Synthesis of Ce/BiFeO3 composites and activation of persulfate for pharmaceutical wastewater degradation

Abstract

Sulfamethoxazole (SMZ) is a prevalent and recalcitrant micropollutant in water, posing a significant threat to both aquatic organisms and human health. Therefore, investigating the removal of SMZ is of critical importance. In order to investigate the effect of rare earth metal doping on the performance of activated persulfate oxidative degradation of SMZ, BiFeO₃ with different Ce doping amounts was successfully prepared by a hydrothermal method. Then, it was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and Brunauer–Emmett–Teller (BET) method. The performance of porous Ce/BiFeO₃ in the catalytic activation of persulfate (PMS) for the degradation of SMZ in water was investigated using SMZ solution as a simulated wastewater. The impact of Ce doping rate, catalyst dosage, temperature variations, common anions, natural organic matter, and PMS concentration on SMZ removal was systematically evaluated. The characterization results show that the octahedral rhombic structure of Ce can be observed on the surface of this doped catalyst, and Ce doping does not change the crystalline shape of Ce/BiFeO₃. The specific surface area of the doped catalyst increases, accompanied by an enlargement of pore size, thereby enhancing the catalyst's adsorption capacity and resistance to contamination by SMZ. Under the optimal conditions of 25 °C, SMZ concentration of 20 mg/L, 0.8 g/L PMS and 0.3 g/L 0.05Ce/BiFeO₃ catalyst, the removal rate of SMZ reaches approximately 95% within 35 min of reaction time. Even after five cycles of reuse, the degradation rate of SMZ remains above 88%, demonstrating the catalyst's good stability and reusability. Bursting experiments show that SO₄^·–, ·OH, ¹O₂ and O₂^·– are involved in the catalytic degradation process, with ¹O₂ playing a dominant role.