In this study, the efficiency of a rotating disk photoreactor for the removal of phenazopyridine (PhP), a drug-resistant contaminant, using the UV/TiO2 process was investigated. The effects of operational parameters – including the initial concentration of PhP, solution pH, solution volume, rotating disk speed, flow rate, and irradiation time – on PhP removal efficiency were examined. The results indicate that increasing the rotating disk speed up to 450 rpm enhances the removal efficiency, while further increasing it to 750 rpm produces no significant improvement. Higher flow rates and longer irradiation times also improve PhP removal efficiency, whereas higher initial concentrations of PhP reduce it. Moreover, the removal efficiency was higher at near-neutral pH (approximately 5.9) compared to acidic or alkaline conditions
