Succinamic Acid Grafted Nanosilica for the Preconcentration of U(VI) from Aqueous Solution

Succinamic acid-functionalized nanosilica (SA@SiO2) was synthesized, characterized, and tested for hexavalent uranium preconcentration from contaminated aqueous solutions. The succinamic acid grafted nanosilica exhibited improved uranium preconcentration capacity in comparison with that of raw nanosilica. The effects of environmental conditions such as pH, ionic strength, solid concentration, foreign ions, and temperature on uranium­(VI) preconcentration performance were investigated by batch technique in detail, and the related mechanism is discussed with the aid of X-ray photoelectron spectroscopy. Results showed that U­(VI) preconcentration by SA@SiO2 was strongly dependent on pH while less dependent on ionic strength; the preconcentration was mainly dominated by inner-sphere surface complexation. The coexisting cations had no effects, while anions influenced U­(VI) preconcentration significantly. The preconcentration of U­(VI) was favorable at lower temperatures; the maximum preconcentration capacity was 44.5 mg/g at pH 4.0 ± 0.1 and T = 298 K. Thermodynamic parameters indicated that the preconcentration process was exothermic and spontaneous. The SA@SiO2 exhibited desirable selectivity for uranium and can be reused at least five times without decreasing capacity. Accordingly, the SA@SiO2 is a potential and suitable candidate for the preconcentration of U­(VI) from a considerable volume of contaminated water.