Purification of waste waters containing 60Co2+, 115mCd2+ and 203Hg2+ radioactive ions by ETS-4 titanosilicate

The sorption of Co-60(2+), Cd-115m(2+) and Hg-203(2+) from diluted solutions (as analogues for radioactive waste waters) on ETS-4 microporous titanosilicate was studied at 277, 293, 313 and 333 K by measuring the sorption kinetics using a batch-method. The sorption of these radiocations was compared by means of the distribution coefficient and of the sorption capacity. The maximum sorption capacities follow the order: Hg-203s(2+)> Cd-115m(2+)>= Co-60(2+). The thermodynamic functions of the sorption processes have been estimated. The increase of the absolute value of Delta G degrees with increasing temperatures shows that higher temperatures favor ionic exchange.