Study on extraction processes of some radioactive isotopes by bentonite from aqueous solutions

The results of investigations on extraction of trace amounts of some radioactive elements (cerium-141, cesium-134, strontium-89) from aqueous solutions by bentonite clay are given. The processes of absorption of radioactive elements from aqueous solutions, the dependence of the degree of their extraction on the solution pH, the size of the sorbent batch, the presence of nonradioactive macrocomponents in solution, and also their desorption by HNO3 solutions of different concentration have been studied. With an increase in solution pH from one to four the extraction of radioactive cesium-134 and cerium-141 increases appreciably; with a further growth of pH the cesium absorption remains at a maximum. But cerium sorption reduces in the pH range from 10 to 12. The dependence of the sorption of strontium-89 on the solution pH is not so pronounced. In the course of desorption of radioelements, Cs-134 is most firmly retained in the sorbent structure, and Sr-89 least firmly. On sorption of radioelements by different bentonite batches the distribution coefficients reduce with increasing amount of sorbent or fluctuate over a definite range, which indicates nonobservance of the adsorption rule for ultratrace concentrations