Degradation of fluoroquinolone antibiotics by ferrate(VI): Effects of water constituents and oxidized products. (15th October 2016)

• Record Type: Journal Article
• Authors: Feng, Mingbao; Wang, Xinghao; Chen, Jing; Qu, Ruijuan; Sui, Yunxia; Cizmas, Leslie; Wang, Zunyao; Sharma, Virender K.
• Is Part Of: Water research. Volume 103(2016)
• Page Start: 48
• Page End: 57
• Publication Date: 2016-10-15
• Subjects: Ferrate(VI) -- Antimicrobials -- Ions -- Humic acid -- Water treatment -- Quantum chemical calculations; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2016.07.014
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The degradation of five fluoroquinolone (FQ) antibiotics (flumequine (FLU), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (OFL) and marbofloxacin (MAR)) by ferrate(VI) (Fe VI O4 2−, Fe(VI)) was examined to demonstrate the potential of this iron-based chemical oxidant to treat antibiotics in water. Experiments were conducted at different molar ratios of Fe(VI) to FQs at pH 7.0. All FQs, except FLU, were degraded within 2 min at [Fe(VI)]:[FQ] ≤ 20.0. Multiple additions of Fe(VI) improved the degradation efficiency, and provided greater degradation than a single addition of Fe(VI). The effects of anions, cations, and humic acid (HA), usually present in source waters and wastewaters, on the removal of FLU were investigated. Anions (Cl −, SO4 2−, NO3 −, and HCO3 − ) and monovalent cations (Na + and K + ) had no influence on the removal of FLU. However, multivalent cations (Ca 2+, Mg 2+, Cu 2+, and Fe 3+ ) in water decreased the efficiency of FLU removal by Fe(VI). An increase in the ionic strength of the solution, and the presence of HA in the water, also decreased the percentage of FLU removed by Fe(VI). Experiments on the removal of selected FQs, present as co-existing antibiotics in pure water, river water, synthetic water and wastewater, were also conducted to demonstrate the practical application of Fe(VI) to remove the antibiotics during water treatment. The seventeen oxidized products (OPs) of FLU were identified using solid phase extraction-liquid chromatography-high-resolution mass spectrometry. The reaction pathways are proposed, and are theoretically confirmed by molecular orbital calculations. Graphical abstract: Highlights: Fluoroquinolones degraded efficiently by Fe(VI) in river water and synthetic water. Multiple additions of Fe(VI) improved degradation of fluoroquinolone in water. Multivalent cations and humic acid in water decreased removal efficiency. Effect of ionic strength on flumequine relates to Fe(VI) speciation. Proposed oxidation pathways of flumequine confirmed by theoretical calculations.