Synergistic degradation of norfloxacin by a nano zero-valent iron-monopersulfate system: Performance, degradation mechanism and pathway

In this study, nano zero-valent iron (nZVI) was synthesized and used as an activator for monopersulfate (PMS) to remove norfloxacin (NOR) in water. The degradation rate of NOR reached 99 % under the optimum conditions in the pH range of 3.0–9.0. The Fe 0 in nZVI was consumed in the reaction and gradually transformed into γ-FeOOH. Furthermore, the SO 4 − · and OH − · were proved to be the main free radicals involved in NOR degradation by nZVI-PMS, and SO 4 − · was the dominant free radical. A possible degradation pathway for NOR was examined via time-of-flight mass spectrometry analysis. NOR was degraded through defluorination, decarboxylation and cleavage of the piperazine ring. The intermediates were oxidized and decomposed into CO 2 , H 2 O, F − and other small organic products. Some NOR and its degradation products were adsorbed by nZVI and γ-FeOOH. This investigation could provide useful guidance for future research on NOR degradation via PMS-based advanced oxidation processes.