Sorption properties of hydrogels of transition and p-metal oxide hydroxides

The experimental data on the sorption properties of hydrogels of Fe-III, Ti-IV, Zr-IV, Sn-IV In-III, Cr-III, Sm-III, Co-II, and Zn-II oxide hydroxides are summarized. The data were obtained by the point of zero-charge method and by measuring the rates of the indicator reaction, viz., heterogeneous hydrolysis of the chloro complexes of platinum group metals. The compositions of the oxide hydroxides, the pH of the point of zero charge in various ionic media, and the rate constants of the indicator reactions were determined. The values obtained were analyzed in terms of their correlation with the charge, the radius, and the electronic structure of the central ion and with the composition and the preparation conditions of the oxide hydroxide. A data base that allows one to choose an appropriate oxide hydroxide sorbent for extraction of particular complex-forming metals from complexing media is presented. The data obtained confirm the model of the mechanism of heterogeneous hydrolysis and extend its predicting ability. The model was tested experimentally in relation to tin(IV) oxide hydroxide.