The study of the Cd(NH3)42+/Cdsup(*) (NH3)42+ exchange ;eaction in hydrous oxides of zirconium(IV), silicon(IV) and tin(IV)

Kinetics of the exchange reaction of cadmium(II)-amine complex ion using radioactive isotope 115Cd in the same chemical form in hydrcus oxides of zirconium(IV), silicon(IV) and tin(IV) has been studied. 250 mg of the washed and dried samples of the exchanger was kept in a set of glass containers; 25 cm3 of the cadmium ammine solution of specified concentration, which was tagged with 115Cd of known specific activity, was added to it and the mixture was shaken. The extent of the resulting exchange of cadmium-ammine, between the .pecies in the solid and that in the solution was determined at fixed intervals of time, radiometrically, using a halogen quenched liquid counter in conjuction with a scaler. It has been found that the major contribution in the overall exchange process is from the surface of the exchanger particles. It has also been found that the rate of exchange follows the order: hydrous ZnO2>hydrous SnO2>hydrous SiO2. (T.G.)