INTERACTION BETWEEN CHITOSAN AND URANYL IONS - PART-2 - MECHANISM OF INTERACTION

In this part of the study-understanding the mechanism of interaction b etween chitosan and uranyl ions, we confirmed the restrictive role of polymer crystallinity on uranyl sorption capacity. The saturation of t he polymer by uranyl ions showed that approximately 1 mol of uranyl io ns was sorbed for 2 mol of amino groups contained in the amorphous dom ain. This result can be related to the intrinsic properties of chitosa n. Desorption experiments are in favour of strong interaction, in fact , no desorption was observed whatever the experimental conditions. Spe ctroscopic characterization was performed on complexes in solution and in the solid stale. U.V.-visible spectrophotometric experiments showe d that a unique type of complex was formed. FT-IR spectroscopy allowed us to observe the appearence of a new band at 1525 cm of amide II typ e and led us to conclude the formation of a unique complex by the coor dination with chitosan amino groups. (C) 1998 Elsevier Science B.V.