Worcester Polytechnic Institute Electronic Theses and Dissertations Collection

Title page for ETD etd-050406-115241


Document Typethesis
Author NameShetty, Ameesha R
Email Address ameeshashetty at gmail.com
URNetd-050406-115241
TitleMetal Anion Removal from Wastewater Using Chitosan in a Polymer Enhanced Diafiltration System
DegreeMS
DepartmentBiology & Biotechnology
Advisors
  • Dr. Alexander A. Di Iorio, Advisor
  • Dr. Theodore C. Crusberg, Co-Advisor
  • Dr. Daniel G. Gibson III, Committee Member
  • Keywords
  • Polymer Enhanced Diafiltration
  • Biosorption
  • Chitosan
  • Date of Presentation/Defense2006-04-11
    Availability unrestricted

    Abstract

    Discharge of metal containing effluents into water has been a cause of major concern. Traditional treatment methods are proving to be ineffective and expensive. Chitosan was studied as a potential biosorbent due to its positive charge and relatively low cost. The study involves evaluating the metal binding performance of chitosan in a polymer enhanced diafiltration (PEDF) system which uses an ultrafiltration membrane to retain the chitosan which, in turn, binds the metal, thereby preventing passage into the permeate stream. Conditions for binding such as pH, concentration of polymer and chromium were studied. Optimal performance was obtained when the system was operated at pH values lower then the pKa of chitosan i.e. 6.3. Using 6 g/L chitosan at pH 4.0, chromium concentration was reduced to less than 1mg/L from a feed concentration of 20 mg/L. Equilibrium dialysis experiments were done to study the kinetics of binding and the uptake of metal per gram of polymer. Rheological measurements demonstrated that in the presence of 1-100 mM chromate, chitosan was found to be slightly shear-thickening at low concentrations such as 4 g/L and 6 g/L whereas it was slightly shear-thinning at higher concentrations like 12 g/L and 20 g/L This suggests that neutralization of chromium anions is due to the interaction of multiple chitosan molecules. This result is consistent with the relatively stiff nature of the polysaccharide. Overall, this study suggests that some modification of the native polymer would be required to improve uptake and make it an industrially workable process.

    Files
  • Shetty.pdf

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