title: Effect of phosphate on heterogeneous Fenton oxidation of catechol by nano-Fe₃O₄ Inhibitor or stabilizer?
abstract: The effect of phosphate on adsorption and oxidation of catechol, 1,2-dihydroxybenzene, in a heterogeneous Fenton system was investigated. In situ attenuated total reflectance infrared spectroscopy (ATR-FTIR) was used to monitor the surface speciation at the nano-Fe3O4 catalyst surface. The presence of phosphate decreased the removal rate of catechol and the abatement of dissolved organic compounds, as well as the decomposition of H2O2. This effect of phosphate was mainly due to its strong reaction with surface sites on the iron oxide catalyst. At neutral and acid pH, phosphate could displace the adsorbed catechol from the surface of catalyst and also could compete for surface sites with H2O2. In situ IR spectra indicated the formation of iron phosphate precipitation at the catalyst surface. The iron phosphate surface species may affect the amount of iron atoms taking part in the catalytic decomposition of H2O2 and formation of hydroxyl radicals, and inhibit the catalytic ability of Fe3O4 catalyst. Therefore, phosphate ions worked as stabilizer and inhibitor in a heterogeneous Fenton reaction at the same time, in effect leading to an increase in oxidation efficiency in this study. However, before use of phosphate as pH buffer or H2O2 stabilizer in a heterogeneous Fenton system, the possible inhibitory effect of phosphate on the actual removal of organic pollutants should be fully considered.
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China. Electronic address: xfyang@rcees.ac.cn.
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Yang
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: hejie10@mails.ucas.ac.cn.
authors.forename: Jie
authors.initials: J
authors.lastname: He
authors.affiliation: School of Chemistry and Chemical Engineering, University of Jinan, Jinan 250022, China.
authors.forename: Zhongxi
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, SE-971 87, Sweden.
authors.forename: Allan
authors.initials: A
authors.lastname: Holmgren
authors.affiliation: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: wgds@rcees.ac.cn.
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Wang
mesh_terms: D000327:Adsorption; D002384:Catalysis; D002396:Catechols / Q000737:chemistry* / Q000302:isolation & purification; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D010710:Phosphates / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D002396:Catechols; C045076:Fenton's reagent; D058185:Magnetite Nanoparticles; D010710:Phosphates; D006861:Hydrogen Peroxide; D007501:Iron; C034221:catechol
keywords: ATR-FTIR; Adsorption; Heterogeneous Fenton oxidation; Interface mechanism