Investigation of U(VI) sorption on silica aerogels: Effects of specific surface area, pH and coexistent electrolyte ions

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. (C) 2017 Elsevier B.V. All rights reserved.