Adsorption techniques for decontaminating liquid radioactive waste and radionuclide-contaminated natural water

The paper reviews the adsorption methods used for decontaminating liquid radioactive waste (LRW) and radioactive-contaminated natural water of different origins from radionuclides. The primary attention is paid to the sorption of long-lived cesium and strontium radionuclides, which, besides the high radiotoxicity, in most cases define the overall activity of radioactive waste. A standard technique was developed for evaluating the efficiency of various sorption materials in relation to cesium and strontium radionuclides by determining the distribution coefficient (K-d) values of tracer Cs-137 and Sr-90 radionuclides in solutions of sodium and calcium salts, the essential bulk components of LRW, and natural water. The results showed that natural aluminosilicate sorbents, zeolites, zirconium phosphate, and ferrocyanide sorbents could effectively remove Cs-137 from low-salt solutions. The sorbent based on manganese (III, IV) oxyhydrate exhibited the highest selectivity to strontium. A correlation between the crystalline and porous structure of the sorbents and the selectivity to cesium and strontium radionuclides was shown. The results obtained provide an adequate choice of the most effective sorbents for the decontamination of radioactively contaminated natural water and technogenic liquid waste from cesium and strontium radionuclides. [GRAPHICS]