title: Characterization and reactivity of biogenic manganese oxides for ciprofloxacin oxidation.
abstract: Biogenic manganese oxides (BioMnOx) were synthesized by the oxidation of Mn(II) with Mn-oxidizing bacteria Pseudomonas sp. G7 under different initial pH values and Mn(II) dosages, and were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and UV-Vis absorption spectroscopy. The crystal structure and Mn oxidation states of BioMnOx depended on the initial pH and Mn(II) dosages of the medium. The superoxide radical (O(·-)2) was observed in Mn-containing (III/IV) BioMnOx suspensions by electron spin resonance measurements. BioMnOx(0.4)-7, with mixed valence of Mn(II/III/IV) and the strongest O(·-)2 signals, was prepared in the initial pH 7 and Mn(II) dosage of 0.4 mmol/L condition, and exhibited the highest activity for ciprofloxacin degradation and no Mn(II) release. During the degradation of ciprofloxacin, the oxidation of the Mn(II) formed came from biotic and abiotic reactions in BioMnOx suspensions on the basis of the Mn(II) release and O(·-)2 formation from different BioMnOx. The degradation process of ciprofloxacin was shown to involve the cleavage of the hexatomic ring having a secondary amine and carbon-carbon double bond connected to a carboxyl group, producing several compounds containing amine groups as well as small organic acids.
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors: Jinjun
authors: J
authors: Tu
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors: Zhendong
authors: Z
authors: Yang
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: huchun@rcees.ac.cn.
authors: Chun
authors: C
authors: Hu
authors: State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
authors: Jiuhui
authors: J
authors: Qu
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002939:Ciprofloxacin / Q000737:chemistry*; D017895:Manganese Compounds / Q000737:chemistry* / Q000378:metabolism*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry* / Q000378:metabolism*; D011549:Pseudomonas / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D017895:Manganese Compounds; D010087:Oxides; D014874:Water Pollutants, Chemical; D002939:Ciprofloxacin; C027424:manganese oxide
keywords: Mn oxidation state; Mn-oxidizing bacteria; ciprofloxacin degradation; superoxide radicals