Thermocatalytic persulfate activation for metronidazole removal in the continuous operation

Abstract

In the present study, thermocatalytic persulfate (PS) activation using zero-valent copper was studied under different conditions to investigate the degradation of metronidazole (MTZ) antibiotic from aqueous media in the continuous system. The results showed that the degradation of MTZ was not affected significantly by the pH of the solution in the thermal activation however, alkaline media promoted the rate of MTZ removal in the thermocatalytic oxidation. Based on the Arrhenius behavior, the activation energy of MTZ oxidation was calculated about 52.32 kJ mol−1 from batch tests. At the fixed concentration of MTZ, it had a direct relationship between MTZ degradation and initial PS concentration as well as temperature. Under the optimal conditions, more than 95% of MTZ was degraded in the steady-state condition. The scavenging study using methanol and t-butanol revealed that both sulfate and hydroxyl radicals were mainly responsible for MTZ degradation. Moreover, low concentration copper leaching was observed in the continuous operation. Based on these results, it seems that thermocatalytic activation of PS was a promising technology which is capable to degrade resistant pollutants.