(4,89) The choice membrane depends on the feed solution. The most efficient application of any membrane is to permeate the minor component of a mixture.(2,35)

1.3.2 Membrane morphology Membranes used for laboratory scale organic mixture separation are generally homogeneous and symmetric (Figure 1.4.1a). These are easy to cast and will directly give the intrinsic separation properties of the polymer. However, to attain commercial viability, membranes need to be prepared in asymmetric or composite form. These two morphologies give a thin effective separation layer, enabling high flux while maintaining the desired mechanical strength of the membrane. Asymmetric membranes have a thin dense layer on top of a porous support layer of the same material (Figure 1.4.1b). They are generally prepared by a phase inversion technique – a homogeneous polymer solution is cast as a thin film or spun as a hollow fibre and immersed in a non-solvent bath after a brief evaporation time in air. The membrane is formed by precipitating polymer when the solvent is replaced by a non-solvent.

Figure 1.4.1. Morphology of the pervaporation composite membrane

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Separation of Binary Mixture By Using Pervaporation Composite membranes consist of a porous support layer with a thin dense skin layer on top (Figure 1.4.1 c). The skin is usually a different polymer material from the support layer. Composite membrane structures minimize membrane cost by reducing the quantity of expensive high-performance material used. In principle, composite membranes allow the properties of the dense separating layer and the porous support layer to be optimized individually, and to a greater extent, than in the phase inversion process. 1.3.3 Membrane module When a highly selective material is selected, membrane performance can be optimized further by reducing the effective membrane thickness. It is best to use a thin film of the discriminating layer deposited on a highly porous support structure. This means that either asymmetric or composite membranes have to be developed with a dense toplayer and an open porous sublayer. The requirements for the sublayer are such that the resistance for permeate transport must be neglectable compared to the resistance of the toplayer. Therefore, optimization of the sublayer is very important [12]. It might even be worthwhile to develop a three layer membrane consisting of a very porous sublayer, than a nonselective intermediate layer and dense toplayer (Fig. 1.4.3) [12]. The composite membranes can be produced either in a flat configuration or in a tubular configuration. Membranes have to be incorporated into modules in order to be used in the process. The main module designs are the plate-and-frame system and the spiral-wound system that are based on the flat membranes and the tubular, capillary and hollow fiber modules that are based on the tubular membrane configuration [39]. Fig. 1.4.2 shows a schema of the plate-and-frame module. Plates made of stainless steel form the feed channels and compartments, which are sealed to the membranes by gaskets. The membranes are supported by stainless steel perforated plates and spacers, which form the permeate channels. The latter ones are open to all sides, allowing for a fast and easy removal of the permeate. The arrangement assures a uniform, parallel flow of the feed mixture over all membranes in a module.

12

Separation of Binary Mixture By Using Pervaporation

Figure 1.4.2. Schema of a plate-and-frame module The spiral wound modules (Fig. 1.4.3) are flat sheets arranged in parallel to form a narrow slit for fluid flow. In a typical construction two flat membrane sheets are placed together with active sides facing the feed spacer.

Figure 1.4.3. Schema of a spiral-wound module Membranes are separated by the permeate spacer and glued together on 3 sides. The fourth side is open and fixed around a perforated centre tube. The feed spacer is placed outside the membrane and forms the feed channel. The whole assembly is roled around the centre tube in a spiral and fitted inside the appropriate housing. Such configuration is compact and relatively inexpensive. Spiral wound modules are used mainly for organic extraction, with low organic concentration and lower temperatures.

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Separation of Binary Mixture By Using Pervaporation 1.4 AIM OF REPORT Pervaporation continues to evolve as a feasible separation technology for many different applications. As a proven method of separation at low temperatures and pressure. Pervaporation have number of application ranging from wastewater treatment to food processing. The objective of present work is to study the separation of binary systems which could be difficult or uneconomical to separate by conventional methods for that a ethanol-water systems was studied by using poly (vinyl alcohol) membrane material and different temperature conditions. Also effect of variation of one component concentration on a flux and selectivity of that component will be studied. Chapter 2 LITERATURE SURVEY 2.1 SEPARATION PRINCIPALS In separation technologies, membranes are defined as the semi-permeable interphase media between two bulk phases [Paul and Yampol'skii 2000]. A membrane process allows selective and controlled transfer of species from one bulk phase to the other. The permeability and selectivity define the characteristics of separation membranes. Generally speaking, components in a mixture are separated by membranes based on the principles as follows [Huang 1990]: 1) Separation occurs because of size/steric effects that are related with macroscopic pores in porous membranes or molecular level interspace between macromolecules in non-porous membranes. The size difference of the two components results in the difference in flow rates, components with large sizes diffusing with more resistance than those with smaller steric factors. A good selectivity can be achieved for mixtures of components with dissimilar steric factors. 2) Separation properties are related with the interactions between the membrane materials and the components to be separated. In non-porous membranes, these factors are often dominant in controlling the separation performances. Mass transport in a membrane occurs when there exists a driving force or a potential difference across the membrane [Timashev and Kemp 1991]. Table 2.1 shows the driving forces and

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Separation of Binary Mixture By Using Pervaporation separation mechanisms for different membrane processes [Moon 2000; Matsuura 1994; Mulder 1991]. Mass transport in non-porous membranes is complicated, but gas separation and pervaporation share many characteristics. 2.2 PERVAPORATION THEORY Polymer films used in PV have a nonporous selective layer, and do not function by a molecular sieving action or convective flow. Binning et al. (1961) were the first to use the “solution-diffusion” model to describe PV through a homogenous polymeric membrane. Overall mass transport through the membrane can be represented by three steps: • Solution of liquid in the membrane surface in contact with the liquid charge Mixture; • Migration (diffusion) through the body of the membrane; • Vaporization of the permeating material at the downstream interface where permeate is immediately swept away. Different from other membrane processes, pervaporation occurs between two different phases in the feed and permeate sides. Some mass transport models have been developed to describe pervaporation processes [Feng and Huang 1997; Shao 2003]. There is not a fully accepted theory for pervaporation, but the following models give some explanation of specific properties. Table 2.1 shows comparison of various membrane separation processes. Membrane processes Microfiltration Ultra filtration Hyper filtration

Phases of feed / permeate Liquid / Liquid Liquid / Liquid Liquid / Liquid

Driving forces

Separation mechanism

Hydrostatic pressure

Sieving

Hydrostatic pressure

Sieving

Effective pressure

Preferential sorption and capillary flow

Dialysis

Liquid / Liquid

Concentration gradient

Sieving and hindered diffusion

Electro dialysis

Liquid / Liquid

Electrical potential gradient

Counter-ion transport

15

Separation of Binary Mixture By Using Pervaporation Reverse osmosis

Liquid / Liquid

Hydrostatic pressure

Pervaporation

Liquid / Vapor

Vapor permeation

Vapor / Vapor

Gas separation

Gas / Gas

Chemical potential gradient Chemical potential gradient Partial pressure difference

Preferential sorption and capillary flow Solution Solution Solution-diffusion and sieving

Table 2.1 Comparison of various membrane separation processes 2.2.1 Solution-Diffusion Model The solution-diffusion model is a semi-empirical or phenomenological model originally developed by Graham in 1866 to describe gas permeation through rubber septa. This model is also used for reverse osmosis, gas separation and PV (Lipnizki et al., 1999). A component’s sorption rate is related to the total energy required to dissolve it in the polymer. The component with the lowest energy requirement is preferentially sorbed into the membrane polymer. Migration through the membrane depends on feed components, 17 membrane polymer and process parameters. Typical chemical potential (μ), pressure (p), and activity gradient (a) profiles through a membrane (Figure 2.1) show that pressure change from feed to permeate has a negligible effect on mass transfer (Lipnizki et al., 1999).

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Separation of Binary Mixture By Using Pervaporation Figure 2:1 Schematic diagram of the solution-diffusion model (Lipnizki et al., 1999).

Transport parameters will depend on whether the retentate is liquid or gaseous. In liquid permeation, the permeating liquid can dissolve in the polymer membrane to give a swollen "solution" of polymer and permeating organic compounds. However, a "dry" membrane exists in gas permeation. Permeation rate in liquid permeation is independent of the pressure differential across the membrane because of the large concentration gradient. However, liquid and gas permeation both follow Fick's first law of diffusion, where the steady-state rate is inversely proportional to membrane thickness (Binning et al., 1961).

q = D (C2 − C1) L

------------------ (2.1) where q is the amount of liquid permeating a unit area of membrane in unit time, L is membrane thickness, D is diffusion coefficient and C2 – C1 is concentration differential across the membrane. The solution-diffusion model is the most widely accepted transport mechanism for many membrane processes, such as reverse osmosis, gas separation and pervaporation [Wijmans and Baker 1995; Baker 2004]. The earliest application of the solution-diffusion model in pervaporation was proposed by Binning et al. [1961], and he suggested that the selectivity took place in a boundary layer between the liquid zone and the gas zone in the membrane. Later, many researchers tried to interpret pervaporation processes based on the solution-diffusion model, and this model is now widely accepted. According to this model, the mass transport can be divided into three steps, as shown in Figure 2.2: 1) Sorption of liquids into the membrane at the feed side, 2) Diffusion of the sorbed components through the membrane, 3) Desorption/evaporation of the sorbed components at the permeate side. Mass transport in solution-diffusion model

17

Separation of Binary Mixture By Using Pervaporation

Figure 2.2 Polymer membrane under liquid permeation conditions with a solution phase zone and vapour phase zone (Binning et al., 1961).

Vaporization at the permeate side of the membrane is generally considered to be a fast and nonselective step if the partial pressure is kept low, i.e. far less than the saturated vapor pressure of the permeates [Ho and Sirkar 1992]. The selectivity and permeability of a pervaporation membrane mainly depend on the first two steps, that is, the solubility and diffusivity of the components in the membrane. Binning et al. (1961) theorized that liquid moves rapidly within the solution phase, and between the liquid feed phase and the solution phase; with most of the selectivity occurring at the interface between the solution phase and the vapour phase. The permeating species slowly diffuses through the vapour phase and is the ratecontrolling step in the process. Because selectivity is not a function of membrane thickness, some researchers suggest that the unswollen fraction of the skin layer (vapour phase) controls permselectivity (Binning et al. 1961, 1974; Néel, 1991). 2.2.1(A) Driving force A difference in chemical potential (due to partial pressure or activity) between feed and permeate side of the membrane is the driving force in PV (Lipnizki et al., 1999). Feed components have different sorption and diffusion rates through the membrane,

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Separation of Binary Mixture By Using Pervaporation which govern selectivity and permeation rate (Qariouh et al., 1999; Villaluenga and Tabe-Mohammadi, 2000). 2.2.1(B) Selectivity Selectivity (or separation factor, α) can be used to express the separation capability of a PV membrane for a binary mixture of components i and j (Smitha et al., 2004). Overall selectivity is the product of sorption selectivity, αS, and diffusion selectivity, αD (Villaluenga and Tabe-Mohammadi, 2000):

αij = xp, i / xp,j = αD* αS xf, i / xf, j

---- (2.2)

where xp,i and xp,j are mole fractions of the preferential and secondary permeants respectively in the permeate, and xf,i and xf,j are the corresponding mole fractions in the feed. Selectivity can vary from unity (no selective permeation) to infinity, and is affected by membrane/component solubility, feed hydrodynamic conditions, permeate resistance due to elevated partial pressures, and changes in diffusion rate due to membrane swelling (Smitha et al., 2004). Membrane selectivity (especially in organic/organic separations with components of comparable size) is mainly governed by αS due to the chemical interaction between permeant molecules and the membrane. Therefore, choosing a membrane with appropriate affinity is a crucial factor in PV (Villaluenga and TabeMohammadi, 2000). 2.2.1(C) Membrane affinity A polymer with higher affinity for one feed component gives greater selectivity. However, if the affinity is too high, the membrane is excessively swollen by the component, loses its integrity and therefore its selectivity. Consequently, it is important to suppress or control the degree of swelling by crosslinking or other methods (Villaluenga and Tabe-Mohammadi, 2000). 2.2.1(D) Flux rate

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Separation of Binary Mixture By Using Pervaporation Component permeate fluxes are commonly obtained using the mass transfer resistance-inseries model (Karlsson and Trägårdh, 1993a; Feng and Huang, 1997). Overall permeate flux (Jk) for component k, where k = i or k = j for a binary feed is defined by:

Jk = Cf, k −Hk Cp, k Rov, k

---------------------- (2.3)

where Cf,k and Cp,k are component feed and permeate concentrations, Hk is a dimensionless equilibrium partition coefficient (i.e. Ck liq/Ck vap) and Rov,k is the overall component mass transfer resistance (Smitha et al., 2004) 2.2.2 Pore-Flow Model The pore-flow model for pervaporation was first proposed by Sourirajan et al. [Matsuura 1994], and Okada et al. [1991] used this model to interpret experimental observations in pervaporation. In the pore-flow model, it is assumed that there are a bundle of straight cylindrical pores of specific lengths penetrating across the active surface layer of the membrane, and all pores are in an isothermal condition [Matsuura 1994]. The mass transport involves 1) Liquid transport from the pore inlet to the liquid-vapor phase boundary, 2) Evaporation at the phase boundary, 3) Vapor transport from the phase boundary to the pore outlet. The main difference between the solution-diffusion model and the pore-flow model is the phase change location in the membrane. In the pore-flow model, as shown in Figure 2.2, the phase change occurs at a certain distance from the membrane surface contacting with the liquid feed, and accordingly the transport mechanism changes from liquid permeation to vapor permeation at the liquid-vapor boundary [Matsuura 1994]. Pore-flow model

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Separation of Binary Mixture By Using Pervaporation

Figure 2.2 Schematic description of pore-flow model The pore-flow model is on the basis of the presence of pores in the membranes, so whether the pores really exist or how small the pore size is remains hard to answer. Nonetheless, the theoretical calculations based on the pore flow model have been shown to be able to reproduce semi-empirical features of the experimental results [Matsuura 1994].

2.2.3 Carrier Transport Mechanism The basic idea of the carrier transport mechanism for pervaporation comes from biological membranes consisting of polypeptides, and is based on the similarity of the molecular interactions between the peptides and the functional groups in synthetic polymers [Moon 2000]. Membranes with carriers are classified into two categories [Shimidzu and Yoshikawa 1991]: Non-fixed carrier membrane (Liquid membrane) and fixed carrier membrane. Figure 2.3 shows the mass transport in non-fixed carrier membranes and fixed carrier membranes. The transport energy in the fixed carrier membranes is much higher than that in the non-fixed carrier membranes, since adsorption and desorption are repeated continuously when a permeating component forms a complex with a carrier in the membrane. On the other hand, once a component forms a complex with a carrier in a non-fixed carrier membrane, the other component can move only after

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Separation of Binary Mixture By Using Pervaporation one carrier is released from the former complex formed previously, for which high selectivity is achieved.

Non-fixed carrier membrane Fixed carrier membrane

C: Carrier, S: Permeating component Figure 2.3 Schematic description of mass transport by the carrier transport mechanism

2.3 ORGANIC-ORGANIC SEPARATIONS Organic-organic liquid separations are commonly classified by the categories polar/non-polar, aromatic/alicyclic, aromatic/aliphatic, and isomeric mixtures. 2.3.1 Polar/non-polar solvent mixtures Smitha et al. (2004) summarised performance of various membranes for separating polar/nonpolar solvents such as alcohols/alkanes and alcohol/ether mixtures. The first demonstrations of polar/non-polar PV separations using cellulose membranes were done in the 1950s (Heisler et al., 1956), but laboratory scale applications for removing organics from diluted organic liquid streams were studied in the 1960’s (Binning et al., 1961) using hydrophobic membranes made from polyethylene (PE) and polypropylene (PP). However, these membranes had

22

Separation of Binary Mixture By Using Pervaporation low selectivities for polar/non-polar organic mixtures, primarily because they did not have any functional groups to create differential interactions between the components being separated (Smitha et al., 2004). 2.3.2 Aromatic/alicyclic mixtures Potential applications of PV for separating aromatics/alicyclic separations include removing cyclohexane from benzene/cyclohexane mixtures formed in benzene, toluene and xylene production plants, and removing aromatics from the feedstock of ethylene plants to enhance their production capacities (Smitha et al., 2004). Benzene/cyclohexane (Bz/cHx), one of the most common aromatic/alicyclic mixtures, is also the most difficult to separate. Many researchers have assessed PV properties of membrane materials for this separation (Cabasso et al., 1974b; Rautenbach and Albrecht, 1980; Suzuki and Onozato, 1982; Terada et al., 1982; Sun and Ruckenstein, 1995; Inui et al., 1997b; Uragami et al., 1998). Smitha et al. (2004) summarised some of the membranes for PV of aromatic/alicyclic mixtures.

2.3.3 Aromatic/aliphatic hydrocarbons Separating aromatic-aliphatic hydrocarbon mixtures was first investigated in a European project (Rautenbach & Albrecht, 1980). Little further research was reported until the mid 1980s when Brun et al. (1985) investigated separating benzene/n-heptane mixtures using elastomers. This research stimulated interest in elastomeric membranes and their blends (Smitha et al., 2004). 2.3.4 Isomers Mulder et al. (1982) used thin membranes of cellulose esters treated with an organic solvent to separate isomeric xylenes. Relatively good fluxes but low selectivities were achieved Since the 1980s a variety of membranes have been used to extract isomeric components such as xylene isomers, and 1º, 2º or 3º alkanes and alcohols (Funke et al., 1997; Gump et al., 1999; Wegner et al., 1999; Chen et al.,

23

Separation of Binary Mixture By Using Pervaporation 2000; Gump et al., 2000; Nair et al., 2001; Schleiffelder and Claudia, 2001). The use of PVA membranes for purifying mixed xylenes on an industrial scale has been limited by the very small separation factors (Smitha et al., 2004). 2.3.5 Miscellaneous separations Smitha et al. (2004) summarised a number of miscellaneous organic/organic separations

including

organic/chlorinated

hydrocarbon,

alkane/alkene,

and

alcohol/ketone mixtures etc. Dutta and Sikdar (1991) used a composite PGSA/Teflon membrane to separate methanol and carbon tetrachloride with good flux rates (60 kg.μm.m-2.h-1) and selectivity (α = 14.6). 2.3 MEMBRANE CHARACTERISTICS 2.3.1Factors affecting membrane performance Specific characteristics of the feed components, the membrane, and process operating parameters influence overall PV performance. These factors include trans-membrane pressure, process temperature, feed composition and concentration, concentration polarization, feed turbulence, membrane thickness and the materials the membranes are made from (Binning et al., 1961; Cabasso, 1983; Néel, 1991; Mathys et al., 1997; Miranda and Campos, 1999; Villaluenga and TabeMohammadi, 2000; Miranda and Campos, 2001a; Matsui and Paul, 2002; Yoshida and Cohen, 2003; Smitha et al., 2004).

Factor

Condition that induces: Major Influence

Minor Influence

Feed pressure

- ----

• 20 atm

Permeate pressure

• Pp > 0.3 Po permeant • Pp ≈ > 10 kPa

• Pp < 0.3 Po permeant • Pp ≈ < 10 kPa

Process temperature

• Close to polymer melting Point • Termolabile product

• Close to normal working temp for polymer

Feed composition and

• One component very

• Components less

24

Separation of Binary Mixture By Using Pervaporation concentration

attracted to polymer

attracted to polymer

Concentration polarization or fouling

• Presence of particulates or cells

• ‘Clean’ organic liquid mixtures

Feed turbulence

-----

• Sub-turbulent flow rates

Membrane thickness

• All thicknesses

-----

Membrane materials

• All membrane materials

-----

Table 2.3.1 Factors influencing pervaporation separation characteristics. 2.3.2 Pressure differential Pressure differential between the feed and permeate side of the membrane is directly related the activity of the components at the permeate side. At pressure differentials close to the vapour pressure of the liquid, permeate pressure strongly influences the pervaporation characteristics (Dutta and Sikdar, 1991; Smitha et al., 2004). Permeate and feed pressure Increasing downstream permeate pressure decreases both selectivity and flux of a polar/nonpolar PV separation. 2.3.3 Effect of temperature on flux Many researchers show that increasing the temperature increases membrane permeability and decreases selectivity (Kucharski and Stelmaszek, 1967; Cabasso et al., 1974a; McCandless et al., 1974; Acharya et al., 1988; Inui et al., 1999; Villaluenga and Tabe-Mohammadi, 2000). Binning et al. (1961) found that flux rate approximately doubled with a 20ºC increase in temperature. Several researchers showed that temperature has an Arrhenius type effect on PV membrane permeability (Huang and Lin, 1968; Cabasso et al., 1974a; Acharya et al., 1988; Inui et al., 1999; Villaluenga and Tabe-Mohammadi, 2000; Smitha et al., 2004):

Qi = Q0i exp {− Ep/ RT} or

J = J0 exp {Ep / RT} -------------

(2.4) 25

Separation of Binary Mixture By Using Pervaporation

where Qi0 is a constant, Ep is activation energy for permeation, R is the universal gas constant, and T is absolute temperature. Sun and Ruckenstein (1995) explained that temperature had two effects on the membrane (Villaluenga and Tabe-Mohammadi, 2000): • Increasing polymer chain mobility, which facilitated diffusion of both components. • Weakening the interaction between the preferentially attracted molecule and the membrane, which lowered its sorption. Huang and Lin (1968) also described how increasing the temperature increased agitational energy or motion of the polymer chains. At lower temperatures, permeation based on diffusional cross section (size) of the permeating molecules is restricted. As agitational energy of the polymer chains increases, there are larger gaps in the amorphous regions of the membrane, so larger molecules that had previously been restricted can permeate. This increases flux and decreases selectivity (Huang and Lin, 1968). 2.3.4 Feed concentration and composition In theory, PV can be used to separate any liquid mixture in all concentration ranges (Johnson and Thomas, 1999). However, it is primarily used for removing or recovering the minor component in organic/organic azeotropic, close-boiling point, or isomeric mixtures (Mulder et al., 1982; Blume et al., 1990; Böddeker et al., 1990). Permselective properties of PV membranes are determined by sorption and diffusivity of the permeating components in the membrane. Because both sorption and diffusion phenomena depend on composition of the liquid mixture, membrane permeation characteristics are usually strongly influenced by feed composition (Johnson and Thomas, 1999). 2.3.5 Feed concentration and composition

26

Separation of Binary Mixture By Using Pervaporation In theory, PV can be used to separate any liquid mixture in all concentration ranges (Johnson and Thomas, 1999). However, it is primarily used for removing or recovering the minor component in organic/organic azeotropic, close-boiling point, or isomeric mixtures (Mulder et al., 1982; Blume et al., 1990; Böddeker et al., 1990). Permselective properties of PV membranes are determined by sorption and diffusivity of the permeating components in the membrane. Because both sorption and diffusion phenomena depend on composition of the liquid mixture, membrane permeation characteristics are usually strongly influenced by feed composition (Johnson and Thomas, 1999). 2.3.6 Membrane material The chemical nature of the polymer used in the membrane, and the presence of plasticizers and solvents, influences permeation rate and separation (Binning et al., 1961). Membranes containing polar groups tend to preferentially permeate polar feed components (and vice versa for non-polar membranes) (Sweeny and Rose, 1965; Huang and Lin, 1968). Chemical and thermal stability of the films in the presence of the feed under operating conditions are also important characteristics. Some thin polymer films are much more stable and selective under permeation conditions than others, depending on their solubility in the feed components (Binning et al., 1961). 2.3.7 Membrane thickness Permeation rate is inversely proportional to membrane thickness but selectivity is said to be independent of thickness in the range considered practical for commercial use. Binning et al. (1961) established a linear inverse relationship between flux and film thickness (0.8- 1.9 mm), yet selectivity of the n-heptane / isooctane mixture (50 Vol%) was essentially the same at all four membrane thicknesses. For film thicknesses that could be produced in 1961, Binning et al. (1961) felt that PV could still retain selectivity and rapid permeation rates even when operating with very thin films (800 μm). Modern polymer membranes can be

27

Separation of Binary Mixture By Using Pervaporation as thin as 10-35 μm (Smitha et al., 2004), and modern literature makes little mention of membrane thickness affecting selectivity. 2.3.8 Membrane swelling If sorption dominates over diffusion in a PV separation, membrane swelling can occur (Sun and Ruckenstein, 1995). Swelling will change both flux and selectivity (Smitha et al., 2004), and the degree of membrane swelling must be suppress or controlled (Villaluenga and Tabe40 Mohammadi, 2000), because swelling decreases membrane performance, and causes loss of membrane integrity (Feng and Huang, 1997). A trade-off between sorption and swelling is needed. For preferential permeation to occur, there must be a high degree of chemical affinity between one component and the membrane. However, if affinity is too great, the membrane will swell and lose integrity. Thus, a membrane suitable for an organic-organic separation such as Bz/cHx, must possess both polar groups to facilitate benzene sorption, and a rigid molecular structure resistant to swelling to maintain membrane integrity (Villaluenga and Tabe-Mohammadi, 2000). Baddour et al. (1964) found that osmotic stresses during swelling fragmented and disoriented the crystalline structure of their PE membranes. Crystallization and or stress relaxation caused steady-state flux to decrease after the rearrangement of chain segments in the swollen state. Cross-linking the polymer membrane strands is the primary method to overcome rearrangement of polymer chain segments due to swelling (Smitha et al., 2004). 2.3.9 Membrane fouling Deposition of impermeable substances in the feed, on the membrane surface is called fouling. Fouling is less a problem in PV than in other membrane separation processes like reverse osmosis, electrodialysis and nanofiltration; and as such is usually caused by scale formation rather than clogging or blocking of pores. Membrane fouling reduces flux and ultimately makes the membrane ineffective. It can be minimised by using a highly turbulent flow regime, ceaning the membrane semi-continuously, or by filtering the feed before PV (Smitha et al., 2004): 28

Separation of Binary Mixture By Using Pervaporation 2.3.10 Performance Parameters of Membranes The performance of a given membrane in pervaporation or vapor permeation is estimated in terms of its selectivity and the permeate flux. The assessment is based on the mass transfer of the preferentially permeating species, regardless of whether the permeate or the retentate is the target product of the pervaporation process [11]. The selectivity of a given membrane can be estimated by using the following two dimensionless parameters [11]:

YA Separation factor

α =>

α=

YA

YB XB

YA =

(1 − YA)

XA

(1 − XA)

-------------------------------

(01) Enrichment factor => β

β=

YA XA

---------------------------------------------------

(02) Where: XA - weight fraction of preferentially permeating species in the feed phase, YA - weight fraction of preferentially permeating species in the permeate phase, with XA + XΒ = 1 and YΑ + YΒ = 1.

Figure 1.3.1 McCabe-Thiele separation diagram. Comparison of pervaporation selectivity with distillation selectivity. System: water-ethanol. Membrane: PVA composite hydrophilic membrane

29

Separation of Binary Mixture By Using Pervaporation Fig. 1.3.1 compares the distillation and pervaporation through hydrophilic polyvinyl alcohol membrane of water-ethanol binary mixture. It is seen that pervaporation with highly hydrophilic membrane favors the transport of the higher boiling water. The high efficiency of pervaporation also occurs near the azeotropic composition of the water-ethanol system. The diagonal line in Fig. 2 represents azeotropic compositions, for which separation does not take place (compositions of the product and the feed mixture are the same, i.e. a = 1). 2.4 MEMBRANES MATERIAL SELECTION AND MEMBRANE MODULES Selecting membrane materials for PV is often done by trial and error. This is time consuming and the best membrane may not be found due to the limited number of membranes tested. A more rational method would match the physicochemical properties of the membrane material with the components of the liquid to be separated. This is done simplistically for common PV applications such as organic liquid dehydration or waste-water treatment by choosing hydrophilic or hydrophobic membranes. However, hydrophobicity is not a major distinguishing factor for components in an organic/organic mixtures so a more comprehensive approach is required. 2.4.1 Membrane selection procedures `Three aspects are important when selecting polymers for a separation: the polymer should have high chemical resistance (compatibility), sorption capacity, and good mechanical strength in the solution. It should also interact preferentially with one of the components being separated (Sridhar et al., 2000). Generally it is more economical to preferentially transport the component with the smallest weight fraction across the membrane. Koops and Smolders (1991) recommend that potential membrane materials be identified by: (1) literature search, (2) properties of the mixture, and (3) chemical and thermal stability of polymer. Literature search

30

Separation of Binary Mixture By Using Pervaporation A literature search will identify prior research for PV separation of the mixture under study. Problems occur if the exact mixture has not been previously studied or if very few membranes have been identified. Most membranes reported in the literature were selected by trial and error, so the number of polymers tested may have been limited, which may have lead to the use of less than optimal membrane materials. Feed mixture properties Membrane selection for aqueous/organic separations has been dominated by choices between ‘organophilic' or ‘hydrophilic’ membranes. However, choosing between these two membranes does not always work and very few investigations have dealt with the criteria for an ideal membrane. Selecting membranes for PV of compounds with widely differing polarity is relatively easy. Thus, silicone rubber membranes are often chosen for removing non-polar organics from water; and polyvinyl alcohol or similar hydrophilic membranes are commonly used for dehydrating organics. Hydrophilic membranes are also effective for separating relatively polar organics such as methanol from non-polar organics such as pentane. Finding a suitable polymeric membrane with good selectivity and flux for compounds of similar polarity is difficult, and the selection criteria may include complex thermodynamic considerations (Ray et al., 1999a). Membrane stability Membranes need to be stable in terms of permeability and selectivity under standard operating conditions for extended periods. Membrane stability is vital in organic/organic separations, and is primarily affected by the chemical, mechanical, and thermal properties of the membrane (Feng and Huang, 1997). The composition and morphology of the membranes are a key to effective use of membrane technology. The choice of the membrane strongly depends on the type of application [12]. It is important which of the component should be separated from the mixture and whether this component is water or an organic liquid. Generally, the component with the smallest weight fraction in the mixture should preferentially be transported across the membrane. Looking at the mixtures to be

31

Separation of Binary Mixture By Using Pervaporation separated and their compositions, the following different kinds of pervaporation and vapor permeation processes can be distinguished [12-23] 2.4.2 Dehydration of organic liquids For the removal of water from water/organic liquid or vapor mixtures hydrophilic polymers have to be chosen. The hydrophilicity is caused by groups present in the polymer chain that are able to interact with water molecules. Examples of hydrophilic polymers are: ionic polymers, polyvinyl alcohol (PVA), polyacrylonitryle (PAN), polyvinylpyrrolidone (PVPD). 2.4.3 Removal of organics from water or air streams Removal of organics from water or air streams. For the removal of an organic liquid from water/organic or organic/air mixture hydrophobic polymers are the most suitable polymers as membrane materials. These polymers possess no groups that show affinity for water. Examples of such polymers are: polydimethylsiloxane

(PDMS),

polyethylene

(PE),

polypropylene

(PP),

polyvinylidenefluoride (PVFD), polytetrafluoroethylene (PTFE). 2.4.4 Separation of two organic solvents. For the mixture of two organic liquids or vapors, again three kinds of mixtures can be distinguished: polar/apolar, polar/polar and polar/apolar mixture. For the removal of the polar component from polar/ apolar mixture polymers with polar groups should be chosen and for the removal of the apolar component completely apolar polymers are favorable. The polar/polar and apolar/apolar mixtures are very difficult to separate, especially when the two components have similar molecular sizes. In principle all kinds of polymers can be used for these systems, the separation has to take place on the basis of differences in molecular size and shape, since no specific interaction of one of the two components can take place. Recently, ceramic membranes and membranes pre pared from conducting polymers have also been used as the selective barriers in pervaporation [24-27]. Ceramic membranes combine high thermal and chemical stability with very high 32

Separation of Binary Mixture By Using Pervaporation performance. Ceramic membranes can be used in a wide range of applications, including separation of mixtures at acid and alkaline conditions [25]. 2.4.5 Membrane materials for Pervaporation:Potentially plastics and rubbers, including homopolymers, copolymers and polymer blends, can be used as membrane materials in pervaporation processes [Huang 1990]. Besides the mechanical properties, chemical and thermal stabilities, high permeability and high selectivity are the important factors that should be considered when choosing polymer materials for membranes. Among these factors, the selectivity should be emphasized over the others, because low separation factors cannot be compensated by other properties [Huang 1990]. A high permeation flux and a high separation factor are always desired for industrial applications. The properties of a pervaporation membrane are determined by the chemical structure and physical properties of the membrane, and the interactions between the membrane material and the permeant. Several methods have been developed for the selection of pervaporation membrane materials [Feng and Huang 1997]: 1) Solubility parameter approach [Matsuura 1994; Mulder 1991], 2) Surface thermodynamics approach [Van Oss et al. 1983; Lee et al. 1989], 3) Polarity approach [Shimidzu and Yoshikawa 1991], 4) Chromatographic approach [Matsuura 1994; Pawlish et al. 1987, 1988], 5) Contact angle approach [Lukas et al. 1997; Nabe et al. 1997]. For pervaporation dehydration of organic liquids, hydrophilic polymers are the most suitable membrane materials. The hydrophilicity of a polymer is caused by the functional groups that are able to interact with water molecules by H-bonding or dipole-dipole interactions. Water normally permeates through hydrophilic membranes preferentially. Poly (vinyl alcohol), poly (acrylic acid), poly (vinyl pyrrolidone), chitosan and polyelectrolytes are the hydrophilic polymers commonly used. For the removal of organics from water, rubbery polymers are favorable. Organic components can preferentially penetrate rubbery polymers, and the membranes show relatively high permeation flux.

33

Separation of Binary Mixture By Using Pervaporation However, for separation of organic liquids, the criteria for selecting proper polymer materials are not very clear yet. Both rubbery polymers and glassy polymers have been used in research. 2.4.6 Poly (vinyl alcohol) Pervaporation Membranes Poly (vinyl alcohol) (PVA) is one of the most important water-soluble vinyl polymers, prepared by partial or complete hydrolysis of poly (vinyl acetate) [Chiellini 2003]. The hydroxyl groups in PVA can form strong hydrogen bonds between intra- and intermolecular hydroxyl groups, which causes PVA to show a high affinity to water [Finch 1973]. The solubility parameters of PVA and the affinity to solvents are shown in Appendix A. Therefore, in pervaporation, PVA is mainly used for dehydration of organic solvents. To be used as membranes, PVA is usually modified before use to attain long-term stability [Finch 1973]. The first commercial composite membrane, crosslinked poly(vinyl alcohol) on a microporous polyacrylonitrile (PAN) support, was developed by GFT in 1982 to dehydrate ethanol/water mixtures [Huang 1990; Volkov 1994]. Though continuous efforts are made to develop new membranes and to explore new separation applications, PVA is still attracting significant interest from researchers because of its excellent film forming property and hydrophilicity. Lee and Hong [1997] investigated the relationship between the degree of hydrolysis of PVA membranes and the pervaporation performance for separation of isopropanol/water mixtures. Upadhyay and Bhat [2005] modified PVA membranes with lithium chloride to investigate the effect of addition of alkali salt on dehydration of isopropanol, and it was shown that the PVA membrane became amorphous by addition of lithium chloride, and the separation performance was also affected. Rhim et al. [1998] crosslinked PVA membranes with sulfosuccinic acid (containing –SO3H), and investigated the effect of the crosslinking density on the pervaporation

properties

in

dehydration

of

water-alcohol

mixtures.

The

performance for water/methanol separation is not good due to the existence of sulfonic acid groups, but the membranes containing 7 wt. % sulf-succinic acid

34

Separation of Binary Mixture By Using Pervaporation showed good selectivity for water-ethanol mixtures. Extensive research was conducted

on

the

pervaporation

properties

of

the

metal-ion-exchanged

PVA/sulfosuccinic acid membranes [Rhim et al. 2002]. Peters et al. [2006] dipcoated PVA on ceramic hollow fiber supports, and crosslinked the ultra-thin layer of PVA with maleic anhydride for dehydration of alcohols.

2.5 SUMMARY OF THE INVENTION The primary factors influencing selectivity and flux of permeants through a PV membrane include: feed component size, shape and chemical nature; membrane materials, thickness, and degree of swelling; process temperature and pressure; feed composition and concentration. Permeation through a PV membrane involves three primary steps: solution of the liquid feed mixture in the film surface; migration of feed components through the body of the film; and vaporization of the permeating material at the downstream interface where permeate is immediately removed (Binning et al., 1961). The primary influence on this process ismolecular affinity between the polymer membrane and permeating molecules. If permeants cannot adsorb onto the membrane surface (e.g., one repelled by the membrane), they cannot begin to diffuse through the membrane to the permeate. The scope of PV process variables that can be studied include the influence of feed composition and concentration,

upstream

and

downstream

pressures,

feed

and

permeate

temperatures, membrane thicknesses and swelling (Binning et al., 1961), feed streams turbulence over membrane surfaces (Miranda and Campos, 1999), membrane concentration polarization or fouling (Miranda and Campos, 2001a), and performances of membrane materials (Cabasso, 1983; Néel, 1991; Mathys et al., 1997; Matsui and Paul, 2002; Yoshida and Cohen, 2003). Of the three major pervaporation separations; dehydrating organic liquids, removing trace organics from aqueous streams, and organic-organic mixture separations; the latter has been the least developed industrially. Despite being a promising alternative to conventional separation techniques, which are energy intensive and far less eco-friendly than pervaporation, this process has not become widespread for organic-organic separations, primarily due to the lack of

35

Separation of Binary Mixture By Using Pervaporation commercially-available high-performance membranes. Literature indicates that pervaporation is suitable for separating a wide variety of organic liquid mixtures including polar/non-polar, aromatic/alicyclic, aromatic/aliphatic, and even isomeric components. Solution-diffusion is believed to be the primary model for transport through a pervaporation membrane. In accordance with the present invention, it has been found that the pervaporation for separation of binary mixture is good and cost effective by other method in accordance with the present invention ethanol water mixture is selected as binary organic mixture and polyvinyl(alcohol) material membrane for the process.

36

Separation of Binary Mixture By Using Pervaporation Chapter 3 ETHANOL - WATER SEPARATION BY PERVAPORATION 3.1 EHANOL ASPECTS:Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatile, flammable, colorless liquid. It is a psychoactive drug, best known as the type of alcohol found in alcoholic beverages and in modern thermometers. Ethanol is one of the oldest recreational drugs known to man. In common usage, it is often referred to simply as alcohol or spirits. Ethanol is a straight-chain alcohol, and its molecular formula is C2H5OH. Its empirical formula is C2H6O. An alternative notation is CH3-CH2-OH, which indicates that the carbon of a methyl group (CH3-) is attached to the carbon of a methylene group (-CH2-), which is attached to the oxygen of a hydroxyl group (OH). It is a constitutional isomer of dimethyl ether. The fermentation of sugar into ethanol is one of the earliest organic reactions employed by humanity. The intoxicating effects of ethanol consumption have been known since ancient times. In modern times, ethanol intended for industrial use is also produced from by-products of petroleum refining.[1] Ethanol has widespread use as a solvent of substances intended for human contact or consumption, including scents, flavorings, colorings, and medicines. In chemistry, it is both an essential solvent and a feedstock for the synthesis of other products. It has a long history as a fuel for heat and light and also as a fuel for internal combustion engines. Ethanol, C2H5OH, (also called Ethyl Alcohol) is the second member of the aliphatic alcohol series. It is a clear colorless liquid with a pleasant smell. Except for alcoholic beverages, nearly all the ethanol used industrially is a mixture of 95% ethanol and 5% water, which is known simply as 95% alcohol. Although pure ethyl

37

Separation of Binary Mixture By Using Pervaporation alcohol (known as absolute alcohol) is available, it is much more expensive and is used only when definitely required.

Fig 3.1 Structure of ethanol Other names: Ethyl alcohol; grain alcohol; pure alcohol; hydroxyethane; drinking alcohol; ethyl hydrate. 3.1.1 Physical properties of ethanol Ethanol is a volatile, colorless liquid that has a strong characteristic odor. It burns with a smokeless blue flame that is not always visible in normal light. It is also used in finger nail polish remover.The physical properties of ethanol stem primarily from the presence of its hydroxyl group and the shortness of its carbon chain. Ethanol’s hydroxyl group is able to participate in hydrogen bonding, rendering it more viscous and less volatile than less polar organic compounds of similar molecular weight. Ethanol is a versatile solvent, miscible with water and with many organic solvents, including acetic acid, acetone, benzene, carbon tetrachloride, chloroform, diethyl ether, ethylene glycol, glycerol, nitromethane, pyridine, and toluene.[9][10] It is also miscible with light aliphatic hydrocarbons, such as pentane and hexane, and with aliphatic chlorides such as trichloroethane and tetrachloroethylene.[10] Ethanol’s miscibility with water contrasts with that of longer-chain alcohols (five or more carbon atoms), whose water miscibility decreases sharply as the number of carbons increases.[11] The miscisbility of ethanol with alkanes is limited to alkanes up to undecane, mixtures with dodecane and higher alkanes show a miscibility gap below a certain temperature (approx. 13 °C for dodecane[12]). The

38

Separation of Binary Mixture By Using Pervaporation miscibility gap tends to get wider with higher alkanes and the temperature for complete miscibility increases.

Physical Properties of ethanol Molecular formula

C2H6O

Molar mass

46.07 g mol−1

Appearance

colorless clear liquid

Density

0.789 g/cm3

Melting point

−114.3 °C, 159 K, -174 °F

Boiling point

78.4 °C, 352 K, 173 °F

Solubility in water

Fully miscible

Acidity (pKa)

15.9

Viscosity

1.200 m Pa·s (cP) at 20.0 °C

Dipole moment

5.64 fC·fm (1.69 D) (gas)

Specific Gravity

0.79

Flash point

286.15 K (13 °C or 55.4 °F)

Ethanol-water mixtures have less volume than the sum of their individual components at the given fractions. Mixing equal volumes of ethanol and water results in only 1.92 volumes of mixture.[9][13] Mixing ethanol and water is exothermic. At 298 K up to approx. 777 J/mol[14] are set free. Mixtures of ethanol and water form an azeotrope at approx. 89 mole-% ethanol and 11 mole-% water[15] or a mixture of about 96 volume percent ethanol and 4 % water

39

Separation of Binary Mixture By Using Pervaporation at normal pressure and T=351 K. This azeotropic composition is strongly temperature- and pressure-dependent and vanishes at temperatures below 303 K[16]. 3.1.2 Source of ethanol Ethanol is an important industrial ingredient and has widespread use as a base chemical for other organic compounds, manufacturing of ethanol the feedstock used as corn, sorghum, cane sugar, cellulose. 3.2 CHEMICAL AND PHYSICAL PROPERTIES OF WATER Water is the chemical substance with chemical formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. •

Water is a tasteless, odorless liquid at standard temperature and pressure. The color of water and ice is, intrinsically, a very light blue hue, although water appears colorless in small quantities. Ice also appears colorless, and water vapor is essentially invisible as a gas.[7]

•

The boiling point of water (and all other liquids) is directly related to the barometric pressure. For example, on the top of Mt. Everest water boils at about 68 °C (154 °F), compared to 100 °C (212 °F) at sea level. Conversely, water deep in the ocean near geothermal vents can reach temperatures of hundreds of degrees and remain liquid.

•

Water has a high surface tension caused by the weak interactions, (Van Der Waals Force) between water molecules because it is polar. The apparent elasticity caused by surface tension drives the capillary waves.

•

Water also has high adhesion properties because of its polar nature.

•

The maximum density of water is at 3.98 °C (39.16 °F).[9] Water becomes even less dense upon freezing, expanding 9%. This causes an unusual phenomenon: ice floats upon water, and so water organisms can live inside a

40

Separation of Binary Mixture By Using Pervaporation partly frozen pond because the water on the bottom has a temperature of around 4 °C (39 °F). Physical Properties of Water Property Molar mass Molar Volume Boiling Point (BP) Freezing point (FP) Triple point Surface Tension Vapor pressure Heat of vaporization Heat of Fusion Heat Capacity (cp) Dielectric Constant Viscosity Density Density maxima Specific heat Heat conductivity Melting heat Evaporation heat Critical Temperature Critical pressure Speed of sound Relative permittivity

•

Value 18.015 55.5 moles/liter 100°C at 1 atm 0°C at 1 atm 273.16 K at 4.6 torr 73 dynes/cm at 20°C 0.0212 atm at 20°C 40.63 kJ/mol 6.013 kJ/mol 4.22 kJ/kg.K 78.54 at 25°C 1.002 centipoise at 20°C 1 g/cc 4°C 4180 J kg-1 K-1 ( T=293…373 K) 0.60 W m-1 K-1 (T=293 K) 3.34 x 105 J/kg 22.6 x 105 J/kg 647 K 22.1 x 106 Pa 1480 m/s (T=293 K) 80 (T=298 K)

Water is miscible with many liquids, for example ethanol, in all proportions, forming a single homogeneous liquid. On the other hand, water and most oils are immiscible usually forming layers according to increasing density from the top. As a gas, water vapor is completely miscible with air.

•

Water forms an azeotrope with many other solvents.

41

Separation of Binary Mixture By Using Pervaporation 3.3 PROCESS DESCRIPTION:3.3.1 System Studied Experiments were conducted with ethanol-water system and effect of variation of ethanol concentration on a flux and selectivity of ethanol was investigated 3.3.2 Experimental Procedure Pervaporation experiments were carried out in a batch-stirred cell operated under vacuum. The downstream pressure was maintained at 10 mm Hg. The cell had two flanged compartments. The upper one is for feed. Ethanol- water mixture of different concentration100 ml is introduced in the upper compartment of Pervaporation cell. The PVA (Polyvinyl alcohol) membrane was supported on a porous stainless steel sintered disc and sealed with rubber oring. Effective membrane separation area was 19.62 cm2 the temperature was maintained at 60 0C and speed of agitation was maintained at 250 rpm and the experiment was carried out for 1 Hr. The permeate was collected in the condenser cooled by salt and ice mixture.

42

Separation of Binary Mixture By Using Pervaporation Chapter 4 EXPERIMENTAL SET-UP & PROCESS 4.1 PERVAPORATION SYETEM Figure shows a typical Pervaporation system. The feed is allowed to flow along one side of the membrane and a fraction of the feed (permeate) passes through the membrane and leaves in the vapor phase on the opposite side of the membrane. The "vapor phase" side of the membrane is either kept under a vacuum or it is purged with a stream of inert carrier gas.

Figure 4.1 Simplified Pervaporation Process The permeate is finally collected in the liquid state after condensation. The liquid product is rich in the more rapidly permeating component of feed mixture. The retentate is made up of the feed materials that cannot pass through the membrane.

43

Separation of Binary Mixture By Using Pervaporation 4.2 Experimental Setup: The Pervaporation experiment is carried out in a batch stirred cell operated under vacuum. The Pervaporation cell was made of SS-304. It consisted of two flange compartment was provided with a jacket through which hot water from a constant temperature bath was circulated. The Pervaporation cell was provided with two opening at the top. A propeller type impeller was introduced through the central opening to agitate the feed liquid whereas the other opening was used to feed and remove the solution continuously. Feed compartment by a tube just above the impeller and the solution continuously overflowed from an outer tube concentrating to the feed tube. A porous stainless steel sintered disc used as support for the membranes was fixed in a rubber o-ring. This rubber o-ring was places in the groove in the permeate compartment. The PVA membrane is placed on porous stainless steel sintered disk and sealed with rubber o-ring. Vacuum on the downstream face of the membrane was generated using a vacuum pump. A condenser was used to trap ethanol and water vapours from the permeate compartment.

Fig. Experimental Setup

44

Separation of Binary Mixture By Using Pervaporation Niacin was first described by Weidel in 1873 in his studies of nicotine. The original preparation remains useful: the oxidation of nicotine using nitric acid. Niacin was extracted from livers by Conrad Elvehjem who later identified the active ingredient, then referred to as the "pellagra-preventing factor" and the "antiblacktongue factor." When the biological significance of nicotinic acid was realized, it was thought appropriate to choose a name to dissociate it from nicotine, in order to avoid the perception that vitamins or niacin-rich food contains nicotine. The resulting name 'niacin' was derived from nicotinic acid + vitamin.

Niacin is

referred to as Vitamin B3 because it was the third of the B vitamins to be discovered. It has historically been referred to as "vitamin PP." 4.2 DIETARY NEEDS Severe deficiency of niacin in the diet causes the disease pellagra, where as mild deficiency slows the metabolism, causing decreased tolerance to cold. Dietary niacin deficiency tends to occur only in areas where people eat corn (maize), the only grain low in niacin, as a staple food, and that do not use lime during meal/flour production. Alkali lime releases the tryptophan from the corn in a process called nixtamalization so that it can be absorbed in the intestine, and converted to niacin. The recommended daily allowance of niacin is 2-12 mg/day for children, 14 mg/day for women, 16 mg/day for men and 18 mg/day for pregnant or breast-feeding women. 4.3 PROPERTIES: 1. Anti pellagra vitamin. 2. Colorless or white crystalline powder. 3. Soluble in water and boiling alcohol. 4. Insoluble in most lipid solvent. 5. No hygroscopic and stable in air. 6. It is resistant to heat, oxidation and alkalis. 7. It is in fact, one of the most stable vitamins. 4.3 PHARMACOLOGICAL USES:-

45

Separation of Binary Mixture By Using Pervaporation Niacin, when taken in large doses, blocks the breakdown of fats in adipose tissue, thus altering blood lipid levels. Niacin is used in the treatment of hyperlipidemia because it reduces very-low-density lipoprotein (VLDL), a precursor of low-density lipoprotein (LDL) or "bad" cholesterol. Because niacin blocks breakdown of fats, it causes a decrease in free fatty acids in the blood and, as a consequence, decreased secretion of VLDL and cholesterol by the liver. By lowering VLDL levels, niacin also increases the level of high-density lipoprotein (HDL) or "good" cholesterol in blood, and therefore it is sometimes prescribed for patients with low HDL, who are also at high risk of a heart attack. Niacin is sometimes consumed in large quantities by people who wish to fool drug screening tests, particularly for lipid soluble drugs such as marijuana. It is believed to "promote metabolism" of the drug and cause it to be "flushed out." Scientific studies have shown it does not affect drug screenings, but can pose a risk of overdose, causing arrhythmias, metabolic acidosis, hyperglycemia, and other serious problems. 4.4 TOXICITY People taking pharmacological doses of niacin (1.5 - 6 g per day) often experience a syndrome of side-effects that can include one or more of the following: 

Dermatological complaints.



Facial flushing and itching.



Dry skin.



Skin rashes including acanthosis nigricans .



Gastrointestinal complaints.



Dyspepsia (indigestion).



Liver toxicity.



Fulminant hepatic failure.



Hyperglycemia.



Cardiac arrhythmias.



Birth defects.

46

Separation of Binary Mixture By Using Pervaporation Facial flushing is the most commonly-reported side-effect. It lasts for about 15 to 30 minutes, and is sometimes accompanied by a prickly or itching sensation, particularly in areas covered by clothing. This effect is mediated by prostaglandin and can be blocked by taking 300 mg of aspirin half an hour before taking niacin, or by taking one tablet of ibuprofen per day. Taking the niacin with meals also helps reduce this side-effect. After 1 to 2 weeks of a stable dose, most patients no longer flush. Slow or "sustained"-release forms of niacin have been developed to lessen these side-effects .One study showed the incidence of flushing was significantly lower with a sustained release formulation though doses above 2 g per day have been associated with liver damage, particularly with slow-release formulations. High-dose niacin may also elevate blood sugar, thereby worsening diabetes mellitus. Hyperuricemia is another side-effect of taking high-dose niacin, and may exacerbate gout. Niacin at doses used in lowering cholesterol has been associated with birth defects in laboratory animals, with possible consequences for infant development in pregnant women. Niacin at extremely high doses can have lifethreatening acute toxic reactions. Extremely high doses of niacin can also cause niacin maculopathy, a thickening of the macula and retina which leads to blurred vision and blindness. 4.5 BIOSYNTHESIS

Biosynthesis:

Tryptophan

→

Kynurenine

→

Niacin

The liver can synthesize niacin from the essential amino acid tryptophan, requiring 60 mg of tryptophan to make one mg of niacin. The 5-membered aromatic heterocycle of tryptophan is cleaved and rearranged with the alpha amino group of tryptophan into the 6-membered aromatic heterocycle of niacin. Vitamin B3 is made up of niacin (nicotinic acid) and its amide, niacinamide, and can be found in many foods, including yeast, meat, fish, milk, eggs, green

47

Separation of Binary Mixture By Using Pervaporation vegetables, and cereal grains. Dietary tryptophan is also converted to niacin in the body. Vitamin B3 is often found in combination with other B vitamins including thiamine, riboflavin, pantothenic acid, pyridoxine, cyanocobalamin, and folic acid. 4.6 PHYSICAL PROPERTIES OF NICOTINIC ACID (11) Property Molecular weight Melting point Sublimation range Density of Crystals True dissociation constants in water at 250C Ka Kb pH of saturated aqueous solution Solubility of Niacin in Water At 00 C At 380 C At 1000C Solubility of Niacin in Ethanol,96 % At 00 C At 780 C Solubility of Niacin in Methanol At 00 C At 620C

Value 123.11 2360 C >1500 C 1.473 gm/cm3 1.5X10-5 1.04X10-12 2.7 8.6 gm/lit. 24.7 gm/lit. 97.6 gm/lit. 5.7 gm/lit. 76.0 gm/lit. 63.0 gm/lit. 345.0 gm/lit.

Basically, the coenzymes of niacin help break down and utilize proteins, fats, and carbohydrates. Vitamin B3 also stimulates circulation, reduces cholesterol levels in the blood of some people, and is important to healthy activity of the nervous system and normal brain function. Niacin supports the health of skin, tongue, and digestive tract tissues. Also, this important vitamin is needed for the synthesis of the sex hormones, such as estrogen, progesterone, and testosterone, as well as other corticosteroids. Niacin, taken orally as nicotinic acid, can produce redness, warmth, and itching over areas of the skin; this "niacin flush" usually occurs when doses of 50 mg. or more are taken and is a result of the release of histamine by the cells, which causes vasodilation. This reaction is harmless; it may even be helpful by enhancing blood flow to the "Flushed" areas, and it lasts only 10-20 minutes. When these larger doses of niacin are taken regularly, this reaction no longer occurs because

48

Separation of Binary Mixture By Using Pervaporation stores of histamine are reduced. Many people feel benefit from this "flush," but if it is not enjoyable, supplements that contain vitamin B3 in the form of niacinamide or nicotinamide can be used, as they will not produce this reaction. (Note: When vitamin B3 is used to lower cholesterol levels, the nicotinic acid form must be used; the niacinamide form does not work for this purpose.) Niacin is used to support a variety of metabolic functions and to treat a number of conditions. Many niacin deficiency symptoms can be treated by adjusting the diet and by supplementing B3 tablets along with other B complex vitamins. Many uses of niacin are based primarily on positive clinical experience and are not as well supported by medical research, although more studies are being done. Niacin helps increase energy through improving food utilization and has been used beneficially for treating fatigue, irritability, and digestive disorders, such as diarrhea, constipation, and indigestion. It may also stimulate extra hydrochloric acid production. Niacin, mainly as nicotinic acid, helps in the regulation of blood sugar (as part of glucose tolerance factor) in people with hypoglycemia problems and gives all of us a greater ability to handle stress. It is helpful in treating anxiety and possibly depression. B3 has been used for various skin reactions and acne, as well as for problems of the teeth and gums. Niacin has many other common uses. It is sometimes helpful in the treatment of migraine-type headaches or arthritis, probably in both cases through stimulation of blood flow in the capillaries. This vitamin has also been used to stimulate the sex drive and enhance sexual experience, to help detoxify the body, and to protect it from certain toxins and pollutants. For most of these problems and the cardiovascular-related ones mentioned below, the preference is to take the "flushing" form of niacin, or nicotinic acid, not niacinamide.

49

Separation of Binary Mixture By Using Pervaporation 4.7 FUNCTIONS OF VITAMIN B3 NIACIN:Niacin is important for proper blood circulation and the healthy functioning of the nervous system. It maintains the normal functions of the gastro-intestinal tract and is essential for the proper metabolism of proteins and carbohydrates. It helps to maintain a healthy skin. Niacin dilates the blood vessels and increases the flow of blood to the peripheral capillary system. This vitamin is also essential for synthesis of the sex hormones, namely, oestrogen, progesterone, and testosterone, as well as cortisone, thyroxin, and insulin. 4.8 CHEMICAL STRUCTURE (25) Nicotinic Acid is water soluble. This is quite important because it may be lost when we cook our food by boiling it in water! It is also important because it cannot be stored in the body and must therefore be present in our diet to replace that which is lost in urine. It is more important for us to understand why a deficiency of this chemical causes pellagra.

Nicotinamide can be used instead of nicotinic acid. As we can see from these two structural formulae they are almost the same.

4.9 BIOLOGICAL SYNTHESIS

50

Separation of Binary Mixture By Using Pervaporation Humans do not have the ability to synthesise sufficient nicotinic acid, this means that it is an essential component of a balanced diet. Some mammals are able to synthesise this chemical so it is not an essential component of their diets. For example, dogs can synthesise nicotinic acid from the amino-acid tryptophan. This might be an essential amino-acid, but for dogs, nicotinic acid is definitely NOT a vitamin. Bacteria in our large intestines, the colon, may convert tryptophan into nicotinic acid; this means that we could survive if sufficient bacterial activity took place. Our intestinal bacteria would require 60 mg of tryptophan to synthesise 1 mg of nicotinic acid so don't count on them. 4.10 SOURCES Nicotinic Acid is found in milk, yeast, eggs, etc. Here is a table of average values for the Nicotinic Acid content of a variety of foods. Food Content mg/100gg/10gm Meat Extract 60.0 Marmite 58.5 Roast Beef 5.0 Sardines in Oil 5.0 Kippers 4.2 Whole meal Bread 3.5 Beer 0.7 Boiled Cabbage 0.15 Milk 0.08 Pellagra is associated with a low standard of living. It is particularly prevalent; in areas where maize forms the staple diet. Maize has a very low content of nicotinic acid; furthermore, the proteins in maize are deficient in tryptophan.

51

Separation of Binary Mixture By Using Pervaporation 4.11 SOURCE CATEGORIES: 

Richest Sources: Yeast, Rice polishing, & Tobacco.



Good sources: Meat, Liver & Poultry.



Fair sources: Milk, Eggs, Tomatoes, Leafy green vegetables.



Poor sources: Most Fruits & Vegetables.

4.12 DEFICIENCY DISEASE: The main deficiency disease caused by lack of nicotinic acid is “pellagra”. This disease affects epithelia & nervous system. It is accused by the accumulation of the intermediate products of respiration; this is because nicotinic acid is required for the synthesis of co-enzymes used by dehydrogenises. Nervousness, headaches, fatigue, mental depression, skin, disorders, muscular weakness, & indigestion are the symptoms of deficiency of niacin. 4.13 IDENTIFICATION TESTS FOR NIACIN (2) 1. Mix about 100 mg with 1 ml of dil NaOH solution & boil, no ammonia is evolved (distinction from nicotinamide). 2. Mix about 100 mg with 10mg of citric acid & 3 drops of acetic anhydride & heat on a water bath, a red – violet colour is produced. Synonyms: - Acid Nicotinique (French), Acidum Nicotinicum, Akotin, Antipellagra Vitamin, Apelagrin, Nico, etc. 4.14 PRECAUTIONS: 

The use of large doses of niacin for long periods causes release of histamine. This in turn can cause severe flushing, severe itching of the skin and gastro intestinal disturbances.



If taken in does of 3gm per day, niacin has been reported to cause elevation of uric acid in the blood and glucose.

52

Separation of Binary Mixture By Using Pervaporation 4.14 NIACIN ANALOGUES:Tobacco products are considered to be predisposing factors in several forms of cancer. Accordingly there are 43 carcinogenic substances in tobacco smoke, and nicotine makes the use of tobacco products addictive. Smokeless tobacco (plug or leaf chewable tobacco or snuff) is considered to be a predisposing factor in oral cancers (US Surgeon General, 1986). Cadmium and nickel also have been implicated in the carcinogenicity of tobacco products. Since removal of tar by filters and the use of smokeless tobacco do not eliminate the risk of cancer associated with tobacco, the question remains "What are the components of tobacco most responsible for the increased risks of cancer?" One obvious possibility from our perspective is nicotine, itself, for its potential to interfere with monooxygenasecatalyzed reactions in about five ways. 1.

Nicotine is a known substrate of this monooxygenase, so this non-

nutritive compound can interfere directly with oxidations of regulatory substrates catalyzed by this enzyme. 2.

Nicotine is also a close structural analogue of nicotinamide and has

the potential for depleting NADPH by competitively inhibiting the absorption and incorporation of the vitamin. 3.

Theoretically, nicotine can also interfere with the production and

redox recycling of NADPH from NADP+, NAD+, and NADH. 4.

In addition to the possibility of causing metabolic losses of NADPH,

nicotine may compete directly with NADPH for the monooxygenase and other critical regulatory enzymic activities Consistent with this inhibitory potential is the observation that porcine liver monooxygenase catalyzes the oxidation of nicotine at a saturated maximum rate that is only 60 to 67% of that reported for good substrates for this monooxygenase. 5.

Finally, any depletion of NADPH by nicotine described, can result in

an additional irreversible inactivation of the monooxygenase by normal

53

Separation of Binary Mixture By Using Pervaporation body temperatures. The monooxygenase is highly vulnerable to thermal inactivation under two very interesting circumstances: 1) When deprived of NADP+ and especially NADPH, or 2) When deprived of oxygen in the presence of NADPH. The latter condition may exist in the center of rapidly growing tumors. An interesting general feature about the regulation of biological systems is that minor inhibition at any one step in a regulatory cascade (10% here, 10% there) can be amplified by multiple affected sites along the entire pathway to produce dramatic inhibition at the end point. The potential for cascade-amplified inhibition of the monooxygenase with nicotine clearly exists. If nicotine proves to be a predisposing factor through this proposed mechanism, nicotine patches will solve a tobacco consumer's risk for cancer only if used to completely end the addiction. 4.15 VITAMIN B3 USES Nicotinic acid, niacinamide, and inositol hexaniacinate (the three forms of Vitamin B3) have all proved very successful in various clinical applications. However, the forms of nicotinic acid and niacinamide consumed in access may prove to be toxic.Conversely, inositol hexaniacinate has been supplemented in excess in scientific studies and proved tolerable. Inositol hexaniacinate has been shown to lower elevated LDL (bad cholesterol) and triglyceride (fat) levels in the blood, while concurrently raising the HDL (good cholesterol) levels. Inositol hexaniacinate has also been used for the prevention and treatment of peripheral vascular disease, especially intermittent claudication (or the atherosclerosis of the blood vessels in the legs that can cause pain with walking).Vitamin B3 may also be helpful in preventing the development of atherosclerosis, and may aid in the reduction of complications arising from those who suffer from specific heart conditions. As well, vitamin B3 may prove to be as effective as prescription medications for treatment of atherosclerosis and problems associated with the heart. Niacin, specifically the form of niacinamide, has also been shown to provide relief with complications resulting from diabetes. In a recent clinical study

54

Separation of Binary Mixture By Using Pervaporation consisting of 343 individuals without diabetes and 125 with the disease, roughly 3000 milligrams per day were administered. Hemoglobin A1C (a particular measure of blood sugar over a period of time) actually decreased in the diabetic group over a 60-week follow-up period. Further research is needed on niacinamide, but intial studies indicate its potentiality in the treatment of arthritis. In addition, Vitamin B3 may reduce inflammation, increase joint mobility, and may also aid in cartilage repair. Eye health is another area of interest regarding the dietary supplementation of niacin. In a recent study that included participants from the U.S. and Australia, participants whose diets were supplemented with the highest amount of protein, Vitamin A, B1, B2, and B3 (niacin) were considerably less likely to develop cataracts. Studies have also shown riboflavin and niacin alone, to be effective in the prevention of cataract formation. Ongoing applications of this B-vitamin compound include; vitamin replacement in burn victims, topical solutions for acne, and as an anti-cancer agent. Taking niacin with food may reduce stomach upset and the risk of stomach ulcer. Doses are usually started low and gradually increased to minimize the common side effect of skin flushing. Taking aspirin or non-steroidal antiinflammatory drugs (NSAIDs) at the same time during the first one to two weeks may reduce this flushing. Use of an antihistamine 15 minutes prior to a niacin dose may also be helpful. The flushing response may decrease on its own after one to two weeks of therapy. Extended release niacin products may cause less flushing than immediate release (crystalline) formulations, but may have a higher risk of stomach upset or liver irritation. In general, not all niacin products are equivalent. Patients switching from one product to another may have an increase or decrease in side effects. Other Members of the Vitamin B Complex Thiamine (B1), Riboflavin (B2), Pyridoxine (B6), Pantothenic Acid, Biotin, Cyanocobalamin (B12). (23)

55

Separation of Binary Mixture By Using Pervaporation Chapter 5

IMPORTANTS OF NIACIN Niacin deficiency symptoms can be seen in diets with niacin intake below 7.5 mg. per day, but often this is not the only deficiency; vitamin B1, vitamin B2, and other B vitamins, as well as protein and iron may be low. To treat pellagra and niacin deficiency disorders, vitamin B3 supplements should be taken along with good protein intake to obtain adequate levels of the amino acid tryptophan. As described earlier, about 50 % of daily niacin comes from the conversion in our liver of tryptophan to niacin with the help of pyridoxine (vitamin B6). 5.1 REQUIREMENTS: Many food charts list only sources that actually contain niacin and do not take into account tryptophan conversion into niacin. Approximately 60 mg. of tryptophan can generate 1 mg. of niacin. But tryptophan is available for conversion only when there are more than sufficient quantities in the diet to synthesize the necessary proteins as tryptophan are used in our body with the other essential amino acids to produce protein. Niacin needs are based on caloric intake. We need about 6.6 mg. per 1,000 calories, and no less than 13 mg. per day. Women need at least 13 mg. and men at least 18 mg. per day and for children ranges from 9-16 mg. Niacin needs are increased during pregnancy, lactation, and growth periods, as well as after physical exercise. Athletes require more B3 than less active people. Stress, illness, and tissue injury also increase the body's need for niacin. People who eat much sugar or refined processed foods require more niacin as well. Realistically, 25-50 mg. per day is adequate intake of niacin if minimum protein requirements are met. On the average, many supplements provide at least 50-100 mg. per day of niacin or niacinamide, which is a good insurance level. For treatment of the variety of conditions described previously, higher amounts of niacin may be needed to really be helpful, and levels up to 2-3 grams per day are

56

Separation of Binary Mixture By Using Pervaporation not uncommon as a therapeutic dose. The other B vitamins should also be supplied so as to not create an imbalanced metabolic condition. Excellent sources of vitamin B3 (niacin) include crimini mushrooms and tuna. Very good sources include salmon, chicken breast, asparagus, halibut, and venison. Vitamin B3, also commonly called niacin, is a member of the B-complex vitamin family whose discovery was related to work by the U.S. Public Health Service in the early 1900's. At that time, a disease called pellagra, characterized by cracked, scaly, discolored skin, digestive problems, and overall bodily weakness was increasingly prevalent in the southern region of the country. The Public Health Service established a connection between the prevalence of the disease and cornmeal-based diets, and addition of protein to these diets was found to cure many cases of pellagra. Several years later, vitamin B3 was formally identified as the missing nutrient in the cornmeal-based diets that had led to the symptoms of pellagra. We now know that corn as a whole food contains significant amounts of vitamin B 3, but that vitamin B3 cannot readily be absorbed from corn unless corn products (like cornmeal) are prepared in a way that releases this vitamin for absorption. For example, the use of lime (as in limestone, the mineral, not lime juice in the fruit) can help release vitamin B3 from corn and make it available for absorption. Native American food practices that involve the addition of ash from cooking fires ("pot ash" or "potash") to corn-based recipes are one type of cooking technique that helps make vitamin B3 available for absorption. The term "niacin" used interchangeably with vitamin B3 is actually a nontechnical term that refers to several different chemical forms of the vitamin. These forms include nicotinic acid and nicotinamide. (Nicotinamide is also sometimes called niacinamide.) The names "niacin," "nicotinic acid," and "nicotinamide" are all derived from research studies on tobacco in the early 1930's. At that time, the first laboratory isolation of vitamin B3 occurred following work on the chemical nicotine that had been obtained from tobacco leaves. 57

Separation of Binary Mixture By Using Pervaporation 5.2 FUNCTION OF VITAMIN B3 Like its fellow B-complex vitamins, niacin is important in energy production. Two unique forms of vitamin B3 (called nicotinamide adenine dinucleotide, or NAD, and nicotinamide adenine dinucleotide phosphate, or NADP) are essential for conversion of the body's proteins, fats, and carbohydrates into usable energy. Niacin is also used to synthesize starch that can be stored in the body's muscles and liver for eventual use as an energy source. 5.3 METABOLISM OF FATS Vitamin B3 plays a critical role in the chemical processing of fats in the body. The fatty acid building blocks for fat-containing structures in the body (like cell membranes) typically require the presence of vitamin B3 for their synthesis, as do many fat-based hormones (called steroid hormones). Interestingly, although niacin is required for production of cholesterol by the liver, the vitamin has repeatedly been used to successfully lower total blood cholesterol in individuals with elevated cholesterol levels. This cholesterol-lowering effect of vitamin B3 only occurs at high doses that must be obtained through nutrient supplementation, and most likely involves a chemical feature of vitamin B3 that is not directly related to fat or fat processing. 5.4 SUPPORT OF GENETIC PROCESSES Components of the primary genetic material in our cells, called deoxyribose nucleic acid (DNA) require vitamin B3 for their production, and deficiency of vitamin B3 (like deficiency of other B-complex vitamins) has been directly linked to genetic (DNA) damage. The relationship between vitamin B3 and DNA damage appears to be particularly important in relationship to cancer and its prevention.

58

Separation of Binary Mixture By Using Pervaporation 5.5 DEFICIENCY SYMPTOMS Because of its unique relationship with energy production, vitamin B3 deficiency is often associated with general weakness, muscular weakness, and lack of appetite. Skin infections and digestive problems can also be associated with niacin deficiency. 5.6 TOXICITY SYMPTOMS Use of high-dose, supplemental niacin to lower serum cholesterol levels has given nutritional researchers a unique opportunity to examine possible toxicity symptoms associated with this vitamin. In the amounts provided by food, no symptoms of toxicity have been reported in the scientific literature. In 1998, the Institute of Medicine at the National Academy of Sciences set a tolerable upper limit (UL) for niacin of 35 milligrams. This UL applies to men and women 19 years or older, and is limited to niacin that is obtained from supplements and/or fortified foods. 5.7 FACTORS THAT AFFECT FUNCTION Intestinal problems, including chronic diarrhea, inflammatory bowel disease, and irritable bowel disease can all trigger vitamin B3 deficiency. Because part of the body's B3 supply comes from conversion of the amino acid tryptophan, deficiency of tryptophan can also increase risk of vitamin B3 deficiency. (Tryptophan deficiency is likely to occur in individuals with poor overall protein intake.) Physical trauma, all types of stress, long-term fever, and excessive consumption of alcohol have also been associated with increased risk of niacin deficiency. 5.8 NIACIN PROTECTS AGAINST ALZHEIMER'S DISEASE AND AGERELATED COGNITIVE DECLINE Niacin (vitamin B3) is already known to lower cholesterol. Now, research published in the August 2004 issue of the Journal of Neurology, Neurosurgery and Psychiatry indicates regular consumption of niacin-rich foods also provides protection against Alzheimer's disease and age-related cognitive decline.

59

Separation of Binary Mixture By Using Pervaporation Researchers from the Chicago Health and Aging Project interviewed 3,718 Chicago residents aged 65 or older about their diet, then tested their cognitive abilities over the following six years. Those getting the most niacin from foods (22 mg per day) were 70% less likely to have developed Alzheimer's disease than those consuming the least (about 13 mg daily), and their rate of age-related cognitive decline was significantly less. In addition to eating the niacin-rich foods, another way to boost our body's niacin levels is to eat more foods rich in the amino acid tryptophan. Our body can convert tryptophan to niacin, with a little help from other B vitamins, iron and vitamin C. Foods high in tryptophan include shrimp, crimini mushrooms, yellow fin, tuna, halibut, chicken breast, scallops, salmon, turkey and tofu. As we can see, several foods rich in tryptophan provide two ways to increase niacin levels as they are also rich in the B vitamin. (August 23, 2004) 5.9 FORMS IN DIETARY SUPPLEMENTS The term "niacin," often used interchangeably with the term "vitamin B3," is a non-chemical term that can actually refer to several different forms of the vitamin. Most often, "niacin" is used to refer to "nicotinic acid," the form of vitamin B 3 with documented cholesterol-lowering potential. This form of the vitamin also carries with it the greatest risk of side effects. Supplements focused on cholesterol reduction and alteration of fat metabolism typically include vitamin B3 in the form of nicotinic acid. The nicotinamide form of vitamin B3 is also widely available in supplement form. This chemical form of vitamin B3 carries a much lower risk of side effects and is commonly used in supplement formulas designed to support health in conditions not involving cholesterol excess or altered fat metabolism. Particularly in formulas for pregnancy or in children's formulas, the nicotinamide version is often preferred. Many formulas include both forms of vitamin B3, with small amounts of nicotinic acid and larger amounts of nicotinamide. 5.10 INTRODUCTION TO NUTRIENT RATING SYSTEM CHART In order to better help we identify foods that feature a high concentration of nutrients for the calories they contain, we created a Food Rating System. This system allows us to highlight the foods that are especially rich in particular

60

Separation of Binary Mixture By Using Pervaporation nutrients. The following chart shows the World's Healthiest Foods that are either an excellent, very good, or good source of vitamin B3 (niacin). Next to each food name, we shall find the serving size we used to calculate the food's nutrient composition, the calories contained in the serving, the amount of vitamin B3 (niacin) contained in one serving size of the food, the percent Daily Value (DV%) that this amount represents, the nutrient density that we calculated for this food and nutrient, and the rating we established in our rating system. For most of our nutrient ratings, we adopted the government standards for food labeling that are found in the U.S. Food and Drug Administration's "Reference Values for Nutrition Labeling."(25) World's Healthiest Foods ranked as quality sources of:vitamin B3 (niacin) World's Nutrien Serving Amount DV Healthiest Food Cals t Size (mg) (%) Foods Density Rating Crimini mushrooms, 26. 5 oz-wt 31.2 5.39 15.6 Excellent raw 9 Tuna, yellowfin, 157. 67. 4 oz-wt 13.54 7.7 Excellent baked/broiled 6 7 Tamari (Soy Sauce) 1 tbs 10.8 0.72 3.6 6.0 Good Chicken breast, 223. 72. 4 oz-wt 14.41 5.8 very good roasted 4 0 187. 48. Calf's liver, braised 4 oz-wt 9.61 4.6 very good 1 0 Halibut, 158. 40. 4 oz-wt 8.08 4.6 very good baked/broiled 8 4 Asparagus, boiled 1 cup 43.2 1.95 9.8 4.1 very good Salmon, chinook, 261. 56. 4 oz-wt 11.34 3.9 very good baked/broiled 9 7 179. 38. Venison 4 oz-wt 7.61 3.8 very good 2 0 Romaine lettuce 2 cup 15.7 0.56 2.8 3.2 Good 229. 38. Lamb loin, roasted 4 oz-wt 7.75 3.0 Good 1 8 214. 36. Turkey breast, roasted 4 oz-wt 7.22 3.0 Good 3 1

61

Separation of Binary Mixture By Using Pervaporation Tomato, ripe Mustard greens, boiled Shrimp, steamed/boiled Summer squash, cooked, slices

1 cup

37.8

1.13

5.6

2.7

Good

1 cup

21.0

0.61

3.0

2.6

Good

2.4

Good

2.3

Good

2.2

Good

2.1

Good

2.0 1.9 1.9

Good Good Good

1.9

Good

1.9

Good

1.9 1.9

Good Good

1.8

Good

1.8

Good

1.7

Good

1.6

Good

4 oz-wt 1 cup

Green peas, boiled

1 cup

Cod, baked/broiled

4 oz-wt

Collard greens, boiled Carrots, raw Broccoli, steamed Eggplant, cooked, cubes Peanuts, raw Spinach, boiled Fennel, raw, sliced Turnip greens, cooked Spelt grains, cooked Beef tenderloin, lean, broiled Raspberries Winter squash, baked, cubes Swiss chard, boiled Cauliflower, boiled Kale, boiled Green beans, boiled Mustard seeds Cantaloupe, cubes World's Healthiest Foods Rating excellent very good

112. 3 36.0 134. 4 119.

1 cup 1 cup 1 cup

1 49.4 52.5 43.7

1 cup

27.7

0.25

207.

cup 1 cup 1 cup

0 41.4 27.0

1 cup

28.8

4 oz-wt 4 oz-wt

144. 0 240.

1 cup

4 60.3

1 cup 1 cup 1 cup 1 cup 1 cup 2 tsp 1 cup

2.94 0.92 3.23 2.82

14. 7 4.6 16. 1 14.

1.09 1.13 0.94

1 5.5 5.6 4.7

0.59

3.0

4.40

22.

0.88 0.56

0 4.4 2.8

0.59

3.0

2.91 4.44

14. 6 22.

1.10

2 5.5

80.0

1.44

7.2

1.6

Good

35.0 28.5 36.4 43.8 35.0 56.0

0.63 0.51 0.65 0.77 0.60 0.92

3.1 2.5 3.3 3.9 3.0 4.6 Rule

1.6 1.6 1.6 1.6 1.5 1.5

Good Good Good Good Good Good

DV>=75% OR Density>=7.6 AND DV>=50% OR Density>=3.4 AND

62

DV>=10% DV>=5%

Separation of Binary Mixture By Using Pervaporation good

DV>=25% OR Density>=1.5 AND DV>=2.5%

63

Separation of Binary Mixture By Using Pervaporation Chapter 6

MATERIAL BALANCE

6.1 BASIS: 1 KG OF TOBACCO PER BATCH (18)

6.1.1 Mixing tank:-

Mixer

5lit of H2O 1 Kg of Raw tobacco

Overall material balance over mixer Water added + Raw tobacco = Wet slurry 5 lit of water + 1Kg of tobacco = Wet slurry ∴ Wet slurry = 6 Kg As tobacco contains 5% nicotine Material balance of nicotine Let “X” be the quantity of nicotine in wet slurry Nicotine in tobacco = Nicotine in wet slurry 0.05 X 1000 = X ∴ X ∴

= 50 gm

Nicotine in wet slurry = 50 gm

64

Wet slurry (6 Kg.)

Separation of Binary Mixture By Using Pervaporation 6.1.2 Filtration:Wet Tobacco Wet slurry

Filtration

(6 Kg)

[i.e.4Kg wet tobacco] Filtrate (1400 ml)

Overall material balance Wet Slurry in = Wet Tobacco + Filtrate + Loss 6000 = 4000 + 1400 + Loss Loss = 600 ml The wet tobacco after filtration can be dried and send to the cigarette manufacturing unit to get non addictive cigarette. 6.1.3 Steam Distillation:-

Nicotine Solution 1400 ml of Filtrate

Steam Distillation

1040 ml Waste 360 ml

Overall material balance Filtrate = Nicotine Solution + Waste 1400 = 1040 + Waste Waste = 360 ml

65

Separation of Binary Mixture By Using Pervaporation 6.1.4 Separation:Nicotine layer Nicotine solution

Separator

(1040 ml) Other constituents Overall material balance over separator Nicotine solution = Nicotine layer + other constituents After measurement we get 1007 ml of other constituents from bottom of separator 1040 = Nicotine layer + 1007 Nicotine layer = 33 ml.

6.1.5 Oxidation Reaction:33ml of HNO3 Reaction 33ml of Nicotine Methylamine;

Reactor 110-115 0 C 30 min

Product Niacin, Oxalic acid &

CO2

Overall material balance: 33 ml of HNO3 + 33 ml of Nicotine = Reaction Product ∴ Reaction Product = 45 gm. The product from oxidation reaction in the form of precipitate was kept in the accumulator for near about half hour. In the accumulator there was formation of two layers due to density difference, the lower layer of Oxalic acid and upper layer of Nicotinic acid, which was send to dryer.

66

Separation of Binary Mixture By Using Pervaporation

Top

Nicotinic

acid (45 gm)

Accumulator

Reaction

layer (36 gm)

Product Bottom Oxalic acid layer (9 gm) Overall material balance Reaction product =

Top Nicotinic acid layer + Bottom Oxalic acid layer

45 = Top Nicotinic acid layer + 9 ∴ Top Nicotinic acid layer = 36 gm

6.1.6

Drying:-

Moisture removed Top Niacin layer 80 % Solid

Tray Dryer

20 % Moisture

Dry Product 95 % Solid

5 % Moisture

Let X and Y are the gm of water removed and product Niacin obtained. Overall material balance Top Nicotinic acid layer = Dried product + Moisture removed 36 =

X+Y

67

Separation of Binary Mixture By Using Pervaporation Solid balance 0.8 X 36 = 0.95 Y Y = 30 gm Nicotinic acid = 30 gm X = 6 gm Moisture removed = 6 gm

6.2 ENERGY BALANCE

(18)

6.2.1 Mixing Tank: T = 250C 5 lit H2O

Wet Slurry (6 Kg.) 0

Mixer at 60 C

(T = 580C)

1Kg of Tobacco (T = 300C)

Amount of heat required to raise the temperature of tobacco mixture in mixing tank from room temp. (i.e. 300C) to 600C Q = m Cp ∆ T Q = 6 X Cp X (60-30) Approximate Specific heat capacity (Cp) values can be calculated for solids and liquids by using a modified form of Kopp’s law, which is given by Werner (1941). (19) Molecular formula of Nicotine is C1OH14 N2 Element

Mol. Mass

Heat capacity

C

120

120 X 7.5

= 900.0

H

14

14 X 9.6

= 134.4

68

Separation of Binary Mixture By Using Pervaporation N

28

28 X 26.0

= 728.0

162

1762.4

1762.4 ∴ Specific heat = ------------ - = 10.88 J / g oc [ KJ / Kg 0C ] Capacity

162

(Of Nicotine extract) ∴ Q = 6 X 10.88 X 30 = 1958.4 KJ 6.2.2 Steam Distillation: Steam in Feed 1400 ml of filtrate

Steam (110 0C) Distillation

(280C) Condensate Amount of heat required in steam distillation section. Q = m Cp ∆ T = 1.4 X 10.88 X (110-28) Q = 1249.024 KJ/hr Amount of steam required is Q = mCp ∆ T 1249.024 = m X 1 X (110-28) ∴ m = 15.232 kg/hr ∴ Amount of steam required was = 15.232 Kg/hr.

69

Product

Separation of Binary Mixture By Using Pervaporation

6.2.3 Oxidation Reactor:

Feed (30 0 C) 33mlof Nicotine

45 gm

Reactor 1100C

Product

33mlofHNO3 Amount of heat required in reactor is Q = mCp ∆ T Q = 0.066X10.88 X (110-30) Q = 57.4464 KJ /hr

70

Separation of Binary Mixture By Using Pervaporation Chapter 7

REACTOR DESIGN For 33 lit. of total reaction mixture. V = 33 lit. 1m3 = 1000 lit. = 33 lit. For design purpose 10 % extra, ∴ V = 33 X 10-3 + 10 % Excess ∴ V = 36.3 X 10-3 m3 Diameter of reactor can be found out from volume of reactor; as we know.(16) Volume = Area X Length --------------- (1) Let, Diameter of reactor = D Length of the reactor = L Volume of the reactor =V ∴ Area of

=

Reactor

π D2 4

For plate thickness up to 50 mm (16) L

= 6

D ∴ Length of reactor = L = 6 D Substituting area & length in equation (1) ∴ Volume = π D 2 X 6 D 4 ∴ V = 1.5π D3

71

Separation of Binary Mixture By Using Pervaporation

36.3X10-3 = 4.712 D 3 ∴ D 3 = 7.7X 10-3 ∴ D = 0.19 m Di = 20 cm ≈ 200mm

Since

L = 6 D

∴ L = 6 D = 6 X 20 = 120 cm L = 1.2 m P = 1atm Thickness is t = PD

=101.325 X103 N/m2

+C

D= 0.2 m

2fJ

F = For Steel plate allowable stress

The steel plate IS : 2041- 1962 3

= 101.325 X 10 X 0.2 + 1 X 10

3

2 X 3.5X106X 0.80 t = 4.62 mm ≈ 5mm

The Volume of metal used for constructing the vessel v = t [π DL + π D 2 ] 2 -3

v = 5X 10 [0.754 +0.063] v= 40.8 X 10-3 m3

72

= 3.5 X 106N/m2 J = 80%

Separation of Binary Mixture By Using Pervaporation Stoichiometric proportion of Nicotine & HNO3 for oxidation reaction (18) According to the oxidation reaction C10H14N2 Nicotine

+ 9[O] --HNO3--- C6H5NO2

+ C2H2O4.H2O + CH3NH2 + CO2

Nascent Oxygen

Nicotinic acid

Oxalic Acid

Ethylamine 1 mole of Nicotine ≡ 3 mole of HNO3 1X162 kg of Nicotine ≡ 3 X 63 kg HNO3 162 kg of Nicotine ≡ 189 kg HNO3 Specific gravity of Nicotine = 1.009 1.009 =

Density of Nicotine Density of H2O

1.009 = Nicotine 1 gm/cm3 ∴ Density of Nicotine = 1.009 gm/cm3 = 1009 kg/m3

But Density =

M

i.e V = M

V

Density

= 162kg 1009 kg/m3

∴ Volume of Nicotine = 0.1605 m3 = 160.5 lit. Volume of Nicotine = 160 lit. Again specific gravity of HNO3 = 1.502 Density of HNO3 ∴ 1.502 =

-----------------Density of H2O

73

= 0.1605m3

Separation of Binary Mixture By Using Pervaporation ∴ Density of HNO3 = 1.502 gm/cm3 = 1502 kg / m3

m

189

Kg

Volume of HNO3 = -------- = --------- = --------- = 0.1258 m3 1502

Kg/m3

∴ Volume of HNO3 = 0.1258 m3 = 125.8 lit Volume HNO3 = 125 lit. So for carrying oxidation reaction, take 1.6 ml of Nicotine & 1.25 ml HNO3 to get the desired product i.e. Nicotinic acid (Niacin). (18)

74

Separation of Binary Mixture By Using Pervaporation Chapter 8

COST ESTIMATION 8.1 COST OF EQUIPMENT:Sr.No . 1 2 3 4 5

Item

Uni

Cost /

Total

t 1 1 1 4 1

Unit 200000 3200000 480000 4000 500000

Cost(Rs.) 200000 320000 480000 16000 500000

1 1 1

100000 25000 150000

100000 25000 150000 1791000

Pulverizer Mixing Tank Filter press Storage Tank Steam Distillation Setup Condensor Reactor Dryer Total ( E )

6 7 8

8.2 FIXED CAPITAL INVESTMENT:8.2.1 Direct Cost:Sr.No . 1 2 3 4 5 6 7 8

Item Purchase Equipment Cost Equipment Installation Instrumentation & Control Piping Cost Electrical Fitting Cost Building Construction & Other Services Yard Investment Land Total Direct Plant Cost (D)

75

%

Cost

E E 30 15 15 5 40

(Rs.) 1791000 537300 268650 268650 89550 716400

3 30

53730 537300 4262580

Separation of Binary Mixture By Using Pervaporation 8.2.2 Indirect Cost:-

Sr.No

Item

%

.

Cost

E

(Rs.)

1

Engineering & Supervision

17

304470

2

Cost Construction Expenses

32

573120

Total Indirect Cost ( I )

877590

Total direct & indirect cost (I + D) = Rs. 5140170 Contractor Fees 5 % (I+D) = Rs.257000 Fixed Capital Investment (FCI) = Rs.5397170 Working Capital (WC) 20 % (I+D) = Rs.1028034 Total Capital Investment = FCI + WC

= 5397170 + 1028034 = Rs. 6425204 8.3 TOTAL PRODUCTION COST:8.3.1 Direct Production Cost:1) Raw Material Cost:Sr.No . 1 2 3

Raw Material

Quantity/Batc

Waste Tobacco NaoH 50 % HNO3

h 500 Kg. 5 Kg. 16.5 lit.

Cost/ Kg

Cost

Rs. 30 / Kg Rs.180 / Kg Rs. 225 /

(Rs.) 15000 900 3713

lit. Raw Material

19613

Cost

For one day three batches Therefore raw material cost per day = 19613 X 3

76

Separation of Binary Mixture By Using Pervaporation = Rs. 58839 Raw material cost per month

= 58839 X 30 = Rs. 1765170

8.3.2 Utilities:-

a) Water:Water requirement per batch = 25000 lit. Cost of Water = Rs. 1 / lit. Cost of Water per batch = Rs.2500 b) Steam:Requirement of Steam per batch = 900 Kg. Cost of Steam = Rs. 5.33 / Kg. Cost of Steam per batch = Rs. 4800 Cost of steam per day = 3 X 4800 = Rs. 14400 c) Electricity:Requirement of Electricity per batch = 800 Kwh Cost of Electricity = Rs. 6 /Kwh Cost of Electricity per batch = 800 X 6 = Rs. 4800 Cost of Electricity per Day = 3 X 4800 = Rs. 14400 B) Total cost of Utilities = 7500 + 14400 + 14400 = Rs. 36300 /day Total cost of Utilities per month = 30 X 36300 = Rs. 1089000

77

Separation of Binary Mixture By Using Pervaporation 8.4 OPERATING LABOUR COST:Post

Number

Salary /

Total

1 2 4 4 1 2

month Rs. 15000 Rs. 10000 Rs. 5000 Rs. 3000 Rs. 3000 Rs.3500

salary Rs. 15000 Rs.20000 Rs.20000 Rs.12000 Rs.3000 Rs.7000

General Manager Engineer Skilled Worker Unskilled Worker Clerk Administrative staff

Total Labour

Rs.77000

Cost

Bonus = 0.3 X Total labour cost = 0.3 X 77000 = Rs.23100 Operating labour cost per month = 77000 + 1925 O.L.C. = Rs. 78925 /month Lab Charges = 10 % OLC = 0.1 X78925 = Rs.7893 /month Maintenance & repair = 0.5 % FCI = 0.005 X 5397170 = Rs. 26986 / month A) Direct production cost = Raw material cost + Cost of Utilities + Operating Cost + Lab Charges + Main. & repair. D.P.C. = 1765170 + 1089000 + 78925 + 78925 + 26986

78

Separation of Binary Mixture By Using Pervaporation = Rs. 2967974 / month B) Depreciation & Taxes = 2 % FCI = 0.02 X 5397170 = Rs. 107943 C) Insurance = 1 % FCI = 0.01 X 5397170 = Rs. 53972 D) Distribution & Marketing = 20 % OLC = 0.2 X 78925 = Rs.15785 E) Other Cost (R & D ) = 1 % FCI = 0.01 X 5397170 = Rs. 53972 Total production cost per month = A + B + C + D + E = 2967974 +107943 + 53972 + 15785 + 53972 = Rs.3199646 Now, 15 Kg Niacin, 15 Kg of Oxalic acid and 450 Kg of nonaddictive tobacco were obtained from one batch process. Therefore for one month, Niacin produced = 15 X 3 = 45 Kg / day = 45 X 30 = 1350 Kg / month Similarly Oxalic acid = 1350 Kg / month And Nonaddictive tobacco = 450 X 3 X 30 = 40500 Kg / month

79

Separation of Binary Mixture By Using Pervaporation Sale:- (14) Selling price of Niacin = Rs. 2100 / Kg Selling price of Oxalic acid = Rs. 280 /Kg Selling price of Tobacco = Rs. 15 / Kg

Monthly Sale:Niacin = 1350 X 2100 = Rs. 2835000 Oxalic acid = 1350 X 280 = Rs. 378000 Tobacco = 40500 X 15 = Rs. 607500 Total monthly sale = 2835000 + 378000 +607500 = Rs. 3820500 Gross profit = Total monthly sale - Total monthly production cost = 3820500 – 3199646 = Rs. 620854 Income tax = 40 % Gross profit = 0.4 X 620854 = Rs. 248342 Net profit = Gross profit – Income tax = 620854 – 248342 = Rs. 372512 /month = 372512 X 12 = Rs. 4470144 /year Rate of return on investment =

Net profit per year Fixed Capital Investment = 4470144 5397170 = 0.83

Rate of return = 0.83 This evaluation is based on laboratory readings & previous literature on Niacin, so before going for large scale production a test on pilot plant is necessary. (14)

80

Separation of Binary Mixture By Using Pervaporation Chapter 9

PLANT LAYOUT After the process flow diagram was completed and before detailed piping design and layout can begin, the layout of process unit must be planned and equipment within these process unit must be planned. This layout can play an important role in determining constructing and manufacturing cost; and thus must be planned carefully. Good plant layout keeps safety, appearance, convenience, overall cost, erecting cost, operating and maintenance cost to the minimum. Safety and optimum utilization of available area should be given prime importance in plant layout. The key to economical construction and efficient operation is a carefully planned functional agreement of equipment, piping and building. An accessible and aesthetically pleasing plot plan can make major contribution to safety, employee satisfaction and sound community relation. The handling of the material is kept to minimum by provision of gravity transportation wherever possible. Provision should be also made for necessary service area; the administration or office building, canteen, workshops, laboratories, etc. The main process plant should be isolated from administration building, canteen, workshops, laboratories, etc, the storage tanks area, security room should be also isolated from main plant. The canteen should also be neat to office building, laboratories; workshops etc. process plant should be located on one side of a tank farm while shipping, transport, and loading/unloading facilities on another side. Intermediate tanks should be located close to the process unit. Administration and service facilities should be located near the process plant entrance. Warehouses, salvage yard should be close together. Cooling towers should be located where water drift from the tower will not cause excessive corrosion of process equipment. They should be oriented cross way to the wind direction in order to minimize recycling of air from the discharge of one tower to an adjacent tower. All hazardous tank of larger size should be located at least 65m away from the building, process plant, fired heaters. Pumping arrangement of liquid from the tank should be decentralized. In process plant there should be sufficient space between the process 81

Separation of Binary Mixture By Using Pervaporation equipment. It avoids congestion after piping, valves, instrumentation is done on equipment. Storage Layout:Raw material storage tank should be located such that the transportation to the process area is done easily loaded and unloaded. Equipment Layout:Equipment should be installed in the process direction, maintaining reasonable space between them. To consume space economically they should be arranged so that the final product and initial reactants are near to storage tanks. The equipment should be installed in the process direction in such a manner that handling of the material is kept to minimum by provision of gravity transportation wherever it is possible; without disturbing the main process. Safety: Fire station should be located nearer to process area. In every unit hose pipes, fire extinguisher should be placed. Plant Expansion: Some space should be allocated for future expansion of the plant. Utilities: Placing them nearer to the process area should effectively do distribution of steam, power, water etc. Administrative building: This should be located at the entrance of the main gate of the factory and there must be provision made for communicating with every plant. Laboratory and Quality Control: These should be located near the process plant. Due to which the evaluation results and hence correction can be easily done within no time. Commodities: 82

Separation of Binary Mixture By Using Pervaporation Parking and canteen should be located near to the unit but not too close to the unit. They should be separated from actual plant by the road. Security Office: The security office and time office (checkers gate) should be located near to the entrance of the factory. In short the plant should fill the following points: 

More efficient use of land space.



Lower cost of construction per square feet floor space.



The upper stores building (e.g. administrative building etc) should be

free from street noise, dust, odor, etc). 

Use of gravity flow of materials, which is cheaper method of

transportation. 

More compact layout because of vertical arrangement of production

area. Market Area: Nicotinic acid is used by wider range of pharmaceutical industries. Major part of nicotinic acid is exported and there were large transportation facilities in Ankalashawar . Previously Amsal Chemical and their group is the only major manufacturer of nicotinic acid. This provides opportunity to capture nearby market easily.

Raw Material Supply: Raw material required for production of Nicotinic Acid i.e. Waste Tobacco was collected from tobacco farming nearby area and also from tobacco processing industries.(13)

83

Separation of Binary Mixture By Using Pervaporation Chapter 10

CONCLUSION Nicotinic acid is an antipellagra factor is a group of vitamin B3 . Majority sources of it are Yeast, Rice polishing, Meatextract & Tobacco. By oxidation of tobacco with the help of HNO3, nicotine is converted to nicotinic acid (Niacin). With this treatment to tobacco the addictive nature of man towards tobacco becomes non-addictive & also provide an improved tobacco product, so that blood plasma nicotine level resulting about 0 to 5 nanograms /ml. The main aim is to go for experimental work in lab-scale for conversion of Nicotine to Nicotinic acid from Tobacco.It is a two step process,firstly Extraction of nicotine from tobacco and secondly conversion of nicotine to nicotinic acid. The reactor was to be designed for this oxidation process and the analysis of product & by- products was to be carried out. The objective of the process is to get non addictive tobacco product, the poisonous Nicotine is converted to Vitamin B3, and to reduce the Carcinogenic effect of tobacco on human health i.e. to get alternate use of tobacco for Nicotine Sulphate (as pesticide), Niacin (Vitamin B3) pharmaceutical product, etc. This invention relates in general to certain new and useful improvement in processing of tobacco to eliminate or convert nicotine in the tobacco in to nicotinic acid as a harmless or beneficial product such that the nicotine level which can be achieved by use of the tobacco product result in a blood plasma level consonant with non-addiction. The primary objects of the present invention is to provide a tobacco product adapted for human use and which eliminates an addictive response to the user there of the another object of the present invention to provide an improved tobacco product of the type which utilized an oxidized tobacco in which nicotine has been converted to nicotinic acid or extraction to a level resulting in the user is about 0 to about 5 nanograms per milliliter. The another object of the present invention to provide an improved tobacco product of the type stated in which a tobacco product is converted chemically or by

84

Separation of Binary Mixture By Using Pervaporation physical means to obviate any effects on the acetykholine brain receptors in an individual smoking or otherwise ingesting such tobacco product. In accordance with the present invention it has been found that by converting the nicotine of a tobacco product in to a harmless and actually beneficial substance, such as nicotinic acid, addiction to the tobacco product can be avoided. Thus the conversion of the nicotine in accordance with the present invention not only elements the addiction but also reduces some of the harmful effects of the identified as being generally recognized as safe or approved. Nicotinic acid is also known as Niacin, Nicotineamide and anti pellagra factor is a group of vitamin B3. Its compound was known before its vitamin activity observed. It is widely used in the food, pharmaceutical & biochemical industries. An odorless, white, crystalline substance, readily soluble in water. It is resistant to heat, oxidation, and alkalis. It is, in fact, one of the most stable vitamins. Cooking causes little actual destruction of niacin, but a considerable amount may be lost in the cooking water and drippings from cooked meat if these are discarded. In a mixed diet, 15 to 25 percent of niacin of the cooked food stuff may be lost in this way. It is excreted in the urine, mostly as its salts, and to a smaller extent, as free niacin. The main deficiency disease caused by lack of nicotinic acid is “pellagra”. This disease affects epithelia & nervous system. It is accused by the accumulation of the intermediate products of respiration, this is because nicotinic acid is required for the synthesis of co-enzymes used by dehydrogenises. Nervousness, headaches, fatigue, mental depression, skin, disorders, muscular weakness, & indigestion are the symptoms of deficiency of niacin. Exposure to nicotine and combustible products from cigarette smoking is toxic to renal function. In particular, nicotine has an adverse effect on behavior as it results in people becoming addicted. Patients are predisposed to urinary tract cancers. Further kidney damage can result from accumulation of heavy metals from tobacco. Associated with altered renal function is a direct effect on nervous innervations, blood pressure and blood vessels. Antismoking campaigns should be focused on achieving more success. For instance, banning smoking in public venues and at workplaces will decrease the deleterious effects of long-term exposure to 85

Separation of Binary Mixture By Using Pervaporation nicotine. From 2nd Oct. 2008 it was banned to smoke at public places and also at work places by the Government. Nicotine could also be removed from combustion tobacco products. Alternatively nicotine-replacement therapies may be used. One should avoid smoking by inhalation either actively or passively

FUTURE PROSPECTS

1. With the help of this treatment to the tobacco the addictive nature of tobacco due to Nicotine becomes non-addictive. 2. The harmful nicotine can be converted to Niacin. 3. The carcinogenic effect of tobacco due to nicotine can be reduced. 4. We can convert the harmful nicotine to the niacin which was pharmaceutical product. 5. For the waste coming from the tobacco industries & also from tobacco farming, this was the important technique to get the valuable product. 6. The treated tobacco can also be used as a fertilizer for the farming purpose. 7. The main aim is to get alternative use of tobacco for Farmers due to the ban of tobacco for beedi, hooka, chewing etc. by the Government. 8. To treat one cancer patient approximately Rs. 3.5 lacks required and near about 7.5 lacks people die due to cancer from tobacco, this can be avoided. 9. Due to commercialization of this process, the addictive tobacco becomes nonaddictive and the pharmaceutical product Niacin can be produced. 10. By this method we can convert waste tobacco to the valuable pharmaceutical product 11. By optimizing the process the yield of Niacin from tobacco can be increased.

86

Separation of Binary Mixture By Using Pervaporation

REFERENCES 1.

Agarwal O.P. “Chemistry of Organic Natural Product”(2004) Volume I, Himalaya Publishing House, (p.280,281).

2. Dr.Deb A. C. “Fundamentals of Biochemistry”(1990) A.Sen New

Central Book Agency, Calcutta,(p.191,192). 3. Kirk- Othmer “Encyclopedia of Chemical Technology”III rd ed.(1984)

Volume 24 A Wiley- Interscience Publication John Wiley & Sons (p.8087). 4. Gurdeep Chatural “Organic Chemistry of Natural Products”(2004)

Volume I Himalaya Publishing House(p.571,573). 5. “The Pharmaceutical Codex” XI

th

ed.(1979) The Pharmaceutical Press

London (p.593,594). 6. Harold Varley “Practical Clinical Biochemistry” IVth ed.(1969), CBS

Publisher & Distributors, Daryaganj New Delhi (p.622). 7. Richard J.Lewis Sr, Van Nostraud Reinhold “Hazardous Chemicals

Desk

Reference” IInd ed. (2002),McGraw Hill Publication New York

(p.844). 8. David L. Nelson & Michael M. Cox “Lehningers Principles of

Biochemistry” IVth ed (2005) W.H. Freeman & company New York (p.514, 515). 9. Finar I .L. “Organic Chemistry”(1994) Vth ed. Longman Singapore

Publishers Ltd. Singapore (p.717) 10. Douglas

M.

Considine

“Chemical

and

Process

Technology

Encyclopedia” (2004) Mc Graw Hill Book Company (page 71, 946).

87

Separation of Binary Mixture By Using Pervaporation 11. Robert H. Perry, Don W. Green, “Perry,s Chemical Engineering Hand

Book” VIIth ed.(1997) Mc Graw Hill Publications,New York (p 241,42,43). 12. Larry Ricci & The Staff of Chemical Engineering “Seperation

Techniques in Liquid-Liquid System”.(2001) McGraw Hill Publications Co, New York (p.552) 13. Khana O.P. “Industrial Engineering & Management” (1999), Dhanpat

Rai Publications (P.) Ltd.(p.4.1-4.35). 14. Peter Timmerhaus, West “Plant Design & Economics for Chemical

Engineers” Vth ed. (2004) Mc Graw Hill Publication, New York (p.323) 15. Warren L. McCabe, J.C. Smith, Peter Harriott, “Unit Operations of Chemical Engineering V th ed. (1993) McGraw Hill Book Co. Singapore (p.614, 615). 16. Dr. S.D. Dawande “ Process Design of Equipments” I

st

ed. (1999),

Central Techno Publications,Nagpur-12 (p.19,20). 17. Robert E. Treybal “Mass– Transfer Operations”III

rd

ed. (1981)

McGraw-Hill Book Co. Singapore (p.717, 718,719). 18. Bhatt B.I. & Vora S.M. “Stoichiometry” III rd ed. (1998) Tata Mc Graw

Hill Publishing Company Ltd. (p.66, 67,187). 19. Richardson and Colusion. “Chemical Engineering Volume IV th ed.

“Chemical Engineering Design” (2008), Elsevier India Private Ltd. (p.322,323). 20. http://icmr.nic.in/ijmr/2006/september/0905.pdf cited on 1/11/2006. 21. http://www.Properties of Tobacco.htm cited on 30/5/2008. 22. http://en.wikipedia.org/wiki/Nicotinicacid, cited on 25/10/2008. 23. http://www.Vitamin B3 Niacin Healthy Body,Healthy Mind, Holistic

Healing,Home Remedi, cited on 18/4/2008

88

Separation of Binary Mixture By Using Pervaporation 24. http://Non-addictive tobacco products – Patents 5713376.htm cited on

22/9/2007. 25. http://www.purchon.com/biology/nicotinic acid cited on 3/3/2007. 26. http://www.Nicotine & its Derivatives from Tobacco Waste.htm, cited

on 30/5/2008.

89

Separation of Binary Mixture By Using Pervaporation

INDEX Introduction to pervaporation

1

1.2MEMBRANE BASED PERVAPORATION SEPARATION:.........................3 .................................................................................................................................6 Literature survey 14 2.1 SEPARATION PRINCIPALS........................................................................14 2.2 PERVAPORATION THEORY..................................................................15 ...........................................................................................................................21 ...........................................................................................................................22 2.5 SUMMARY OF THE INVENTION .............................................................35 ETHANOl - WATER SEPARATION BY PERVAPORATION 37 3.1 EHANOL ASPECTS:-...................................................................................37 3.3 Process Description:- .....................................................................................42 experimental set-up & process 43 4.1 PERVAPORATION SYETEM......................................................................43 ...............................................................................................................................43 4.2 Dietary needs..................................................................................................45 4.3 Properties: .....................................................................................................45 4.3 Pharmacological uses:-...................................................................................45 4.4 Toxicity...........................................................................................................46 4.5 Biosynthesis....................................................................................................47 4.6 Physical Properties of Nicotinic Acid (11).....................................................48 4.7 Functions of Vitamin B3 Niacin:-...................................................................50 4.8 Chemical Structure (25)..................................................................................50 4.9 Biological Synthesis .......................................................................................50 4.10 Sources..........................................................................................................51 4.11 Source Categories:........................................................................................52 4.12 Deficiency Disease:......................................................................................52 4.13 Identification Tests for NIACIN (2).............................................................52 4.14 Precautions:...................................................................................................52 4.14 Niacin Analogues:-.......................................................................................53 4.15 Vitamin B3 Uses...........................................................................................54 IMPORTANTS OF NIACIN 56 5.1 Requirements: ...............................................................................................56 5.2 Function of vitamin B3...................................................................................58 5.3 Metabolism of Fats .......................................................................................58 5.4 Support of genetic processes...........................................................................58 5.5 Deficiency Symptoms.....................................................................................59 5.6 Toxicity Symptoms.........................................................................................59 5.7 Factors that Affect Function...........................................................................59 5.8 Niacin Protects against Alzheimer's disease and Age-related Cognitive Decline..................................................................................................................59 5.9 FORMS in Dietary Supplements....................................................................60 90

Separation of Binary Mixture By Using Pervaporation 5.10 Introduction to Nutrient Rating System Chart..............................................60 MATERIAL BALANCE 64 6.1 Basis: 1 Kg of tobacco per BATCH (18)........................................................64 6.1.1 Mixing tank:-...........................................................................................64 6.1.2 Filtration:-................................................................................................65 6.1.3 Steam Distillation:-..................................................................................65 ..........................................................................................................................65 6.1.4 Separation:-..............................................................................................66 6.1.5 Oxidation Reaction:-..............................................................................66 6.1.6Drying:- ....................................................................................................67 6.2 Energy Balance (18) ...............................................68 6.2.1 Mixing Tank: ..........................................................................................68 6.2.2 Steam Distillation:...................................................................................69 6.2.3 Oxidation Reactor:...................................................................................70 Reactor Design 71 Cost Estimation

75

8.1 Cost of Equipment:-........................................................................................75 8.2 Fixed Capital Investment:-..............................................................................75 8.2.1 Direct Cost:-.............................................................................................75 8.2.2 Indirect Cost:-..........................................................................................76 8.3 Total Production Cost:-...................................................................................76 8.3.1 Direct Production Cost:-..........................................................................76 8.3.2 Utilities:-..................................................................................................77 8.4 Operating Labour Cost:-.................................................................................78 PLANT LAYOUT 81 CONCLUSION

84

Future Prospects....................................................................................................86 REFERENCES 87 Index

90

91

Separation of Binary Mixture By Using Pervaporation

LIST OF TABLE SR.

DESCRIPTION

NO.

PAGE NO.

1

Liquid phase o`xidation reaction yields

10

2

Sources

22

3

Physical properties

24

4

Physical properties of Niacin

30

5

Food Sources

33

6

Worlds healthiest foods ranked as quality sources of Niacin

92

43, 44