Iop Journal Opm_yori Alna Nanda Annisa Ahmad Reza.docx

IOP Publishing Journal XX (XXXX) XXXXXX

Journal Title https://doi.org/XXXX/XXXX

A review on heavy metals ions adsorption from toxic waste by low-cost adsorbent materials Lia Cundari1, M. Yori Pratama2, Alna Livia Fanneza3, Nanda Citra Arisma4, Annisa Fadhila Ramadhani5, Ahmad Reza Aditya Amin6 Departement of Chemical Engineering, Universitas of Sriwijaya, Inderalaya, Ogan Ilir 30662

E-mail: [email protected]

Abstract Heavy metals which are natural components of the Earth's crust are usually associated with toxicity. Exposure to heavy metals, even at trace level, is known to be a risk for human beings. Because of the continuous deterioration of water quality and persisting contamination level, it has been observed and concerned by the scientists. In conventional technologies, heavy metal removal/remediation is provided expensive because of non-regenerable materials used and high costs. Adsorption has been proved to be an excellent way to treat industrial waste effluents, offering significant advantages like the low-cost, availability, profitability, ease of operation and efficiency. As adsorption technology reduces the heavy metal ions concentrations to very low levels and because of using various low-cost adsorbent materials including carbon active, biosorbent, zeolite, active alumina, and graphene oxide for removal of different heavy metal ions like As(V), Pb(II), Cd(II), Cr(VI), Th(IV) and Eu(III) from water/wastewater.

Keywords: Heavy Metal, Adsroption, Adsorbent

Even at trace level, exposure to heavy metals can cause risk for human beings [6, 7, 8, 9]. Because of heavy metals tend to accumulate in living organisms and most of they are carcinogenic and teratogenic. They can cause various symptoms including organ damage, high blood pressure, reduced growth and development, speech disorders, sleep disabilities, fatigue, poor concentration, aggressive behavior, irritability depression, mood swings, increased allergic reactions, vascular occlusion, autoimmune diseases, oxidative stress and memory loss [10]. Also they can disrupt the human cellular enzymes [11]. Due to the increase in the importance of using friendly and economical new methods, studies on the production of adsorbents that can be used for this purpose have increased. In many studies, several techniques such as adsorption, chemical precipitation, electrochemical technologies, ion exchange, membrane filtration and many other techniques are effective methods for heavy metal removal from contaminated water [12, 1, 19]. However, from these mentioned techniques, adsorption is more advantageous in terms of economy, design

1. Introduction Heavy metals that have atomic density greater than 5 g cm3 and atomic weights range from 63.5 to 200.6 such as arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), mercury (Hg) and nickel (Ni), are considered the major pollutants for fresh water reserves because of direct effect on living creatures [1, 2, 3, 4]. At the same time, they are non-biodegradable unlike organic contaminants and persistent in environment. When heavy metals release into ecosystem by various pollution source they have been causing worldwide problem. Particularly fast industrialization has caused releasing heavy metals into the environment and environmental pollution. The main sources of heavy metals are the wastewaters from modern industrial sources include chemical industries such as mining, metal plating facilities, surface coating, battery manufacturing, electrolysis, tannery, metallurgical, fossil fuel, paper and production of different plastics [5].

xxxx-xxxx/xx/xxxxxx

1

© xxxx IOP Publishing Ltd

Journal XX (XXXX) XXXXXX

Author et al.

and working flexibility, effectiveness, efficiency and highquality purified product. It is also important that the adsorbents used in the adsorption technique can be used repeatedly after some of the applied processes. [13, 14] Adsorption technique comes to the forefront, removal heavy metals from water/wastewater according to other techniques because of these advantages [18] So far, many researches have been investigations on sorption kinetics and thermodynamics, factors that affect sorption properties, possible absorption mechanisms and modification of adsorbents [14]. In this article reviewed the suitability of adsorbents that used in adsorption technique for purification heavy metals from water/wastewater. In addition to the suitability of adsorbents, studies on the use of environmentally friendly, easily obtained and economical materials such as clay, astragalus, sawdust, and adsorbents obtained from the assessment of wastes such as chestnut shells, egg shells, tea waste and banana peel, are also considered in particular. The adsorption capacities of the adsorbents were also compared. Results revealed that these adsorbents have proved magnificent removal capabilities for most of heavy metal ions.

equilibrium concentration (mg/L). q is the amount of metals adsorbed at equilibrium (mg/g) (Shen et al., 2012).

2. Adsorption models

3. Adsorption types

Isotherm adsorption models have been used in waste stream treatment to predict the ability of a certain adsorbent to remove a pollutant down to a specific discharge value. The equilibrium adsorption isotherm models such as Langmuir and Freundlich models are discussed in detail in order to understand adsorption kinetics.

3.1. Activated carbon

2.2. Freundlich model This model is permitting multilayer adsorption on sorbent. The linear form of Freundlich model is:

where KF is indicator of sorption capacity (mg1−n Ln g−1), qe is loading of adsorbate on adsorbent at equilibrium (mg/g), Ce is aqueous concentration of adsorbate at equilibrium (mg/L) and n is adsorption energetics. These models explore a detailed representation of adsorption equilibrium between the surface of the adsorbent and an adsorbate in solution [15].

Heavy metals (Cadmium, Nickel, Lead and Chromium) which are natural components of the Earth's crust are usually associated with toxicity. Exposure to heavy metals, even at trace level, is known to be a risk for humanbeings The presence of zinc, cadmium, nickel and others metals in the aqueous environment has a potentially damaging effect on human physiology and other biological systems when the acceptable levels are exceeded [18]. Heavy metals cannot be degraded or destroyed. Heavy metal toxicity could result, for instance, from drinking-water contamination (e.g. lead pipes), increased ambient air concentrations near sources of emission, or ingestion via the food chain [13]. The increased use of heavy metals in industry has resulted in increased availability of metallic substances in natural water sources [20]. Several adsorbents such as activated carbon, silica, and graphene can be used in the purification of water. Activated carbon has shown to be an efficient adsorbent for the removal of a wide variety of organic and inorganic contaminants present in the aquatic environment. Because of its high surface areas that range from 500 to 1500 m2 gí1 it is widely used in the treatment of wastewaters. The effectiveness of Activated carbon in cleaning up polluted water is due to its well developed porosity structure as well as the presence of a wide spectrum of surface functional groups. This makes it capable of distributing pollutants on its large internal surface, making them accessible to reactants [22]. Effectiveness of activated carbons to act as adsorbents for a wide range of contaminants is well noted [23]. Activated carbon (AC) was modified by heat treatment [24] where it was washed with deionized water and then heated to 450°C for 4 hours, the adsorption of heavy metals by the adsorbents was studied using batch experiments.

2.1. Langmuir model The single layer adsorption mechanics on the surface of the adsorbent can be analyzed by Langmuir isotherm. This model explains about the uniform adsorption which occurs on the active sites of the nano-adsorbents. The absorption process is terminated naturally once all the active sites are occupied by adsorbates. If the adsorption obeys Langmuir model, Ce/qe versus qe should be a linear plot. The linear Langmuir adsorption equation is given by the following equation.

where qm is the saturated monolayer adsorption capacity and b is the adsorption equilibrium constant. Ce is the equilibrium concentration (mg/L). A plot of Ce/qe versus Ce results in a straight line. The maximum adsorption capacity and bond energy of adsorbates can be calculated from the slope and intercept. The nonlinear form of Langmuir expression can be expressed as follows:

where qmax is the maximum adsorption capacity (mg/g) of absorbent, KL is equilibrium constant (L/mg) and, C is the

2

Commented [A1]: [17] Hua, M., Zhang, S., Pan B., Zhang, W., Lv, L., Zhang, Q., 2012. Heavy metal removal from water/wastewater by nanosized metal oxides: A review. Journal of Hazardous Materials, 211212:317-331.

Journal XX (XXXX) XXXXXX

Author et al.

Twenty milligram of AC was added to 20 ml of different concentrations of heavy metal standard solutions (30, 50, 100 & 200 ppm), while the pH of the solution was adjusted to 2.0 using 1.0 N HCl. The solution was sonicated for 20 min. at 100 rpm and then allowed to cool and followed by equilibration at room temperature for 24 hrs. Solids were allowed to settle down and were removed using syringe filtration. The residual heavy metals were determined by atomic absorption spectrophotometer (AAS) analysis [25]. The adsorption isotherms were obtained by increasing the concentration of heavy metal solutions from 50 up to 200 ppm. The removal percentage of the adsorbed heavy metal concentration was estimated followed the method adapted [10]. AC showed the greatest affinity towards nickel with 90 % removal percentage; the shifts in IR wave numbers reflected the bondings between AC and the adsorbed metals as presented by Freundlich isotherm. AC composite showed the greatest removal percentage for 30 & 200 ppm nickel. SEM images revealed that AC was a microparticle with an average size of 25 μm were nanoparticles having an average size of 12 nm. AC composite was the most effective microparticle for nickel removal and it is highly recommended to be used in water treatment for its high adsorptive capacity followed by AC. The other main challenge in heavy metals removal is to be able to select the activated carbon with suitable properties. Two aspects must be considered: the thermodynamic equilibrium of adsorption at operating temperature and the dynamic process or kinetic rate of the adsorption. A lot of published works have addressed at the same time the thermodynamics and the kinetics of metals adsorption on AC from aqueous solutions, but most of them examined only single-cation adsorption systems. As in multicomponent adsorption from the gas-phase, various Langmuir models are often used to describe multicomponent adsorption equilibrium. Olive stones, solid waste of the oleic industry, are available in important quantity in olive oil producing countries as Tunisia, where there are more than 60 million olive trees [26]. In order to valorize this waste byproduct generated during olive oil production, activated carbon (COSAC) was prepared by chemical processing using H3PO4 as an activating agent. The activated carbon produced is characterized by its high surface area, its developed micropores and heterogeneous surface functional groups [27]. The olive-stone-activated carbon was obtained by chemical activation using phosphoric acid as an activating agent according to the protocol optimized [28]. Raw milled olive stones were impregnated with a phosphoric acid solution (50% by weight) at 110 8C for 9 h. After drying, the impregnated material was subjected to thermal activation at 380 8C for 2.5 h in a vertical tubular reactor fed by a stream of nitrogen and heated by an electric furnace. The activated carbon obtained, labeled as COSAC, was washed thoroughly with distilled water to eliminate impurities, dried at 60 8C for 24 h and then sieved to the desired particle sizes to be used for adsorption experiments. The removal of heavy metal and lead metal ions from aqueous solution by adsorption on olive-stone activated carbon

produced by thermo chemical process using phosphoric acid (COSAC) was investigated. The obtained results show that metal adsorption is pH-dependent and maximum adsorption was found to occur at an initial pH of 5.0. The adsorption equilibrium was fast and was achieved, in our experimental conditions, after 200 min for the three metal ions studied. The kinetics of metal adsorption on COSAC follows the pseudo-second-order rate model and calculated initial rate constants (h) and external mass transfer coefficients (kL) follow the order: Pb(II) > C-Cd(II) > Cu(II). The equilibrium adsorption data are best fitted by the Redlich– Peterson model as compared to Langmuir, Freundlich and Sips models, and the adsorption capacity of COSAC decreased in the order: Pb(II) (147.526 mg/g) > Cd(II) (57.098 mg/g) > Cu(II) (17.665 mg/g).The results evidence that COSAC is a promising material for metal ions elimination in single and binary mixtures, due to its high specific surface area and to the presence of specific oxygen functional groups such as carbonyl, phenol and carboxylic ones, responsible for heavy metal ion uptake.

3.2. Activated alumina Activated alumina is a filter media made by aluminum ore so that it becomes porous and highly adsorptive. It can also be described as a granulated form of aluminum oxide. Activated alumina removes a variety of contaminants that often co-exist with fluoride such as excessive arsenic. The medium requires periodic cleaning with an appropriate regenerator such as alum or acid in order to remain effective. Activated alumina has been used as an effective adsorbent especially for point of use applications. The main disadvantage of activated alumina is that the adsorption efficiency is highest only at low pH and contaminants like arsenates must be peroxided to arsenates before adsorption in addition, the use of other treatment methods would be necessary to reduce levels of other contaminants of health concern. Activated alumina is materials, which utilizes the principle of adsorption to prevent environmental pollution and can be regenerated merely burning it with high temperature between 300 to 4000 C, It has been used for recently in industrials as adsorbent to remove impurities from gaseous or liquids and to polish effluent for meeting stringent discharge standard; as catalyst to improve process efficiency; and as gases container to store pure gas and other product. This makes activated alumina very useful in the clean up of toxic wastes and rain water runoff from contaminated areas. Rainwater can pick up contaminants such as soluble metals from industrial activity. It can also wash contaminants such as arsenic and lead into ground water from mining operations. Activated alumina is also an excellent desiccant it can dry air and other gases that have a high humidity. And so, it is used for dehydration and purification in the manufacturing of hydrogen peroxide, natural gas and gasoline. The adsorption potential of iron acetate coated activated alumina (IACAA) for removal of arsenic [As (III)] as arsenate by batch sorption technique is good. IACAA was characterized by XRD, FTIR, EDAX and SEM instruments. Percentage adsorption on IACAA was determined as a

3

Journal XX (XXXX) XXXXXX

Author et al.

function of pH, contact time and adsorbent dose. The study revealed that the removal of As (III) was best achieved at pH =7.4. The initial As (III) concentration (0.45 mg/L) came down to less than 0.01 mg/L at contact time 90 min with adsorbent dose of 1 g/100 mL. The adsorption was reasonably explained with Langmuir and Freundlich isotherms. The overall study reveals that the adsorption of arsenic onto IACAA is found to be dependent on pH, adsorbent dose and contact time. Best removal of As (III) is achieved at pH = 7.4. The initial As (III) concentration (0.45 mg/L) comes down to less than 0.01 mg/L with the minimal adsorbent dose (1 g/100 mL) at contact time 90 minutes. The thermodynamic studies of sorption of arsenic on IACAA show that the reaction is spontaneous and endothermic process. The equilibrium data are fitted to both Langmuir and Freundlich adsorption isotherm. But it is found that Langmuir isotherm model fitted well followed by Freundlich. The pseudo second order kinetic model is found to be the best correlation of the data for sorption of arsenic on IACAA. The kinetic of the reaction follows intraparticle diffusion model.

on a waste product of the paper industry were investigated by Guo et al (2008). They reported that lignin had affinity with metal ions from aqueous solution following order: Pb(II)>Cu(II)>Cd(II)>Zn(II)>Ni(II). To remove Cu(II) from aqueous solutions several biomass shells such as rice and wheat were performed by Aydın et al (2008). They found the maximum adsorption capacities as 8.977, 9.510 and 9.588; 7.391, 16.077 and 17.422; 1.854, 2.314 and 2.954 mg g -1 for lentil, wheat and rice adsorbents for Cu(II) at 293, 313, 333 K, respectively. Ince et al (2017), investigated Cu(II) ion adsorption onto various dried biomass such as banana peel, chestnut shell, and tea leaf waste in aqueous solutions. Several experimental parameters that influence on adsorption such as contact time, adsorbent amount and pH were performed. Developed method using these food waste biomass adsorbents were applied to mineral water and industrial wastewater samples and their Cu(II) removal potentials were compared. Based on results, maximum adsorption capacity of banana peel, chestnut shell, and tea waste were found as 1.94 mg g −1 −1 , 2.25 mg g , and 3.36 mg −1 g , respectively. Ince and Kaplan Ince (2017) using Box-Behnken design approach for removal of copper from wastewater performed several experimental parameters that influence on adsorption. Ince, (2014) used tea waste, astragalus plant and chestnut shell as inexpensive and environmentally friendly biosorbents for Ni(II) removal from aqueous solutions. Their adsorption capacity for Ni(II) was found to be 5.4 mg g -1 -1 , 1.3 mg g -1 and 5.6 mg g , respectively. This study pointed out the utilization of ecofriendly and low-cost biosorbents as an alternative natural adsorbent for Ni(II) ions removal. In another study, Ince and Kaplan Ince (2017) were to apply the Box–Behnken experimental design and response surface methodology for modeling of Cu(II) ions from an industrial wastewater and leachate pretreated astragalus herbal plant. Three independent variables (pH, contact time, and adsorbent amount) were studied. The significance of the independent variables and their interactions were tested by means of the analysis of variance (ANOVA). Biomass adsorption capacity was found as 1.98 mg g-1. Brinza et al (2007), studied heavy metals removal from wastewater using various algal biomasses. Also it was reported that the ability of algal species to remove heavy metals from wastewater depends on process or environmental factors. When compared uptake capacities of algal biomass for heavy metal removal it was found brown algae uptake capacities higher than red and green algae.

3.3. Biosorbents Because of to be new process using low-cost adsorbents derived from agricultural materials, biosorption is preferred by a lot of researchers to perform in various studies especially to remove heavy metals from aqueous effluents. Biosorption have some advantages including eco-friendly, inexpensive, high efficiency, reuse and possibility of metal recovery compared with adsorption other techniques. Commonly, the uses of food waste or agricultural residues are preferred because they contain three major structural components including hemicelluloses, cellulose and lignin. Qi and Aldrich (2008) investigated tobacco dust that a typical lignocellulosic agricultural residue for heavy metal adsorption efficiency. They reported that it set out a strong capacity for heavy metals including Cd(II), Zn(II), Ni(II), Pb(II) and Cu(II), and because their adsorption amount on biosorbent was calculated as 29.6 mg/g , 25.1 mg/g, 24.5 mg/g, 39.6 mg/g, and 36.0 mg/g, respectively. Solanum melongena leaves were used as inexpensive biosorbent material by Yuvaraja et al (2014). They characterized and used it to remove Pb (II) from aqueous solutions. Experimental data revealed that the biosorption processes of Pb (II) compatible with pseudosecond-order kinetics and maximum sorption capacity of biosorbent was found 71.42 mg/g for Pb(II) ions. Witek-Krowiak et al (2011), studied Cr(III) and Cu(II) ions biosorption from aqueous media using peanut shell under different experimental conditions for example biomass amount, temperature and pH. Based on biosorption equilibrium isotherms of peanut shells, their adsorption capacity was calculated for Cr(III) and Cu(II) as 27.86 mg g 1 -1 and 25.39 mg g Cu(II), respectively. Some biomass materials including Eichhornia crassipes, were used as dried biomass for heavy metals (Cr, Cd, Pb, Ni, Cu, and Zn) removal from aqueous media (Verma et al , 2008). Results revealed that all the biomass were efficiently removed Zn, Cd and Pb from aqueous media. Ni(II), Cu(II), Pb(II) and Zn(II) sorption

3.4. Graphene oxides Nanomaterials have gradually developed important roles to resolve heavy metal contamination because of their high surface area, enhanced active sites, and abundant function groups on the surfaces. Graphene is an atomically thin twodimensional carbon based nanomaterial that is composed of sp2 hybridized carbon atoms as found in graphite. Graphene is extensively used in electronics, biological engineering, filtration, lightweight/strong composite materials, and energy storage due to excellent electrical conductivity, high

4

Journal XX (XXXX) XXXXXX

Author et al.

mechanical strength and thermal conductivity, high impermeability to gases and optical transperancy [35]. Graphene oxide is considered as the oxidized form of graphene, functionalized by a range of reactive oxygenous functional groups [22]. It is generally prepared by chemical oxidation of graphite resulting in extended graphene sheets decorated with epoxy and hydroxyl functional groups in the basal planes and carboxylic acid groups at the edges and the oxygenous functional groups on graphene oxide make a significant contribution to its hydrophilicity and high negative charge density. The idea for using graphene oxide has been attracting increasing interest in some wastewater treatment because of high effectiveness, eco-friendliness, low-cost, mild reaction conditions and simple operation. Peng et al. (2016) found that 2D graphene oxide exhibits a typically wrinkled and sheet-like structure. XPS and FT-IR evidenced the oxygenous functional groups on the graphene oxide surface such as C-O-C group at 1228 cm-1 and 053 cm1 , -COOH group at 1722 cm -1 and C=C group at 1615 cm -1. Furthermore, it is widely believed that graphene oxide sheet was decorated with epoxy and hydroxyl functional groups in the basal planes and carboxylic acid groups at the edges. The –COOH and –OH groups presented at the edges of graphene oxide led to a negatively charged surface or acidic surface at a particular pH range attributed to the deprotonization in solution. The small highly negative charged graphene oxide particles in suspension could resist aggregation and make them disperse homogeneously due to the strong electrostatic repulsion. Moreover, the highly negative charge density on the surface of graphene oxide sheets dominated mainly in the adsorption of multivalent metal ions. Compared to other adsorbents, graphene oxide is regarded as the most promising adsorbent to adsorb various heavy metal ions due to its large theoretically specific surface are, surface hydrophobic π-π interaction, hydrophilicity, high negative charge density and easily synthesized from abundant natural graphite in large-scale using chemical oxidation and exfoliation method [45]. Graphene oxide is conventionally prepared by chemical oxidation and subsequent exfoliation of pristine graphite with either the Brodie, Staudenmaier, or Hummers methods, or some variations of these methods. Arthi et al (2015) used modified Hummers method for synthesized graphene oxide nanoparticles in which expandable graphite powder was used as the starting material. The interlayer distance of graphite increased until 226 nm that attributed to the π-π* of the aromatic C-C bonds. As for heavy metal ions adsorption, graphite adsorbent is considered as a promising adsorbent due to several researches on removal of heavy metal ions. Lingamdinne et al. (2015) have shown that maximum adsorption capacities on removal Co(II) using graphene oxide reached 21,28 mg/g at pH 5,5 and 298 K. Najafi et al. (2015) also used graphene oxide for removing Ni(II) content in a solution and reached 38,61 mg/g at pH 6.0 and 298 K. The maximum adsorption capacities of graphene oxide gave excellent result that shown graphene oxide had strong adsorption affinity to various heavy metal ions and the

maximum adsorption capacities generally greater than those of other adsorbents. As for the adsorbent dosage, increasing the concentration of adsorbent in a settled volume could reduce the available sites due to the effective surface area is likely decreased. Heavy metal ions at this stage can rapidly induce aggregation of graphene oxide by the strong interaction between them and carboxyl group [47]. With higher solid content, the interactions between graphene oxide sheets perhaps physically hinder partial reactive sites from the adsorbate, leading to the decrease of adsorption capacity or electrostatic attraction between the adsorbate and individual graphene oxide sheet reduces. Cui et al. (2015) shown that removal of Pb(II), Hg (II) and Cu(II) increased with the adsorbent dosage in the initial. However, when the adsorption reached saturation, continuingly increase of the adsorbent dosage could not increase the removal. Contrary it would lead to the waste of the adsorbent. The contact time between heavy metal ions and graphene oxide is a vital parameter for the adsorption capacity. The removal efficiency of most heavy metal ions increases sharply initially, and then slowly until reach maximum equilibrium as the contact time prolonged. With the increase of contact time, Cui et al. (2015) evidenced that both the remained available adsorption sites and the driving force between heavy metal ions and graphite sheets decreased, leading to the slow adsorptive process, and finally reach its saturating adsorption capacity. In order to increase the adsorption capacity, improve the adsorption selectivity of heavy metal ions or facilitate the separation of the spent graphene oxide from water, numerous materials have been used to functionalize graphene oxide. Polyacrylamide have been applied to modify graphene oxide by Xu et al. (2014) and gave outrageous result on removal Pb(II) in which maximum adsorption capacity reached 819,67 mg/g at pH 6 and 293 K. Ge et al. (2015) modified graphene oxide with triethylenetetramine for removing Cr(VI) and resulted maximum adsorption capacity 219.5 mg/g at pH 2 and 303 K. It has been confirmed that the oxygenous functional groups and thickness of graphene oxide, species of heavy metal ions in solute on and experimental conditions had a certain extent effect on the adsorption process. Additionally, the functionalized graphene oxide could not only increase the adsorption capacity and improve the adsorption selectivity, but also facilitate the separation of spent adsorbents from water which that means graphene oxide is one of best and lowcost options to remove heavy metal from toxic waterwaste.

3.5. Zeolites Zeolites are crystalline microporous materials that show interesting properties in catalysis, gas separation, and other important technological applications. Zeolites are acted as ion-exchange materials because of structural characteristics and valuable properties. Therefore, zeolites are widely used for metal ions removal from the aqueous medium because of their easily ion exchange with the metal cations, relatively high specific surface areas, high ion-exchange capacity

5

Journal XX (XXXX) XXXXXX

Author et al. and Pb2+ [30,31]. Zn, Cu Mn, and Pb in which the adsorption capacity rose between 2 and 25 times after zeolitisation. Origin of coal fly ash also has an effect on the adsorption capacity of the resultant zeolite.

besides low prices. Most of zeolites are the most abundant and they have high selectivity for certain pollutants such as heavy metals. According to Freundlich isotherm, the results revealed that Brazilian natural zeolite have a good removal performance for metals removal. Some natural zeolites including mordenite, clinoptilolite and modified zeolites were performed to remove As(V) from aqueous media. Results revealed that modified zeolites were more effective adsorbent for As(V) removal from aqueous solutions. To recover Eu(III), Fe(III) and Th(IV) from aqueous medium. Zeolites are a group of hydrated aluminosilicates of the alkali or alkaline earth metals: principally sodium, potassium, magnesium, lithium, barium and calcium. Zeolites are inorganic porous materials having a highly regular structure of pores and chambers that allow molecules to pass through and cause others to be either excluded or broken down. Differences in zeolites arise from pore diameter, pore shape and the way these pores are interconnected. The pore size plays a significant role in the use of zeolites: allowing or prohibiting the entrance of the molecules to the system. Following their discovery zeolites were found to be characterized by the following properties, catalytic properties; high hydration propensity; stable crystal structure when dehydrated; low density and high void volume when dehydrated; and cation exchange and sorption properties. Synthesized zeolites compared to natural zeolites have several advantages such as purity, uniform pore size and better ion exchange abilities. Zeolites can be used for gas purification and separation, ion exchange, catalysis, lightweight construction materials, waste water treatment media, radioactive waste treatment, pool filtration media, fertilizer and feed additive fillers, aquaculture, and gases,and as replacements for phosphates in detergents. There are three traditional fields for zeolite application namely separation, purification and environmental treatment process; petroleum refining, petrochemical, coal and fine chemical industry. One major area of concern where zeolites have found much application is the removal of heavy metals. Adsorption is a special characteristic of zeolites. The amount of metal adsorbed is affected by conditions like the nature and concentration of counter ions, pH, and metal solubility. Heavy metals ions such as Cu2+, Pb2+ and Cd2+ can be easily removed by zeolites. Removal of heavy metals by newly formed zeolites depend on selectivity of different ions, the composition of the water and temperature. Samples were taken from metallurgical industrial waste and treated with newly synthesised zeolite and there was great reduction in heavy metals in the effluent. For example Fe2+ changed from 124 ppm to 0.95 ppm and Zn 2+ from 583 ppm to 0.31ppm. Products of hydrothermal syntheses of zeolites from coal fly ash have a large exchange capacity as cation exchangers making them efficient inremoving heavy metals .in aqueous solutions. Most studies done show that the resultant zeolites have a high efficiency of metal uptake as compared to coal fly ash examples being in the case of Cu2+, Co2+ and Ni2+ at different pH and temperature with Indian ash, Cr (III) from aqueous solution, Cu2+, Cd2+,

4. Conclusions A review of various low cost adsorbents presented here shows the effectiveness and potential of the adsorption process by using low cost adsorbent for heavy metal removal. Toxic heavy metals such as Pb(II), Cd(II), Hg(II), Cu(II), Ni(II), Th(IV), Cr(VI), as well as other elements have been successfully removed from contaminated industrial, municipal waste waters and toxic waste using various low cost adsorbents. More studies should be carried out for a better understanding of the process of low-cost adsorption instead of promoting the use of non-conventional adsorbents on a large scale. Table 1. Classification of Heavy Metal Adsorbent Adsorbent Heavy Metal pH Adsorption Types Adsorbed Condition Performance Activated Pb(II), Cu(II), 5.0 90% Ni Carbon Cd(II), Ni removed Activated As(III) 7.4 0,01 mg/g Alumina As(III) Biosorbent Zn, Cd, Pb, Ni Zn 25,1 mg/g Cd 29,6 mg/g Pb 39,6 mg/g Ni 24,5 mg/g Graphene Oxide Zeolite

Co Fe2+, Zn2+

5.5-6.0

21,28 mg/g Co Fe2+ 248-0,95 ppm Zn2+583-0,31 ppm

References [1] O’Connell, D.W., Birkinshaw, C., O’Dwyer, T.F., 2008. Heavy metal adsorbents prepared from the modification of cellulose: a review. Bioresource Technology, 99:6709-6724. [2] Srivastava, N.K., Majumder, C.B., 2008. Novel biofiltration methods for the treatment of heavy metals from industrial wastewater. Journal of Hazardous Materials, 151:1-8 [3] Fu, F.L., Wang, Q., 2011. Removal of heavy metal ions from wastewaters: a review. Journal of Environmental Management, 92:407-418. [4] Barakat, M.A., 2011. New trends in removing heavy metals from industrial wastewater. Arabian Journal of Chemistry, 4:361-377. [5] Marques, P.A.S.S., Rosa, M.F., Pinheiro, H.M. 2000. pH effects on the removal of Cu2+, Cd2+ and Pb2+ from aqueous solution by waste brewery waste. Bioprocess Engineering, 23:135-141. [6] Jamil, M., Zia, M.S., Qasim, M., 2010. Contamination of agroecosystem and human health hazards from wastewater used for

6

Journal XX (XXXX) XXXXXX

Author et al.

irrigation. Journal of the Chemical Society of Pakistan, 32:370378. [7] Khan, S., Cao, Q., Zheng, Y.M., Huang, Y.Z., Zhu, Y.G., 2008. Health risks of heavy metals in contaminated soils and food crops irrigated with wastewater in Beijing, China. Environmental Pollution, 152:686-692 [8] Singh, A., Sharma, R.K., Agrawal, M., Marshall, F.M., 2010. Health risk assessment of heavy metals via dietary intake of foodstuffs from the wastewater irrigated site of a dry tropical area of India. Food and Chemical Toxicology, 48:611619. [9] Peng, S.H., Wang, W.X., Li, X.D., Yen, Y.F., 2004. Metal partitioning in river sediments measured by sequential extraction and biomimetic approaches. Chemosphere, 57:839-851. [10] Qu, X., Alvarez, P.J.J., Li, Q., 2013. Applications of nanotechnology in water and wastewater treatment. Water Research, 47(12):3931-3946. [11] Ageena, N.A., 2010. The use of local sawdust as an adsorbent for the removal of copper Ion from wastewater using fixed bed adsorption. Engineering & Technology Journal, 28(2):224235. [12] Kurniawan, T.A., Chan, G.Y.S., Lo, W.H., Babel, S., 2006. Physico-chemical treatment techniques for wastewater laden with heavy metals. Chemical Engineering Journal, 118:83-98. [13] Pan, B., Pan, B., Zhang, W., Lv, L., Zhang, Q., Zheng, S., 2009. Development of polymeric and polymer-based hybrid adsorbents for pollutants removal from waters. Chemical Engineering Journal, 151:19-29. [14] Zhao, G., Wu, X., Tan, X., Wang, X., 2011. Sorption of heavy metal ions from aqueous solutions: A review. The Open Colloid Science Journal, 4:1931. [15] A. Rahmani, H. Z. Mousavi, and M. Fazli. Effect of Nanostructure Alumina on Adsorption of Heavy Metals. Desalination 253, (2010): 94-100. [16] W. Shen, S. Chen, S. Shi, X. Li, and X. Zhang. Adsorption of Cu(II) and Pb(II) onto Diethylenetriamine-bacterial Cellulose. Carbohydrate Polymers 75, no. 1 (2009): 110-114. [17] Demirbas A. Heavy metal adsorption onto agro-based waste materials: A review. Journal of Hazardous Materials 2008; 157: 220–229 [18] Hua M, Zhang S, Pan B, Zhang W, Lv L, Zhang Q. Heavy metal removal from water/wastewater by nanosized metal oxides: A review. Journal of Hazardous Materials 2012; 211:317– 331 [19] Fu F, Wang Q Removal of heavy metal ions from wastewaters: A review. Journal of Environmental Management 2011; 92:407-418 [20] Kadirvelu K, Goe J, Rajagopal l. Sorption of lead, mercury and cadmium ions in multi- component system using carbon aerogel as adsorbent. Journal of Hazardous Materials 2008; 153:502-507, [21] Immamuglu M, Tekir O. Removal of copper (II) and lead (II) ions from aqueous solutions by adsorption on activated carbon from a new precursor hazelnut husks. Desalination 2008; 228:108-113. [22] ] Liu Q, Zheng T, Wang P, Jiang J, Li N. Adsorption isotherm, kinetic and mechanism studies of some substituted phenols on activated carbon fibers. Chemical Engineering Journal 2010; 157:348–356 [23] Bhatnagar A, Hogland W, Marques M, Sillanpaa M. An overview of the modification methods of activated carbon for its water treatment applications. Chemical Engineering Journal 2013; 219:499–511

[24] Yin C, Aroua M, Daud W. Review of modifications of activated carbon for enhancing contaminant uptakes from aqueous solutions. Separation and Purification Technology 2007; 52:403–415 [25] Gao W, Majumder M, Alemany B, Narayanan T, Ibarra M, Pradhan B, Ajayan P, Engineered Graphite Oxide Materials for application in water purification. Journal American Chemical Society Applied Materials and interfaces 2011; 3:1821-1826 [26] H. Hannachi, M. Msallem, S.B. Elhadj, M. El Gazzah, C. R. Biologies 330(2007) 135. [27] T. Bohli, N. Fiol, I. Villaescusa, A. Ouederni, J. Chem. Eng. Process.Technol. 4 (2013) 1. [28] H. Gharib, A. Ouederni, Re´cents progre`s en ge´nie des proce´de´s, SFGP,Paris, France, 2005 p. 92[ISBN 2-910239-667]. [29] Aydın, H., Bulut, Y., Yerlikaya, Ç., 2008. Removal of copper (II) from aqueous solution by adsorption onto low-cost. adsorbents. Journal of Environmental Management, 87:37-45. [30] Brinza LDring MJ, Gavrilescu M. Marine micro- and macroalgal species as biosorbents for heavy metals. Environ Eng Manage J 2007;6:237–51 [31] Ince, M., 2014. Comparision of low-cost and ecofriendly adsorbent for adsorption of Ni(II). Atomic Spectroscopy, 35(5):223-233. [32] Ince, M., Ince, O.K., Asam, E., Önal, A., 2017. Using food waste biomass as effective adsorbents in water and wastewater treatment for Cu(II) removal. Atomic spectroscopy, 38(5):142148. [33] Ince, M., Kaplan Ince O., 2017. Box–Behnken design approach for optimizing removal of copper from wastewater using a novel and green adsorbent. Atomic spectroscopy, 38(6):200-207. [34] Qi, B.C., Aldrich, C., 2008. Biosorption of heavy metals from aqueous solutions with tobacco dust. Bioresource Technology, 99:5595-5601. [35] Witek-Krowiak, A., Szafran, R.G., Modelski, S., 2011. Biosorption of heavy metals from aqueous solutions onto peanut shell as a low-cost biosorbent. Desalination, 265:126-134. [36] Yuvaraja, G., Krishnaiah, N., Subbaiah, M.V., Krishnaiah, A., 2014. Biosorption of Pb(II) from aqueous solution by Solanum melongena leaf powder as a low-cost biosorbent prepared from agricultural waste. Colloids and Surfaces B: Biointerfaces, 114:75- 81. [37] P. Solis-Fernandez, R. Rozada, J.I. Paredes, S. Villar-Rodil, M.J. Fernandez-Merino, L. Guardia, A. Martinez-Alonso, and J.M.D. Tascon. Chemical and Microscopic Analysis of Graphene Prepared by different reduction degrees of graphene oxide. Journal of Alloys and Compound 536, no. 1 (2012): 532-537. [38] Majumdar, D. 2017. Proficiency of Graphene Oxide in Adsorption and Removal of Methylene Blue from Water: An Overview. Pulsus Journals, 2017. [39] G. Arthi, K. Rajasekar, T. Sakhtivei, V. Gunasekaran, and Sangjae Kim. Removal of Heavy Metal Ions from PharmaEffluents using Graphene-Oxide Nanosorbents and Study of Their Adsorption Kinetics. Journal of Industrial and Engineering Chemistry 5, no. 6 (2015): 1-27. [40] Z. Guizia, L. Jiaxing, R. XUemei, C. Changlun, and W. Xiangke. Few-Layered Graphene Oxide Nanosheets As Superior Sorbents for Heavy Metal Ion Pollution Management.

7

Journal XX (XXXX) XXXXXX

Author et al.

Environmental Science and Technology 45, no. 24 (2011): 10454-10462. [41] Sakthivel, R. Nivea, R. Govindan, S. J. Kim, and V. Gunasekaran. Structural and Mechanical Properties of MgOPoly(Vinyl Alcohol) Nanocomposite Film. Advanced Science Engineering and Medicine 7, (2015): 1-8. [42] D.Li, M.B. Mueller, S. Gilje, R.B. Kaner, and G.G. Wallace. Processable Aqueous Dispersions of Graphene Nanosheets. Nature Nanotechnology 3, (2008): 101-105. [43] S. Sheshmani, M. Akhundi Nematzadeh, S. Shokrollahzadeh and A. Ashori. Preperation of Graphene Oxide/Chitosan/FeOOH Nanocomposite for the Removal of Pb(II) from Aqueous Solution. Journal of Biological Macromolecules 80, (2015): 475480. [44] G. Arthi, K. Rajasekar, T. Sakthivel, V. Gunasekaran and Sang-Jae Kim. Removal of Heavy Metal Ions from PharmaEffluents using Graphene-Oxide Nanosorbents and Study of Their Adsorption Kinetics. Journal of Industrial and Engineering Chemistry, (2015): 1-27. [45] D. Gu and J. B. Fein. Adsorption of Metals onto Graphene Oxide: Surface Complexation Modeling and Linear Free Energy Relationships. Colloids and Surfaces A: Physicochemical and Engineering Aspects 481, (2015): 319-327 [46] L.P. Lingamdinne, J.R. Koduru, H. Roh, Y.L. Choi, Y. Y. Chang, and J. K. Yang. Biogenic Reductive Preparation of Magnetic Inverse Spinel Iron Oxide Nanoparticles for the Adsorption Removal of Heavy Metals. Chemical Engineering Journal 307, (2017): 74-84. [47] S.T.Yang, Y. Chang, H Wang, G. Liu, S. Chen, Y. Wang, Y. Liu, and A.Cao. Folding/ggregation of Graphene Oxide and its Application in Cu2+ removal. Journal of Colloid Interface 351, no. 1 (2010): 122-127 [48] L. Cui, Y. Wang, L. Gao, L.Hu, L. Yan, Q. Wei, and B. Du. EDTA Functionalized Magnetic Graphene Oxide for Removal of Pb(II), Hg(II), and Cu(II) in water treatment: Adsorption Mechanism and Separation Property. Chemical Engineering 281, (2015): 1-10. [49] Z. Xu, Y. Zhang, X.Qian, J. Shi, L. Chen, B. Li, J. Niu, and L. Liu. One Step Synthesis of Polyacrylamide Functionalized Graphene and Its Application in Pb(II) Removal. Applied Surface Science 316, (2014): 308-314. [50] H. Ge and Z. Ma. Microwave Preparation of Triethylenetetramine Modified Graphene Oxide/Chitosan Composite for Adsorption of Cr(VI). Carbohydrate Polymers 131, (2015): 280-287. [51] Ince M, Ince O. An Overview Of Adsorption Technique For Heavy Metal Removal From Water/Wastewater: A Critical Review. Review Critical 2017; 3:10-19. [52] Sumba M, Chigondo M, Guyo U, Chigondo F, Moyo M, Nharingo T, Sebata E. Synthesis of Zeolites and Their Applications in Heavy Metals Removal: A Review. Engineering Science and Technology: An International Journal (ESTIJ) 2011; 3:111-114.

8