Cs+ and Sr2+ adsorption selectivity of zeolites in relation to radioactive decontamination

Abstract

Zeolites are used as adsorbents of cationic elements in the radioactive decontamination process of water, soil and others. We determined Cs+ and Sr2+ adsorption selectivity of some zeolites to know effective zeolite species for the decontamination of radioactive Cs and Sr. A 30 mL mixed solution containing up to 15 mg L−1 of non-radioactive Cs+ or Sr+ and up to 0.50 M of Na+ or K+ was mixed with 0.5 g of Linde-type A, Na-P1, faujasite X, faujasite Y and mordenite. Among the zeolites, mordenite had the highest Cs+ adsorption selectivity, and the selectivity had no correlation to the cation exchange capacity (CEC) of the zeolites. In contrast, Sr2+ adsorption selectivity of the zeolites positively correlated with the CEC of the zeolites; Linde-type A with the highest CEC showed the highest adsorption selectivity, and its adsorption rate was more than 99.9% even in the presence of 0.5 M K+. A simulated soil decontamination experiment of Cs from a Cs-retaining vermiculite by using mordenite and that of Sr from a Sr-retaining vermiculite by using Linde-type A showed decontamination rates of more than 90%.

Keywords

• Cesium
• Strontium
• Zeolite
• Adsorption selectivity
• Radioactive decontamination