Efficient and selective removal of ReO4− from highly acid solutions by SnS nanoflowers: implications for TcO4− sequestration

Abstract

This study focused on a promising selective capture strategy for the sequestration of TcO₄⁻ under highly acidic conditions by exploring its analog, ReO₄⁻, to simplify the experimental conditions. A reductive SnS nanoflower (SSF) adsorbent system was synthesized and applied for the selective removal of ReO₄⁻ under highly acidic conditions. The synthesized SSF possessed an excellent adsorption capacity of 584 mg g⁻¹, reached saturation within 60 min, and maintained the ReO₄⁻ capture ability in the presence of competing anions. The removal efficiency of ReO₄⁻ was up to 98.37% with a distribution coefficient of ∼6.03 × 10⁴ mL g⁻¹ in a 3 M HCl solution. Microscopy images indicated that the SSF retained its nanoflower structure after adsorbing ReO₄⁻. Based on the characterization data, a capture mechanism is proposed, whereby ReO₄⁻ is reduced to Re(IV) by the SSF to generate ReS₂. In addition, the use of the SSF adsorbent for the capture of TcO₄⁻ resulted in the almost complete removal of these ions, even at very low concentrations. Moreover, the SSF successfully removed ReO₄⁻ in 2 M HNO₃ by adding KCl. These excellent properties suggest that inorganic reducing materials can be used for the practical application of TcO₄⁻ sequestering from nuclear wastewater.