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

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 similar to 6.03 x 10(4) 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.