Adsorption kinetics of strontium and cesium cation on rock material

Effect of temperature on intraparticle diffusion and adsorption of strontium, cesium ions in granite particles have been studied using batch technique. Crushed and sieved granite was stirred in strontium chloride or cesium chloride solution of 10 ppm at 5 - 60 0C. Intraparticle diffusivity was estimated from time dependence of concentration and distribution coefficient was calculated from equilibrium concentration. Intraparticle diffusivities were from 10-9 to 10-8 cm2/sec and increased with increasing temperature. Apparent activation energy of the intraparticle diffusion obtained were about 5.0 kcal/mol for strontium and about 8.8 kcal/mol for cesium. Distribution coefficients of both elements ranged from 16 to 20 ml/g. Adsorption of these elements showed small temperature dependence and apparent adsorption heat obtained were about 0.8 kcal/mol for strontium, and about minus 1.3 kcal/mol for cesium. Migration length of these elements in granite was estimated to be about 40 cm in 1,000 years from their diffusivities. Retardation factor was calculated to be about 12,000 from distribution coefficients. (author)