A systematic review on the performance evaluation of photocatalytic processes for erythromycin removal from aqueous environments

Erythromycin (ERY), a widely used macrolide antibiotic, has emerged as a persistent aquatic contaminant due to its complex structure and resistance to conventional wastewater treatment. Heterogeneous photocatalysis is considered a promising advanced oxidation process for ERY remediation. This systematic review, conducted in alignment with the PRISMA framework, evaluates photocatalytic systems reported up to September 17, 2025 for ERY degradation. Key operational parameters, including catalyst dosage, solution pH, irradiation time, initial contaminant concentration, and light source characteristics, were analyzed to identify optimal conditions and research trends. The relationship between parent compound degradation and total organic carbon (TOC) removal was also investigated. Results indicate a shift from conventional UV-responsive metal oxides toward visible-light-active composite photocatalysts, such as ferrites and Z-scheme heterojunctions, due to their enhanced charge separation and visible-light utilization. Although degradation efficiencies of the parent compound frequently exceeded 80-90% under optimal laboratory conditions following pseudo-first-order kinetics, a significant gap remained between contaminant removal and mineralization. Persistent transformation products limited complete detoxification, highlighting the need for prolonged irradiation or catalyst modifications to improve deep mineralization. Future studies should focus on solar-responsive photocatalysts, evaluating practical matrix effects (e.g., natural organic matter and co-existing ions), and strategies that achieve complete detoxification of treated effluents.