Photocatalytic degradation of metronidazole from aquatic solution by TiO2-doped Fe3+ nano-photocatalyst

Indiscriminate consumption of antibiotics, their discharge into the environment, and the development of resistant genes in a natural ecosystem are ever-increasing global threats. Metronidazole is applied to treat infection diseases caused by anaerobic bacteria and protozoa. In this research, TiO2/Fe+3 was used as a heterogeneous nano-photocatalyst for the degradation of metronidazole with UV-C radiation as the energy source. Parameters tested in the removal process were pH=3, 7, and 11; antibiotic concentration of 80mg/L; contact times of 30, 60, 90, and 120min; and nano-photocatalyst of TiO2/Fe+3 with concentrations of 30, 60, 90, 250, 500, 750, and 1000mg/L. The photocatalytic degradation kinetics of metronidazole was studied. Optimal conditions were achieved on synthetic solutions; then, all experiments were performed on wastewater from the pharmaceutical industry. Antibiotic concentrations were measured using an HPLC device. All tests were replicated three times according to the standard methods of water and wastewater experiments, the 20th edition. Data were analyzed using SPSS 19 and the statistical test ANOVA. The optimal conditions for removing metronidazole from synthetic solution included, 500 mg/L for nano-photocatalyst concentration, pH=11 and 120min contact time. Removal efficiency of antibiotic under optimal conditions was 97% from synthetic solutions and 69.85% from pharmaceutical wastewater. Finally, Fe+3-TiO2/UV-C were identified as a promising technique for the removal of metronidazole with high efficiency from aqueous solutions.