A novel quadripartite Cu2O-CdS-BiVO4-WO3 visible-light driven photocatalyst: Brief characterization and study the kinetic of the photodegradation and mineralization of sulfasalazine

A novel quadripartite Cu2O-CdS-BiVO4-WO3 nanocomposite (NC) was prepared by mechanical mixing of the individual semiconductor nanoparticles (NPs). The work focused on the kinetic study of the photodegradation and photo mineralization processes of sulfasalazine (SZ) by the quadripartite NC. XRD patterns showed the cubic phase of CdS and WO3 crystals, the monoclinic BiVO4, and the hexagonal CdS crystals in the composite, which relatively also confirmed by SEM and TEM images. The average crystallite sizes of about 28 nm and 22.5 nm were obtained for the NC by the Scherrer and Williamson-Hall equations, respectively. Photoluminescence (PL) spectra showed the lowest intensity for the composite. Both the lowest PL intensity and the highest photocatalytic activity were achieved when the moles of Cu2O in the composite was 3 times greater than the other components. Diffuse reflectance spectroscopy (DRS) results also showed a relative enhancement in the band gap energy of the composite especially for WO3 NPs alone. The photodegraded SZ solutions were subjected to the COD experiment to estimate the mineralization extent of SZ molecules or its degradation intermediates. Kinetic of both processes obeyed the Hinshelwood kinetic model and the rate constants of 0.0265 min(-1) (t(1/2) of 26.2 min) and 0.0323 min(-1) (t(1/2) of 21.5 min) were respectively obtained for the photodegradation and mineralization processes of SZ molecules, confirming that the mineralization of SZ is about 1.23 times faster than its photodegradation extent.