Desorption properties of preadsorbed metal ions from sodium polyacrylate gel

Desorption properties of preadsorbed metal ions, whose valences are monoval ent, divalent and trivalent , from sodium polyacrylate gel are investigated over the range of pH of buffer solutions. It is considered that in the gel which forms metal complexes, carboxyl groups combine with the metal ions a ccording to their charge number stoichiometrically. From this fact, the des orption mechanism of the preadsorbed metal ions from the gel into aqueous p hase is theoretically analyzed on the basis of dissociation equilibrium for polyacrylic acids and mass balance of the fixed carboxyl group species. Co nsequently, the model equations which allow quantitative consideration of t he desorption mechanism in these systems, can be derived as a function of t he hydrogen ion concentration, measured easily in the outer aqueous solutio n. The desorption equilibrium of monovalent, divalent and trivalent metal i ons from the gel can be explained fairly well by the models.