Photocatalytic degradation of pharmaceutical contaminants in water

The increasing presence of pharmaceutical contaminants in aquatic environments has raised significant concerns related to their environmental persistence and potential health impacts. Among these contaminants, paracetamol is frequently detected in wastewater and is resistant to conventional treatment processes. This thesis focuses on the development of TiO2 nanobelts, visible-light-driven bismuth oxybromides, and their heterostructures for efficient degradation of paracetamol and the treatment of pharmaceutical wastewater. Bismuth oxybromide (BiOBr) and bismuth-rich oxybromides (Bi3O4Br and Bi24O31Br10) were synthesized via a controlled solvothermal process. The influence of synthesis parameters, particularly pH and temperature, on phase formation, morphology, and electronic properties was systematically investigated. The results demonstrated that bismuth-rich oxybromides exhibit enhanced visible-light absorption and improved charge separation compared to BiOBr, leading to better photocatalytic performance. To enhance photocatalytic efficiency of TiO2 nanobelts, heterojunctions were synthesized by coupling bismuth oxybromides with TiO2 nanobelts. These heterostructures exhibited improved charge carrier separation and extended light absorption into the visible region compared to pure TiO2 nanobelts, resulting in enhanced degradation and mineralization of paracetamol. Furthermore, hydrochar containing photocatalysts were developed to facilitate charge transfer, improve photocatalytic activity, and generation of reactive oxygen species. Electron paramagnetic resonance (EPR) and scavenger experiments revealed that reactive oxygen species, including hydroxyl radicals, superoxide radicals, holes, and singlet oxygen, play a key role in the photocatalytic degradation mechanism. The photocatalysts demonstrated effective performance in both paracetamol degradation and pharmaceutical wastewater treatment, highlighting their practical applicability. Overall, this thesis provides new insights into the design of bismuth-based photocatalysts and advanced heterostructures for efficient visible-light-driven environmental remediation.