Functional monomers and polymers. LXX. On the adsorption of iodine onto chitosan

The ability of adsorbing iodine in different organic solutions by chitosan was studied by sorption isotherm measurements. The ability was found to be larger in polar solvents than in nonpolar solvents. The form of the chitosan samples, such as film, powder, and flake, had no influence on the adsorption behavior. On the other hand, chitin had only small adsorbing ability of iodine. It is concluded that the adsorption of iodine is caused by charge—transfer complexes between aminogroups of chitosan and iodine molecules, but their structure differs from that of inclusion compounds as seen in amylose–iodine complexes. The adsorption was also studied on chitosan films with different degrees of acetylation.