Design and performance of a dual Z-scheme YFeO₃/g-C₃N₅/WO₃ heterojunction with enhanced PDS-assisted sonophotocatalytic activity for sulfamethoxazole degradation: Mechanistic insights and ecotoxicity analysis

In the present study, a double Z-scheme YFeO₃/g-C₃N₅/WO₃ (YCW) nanocomposite was successfully synthesized using a simple wet chemical process. The surface morphology, crystal structure, and photosensitive behavior of YCW were characterized using appropriate techniques. Compared to pure and binary nanocomposites, the ternary YCW catalyst prolonged the charge-carrier lifetime and generated large numbers of reactive oxygen species (ROS) via Z-type charge transfer. Moreover, the inclusion of sonication effects with peroxydisulfate (PDS) could potentially enhance the impulsive generation of free radicals via interlinked cavitation bubbles in the reaction medium. The proposed PDS-assisted sonophotocatalytic (SPC) YCW-4 system achieved a sulfamethoxazole (SMX) removal efficiency of 95.6% (k = 0.0438/min), which is higher than that of the SPC-only system (58.1%, k = 0.0151/min) within 60 min of reaction time. The synergistic effects of the SPC/PDS/YCW-4 system reflected the higher utilization of PDS in the effective degradation of SMX into smaller metabolites. To validate the presence of the generated ROS, scavenger tests and electron spin resonance analysis were conducted. The resultant SMX intermediates and their toxicity were elucidated using computational methods. Overall, this study illustrates the considerable potential of the proposed SPC/PDS/YCW-4 system for the effective removal of SMX from contaminated wastewater.