Open-framework hybrid zinc/tin selenide as an ultrafast adsorbent for Cs+, Ba2+, Co2+, and Ni2+

Efficient adsorption of radioactive 137Cs+ and 60Co2+ and their decay products 137Ba2+ and 60Ni2+ bears significance for hazard elimination in case of nuclear emergency, which relies on the adsorption rate enhancement that takes advantages of compositional and structural optimization. Herein, we report a zinc-doped selenidostannate constructed from T2-supertetrahedral clusters, namely K3.4(CH3NH3)0.45(NH4)0.15Zn2Sn3Se10·3.4 H2O (ZnSnSe‐1K). The soft Se and micro-porosity synergistically endow this material with a binding affinity to Cs+, Ba2+, Co2+, and Ni2+ ions and ultrafast kinetics with R > 97.6% in 2–60 min. In particular, ZnSnSe‐1K can remove 99.34% of Cs+ in 2 min (KdCs > 1.5 × 105 mL g−1), contributing to a record rate constant k2 of 9.240 g mg−1 min−1 that surpasses all metal chalcogenide adsorbents. ZnSnSe‐1K exhibits good acid/base tolerance (pH = 0–12), and the adsorption capacities at neutral are 253.61 ± 9.15, 108.94 ± 25.32, 45.76 ± 14.19 and 38.49 ± 2.99 mg g−1 for Cs+, Ba2+, Co2+, and Ni2+, respectively. The adsorption performances resist well co-existing cations and anions, and the removal rates can keep above or close to 90% even in sea water. ZnSnSe‐1K is employed in continuous column and membrane filtration, both of which shows excellent elimination efficiency (R > 99%) for mixed Cs+, Ba2+, Co2+, and Ni2+. Especially, the membrane with an ultrathin (70 µm) ZnSnSe‐1K layer can remove 97–100% Cs+ in suction filtration with a short contact time of 0.33 s. Combined with the simple synthesis, facile elution and great irradiation resistance, ZnSnSe‐1K emerges as a selenide adsorbent candidate for use in environmental remediation especially that involving nuclear waste disposal.