Selective Capture of Ba²⁺, Ni²⁺, and Co²⁺ by a Robust Layered Metal Sulfide

¹³³Ba, ⁶³Ni, and ⁶⁰Co are hazardous to the ecosystem and human health. Their nonradioactive isotopes are also worthy of concern as toxic metal ions. Barium can be studied as a simulant of hazardous ²²⁶Ra because of their comparable ionic radii and similar ion exchange behaviors. Herein, we report that the layered metal sulfide (Me₂NH₂)_1.33(Me₃NH)_0.67Sn₃S₇·1.25H₂O (FJSM-SnS) exhibits excellent capture properties for Ba²⁺, Ni²⁺, and Co²⁺ with high capacities (qmBa = 289.0 mg/g; qmNi = 83.27 mg/g; and qmCo = 51.98 mg/g), fast kinetics (within 5 min), wide pH durability, and outstanding Ba²⁺ selectivity. FJSM-SnS exhibits high removal efficiencies (>99%) for these ions in ion-exchange column experiments. The material possesses radiation resistance with good structural and crystal stability; it survives highly acidic conditions. Our results point to a promising scavenger for Ba²⁺, Ni²⁺, and Co²⁺ and, by extension, the even more harmful ²²⁶Ra, which suggest that metal sulfide materials should be considered as effective scavengers for these ions from complex wastewater.