Selenium oxyanions: Highly selective uptake by a novel anion exchanger

We report the extremely high and selective uptake of selenium oxyanions by a novel anion exchanger, Ni1-xZn2x(OH)(2)(OCOCH3)(2x) . nH(2)O (0.15 < x < 0.25). The tested Ni-Zn basic salt (x = 0.24) exhibited very high selectivity for Se(IV) [K-d = 9.0 x 10(4) cm(3)/g with an initial Se(IV) concentration of 1 x 10(-4) M] in the presence of 0.1 M Cl- solution. The uptake of Se(IV) on the Ni-Zn basic salt was irreversible when treated with solutions containing 1 N Cl-, 1 N NO3-, or 1 N PO43-. This novel exchanger also showed high K-d (2.6 x 10(3) cm(3)/g) for Se(VI), and therefore it is expected to be useful for decontamination and removal of selenium oxyanions from contaminated water.