Permeable Layered Tin Sulfide Ion Exchanger for Rapid Elimination of Cs+ and Sr2+

A porous layered tin sulfide material, [(CH3)2NH2]2Sn3S7·0.4H2O (SnS-1), is developed for rapid Cs+ and Sr2+ removal from aqueous solutions. The alignment of hexagonal windows (8.3 × 8.3 Å2 in cross-section) across the stacked layers forms straight pseudochannels that enables effective ion diffusion and accommodation. SnS-1 exhibits outstanding ion exchange kinetics (k2Cs = 0.256 g mg–1 min–1; k2Sr = 0.272 g mg–1 min–1) and capacities (qmCs = 417.24 mg g–1; qmSr = 116.18 mg g–1), exceeding most chalcogenide-based exchangers. It exhibits acid–base resistance across a broad pH range (0–11) and remarkable selectivity for Cs+ and Sr2+ over various competing ions. Dynamic column filtration confirms the separation applicability of SnS-1, featuring sustained Sr2+ removal (RSr = 94.45–99.51%) against Cs+ (RCs = −20 ± 5%). The SnS-1/PTFE composite membrane can efficiently remove Cs+ and Sr2+ from continuous flow (2.0 mL min–1 cm–2), with removal efficiencies exceeding 91.71 and 98.91%, respectively. Moreover, the adsorbed Cs+ and Sr2+ ions can be readily eluted from the spent column and membrane using a 2 M NaCl solution. Combined with simple synthesis, radiolytic stability, and superior performance, microporous SnS-1 emerges as a promising candidate for nuclear wastewater remediation.