Background and purpose: Antibiotics are non-biodegradable and wastewater treatment processes are not fully effective in their removal. Therefore, presence of some antibiotics such as erythromycin and metronidazole in environment has become a major concern in recent years. The aim of this study was to evaluate TiO₂ nano-particles for removal of these two antibiotics from aqueous solution based on the response surface methodology (RSM).
Materials and methods: Effect of independent variables including pH, catalyst dose, contact time, and initial concentrations of erythromycin and metronidazole on the removal efficiency of these antibiotics were evaluated using RSM based on Box-Behnken design. All experiments were performed under ultrasonic irradiation in ultrasonic bath at a frequency of 35 kHz.
Results: According to ANOVA analysis and the model proposed, the optimum condition of pH, nano-particle concentration, reaction time and initial concentration of antibiotics for removal of erythromycin and metronidazole were 3, 0.4 g/l, 89.8 min, and 50.0 mg/l for erythromycin and 3, 0.4 g/l, 85.5 min, and 50.0mg/l for metronidazole. Under these conditions, efficiency of COD removal in erythromycin and metronidazole was 98.5% and 99.4 %, respectively.
Conclusion: In current study, sono-catalytic process was accelerated in the presence of TiO₂ nano-particle and enhanced the removal of erythromycin and metronidazole.