Sorption of europium(III) on polymeric silica in perchlorate media

Abstract

Sorption of europium, Eu(III) with polymeric silicic acid has been studied under varying experimental conditions such as pH, ionic strength (I), concentration of silicic acid and of Eu(III), the presence of carbonate ions, and aging time. Sorption studies of Eu(III) at pH 7.50 ± 0.50) and I = 0.20 M NaClO 4 indicate 1.32 ± 0.06 × 10 −5 M Eu as the Critical Coagulation Concentration, CCC. Sorption of Eu(III) on colloidal silica increases with increased ionic strength from 80% (0.20 M NaClO 4 ) to 93% (0.89 M NaClO 4 ). The coagulation process is favored by an increase in silica concentration. The influence of CO 3 2− (1.00 × 10 −3 M) on the reaction of Eu(III) with polysilicic acid was negligible in the pH range 7.0 to 9.0. Dissolved Eu 3+ binds more strongly to the silicate polymers than do Cs + and Cu 2+ .

Sorption of uranyl(VI) cations on suspended silicate: effects ofN-donor ligands, carboxylic acids, organic cosolvents, and metal ions

“…The small increase in % Sorbed values with increased ionic strength reflected a decrease in the magnitude of negative zeta potential of silicate sols with increasing salt concentration at each pcH. This decrease allows closer approach of these particles due to the increased degree of van der Waals attraction which facilitates enhanced sorption through Si−O · · · Mn + · · · O−Si bond formation of the silicate particles and the metal cations [31][32][33][34]. The uranyl sorption behavior as a function of ionic strength is consistent with our earlier observations on uranyl sorption onto hydrous silica [6].…”