An insight into the photocatalytic degradation of the antibiotic rifampicin by titanium dioxide nanoparticles in aqueous solution under UV light irradiation

Photocatalytic degradation of antibiotic rifampicin (RIF) in aqueous solution, employing 100-nm sized anatase TiO₂ nanoparticles (NPs) as a catalyst, under 365-nm light irradiation (0.28 mW cm^‒2) was investigated. The direct photolysis and adsorptive removal of the ansamycin antibiotic were found to be negligibly inefficient. The experimental data suggest that photocatalysis efficiently degrades RIF, and the effect of irradiation time, catalyst dosage, pH of medium, and temperature was elucidated. The optimum photocatalytic degradation occurred in the colloidal mixture of 30.38 μM RIF solution and 10 mg TiO₂ NPs at pH 5.63. The activation energy was estimated to be 1.585 ± 0.079 kJ mol^‒1. The photocatalytic degradation kinetics of the antibiotic followed the Langmuir–Hinshelwood model with the rate constant of 0.016 ± 0.002 min^‒1, and the additional of a small amount of H₂O₂ accelerates the photocatalytic process. The degradation pathway was discussed based on vibrational spectroscopic data of RIF and its by-products. Overall, the findings in this study suggest that photocatalysis employing anatase TiO₂ NPs under UV light irradiation is a promising approach for the degradation of antibiotics and other pharmaceuticals in wastewater treatment plants. Graphical abstract: (Figure presented.)