Wen Ma*, Tian-Yu Pan, Tian-Tian Lv, Yan-Ling Guo, Hai-Yan Sun, Rui-Ping Yang, Jun-Hao Tang, Ting-Hui Zhuang, Kai-Qiang Jing, Mei-Ling Feng*, Xiao-Ying Huang

Cite this article: https://doi.org/10.1016/j.cjsc.2025.100829

Publication date:

Keywords: Cesium removal; layered materials; oxalatophosphate; ion exchange; structural transformation

ABSTRACT

It is of vital importance to effectively capture 137Cs for human health and ecological protection due to its strong radioactivity and biotoxicity. Herein, the efficient uptake of Cs+ has been achieved by a new layered gallium oxalatophosphonate {[(CH3)2NH2][CH3CH2NH3]}2[Ga4(PO4)4(H2PO4)2(C2O4)] (FJSM-NGAPC), whose structure features the anionic gallium oxalatophosphate layer of [Ga4(PO4)4(H2PO4)2(C2O4)]n4n- with [(CH3)2NH2]+ and [CH3CH2NH3]+ cations in the interlayer spaces. The maximum Cs+ adsorption capacity of FJSM-NGAPC can reach 407.81 mg/g, which surpasses that of common Cs+ scavengers. In the presence of a large excess of interfering Na+ ions, it shows high selectivity for Cs+ ions and the maximum KdCs can reach 1.36 × 104 mL/g. In particular, FJSM-NGAPC can maintain removal performance for Cs+ in the pH range from 3.07 to 10.01 with KdCs values all above 103 mL/g. Impressively, the Cs+ adsorption mechanism is clearly revealed at the molecular level by the single crystal to single crystal (SC-SC) structural transformation. This process confirms ion exchange between Cs+ and interlayer [(CH3)2NH2]+ and [CH3CH2NH3]+ cations, accompanied by strong Cs···O interactions. This work provides an efficient metal oxalatophosphate as the scavenger for radiocesium and clearly elucidates the radiocesium capture mechanism, facilitating the design of new oxalatophosphates materials for radionuclide remediation.