Selective Capture of Toxic Selenite Anions by Bismuth‐based Metal–Organic Frameworks

Abstract Chemically durable and effective absorbent materials for selenite (SeO 3 2− ) remain highly desirable for contamination remediation. Now a bismuth‐based metal–organic framework (Bi‐MOF, CAU‐17) was used as adsorbent to capture SeO 3 2− anions from aqueous solution with ultrahigh adsorption capacity of 255.3 mg g −1 and fast kinetics. Furthermore, the adsorbent showed excellent selectivity for SeO 3 2− and was able to work steadily in a broad pH range of 4–11. Density functional theory (DFT) calculation, XANES modeling, and EXAFS fitting suggested that SeO 3 2− anions were immobilized by forming Bi−O−Se bonds (T‐3 structural model) though splitting the O−Bi−O bond in the crystal structure, leading to a structural transformation of CAU‐17 in the solid state.