COMPETITIVE ADSORPTION OF SR-90 ON SOIL SEDIMENTS, PURE CLAY PHASES AND FELDSPAR MINERALS

Study of the adsorption of Sr-90 by a soil sediment, mineralogically pure clay phases and feldspar minerals as a function of ionic composition of Ca, Mg and Na has been conducted. It is shown that a theoretical slope value of -1 for a pure ion-exchange mechanism of strontium adsorption onto Ca-saturated clay is predicted. Experimentally determined slopes represent an average of adsorption on several different mineral surfaces having different relative affinities for strontium, calcium and magnesium. Strontium was found to be adsorbed to ion-exchange sites and calcium and magnesium cations were observed to be effective competitors for these sites. Pure clay minerals yielded adsorption coefficients from equations with slopes of -10.