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 ext raction of Cr(VI) from dilute solutions using Aliquat 336 as the carrier. C hitosan membranes serve as a reactive barrier between aqueous and organic p hases: both passive and active transport through the membranes are suspecte d to occur, depending on the experimental conditions and the characteristic s of the membrane. The pH of the solution is a key parameter for the effici ent 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 o f chitosan, resulting from the reaction of acetic anhydride with the biopol ymer (after water exchange with methanol as the solvent), is expected to in crease its resistance to chemical degradation in very acidic solutions but decreases its extraction efficiency.