Influence of the nature of the metal ions on the complexation with chitosan.: Application to the treatment of liquid waste

The capacity of the chitosan to complex metallic ions is one of its most important potentialities. This polymer shows a selectivity according to the considered cation. In the case of divalent ions the capacity to fix the metallic ions increases from 0.02 mmol/g of chitosan for Co2+, Ca2+ to 1.2 for Cu2+ in the same external conditions. Considering trivalent ions this capacity is from 0.2 mmol/g of chitosan for Pr3+ and Cr3+ to 1.47 for Eu3+ and Nd3+. This selectivity seems to be independent on the size and the hardness of the ions. This order in the selectivity is confirmed using potentiometric and spectrophotometric methods and does not depend on the physical form of chitosan. Recovery tests of metals were carried out on real effluents. The first results obtained confirm the initial interest in using chitosan as a depolluting agent, especially as a film. (C) 2002 Elsevier Science Ltd. All rights reserved.