Selenium-79 (79Se) is one of the important long-lived fission products exists in radioactive waste and has toxic anionic species in an aqueous environment. Consequently, 79Se is considered as a key radionuclide that should be taken into consideration in safety assessments in radioactive waste repository. Commenly, the usage of bentonite as a buffer material is suggested in radioactive waste repositories. Although bentonite expresses high sorption abilities to cations, the situation seems different to anions due to the negative surface charge of bentonite. Recently, the preparation of modified bentonite was studied to investigate their sorption properties in aqueous.
The present work focuses on the sorption behavior of Se(IV) and Se(VI) on inorganic and organic modification bentonites, which were produced by modification of sodium bentonite with iron hydroxy oxide (Fe-OOH) and hexadecyl trimethyl ammonium bromide (HDTMA). Batch techniques were used to investigate the sorption ability of modification bentonites to Se(IV) and Se(VI) under different environmental conditions. The results show that the bentonite sample was successfully modified and the host structure is significant changed, leading to obvious increase Se(IV) and Se(VI) sorption. Compared to organic modification, the inorganic modification with iron hydroxy oxide shows more powerful sorption abilities towards Se(IV) and Se(VI).