Mesoporous cerium oxide-anchored magnetic polyhedrons derived from MIL-100(Fe) for enhanced removal of arsenite from aqueous solution.

Efficient elimination of As(III) from drinking water and wastewater has been a challenge because of its neutral molecular form. To address this problem, a novel nanocomposite, mesoporous cerium oxide-anchored magnetic polyhedrons derived from MIL-100(Fe) was fabricated via a strategy combining impregnation and calcination. The resultant products (denoted as Fe2O3/CeO2-t) exhibited a unique octahedral nanostructure decorated by mesoporous cerium oxide. Surface modification of CeO2 enhanced As(III) removal in comparison to unmodified Fe2O3. Particularly, Fe2O3/CeO2-4 h can reduce As(III) concentration from 180 to 10 µg/L within 20 min, which was almost 9 times faster than unmodified Fe2O3. The adsorption behavior conformed to the pseudo-second-order kinetic model (R2 = 0.9908) and the Freundlich isotherm model (R2 = 0.9943). The maximum adsorption capacity of As(III) by Fe2O3/CeO2-4 h was 68.25 mg/g, higher than those reported for similar adsorbents. Its enhanced removal mechanism can be attributed mainly to the mesoporous characteristics and oxidization ability of surface ceria. The composite can be separated from water by external magnets and easily regenerated. This study may offer a clue to the design of metal-organic framework-based composites as an alternative adsorbent for arsenite cleanup.