Addition of Al2O3 nanoparticles to bentonite: effects on surface charge and Cd sorption properties

Abstract

Compacted bentonite barrier in radioactive waste repositories is expected to prevent radionuclide migration, due to its high sorption capability for many radionuclides. This study analyses whether the addition of Al2O3 nanoparticles (NPs) enhances the sorption properties of bentonite. The study was carried out with Cd, highly pollutant heavy metal and divalent fission product. Sorption experiments were conducted in NaClO4 at different ionic strengths (5·10-4 to 10-1 M) and pH (2 to 10), using mixtures ofsodium homoionised bentonite and Al2O3 in different proportions. 1t has been probed that addition of Al2O3 NPs to bentonite enhances Cd sorption at pH higher than 6. The effect of Al2O3 NPs addition on the surface properties ofbentonite colloids was also analyzed by measuring particle size and surface charge in all studied systems.