Enhanced Degradation of Metronidazole (MNZ) in Aqueous Solutions Using Combined Ultrasonic, Hydrogen Peroxide, and Peroxymonosulfate Processes

Abstract

Background: Metronidazole (MNZ) is a widely used pharmaceutical compound that has recently emerged as a significant environmental contaminant. Due to its potential mutagenic properties, MNZ poses risks of DNA damage and carcinogenesis.<br /> Methods: This experimental study was conducted at the laboratory scale to investigate the efficiency of MNZ removal in aqueous solutions using a novel combination of ultrasonic waves (US), hydrogen peroxide (H2O2), and peroxymonosulfate (PMS).<br /> Results: In the US/PMS/H2O2 process, the removal efficiency ranged from 4.3 to 99.5 under the best conditions (PMS dose = 6 mmol/L, H2O2 dose = 20 mmol/L, time = 30 min, US power = 120 W, MNZ concentration = 2 mg/L). A comparative analysis of the maximum removal efficiency between the two processes showed that incorporating US significantly increased MNZ removal, resulting in a 3-fold increase in efficiency under different conditions. Furthermore, in the PMS/H2O2 process, the H2O2 dose exerted the most pronounced impact, followed sequentially by reaction time, PMS dosage, MNZ concentration, and pH. In the US/PMS/H2O2 process, reaction time was identified as the most influential factor, followed by MNZ concentration, PMS dosage, US power, and H2O2 dosage. The results of the Taguchi design model further underscored the substantial contribution of ultrasonic irradiation to MNZ removal.<br /> Conclusion: Overall, the findings demonstrate that US treatment is highly effective at significantly reducing MNZ concentrations in water and wastewater, highlighting the critical importance of parameter optimization in developing efficient US-based treatment technologies.