Photocatalytic degradation of veterinary antibiotics in wastewaters: A review

The extensive use of veterinary antibiotics worldwide has led to their increasing accumulation in aquatic environments, adversely affecting both ecosystems and human health and leading to the emergence of antibiotic-resistant bacteria. Antibiotic residues enter water bodies primarily through wastewater effluent discharge, agricultural runoff, and improper disposal of pharmaceuticals. Several emerging technologies have been developed in response to the challenge of antibiotic contamination in wastewater. Among these, advanced oxidation processes (AOPs), including photocatalysis, have demonstrated significant potential for antibiotic degradation. Photocatalysis relies on the production of powerful oxidants to degrade pollutants under simulated or solar-light irradiation. Apart from the well-known TiO₂, various photocatalytic materials have been used with metal oxides on the frontline. In this context, metal doping has been used to reduce the bandgap energy and enhance the absorption of visible light and charge-carrier separation. Doping with non-metals and carbon-based materials is another attractive alternative that promotes better degradation efficiency and suppresses recombination. Moreover, advanced designs, such as heterojunction constructions, have been developed for effective charge separation and wider utilization of the light spectrum. This comprehensive review summarizes recent advances in the design, characterization, efficiency, and mechanisms of various photocatalysts for degrading veterinary antibiotics in wastewater, along with toxicity assessments of the resulting transformation products. By examining these parameters, the current body of knowledge is consolidated, providing valuable insights into wastewater purification processes for effective antibiotic removal. Finally, by emphasizing the critical environmental importance of streamlined photocatalysis and the challenges associated with scaling up the process, this review highlights its feasibility in mitigating veterinary antibiotic pollution, thereby safeguarding aquatic ecosystems and reducing the risks of antibiotic resistance.