Activation of peroxymonosulfate by iron oxychloride with hydroxylamine for ciprofloxacin degradation and bacterial disinfection

• Published in: The Science of the total environment Vol. 799; p. 149506
• Main Authors: Luo, Hongwei, Zeng, Yifeng, Cheng, Ying, He, Dongqin, Pan, Xiangliang
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 10.12.2021
• Subjects: catalysts; ciprofloxacin; disinfection; environment; Escherichia coli; Fe(III)/Fe(II) cycle; Free radicals; Hydroxylamine; Iron-based catalyst; liquids; oxidation; PMS activation; spectrometers; PMS activation; Iron-based catalyst; Hydroxylamine; Free radicals; Fe(III)/Fe(II) cycle
• ISSN: 0048-9697; 1879-1026; 1879-1026
• DOI: 10.1016/j.scitotenv.2021.149506

Iron oxychloride (FeOCl) is a known effective iron-based catalyst and has been used in advanced oxidation processes (AOPs). This study intends to achieve more facile free radicals generation from peroxymonosulfate (PMS) activation by exploring the Fe(III)/Fe(II) cycle of FeOCl in the presence of hydroxylamine (HA). With 0.2 g/L FeOCl, 1.5 mM PMS, and 1 mM HA, the PMS/FeOCl/HA system could effectively achieve 98.88% of the oxidative degradation of 5 mg/L ciprofloxacin (CIP) in 15 min and quickly inactivate 99.99% of E. coli (108 CFU/mL) in 5 min at near-neutral pH. HA played an important role in promoting the Fe(III)/Fe(II) cycle, thereby greatly improving the oxidation activity of the system. The reactive oxygen species (ROS) such as HO, SO4− and O2− were identified as the dominated free radicals produced in the system. The intermediate products of CIP detected by liquid chromatograph-mass spectrometer (LC-MS) and three possible degradation pathways of CIP were proposed. The presence of common anions in the PMS/FeOCl/HA system, including HCO3−, Cl−, SO42−, and NO3−, enhanced the degradation efficiency of CIP to varying degrees at the concentrations of 10 mM. Moreover, FeOCl maintained a high degradation capability for CIP after several recycles. This work offers a new promising means of catalyzing the PMS-based AOPs in the degradation of refractory organics. [Display omitted] •PMS/FeOCl/HA system was constructed for CIP degradation and E. coli disinfection.•The working pH range of PMS/FeOCl/HA system was extended to near-neutral.•Role of HA in the PMS/FeOCl/HA system was explored.•Degradation pathways of CIP and reaction mechanism of the system were proposed.