title: Treatment of halogenated phenolic compounds by sequential tri-metal reduction and laccase-catalytic oxidation.
abstract: Halogenated phenolic compounds (HPCs) are exerting negative effects on human beings and ecological health. Zero-valence metal reduction can dehalogenate HPCs rapidly but cannot mineralize them. Enzymatic catalysis can oxidize phenolic compounds but fails to dehalogenate efficiently, and sometimes even produces more toxic products. In this study, [Fe|Ni|Cu] tri-metallic reduction (TMR) and laccase-catalytic oxidation (LCO) processes were combined to sequentially remove HPCs, including triclosan, tetrabromobisphenol A, and 2-bromo-4-fluorophenol in water. The kinetics, pH and temperature dependences of TMR and LCO were obtained. The detailed TMR, LCO, and TMR-LCO transformation pathways of three HPCs were well described based on the identification of intermediate products and frontier molecular orbitals (FMOs) theory. The results showed that the two-stage process worked synergically: TMR that reductively dehalogenated HPCs followed by LCO that completely removed dehalogenated products. TMR was proven to not only improve biodegradability of HPCs but also reduce the yield of potential carcinogenic by-products. Furthermore, a TMR-LCO flow reactor was assembled and launched for 256 h, during which >95% HPCs and >75% TOC were removed. Meanwhile, monitored by microorganism indicators, 83.2%-92.7% acute toxicity of HPCs was eliminated, and the genotoxicity, produced by LCO, was also avoided by using TMR as pretreatment process.
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China; Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China. Electronic address: daiyr@craes.org.cn.
authors.forename: Yunrong
authors.initials: Y
authors.lastname: Dai
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China; Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China. Electronic address: songyh@craes.org.cn.
authors.forename: Yonghui
authors.initials: Y
authors.lastname: Song
authors.affiliation: State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China; Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China. Electronic address: wangsy@craes.org.cn.
authors.forename: Siyu
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Urban Water Environmental Research, Chinese Research Academy of Environmental Sciences, 100012 Beijing, PR China. Electronic address: yhzmlyy90311@126.com.
authors.forename: Yu
authors.initials: Y
authors.lastname: Yuan
mesh_terms: D002384:Catalysis; D004926:Escherichia coli; D054879:Halogenation; D007700:Kinetics; D042845:Laccase / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry; D009152:Mutagenicity Tests; D010084:Oxidation-Reduction; D011075:Polybrominated Biphenyls / Q000737:chemistry* / Q000633:toxicity; D012486:Salmonella typhimurium; D014260:Triclosan / Q000737:chemistry* / Q000633:toxicity; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000633:toxicity
chemical_list: D011075:Polybrominated Biphenyls; D014874:Water Pollutants, Chemical; D014260:Triclosan; D042845:Laccase
keywords: Detoxification; Halogenated phenolic compound; Laccase-catalytic oxidation; Sequential treatment; Tri-metal reduction