Study of the mechanism pathway of sulfasalazine degradation on a novel quadripartite visible-light-driven photocatalyst

A novel coupled Cu 2 O-CdS-BiVO 4 -WO 3 quadripartite nanoscale catalyst was prepared and characterized by XRD, SEM-DX, x-ray mapping, and DRS techniques. Its pHpzc was also determined to be about 9. The photodegradation experiments were designed via RSM. The optimal run in the photodegradation of sulfasalazine (SSZ) included the CSSZ: 7 mg/L, pH 6.25, 30 min irradiation time, 0.45 g/L of the catalyst dose, by a catalyst with a Cu 2 O-CdS-BiVO 4 -WO 3 mole ratio 3:1:1:1 under visible light illumination. The effects of the scavenging agents were also studied, and the results confirmed the critical role of superoxide in SFSZ photodegradation and the hydroxyl radicals. The photodegradation pathway obeyed the direct Z-scheme mechanism, which involved three successive binary Z-scheme components involving WO 3 -BiVO 4 , BiVO 4 -CdS, and CdS-Cu 2 O, which accumulates the photoinduced electrons in the CB-Cu 2 O and the holes in the VB-WO 3 , the more powerful reducing and oxidizing centers, respectively.