FORMATION OF A TERNARY COMPLEX BETWEEN CHITOSAN AND ION-PAIRS OF STRONTIUM CARBONATE

This work deals essentially with the study of the interactions between chitosan and an alkaline-earth metal: Sr-85. We showed that addition of carbonate ions is necessary to observe this interaction, but only f or pH values over 11. The use of an appropriate calculation software a llowed us to determine the nature of the strontium ionic species prese nt in solution. In order to understand the mechanism of interaction, t he influence of various parameters on the complexation was studied. Th us, the interaction was maximum for a CO32- concentration close to 10( -2) mol/l, the lowest ionic strength, the most expanded physical form (lyophilisate) and the lowest degree of acetylation of the polymer. We conclude to the formation of a ternary complex between the ion pair S r-2 + CO32- and the amino groups of chitosan. We also showed the prese nce of interactions between chitosan and carbonate ions which hinder f urther interactions with strontium ions. (C) 1998 Elsevier Science B.V . All rights reserved.