Abstract
The very large surface associated with aerogels made them attractive in the field of sorption. Herein, silica aerogels were characterized and used for the sorption of U(VI) in solution. The effects of specific surface area (SSA), pH and coexistent electrolyte ions on the surface site density, aggregation and sorption properties have been carefully investigated. The site distributions of silica aerogels were calculated with Visual MINTEQ. The sorption of U(VI) is affected significantly by the solution pH. The sorption increases with increasing SSA due to the increased amount of surface active sites of silica aerogels. Electrolyte ions (Na+, K+, NO3−, Cl−) were added to investigate the competition ability to U(VI) adsorbed on active sites. The influence of humic acid (HA), silicate and phosphate on U(VI) sorption in multiphase systems were also discussed. The kinetics data were used to investigate the sorption process and pseudo-second-order model was used to simulate the kinetic data. Spectroscopic analyses were also utilized to explain the role of OH groups in the U(VI) sorption.
U(VI) sorption on silica aerogels in multi-component systems [Display omitted]
•The aggregation of silica aerogels in the presence of coexistent electrolyte ions and HA were investigated.•The sorption mechanism of U(VI) sorption on silica aerogels is the inner-sphere complexation.•The influence of HA, silicate and phosphate on U(VI) sorption in the whole pH range were discussed.•The kinetic and thermodynamic data of U(VI) sorption on silica aerogels were analyzed.•U(VI) sorption is mainly due to the interaction of U(VI) with –OH on silica aerogel surfaces.