Abstract
Ion-exchange adsorption could be expressed in terms of the corrected selectivity coefficient for prediction of ion-exchange property at concentration and temperature conditions different from those used for their determhlations. The plot of corrected selectivity coefficient vs. the concentration of exchanging ions in exchanger is conjugative with the expression of thermodynamic constant. It also generates the ion-exchange isotherm and distribution coefficients.
Amorphous titanic acid has ben established for selective recovery of multivalent oxoanions in concentrated sea water. The ion-exchange selectivity was studied for halide ions and various oxoanions such as BrO3-, IO3-, Te (IV), Se (IV), V (V), P (V), Sb (V), As (V), W (IV). The latter oxoanions have been found to be very selectively adsorbed from sea water and could be removed efficiently. Chromatographic separations of BrO3- from IO3- and I- from Te (IV) were successfully performed using a small titanic acid column with 5mm internal diameter and 4cm length at room temperature. These oxoanions could be eluted using 0.1-1 M NaOH solution.
