Sorption of alkaline and alkaline-earth radionuclides on zirconium phosphate sorbent Termoxid-3A from aqueous solutions

Abstract

Sorption kinetic behavior of¹³⁷Cs,⁸⁵Sr,¹³³Ba and²²³Ra has been studied in the system: inorganic sorbent on the base of zirconium phosphate, Temoxid-3A, and diluted aqeous solutions. Chemosorption mechanism with the limiting step of external diffusion of the reaction between radiostrontium and the sorbent was established (n=1.304±0.0). For barium, radium and cesium radionuclides this mechanism was found to have an ion-exchange character (n<1), with limiting step of external diffusion for barium and radium radionuclides and internal diffusion for radiocesium. Termoxid-3A possesses good sorption kinetic properties. Values of the equilibrium distribution coefficients of the radionuclides studied in the suggested conditions were ∼n·10³. Time for attaining equilibrium does not exeed 40 minutes. Purification coefficient of Moscow potable water from radiostrontium was equal to ∼100 when 1000 column volumes passed through. Immobilized with strontium sorbent (1.5 mg equiv. of Sr/g sorbent) keeps all its good sorption kinetic characteristics towards radionuclides studied but the mechanism of radiostrontium interaction with the sorbent changes its character from chemosorption to ion exchange (n=0.75).