Photodegradation pathways of phenazopyridine by the CdS-WO3 hybrid system and its capability for the hydrogen generation

Abstract

The increased global use of antibiotics caused increased water pollution and of persist microorganisms. Thus, introducing/developing novel catalyst for effective degradation of these water pollutants is of great importance. Here, coupled CdS-WO3 system was used to degrade phenazopyridine (PhP). The as-synthesized CdS-WO3 hybrid system (HS) with a nano dimension has a crystallite size of about 85 nm by the Williamson-Hall (W-H) equation and 22.4 nm by the Scherrer methods. The Eg of 2.36, 2.96, and 2.94 eV for CdS and WO3 NPs and the resulted HS were obtained by the Kubelka-Munk equation, respectively. The increased photocatalytic activity of HS was achieved in the removal of PhP. The optimal photodegradation conditions were 10 mg/L PhP concentration, pH 4, and 0.9 g/L of the HS. The sequence of the photogenerated hole> •OH> •O2−> photogenerated electrons was obtained for the importance of the role of the reactive species in PhP photodegradation. The composite can degrade PhP molecules via the Z-scheme mechanism.