Remediation of heavy metals from industrial effluents and ground water sources poses a significant challenge. Hexavalent chromium is one such heavy metal, prevalent in industrial wastewaters, which has been proven to be toxic to humans and other living organisms. Most of the conventional methods available for dealing with chromium are either cost prohibitive or generate secondary effluents which are difficult to deal with. The idea of bioremediation has gained much momentum over the last few decades because of its potential low cost and minimum impact on the environment. This study explored the potential for hexavalent chromium bioremediation using a synthetic cationic biopolymer alpha-poly-l-lysine (alpha-PLL) as a biosorbent. In the present research work, equilibrium batch studies were performed in a specially designed dialysis apparatus to obtain preliminary information about the adsorption capacity of the polymer. Metal uptake by the polymer was found to be maximum when the pH of chromium solution (pH 4.6) and that of poly-lysine (pH 5.7) was not changed at the beginning of the experiment. Applying the Langmuir adsorption isotherm model showed that alpha-PLL has a maximum uptake capacity of 42.2 microgram Cr/mg alpha-PLL, and a binding constant of 1.2 microgram/mL +/- 10%. The metal uptake performance of the polymer was also evaluated in a Polymer Enhanced Diafiltration (PEDF) system. The polymer-metal complex was retained and concentrated by the PEDF set up using a tangential flow filtration membrane, while the clean filtrate flowed through. When 3.4 L of 10 mg/L chromium solution in the Cr2O72- form was processed using 300 mL of 2 gm/L PLL, the concentration of chromium in the permeate reached a maximum of 0.79 mg/L. When 30 mg/L chromium solution was used, 2 L could be processed using 300 mL of 2gm/L PLL, and 7.8 mg/L chromium could be detected in the permeate in the end.
| Identifer | oai:union.ndltd.org:wpi.edu/oai:digitalcommons.wpi.edu:etd-theses-1600 |
| Date | 01 May 2009 |
| Creators | Chakraborti, Amrita |
| Contributors | Daniel G. Gibson III, Committee Member, Alex DiIorio, Advisor, , Theodore C. Crusberg |
| Publisher | Digital WPI |
| Source Sets | Worcester Polytechnic Institute |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Masters Theses (All Theses, All Years) |
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