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A stable metal-organic framework (MOF), MIL-101(Fe), was successfully synthesised using a solvothermal method and employed as a novel photocatalyst for degrading crude oil in oilfield wastewater. Through optimisation of reaction conditions, the following optimal parameters were determined: a dark reaction time of 30 min, a light reaction time of 30 min, a pH of 5.5, a catalyst amount of 150 mg/L, and a reaction temperature of 303.15 K. Under these reaction conditions, an impressive removal of 94.73% was achieved. This study represents the first application of Fe-based MOFs in the photocatalytic degradation of oilfield wastewater. MIL-101(Fe) notably demonstrated excellent stability under mild acid conditions and can be efficiently recycled. These findings offer valuable insights into using MIL-101(Fe) as a promising material for industrial applications in removing crude oil from oil-polluted water through photocatalytic degradation.

In this work, a hierarchical Ag3VO4/ZnO/BC composite (abbreviated as AZB) is firstly prepared via a microwave-assisted solvothermal strategy and used as photocatalyst to degrade levofloxacin (LFX) under visible-light irradiation. After optimizing the mass ratio of components and the photoreaction operation parameters, the optimal 0.2Ag3VO4/ZnO/0.1BC (denoted as A0.2ZB0.1) endows the superior photocatalytic removal rate toward LFX (10 mg/L) up to 91.2% at 120 min, revealing approximately 10 times enhancement than that of ZnO (9.4%). Meanwhile, the A0.2ZB0.1displays desirable reusability and stability after cycling 5 cycles and the •O2-and h+are the dominating reactive species during photocatalysis process. The improved photocatalytic performance can be primarily attributed to successful establishment of a heterojunction with n-n scheme between ZnO and Ag3VO4. This leads to enhanced responsive capability to visible light and increased separation and transmission efficiency of the photogenerated electron/hole (e-/h+) pairs. Furthermore, the biochar (BC) with excellent conductivity can act as a charge-transfer bridge for further accelerating the charges transfer in composite. In addition, the analysis of intermediates identified through liquid chromatography-mass spectrometry (LC-MS) allowed for a reasonable inference for the potential mechanism and pathway involved in photodegradation. Overall, our study demonstrates an innovative strategy to enhance the photocatalytic activity of ZnO through the simultaneous incorporation of BC and the creation of a heterojunction composite.