Direct Z-scheme MIL-100(Fe)/BiOBr heterojunctions: Construction and photo-Fenton degradation for sulfamethoxazole

A series of MIL-100(Fe)/BiOBr direct Z -scheme heterojunctions was fabricated by the in -situ precipitation method. The crystal structures, micromorphology, optical adsorption property, and chemical states were estimated by powder X-ray diffraction (PXRD), Fourier transforms infrared (FTIR) spectra, UV-Vis diffuse reflectance spectra (UV-Vis DRS), scanning electron microscopy (SEM), high -resolution transmission electron microscope (HRTEM) and X-ray photoelectron spectra (XPS). The performance of photo -Fenton degradation for sulfamethoxazole (SMX) under low -powered light emitting diode lamp irradiation was explored. The catalytic degradation efficiency of SMX (5 mg center dot L-1) in the optimal reaction system (MB-7/Vis/H2O2, MB -7 was prepared when the mass of MIL -100 (Fe) was 70% of the mass of BiOBr) could reach 99.8% upon 70 min illumination. Meanwhile, the effects of H2O2 concentration, catalyst dosage, pH, and co -existing inorganic anions on SMX removal over MB-7/Vis/H2O2 were studied. The removal efficiency of SMX could reach above 95% after five consecutive operations, suggesting that MB -7 had good stability and reusability. The possible catalytic mechanism was unraveled by photoluminescence (PL) spectra, elec- trochemical measurements, radical trapping experiments, and electronic spin resonance (ESR) technique. The enhanced photo-Fenton reactivity could be attributed to the fabrication of heterostructures accelerated separation photocarriers and then induced the generation of reactive species and Fe3+/Fe2+ redox cycle.