Exploring the efficacy of WO3/xCeO2/PMS photocatalytic system for carbamazepine degradation: optimization of natural water parameters, toxicity assessment and degradation pathways

Abstract

This study investigates the synthesis of tungsten oxide with varying percentages of cerium oxide (WO₃/xCeO₂), produced via hydrothermal and precipitation methods, as potential photocatalysts for the degradation of carbamazepine (CBZ). EDX analysis confirmed the presence of W, Ce, and O in the synthesized WO₃/xCeO₂ composites. XRD and FTIR spectroscopy analyses indicated successful incorporation and interaction of CeO₂ with WO₃, confirming the formation of the desired WO₃/xCeO₂ structure. UV-DRS results demonstrated that band gap energy of CeO₂, WO₃ and WO₃/10 %CeO₂ were determined to be 2.79 eV, 2.29 eV and 2.22 eV, respectively. Notably, the WO₃/10 %CeO₂ composite exhibited superior generation of hydroxyl radicals (OH), as evidenced by PL analysis. This enhanced formation of ^•OH indicates improved charge separation and reduced recombination rates of photo-generated electron-hole pairs in WO₃/10 %CeO₂. The degradation efficiency of CBZ increased from 56.5 % (k_app = 0.012 min⁻¹) to 83.1 % (k_app = 0.025 min⁻¹) when WO₃/10 %CeO₂ was coupled with peroxymonosulfate (PMS) under UV light for 25 min. Additionally, various natural water operational parameters including water matrices, influence of naturally existing ions, initial CBZ concentration, and the pH effects were explored to enhance the practical applicability of WO₃/10 %CeO₂/PMS photocatalytic system. The degradation products of CBZ were analyzed using GC–MS, leading to the proposal of potential degradation pathways. Importantly, the formation of non-toxic degradation products at the end of the process highlights the effectiveness of this photocatalytic approach in mitigating environmental risks associated with pharmaceutical contaminants.