Preparation of Ag-BiOBr/WO₃ composites and enhanced sulfisoxazole removal performance

Antibiotics have been widely used to treat human and animal diseases with good antibacterial effect. However, antibiotics are difficult to be degraded naturally in natural environment. The photocatalytic oxidation technology has bright application prospects in the degradation of persistent organic compounds. However, the spectral absorption range of conventional photocatalytic materials is not wide enough, and the recombination rate of photogenerated carriers is too high, which seriously restricts the application and promotion of catalytic materials. So, it is urgent to develop more effective and safe removal technologies. The photodeposition method was used to load Ag element on the surface of BiOBr/WO₃ p-n type heterojunction material to construct a new type of Ag-BiOBr/WO₃ material and apply to the photocatalytic degradation of sulfisoxazole. The samples were characterized by various techniques, such as XRD, TEM, XPS, UV-vis DRS et al. The result show that the deposition of Ag expands the photo-response range of the material, significantly accelerates the separation speed of photogenerated carriers, and thus improves the photocatalytic performance. The 15wt%Ag-BiOBr/WO₃ with an Ag content of 15wt% is considered to be the most efficient composite material for the removal of sulfisoxazole. When the catalyst concentration is 0.3 g/L, the sulfisoxazole concentration is 5 mg/L, and the pH is 7, 15wt%Ag-BiOBr/WO₃ demonstrates the highest photocatalytic degradation efficiency of sulfisoxazole in 60 min, which reaches up to 98.1%. The degradation rate is 28.79, 36.37 and 7.59 times higher than those of BiOBr, WO₃ and BiOBr/WO₃, respectively. After 5 cycles of experiments, the 15wt%Ag-BiOBr/WO₃ composite material still maintains high photocatalytic activity, indicating that the material can be recycled and reuses with good stability. The quenching experiments and electron spin resonance (ESR) shows that •O₂^– is the most active radical group in the BiOBr/WO₃ system, while ¹O₂ and h⁺ played relatively minor roles. This provides a theoretical basis for the preparation of catalytic materials and the degradation of antibiotics.