Estudo da sorção de césio em solos: avaliação do desempenho em repositório de rejeitos radioativos

Soil samples of Minas Gerais State (Brazil) were investigated regarding the Cs sorption capacity in order to use them as back filling materials in a disposal facility for low-level radioactive waste. Five samples were evaluated according to their maximum sorption capacity of cesium (Q) and distribution coefficient (Kd), and also other parameters related to sorption: cation exchange capacity, grain size, chemical and mineralogical composition. The sorption parameters (Q and Kd) were determined from adjustments of experimental data, obtained from batch procedures, to appropriate isotherm models. In addition, a correlation study between isotherm parameters and other soil properties was conducted. It was evidenced a strong correlation between some of these properties and the sorption of Cs, in a way that they can be used as indicators in soil selection to be used as backfilling material in a disposal facility for radioactive waste. Among the samples investigated, the claysoil from Conselheiro Pena presented the best sorption characteristics, with Kd value of 90.50 mg.g-1 and maximum sorption capacity of 18.35 mg.g-1, being the most promising soil to be used as back filling material.