Use of Benzoylthiourea Immobilized on Silica Gel for Separation and Preconcentration of Uranium(VI)

Abstract.

Benzoylthiourea immobilized on silica gel was prepared by two-step post-synthesis modification. The capacity of the chelating silica gel, which was characterized by FTIR, was 3.21 mmol · g⁻¹. The separation and enrichment of uranium(VI) from solutions was investigated. Effective extraction conditions were optimized in both batch and column methods prior to determination by spectrophotometry using arsenazo(III). The optimum pH range for quantitative adsorption is 4–7. Quantitative recovery of U(VI) was achieved by stripping with 0.1 mol · L⁻¹ HCl. The sorption capacity of modified silica gel was 0.85 mmol · g⁻¹ uranium(VI). Recovery of U(VI) was 99.1 ± 2.3% with a detection limit of 2 µg · L⁻¹. The preconcentration factor was 250, and the relative standard deviation was 1.53% for a 1 µg · L⁻¹ U(VI) solution. The method was used for the determination of uranium in synthetic samples and a soil sample.