Cr(VI) Extraction Using Aliquat 336 in a Hollow Fiber Module Made of Chitosan

Chitosan hollow fiber modules have been prepared and tested for solvent extraction of Cr(VI) from dilute solutions using Aliquat 336 as the carrier. Chitosan membranes serve as a reactive barrier between aqueous and organic phases: both passive and active transport through the membranes are suspected to occur, depending on the experimental conditions and the characteristics of the membrane. The pH of the solution is a key parameter for the efficient extraction of Cr(VI): pH should be maintained below pH 4.5. Extraction kinetics and equilibrium are also controlled by the solvent used to dilute the carrier: kerosene is better than cumene and xylene. The reacetylation of chitosan, resulting from the reaction of acetic anhydride with the biopolymer (after water exchange with methanol as the solvent), is expected to increase its resistance to chemical degradation in very acidic solutions but decreases its extraction efficiency.