Open-framework hybrid zinc/tin selenide as an ultrafast adsorbent for Cs, Ba, Co, and Ni.

Efficient adsorption of radioactive Cs and Co and their decay products Ba and Ni 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 K(CHNH)(NH)ZnSnSe·3.4 HO (ZnSnSe-1K). The soft Se and micro-porosity synergistically endow this material with a binding affinity to Cs, Ba, Co, and Ni 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 K > 1.5 × 10 mL g), contributing to a record rate constant k of 9.240 g mg min 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 for Cs, Ba, Co, and Ni, 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, Ba, Co, and Ni. 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.