A pg-C3N4/BiOBr/Ag composite was successfully prepared by simple high-temperature calcination and co-precipitation methods. The composite was characterized by means of XRD, SEM, TEM, XPS, UV-Vis, BET, and photocurrent analyses alongside other detection methods, and the degradation of 10 mg·L-1 sulfamethoxazole was investigated under simulated visible light irradiation. The results showed that the pg-C3N4/BiOBr/Ag composite had the best degradation effect on sulfamethoxazole when the loading ratio of silver was 5%. Compared with pg-C3N4, BiOBr monomer, and pg-C3N4/BiOBr composite, the photocatalytic degradation effect of the pg-C3N4/BiOBr/Ag (5%) was significantly improved, and the degradation rate was almost 100% within 30 min. The reaction rate constant (0.21016 min-1) was 13.15 times that of pg-C3N4/BiOBr. Through radical quenching experiments, it was shown that the main active substances in the photocatalytic degradation were holes (h+), superoxide radicals (·O2-), and singlet oxygen (1O2), among which superoxide radicals (·O2-) contributed the most. Cyclic tests of pg-C3N4/BiOBr/Ag showed that the synthesized material has good recyclability and application prospects.
Keywords: Ag; BiOBr; carbon nitride; photocatalytic; sulfamethoxazole.