Degradation of ciprofloxacin and metronidazole and their Combination using UV-activated persulfate process

Abstract

Metronidazole (MNZ) and Ciprofloxacin (CIP) have been recognized as emerging environmental contaminants since these are largely used and are difficult for biological degradation. These contaminants have adverse effects on aquatic ecosystems and public and animal health even at very low concentrations. Advanced oxidation processes (AOPs) in presence of UV irradiation showed effective treatment techniques for the degradation of these antibiotic compounds from pharmaceutical wastewater. This study was performed to assess the degradation of MNZ and CIP using potassium persulfate (K_2 S_2 O_8) in the presence of UV-irradiation. The impact of the addition of hydrogen peroxide (H2O2) as oxidant was also investigated. For this purpose, experiments were carried out in batch reactors for a 50 ml solution of 10 ppm CIP, MNZ and their binary mixture. The consequences of functioning parameters, that is, initial and final pH, the concentration of antibiotics, the individual and combined dosage of K_2 S_2 O_8, H2O2 and UV light power (30-120 watts) were assessed. The consequences of this analysis revealed that under favorable conditions without adjusting PH, the degradation effectiveness after 420 min for CIP using UV, UV/H2O2, UV/K_2 S_2 O_8, and UV/K_2 S_2 O_8/H2O2 were 33.11, 44.05, 97.56 and 100%, respectively and for MNZ, degradation percentages were 40.38, 66.14, 99.77 and 100%, respectively, at the same dosage. The results were satisfactory for the mixture of the CIP and MNZ solution also. The outcomes related to the kinetics showed that MNZ and CIP antibiotics degradation followed the pseudo-first-order kinetics. The result from this study shows that UV/K_2 S_2 O_8/H2O2 as Advanced Oxidation Process is an innovative and efficient method to degrade the MNZ and CIP antibiotics.