Focus on scavengers' effects and GC-MASS analysis of photodegradation intermediates of sulfasalazine by Cu2O/CdS nanocomposite

Coupling of Cu2O and CdS nanoparticles (NPs) showed a boosted photocatalytic activity in the degradation of Sulfasalazine (SSZ) in aqueous solution. Some characterization techniques including x-ray diffraction (XRD), scanning electron microscope equipped with an energy dispersive X-ray (EDX) analyzer, Transmission electron microscope (TEM), x-ray mapping, photoluminescence spectroscopy (PL) and diffuse reflectance spectroscopy (DRS) was used for characterizing of samples. A blue shift in band gap energy was obtained for the composite concerning the single semiconductors and values of 2.42, 2.43 and 2.52 eV were obtained for the direct electronic transition of Cu2O, CdS and CdS/Cu2O samples, respectively. PL results confirmed an elongate lifetime of e/h pairs in the composite. The optimal conditions were C-ssz: 10 mg L-1, pH 5, 25 min irradiation time and 0.5 g L-1 of the Cu2O/CdS catalyst. The chemical oxygen demand (COD) showed about 82% of SSZ molecules were mineralized during the photodegradation process. The effects of scavengers showed that the photogenerated holes have a major role in SSZ degradation with respect to other reactive species. GC-Mass analysis was done for detecting the degradation intermediates formed during the photodegradation process. The initial pH of the solution was changed from 5 to about 7.5 at the end of the photodegradation process.