Oxidation of fluoroquinolone antibiotics by peroxymonosulfate without activation: Kinetics, products, and antibacterial deactivation

Water Research
Yang ZhouQin Guo

Abstract

While fluoroquinolone (FQ) antibiotics are susceptible to degradation by sulfate and/or hydroxyl radicals formed in peroxymonosulfate (PMS) based advanced oxidation processes, here we report that unactivated PMS itself exhibits a specific high reactivity toward FQs for the first time. Reaction kinetics of PMS with two model FQs, ciprofloxacin (CF) and enrofloxacin (EF), showed a strong pH dependency with apparent second-order rate constants of 0.10-13.05 M-1s-1 for CF and 0.51-33.17 M-1s-1 for EF at pH 5-10. This pH dependency was well described by species-specific parallel reactions. On the basis of reaction kinetics and structure-activity assessment, the tertiary and secondary aliphatic N4 amines on the FQs' piperazine ring were proposed to be the main reaction sites. High performance liquid chromatography/electrospray ionization tandem mass analysis showed the formation of hydroxylated, N-oxide, and dealkylated products. Bacterial growth inhibition bioassays using Escherichia coli showed that oxidation products of FQs by PMS retained negligible antibacterial potency in comparison to parent FQs. Kinetic modeling using the rate constants estimated from pure water well predicted the oxidation kinetics of low levels of CF and EF...Continue Reading

Citations

Nov 5, 2019·Water Research·Maolida NihemaitiJean-Philippe Croué
Apr 24, 2021·Environmental Science and Pollution Research International·Yanli ZhuYouxian Zhang

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