Preparation and characterization of SnO2-BiVO4-CuO catalyst and kinetics of phenazopyridine photodegradation

Here, SnO2, BiVO4, and CuO nanoparticles (NPs) were hydrothermally synthesized and mixed in an agate mortar mechanically. The coupled ternary SnO2-BiVO4-CuO (SBC) catalyst and the individual NPs were then briefly characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM), and diffuse reflectance spectroscopy (DRS). Average crystallite size of 25 nm was obtained from the XRD data based on the Scherrer formula. The absorption edge (λAE) values of 1095, 430, 558, and 636 nm, corresponding to the band gap (Eg) values of 1.13, 2.88, 2.22, and 1.95 eV, were respectively obtained for the as-synthesized CuO, SnO2, and BiVO4 NPs and the as-prepared ternary SBC catalyst based on DRS results. The PZP degradation% of 11, 15, 17, and 24% were obtained by the CuO, SnO2, BiVO4 NPs, and SBC catalyst (with the same moles of each component). But, when the moles of BiVO4 in the SBC were two times greater than the others, about 43% of PZP were removed. The k-value of 9.9 × 10-3 min-1 corresponding to the t1/2-value of 70 min was obtained by applying the Hinshelwood plot on the photodegradation results. Photodegradation experiments were carried out in pH 5, CPhP: 3.35 ppm, and catalyst dosage: 0.55 g L-1. Further, when the photodegraded solutions were subject to the COD experiment, the Hinshelwood plots showed a slope of 0.01 min-1 which corresponds to the t1/2-value of 69.3 min.