EVALUATION OF SYNTHETIC INORGANIC ION EXCHANGERS FOR CESIUM AND STRONTIUM REMOVAL FROM CONTAMINATED GROUNDWATER AND WASTEWATER

Abstract

The ion exchange testing of 30 synthetic adsorbents including layered and framework polyvalent metal silicates and phosphates, as well as amorphous exchangers was carried out. Their selectivity to alkali and alkaline earth metal cations in individual and complex solutions was determined. Several exchangers were found to have high selectivity for cesium and strontium. These exchangers are sodium phlogopite, layered sodium titanium silicate Na₂TiSi₂O₇·2H₂O, framework niobium (Na₂Nb₄Si₂O₁₅·4H₂O, tentative formula), zirconium (Na₂ZrSi₃O₉·H₂O) and titanium (Na₂Ti₂SiO₇·2H₂O) silicates, and a layered δ-tin phosphate (Sn(HPO₄)·2H₂O). For all these materials cesium and strontium ion exchange capacities as a function of pH were determined. The effect of sodium, magnesium and calcium on Cs⁻ and Sr²⁻ ions sorption was also studied over the concentration range 0.005 M - 1 0 M and the explanations for the phenomena observed were proposed based on the knowledge of the crystal structure of the exchangers. Testing of the most promising exchangers for selective cesium and strontium recovery from ground water simulant in batch regime was carried out.