Bowknot-like Zr/La bimetallic organic frameworks for enhanced arsenate and phosphate removal: Combined experimental and DFT studies

• DOI: 10.1016/j.jcis.2022.01.033
• Publication Date: 2022-01-10T10:28:39Z
• Authors: Lingchao Kong; Jun Zhang; Yi Wang; Qinlin Yan; Jiayu Xu; Xi Quan; Charles B. Andrews; Zuotai Zhang; Chunmiao Zheng
• Keywords: Arsenates; Water; Adsorption; 01 natural sciences; Phosphates; 0105 earth and related environmental sciences

Hazardous oxyanions in water bodies are potentially toxic to aquatic life, and the coexistence of multiple anions aggravates the toxicity. Herein, bowknot-like Zr/La bimetallic organic frameworks (Zr/La-BTC) were developed with superior hazardous oxyanion adsorption capacities, i.e., approximately 102 mg/g for arsenate and 159 mg/g for phosphate, respectively. The molar ratio of Zr to La in Zr/La-BTC plays a significant role in the structure and the adsorption efficiencies. Notably, the experiment-derived adsorption capacities of various Zr/La-BTC samples were consistent with their adsorption energies calculated by density-function theory (DFT). Further mechanism analysis revealed that coordination of Zr/La atoms with the target anion groups occurred during adsorption. The positive shift of binding energies in La 3d and Zr 3d XPS spectra and Bader charge analysis unveiled that back-donation interactions dominated the adsorption process. The reliable adsorption selectivity and reusability of 0.1Zr/La-BTC were verified with anion competition experiments and four adsorption-desorption cycles. Overall, this study provides significant insight into the design of high-performance bimetallic organic frameworks for the enhanced removal of hazardous oxyanions from water.