THE USE OF ZEOLITES AS AMENDMENTS IN RADIOCESIUM-CONTAMINATED AND RADIOSTRONTIUM-CONTAMINATED SOILS - A SOIL-CHEMICAL APPROACH .1. CS-K EXCHANGE IN CLINOPTILOLITE AND MORDENITE

Zeolites of the clinoptilolite and mordenite type have been frequently proposed as countermeasure amendments to reduce radiocaesium soil-to- plant transfer in contaminated soils. The radiocaesium ion exchange be havior has been studied on a natural clinoptilolite and on a natural a nd a synthetic mordenite, in order to obtain quantitative data on the radiocaesium sorption competition of these zeolites relative to soils. The relative effect of K, NH4 and Ca-the most important competitive c ations under soil conditions-was assessed, and a multisite ion exchang e model has been applied to describe the change of the Cs-K selectivit y coefficient as a function of the Cs loading. The relevance of the re sults in regard to the potential use of these zeolites as countermeasu re amendments in radiocaesium-contaminated soils is discussed. (C) Els evier Science Inc. 1997.