Rapid in situ microwave synthesis of Fe3O4@MIL-100(Fe) for aqueous diclofenac sodium removal through integrated adsorption and photodegradation

Highlights: • Fe₃O₄@MIL-100(Fe) was prepared via microwave-assisted in situ synthesis. • Fe₃O₄@MIL-100(Fe) was used to remove diclofenac sodium (DCF) from water. • More than 99% DCF was removed in Fe₃O₄@MIL-100(Fe)/vis/H₂O₂ system. • Fe₃O₄@MIL-100(Fe) was an excellent photocatalytic adsorbent. • The degradation pathways of DCF were proposed. -- Abstract: Metal-Organic Frameworks (MOFs) are efficient adsorbent and catalyst, however, the prepare of MOFs can be extremely time consuming. The rapid in situ microwave synthesis process offers the possibility of MOFs to a large-scale application. In this study, Fe₃O₄@MIL-100(Fe) was rapidly prepared via microwave in 30 min using Fe₃O₄ as metal precursor and applied as the adsorbent and photocatalyst to remove diclofenac sodium (DCF) from water. Fe₃O₄@MIL-100(Fe) exhibited an excellent adsorption effect to DCF with the maximum adsorption capacities of 400 mg/L. The presence of H₂O₂ could promote the removal of DCF during photocatalytic process. Approximately 99.4% of the DCF was removed in Fe₃O₄@MIL-100(Fe)/vis/H₂O₂ system via adsorption removal and consequent photocatalytic degradation. The high efficiency was attributed to the large BET surface area (1244.62 m²/g) and abundant iron metal sites (Fe(III) and Fe(II)) of Fe₃O₄@MIL-100(Fe). The adsorptive, photocatalytic property of Fe₃O₄@MIL-100(Fe) and the Fenton-like reaction were the main mechanisms for DCF removal. TOC analyzer was served to assess the mineralization of solutions treated by Fe₃O₄@MIL-100(Fe)/vis/H₂O₂ in 12 h. High elimination of TOC (87.8%) was observed during the DCF mineralization process. In addition, the major products were illuminated using HPLC-Q-TOF-MS and DCF degradation pathways were also proposed.