Sorption Of Nickel

Sorption of Nickel from Waste Water using Plants Biomasses Dr. Abida Begum Department of Chemistry, P.E.S School of Engineering, Bangalore- 560 100 Email: [email protected]

Abstract Adsortion of Nickel Ions in dynamic experiments on columns packed with the shoots of Gloriosa Surparba (GS), Rice (RS) , Jowar (JS); Bengal gram (BS); Pigeon Pea (PS) was studied and examined for their ability to bind nickel ions from aqueous solution, between PH 2 and 6.5 and temperatures 30, 40and 50 and also time dependency studies were determined between 5 to 50 minutes. The removal of nickel ions in general is favourable at high temperature and 6.5 pH, and with respect to time. The ability of binding nickel ions Specifically in GS and PS was reasonably high

Key Words: Gloriosa Surparba shoots (GS); Rice Shoots (RS); Jowar shoots (JS) ; Bengal gram Shoots (BS); Pigeon Pea Shoots (PS); nickel binding. INTRODUCTION Gloriosa Surparba (GS) grows in rural parts of Karnataka state especially near the fields where more inorganic fertilizer is used . It grows during October and November. The plant is commonly called as morning glory, produced large flowers and the leaves produced tendrils at the leaf tip. These tendrils help the plant to hold on to other plants to hold on to other plants for support and climb on them. It belongs to liliceae family, popularly known as gowri in Kannada. It is also called as Agnimuchi, Nimbhi and vishakanye. Rice( RS) is a staple food, belongs to the family of Gramineae (Poacea), the scientific name of the plant is Oryza sativa L Rice Hay is used for our study as biomass.Jowar (JS) is also a staple food belongs to Gramineae (Poaceae) its scientitfis name is Sorgham Vulgare L Jowar stalks are used for our study as biomass. The Stalks of Bengal gram (BS) and Pigeon pea (PS) which comes under the family Leguminosea its scientific name is Cicer arietinum L and Cajanus cajan L are used for our study as biomass These shoots were taken for our study from heavily fertilized fields. We know many researchers have investigated methods to prevent or reduce metals in the environment. Biological methods are the best for remediation [5-10]. Many live microbial and fungal systems have been studied and have shown good results [11-13]. Recently, plants have been studied for their ability to remove contaminants from the environment [14-19]. However, dead systems offer many advantages over live systems because they don’t fall prey to the toxicological effects of high concentrations of contaminants and can be obtained inexpensively. Dead or inactivated systems may be more practical because they don’t require pretreatment with nutrients to maintain the biological activity of the system [20-23]. The immobilization of biomaterial has also proven to be a good method for metal accumulation from contaminated waters under flow conditions [24-26]. Thus, a combination of these methods into a dead or inactivated immobilized system may prove to be very efficient and practical for the removal of metals from contaminated waters. We chose GS, RS,JS,BS and PS biomass as a source for biomaterial thinking that it may be having a higher tolerance to concentrated metal contamination than many other plants. [27- 28]. The study of , alfalfa shows potential for a biomaterial to be

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used in a dead immobilized system for the removal of metals from contaminated waters. The objective of our study was to investigate the binding of nickel ions from solutions of five different biomass. Laboratory batch experiments were performed with ground, powdered, washed and filtered biomass to determine optimal pH, temperature and the time required for nickel binding to all the above biomasses. Column experiments were performed examine nickel removal and recovery under flow conditions.

Experimental Data analysis-The experiments were performed in triplicate and the samples was analyzed in triplicate .For each set of given data, standard statistical methods were used to determinethe mean values and standard deviations .Confidence intervals of 95% were calculated for each set of samples to determine the error margin.

Analytical procedure Analysis for nickel was performed using a Perkin Elmer model 3110 Atomic Absorption Spectrometer with deuterium background subtraction. Impact bead was utilized to improve the sensitivity at a wave length of 352.4 nm. Samples were read three times, and a mean value and relative standard deviation was computed. Calibrations were performed in the range of analysis, and a correlation coefficient for the calibration curve of 0.98 or greater was obtained. The instrument response was periodically checked with known nickel standards. The difference between the initial metal concentration and the remaining metal concentration in effluents was assumed to be taken up by the biomass. A pH meter Elico Li-129 Model glass –calomel combined electrode was employed for measuring pH values, Centrifuge machine and Remi Shaker were used.

Table-1 Effect of pH on nickel binding by different family of biomasses at 30 oC Samples of Biomass 0.5 mM of nickel

pH 2.0

pH 3.0

pH 3.5

pH 5.5

pH 6.5

Gloriosa Surparba shoots (GS)

13

45

57

87

98

Rice Shoots (RS)

12

33

45

56

88

Jowar shoots (JS)

11

44

56

66

80

Bengal gram Shoots (BS)

10

33

50

67

77

Pigeon Pea Shoots (PS)

14

40

55

77

98

Preparation of Column The column was washed with 10 bed volumes of 0.01 M sodium acetate buffer at pH 4.5 and the effluent pH was checked to ensure that the column was at the optimal binding pH. Six ml of the immobilized biomas was used in the column A flow rate of 1 ml per minute was used to pass 120 bed volumes of 5.0 ppm nickel solution in 0.01 M sodium acetate at pH 5.0. Each bed volume was collected and analyzed .

Table-2 Effect of pH on nickel binding by different family of biomasses at 40 oC 2

Samples of Biomass 0.5 mM of nickel Gloriosa Surparba shoots (GS)

pH 2.0 44

pH 3.0 51

pH 3.5 62

pH 5.5 89

pH 6.5 98

Rice Shoots (RS)

15

40

51

54

60

Jowar shoots (JS)

13

51

59

66

71

Bengal gram Shoots (BS) Pigeon Pea Shoots (PS)

23 44

46 45

62 64

67 78

78 98

Immobilization of the biomass The method for immobilization of cell wall material within a polysilicate matrix was similar to that reported in literature. A 5 g sample of each biomass was washed twice by vortexing the sample with water and was centrifuged for three minutes This is done to ll remove solubles and impurities debris. Next, 75 ml of 5% H2SO4 was mixed with enough 6% Na2SiO3 solution to raise the pH to 2.0. At pH 2.0, the 5 g each of washed biomass was added to the silica solution and allowed to stir for 15 minutes .The pH was then raised slowly by addition of 6% sodium silicate (Na 2SiO3 ) to reach a final pH of 7.0. The polymer gel was washed with water enough times so that by the addition of two drops of barium chloride (BaCl 2) there was no white precipitate forming. BaCl2 was used to indicate whether the sulfates had been removed. The polymer gel with the immobilized biomass was dried overnight at 60ºC and then ground by mortar and pestle and sieved to20-40 mesh size.

Amount of nickel bound at different intervals of time at 50 oC Samples of Biomass 0.5 mM of nickel

pH 2.0

pH 3.0

pH 3.5

pH 5.5

pH 6.5

Gloriosa Surparba shoots (GS)

52

55

71

92

98

Rice Shoots (RS)

20

42

53

52

88

Jowar shoots (JS)

22

53

60

68

82

Bengal gram Shoots (BS)

19

46

67

72

78

Pigeon Pea Shoots (PS)

48

49

66

89

97

Effect of pH on nickel binding Eight different samples of biomass were washed twice with 0.02 M hydrochloric acid (HCl) to remove any impurities or soluble biomolecules that might interact with metal ions, dried and weighed to account for any biomass weight loss. Each biomass sample was resuspended in 50 ml of 0.01 M HCl to make the concentration approximately to 5 mg/mL solution. Batch laboratory techniques were used for the pH studies. The pH was then

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adjusted and allowed to equilibrate at pH 2.0,3.0, 3.5, 5.5 and 6.5, and 2 ml aliquot of the suspensions at each pH were transferred into 3 tubes for each pH into 5 ml plastic tubes. The suspensions were centrifuged for three minutes and the supernatants were kept for testing to determine if soluble materials were binding the metal. A solution of 0.2 mM nickel nitrate (Ni(NO3)2) was prepared and pH adjusted to 2.0, 3.0, 3.5, 5.5 and 6.5. At each pH, 2 ml of the nickel solution was added to the respective pH biomass pellet and separated supernatant. In addition, at each respective pH, 2 ml of the 0.1 mM nickel solution was transferred to 3 tubes for controls. All the tubes were equilibrated on a rocker for 1 hour. The samples were then centrifuged for three minutes and the supernatants for the pellets were transferred to clean respective tubes. Final pHs for all tubes were recorded and analysis for nickel was performed

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Effect of contact time A 500 mg sample of biomass was washed twice with 0.01 M HCl to remove any impurity or soluble biomolecules that might interact with metal ions. The washings were collected, dried and weighed to account for any biomass weight loss. Each biomass sample was resuspended in 100 ml of deionized water with tissue concentration approximately 5 mg per ml solution. The solution was then adjusted to pH 6.5 and allowed to equilibrate. Two ml of the suspension was transferred to 24 tubes; 3 tubes for each time interval of 5, 10, 15, 20,25, 30, 45 and 50 minutes. After centrifugation,2 ml of 0.1 mM nickel solution was added to each of the tubes and controls. All the tubes were equilibrated by rocking and were removed at the appropriate time intervals. The samples were then centrifuged for three minutes and the supernatants from the pellets were transferred to clean respective tubes. Final pHs for all tubes were recorded, and analysis for nickel was performed.

Nickel binding capacity Samples of 100 mg of biomass were washed twice with 0.01 M HCl, and washings were collected and weighed to determine biomass loss. Washed biomass was resuspended in 20 ml of deionized water and pH adjusted to 6.5. Two ml of the suspension was transferred to 3 tubes and then centrifuged. The supernatants were saved for testing. Two ml of 0.3 mM nickel solution was added to each of the tubes and controls and were equilibrated for 10minutes. After centrifugation, the supernatants were saved for analysis and again 2 ml of 0.3 mM nickel solution was added. This was repeated 12 times or until the saturation point was achieved and a final pH for all

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tubes was recorded. Samples were diluted as required to stay within the calibration linear range and analysis for nickel was performed

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Desorption of the adsorbed nickel To remove the bound nickel, 0.01 M HCl was passed at a flow rate of 1 ml per minute.Each bed volume was collected and analyzed as indicated. Pellets from capacity studies with adsorbed nickel were exposed to 2 ml of 0.1 M HCl, equilibrated by rocking for 5 minutes, and then centrifuged. Supernatants were collected for analysis and diluted as required to stay within the calibration range. Pellets were then exposed to 2 ml of 1 M HCl to strip any remaining metal and equilibrated by rocking for 5 minutes. After centrifugation, the supernatants were analyzed. All analysis for nickel was performed.

Samples of Biomass 0.5 mM of nickel

Time in minutes 5

10

15

20

25

30

35

40

45

50

Gloriosa Surparba shoots (GS)

76

85

87

89

92

92

98

98

98

98

Rice Shoots (RS)

4

8

12

15

20

22

57

68

79

88

Jowar shoots (JS)

8

9

10

14

46

58

58

69

78

82

Bengal gram Shoots (BS)

8

10

11

16

19

21

25

68

70

78

Pigeon Pea Shoots (PS)

66

69

75

74

75

76

77

77

77

97

RESULTS AND DISCUSSION

The pH studies performed on the Five different populations of organic matter showed that binding of nickel to the all the different biomasses is pH dependent .Figures 1,2 and 3 show the binding of nickel ions to the various biomass shoots as the pH is raised from 2.0 to 6.5. For all the varieties tested, 60% to 98% binding of nickel ions occurred at 6.5 and 50 o C. From Figures 1, 2 and 3, it can be observed that as the pH decreased the binding of nickel ions to the biomass also decreased. This trend observed as pH dependent and also temperature dependent, binding might be due to an ion-exchange type of binding mechanism as proposed by other researchers. When the pH is higher than 3-4, the carboxyl groups are deprotonated and left with a negative charge. Time dependency experiments were conducted in order to determine how long the above biomass would

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take to bind the nickel ions at optimal pH and temperature. Since all soluble materials were eliminated during prior washings, the binding could only have occurred by the above biomass. Figure 4 shows the binding time for nickel by the shoots for all the populations studied. As can be seen in the figures, nickel bound to the different population of biomass was maximum at 50 minutes and in particular GS and PS binding was very fast i.e., in less than five minutes at 50 o C.

Figure-1 Effect of pH on nickel binding by different family of biomasses at 50 oC

Figure-2 Amount of nickel bound at different intervals of time at 40 oC

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Figure-3 Effect of pH on nickel binding by different family of biomasses at 50 oC

Figure-4 Time dependency of nickel binding at 50 oC

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