Visualization of the ion exchange mechanism for ^(137)Cs and ^(90)Sr decontamination is important for safe radioactive liquid waste reprocessing and emergency response improvement in the event of a nuclear accident.He...Visualization of the ion exchange mechanism for ^(137)Cs and ^(90)Sr decontamination is important for safe radioactive liquid waste reprocessing and emergency response improvement in the event of a nuclear accident.Here,the remediation of Cs^(+)and Sr^(2+)was achieved through ion exchange using a cadmium selenidostannate,[CH_(3)NH_(3)]3[NH_(4)]_(3)Cd_(4)Sn_(3)Se_(13)·3H_(2)O(CdSnSe-1),with rapid exchange kinetics,high β/γ radiation resistances,broad pH durability and facile elution.The framework constructed from monolacunary supertetrahedral clusters features a great negative charge density of 3.27×10^(-3) that accounts for the superhigh exchange capacities of 371.4(Cs^(+))and 128.4 mg g-1(Sr^(2+)).Single-crystal structural analysis on the exchanger during the“pristine-ion exchange-elution”cycle supplies instructive information to elucidate the uptake and recycle mechanism for Cs^(+)and Sr^(2+).The broken symmetry of the cluster caused by a vacant site,combined with the co-templating effects of mixed methylammonium/ammonium,contributes to the formation of voids Ⅰ and Ⅱ that show adsorption activity for both Cs^(+)and K^(+)ions.In comparison,the divalent Sr^(2+)ions with higher hydration degree exchange with(alkyl)ammonium cations in a 1:2 molar ratio,resulting in its location at a new void(Ⅲ)closer to the framework and thus a higher binding strength.The energy variation during the adsorption process based on a DFT calculation illustrates the high efficiency of CdSnSe-1 for capture of both Cs^(+)and Sr^(2+).This“visualized”ion exchange underlines the robustness and flexibility of CdSnSe-1 as a Cs^(+)and Sr^(2+)trapper,and reveals the deeper structure-function relationship from a new surface interaction viewpoint.展开更多
基金financially supported by the National Natural Science Foundation of China(21701123)the Foundation Enhancement Program(2021-JCJQ-JJ-1061)+1 种基金the Fund of the State Key Laboratory of Structural Chemistry(20190009)the Fund of the National Engineering Research Center for Optoelectronic Crystalline Materials(OCM-2020-02).
文摘Visualization of the ion exchange mechanism for ^(137)Cs and ^(90)Sr decontamination is important for safe radioactive liquid waste reprocessing and emergency response improvement in the event of a nuclear accident.Here,the remediation of Cs^(+)and Sr^(2+)was achieved through ion exchange using a cadmium selenidostannate,[CH_(3)NH_(3)]3[NH_(4)]_(3)Cd_(4)Sn_(3)Se_(13)·3H_(2)O(CdSnSe-1),with rapid exchange kinetics,high β/γ radiation resistances,broad pH durability and facile elution.The framework constructed from monolacunary supertetrahedral clusters features a great negative charge density of 3.27×10^(-3) that accounts for the superhigh exchange capacities of 371.4(Cs^(+))and 128.4 mg g-1(Sr^(2+)).Single-crystal structural analysis on the exchanger during the“pristine-ion exchange-elution”cycle supplies instructive information to elucidate the uptake and recycle mechanism for Cs^(+)and Sr^(2+).The broken symmetry of the cluster caused by a vacant site,combined with the co-templating effects of mixed methylammonium/ammonium,contributes to the formation of voids Ⅰ and Ⅱ that show adsorption activity for both Cs^(+)and K^(+)ions.In comparison,the divalent Sr^(2+)ions with higher hydration degree exchange with(alkyl)ammonium cations in a 1:2 molar ratio,resulting in its location at a new void(Ⅲ)closer to the framework and thus a higher binding strength.The energy variation during the adsorption process based on a DFT calculation illustrates the high efficiency of CdSnSe-1 for capture of both Cs^(+)and Sr^(2+).This“visualized”ion exchange underlines the robustness and flexibility of CdSnSe-1 as a Cs^(+)and Sr^(2+)trapper,and reveals the deeper structure-function relationship from a new surface interaction viewpoint.
