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

Abstract: Chemically durable and effective absorbent materials for selenite (SeO₃²⁻) remain highly desirable for contamination remediation. Now a bismuth‐based metal–organic framework (Bi‐MOF, CAU‐17) was used as adsorbent to capture SeO₃²⁻ anions from aqueous solution with ultrahigh adsorption capacity of 255.3 mg g⁻¹ and fast kinetics. Furthermore, the adsorbent showed excellent selectivity for SeO₃²⁻ 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 SeO₃²⁻ 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. [ABSTRACT FROM AUTHOR]