Enhanced mineralization of bisphenol A by eco-friendly BiFeO3–MnO2 composite: Performance, mechanism and toxicity assessment

Abstract An eco-friendly BiFeO3–MnO2 composite with dual functionalities of adsorption and catalysis was successfully constructed by using a simple one-step hydrothermal method for the removal of bisphenol A (BPA) pollution from water. Several characterization methods, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), were applied to verify the combination of BiFeO3 and MnO2. BiFeO3–MnO2 (BFO–MO) exhibited excellent adsorption and catalytic activity compared with those of pure BiFeO3. The adsorption process followed a pseudo-second-order kinetic model and matched the Langmuir isotherm model. Effects of the catalyst and peroxymonosulfate (PMS) concentrations, pH and real water matrix were also analyzed, and BFO–MO displayed perfect adsorption and degradation performance under different conditions. Meanwhile, mineralization performance was tested, and the total organic carbon removal rate was nearly 85%. Moreover, BFO–MO exhibited good stability and reusability after five cycles. Based on radical quenching experiments, SO4− and OH were the primary reactive species responsible for BPA oxidation, and the possible reaction mechanism of BFO–MO/PMS was proposed. Finally, the degradation intermediates were identified, and the toxicity of intermediates was assessed. The novel BFO–MO composite is a promising catalyst for synchronous adsorption and degradation to purify wastewater.