title: Mechanism of hydroxyl radical generation from biochar suspensions: Implications to diethyl phthalate degradation.
abstract: This paper investigated hydroxyl radical (OH) generation from biochar suspensions for diethyl phthalate (DEP) degradation in the presence of oxygen. Electron paramagnetic resonance (EPR) coupled with a salicylic acid trapping method were used to detect free radicals in biochar and verify OH generation from biochar suspensions. Free radicals (FRs) in biochar could induce OH generation, and ≈12 spins of FRs were consumed to produce one trapped [OH] molecule. The proposed mechanism of OH generation was that FRs in biochar transferred electrons to O2 to produce the superoxide radical anion and hydrogen peroxide, which reacted further with FRs to produce OH. Free radical-quenching studies utilizing superoxide dismutase, catalase, and deferoxamine as scavengers were used to testify this mechanism. Furthermore, OH generated from biochar suspensions could degrade DEP efficiently. These findings of this study provide new insights into the physicochemical properties and environmental implications of biochar.
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China.
authors.forename: Guodong
authors.initials: G
authors.lastname: Fang
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China; School of Resources and Environment, Anhui Agricultural University, Hefei 230036, PR China.
authors.forename: Changyin
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Environmental Engineering and Science Program, University of Cincinnati, Cincinnati, OH 45221-0012, USA.
authors.forename: Dionysios D
authors.initials: DD
authors.lastname: Dionysiou
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: juangao@issas.ac.cn.
authors.forename: Juan
authors.initials: J
authors.lastname: Gao
authors.affiliation: Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, PR China. Electronic address: dmzhou@issas.ac.cn.
authors.forename: Dongmei
authors.initials: D
authors.lastname: Zhou
mesh_terms: D002374:Catalase / Q000378:metabolism; D002606:Charcoal / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D005609:Free Radicals / Q000737:chemistry; D006861:Hydrogen Peroxide / Q000737:chemistry; D017665:Hydroxyl Radical / Q000737:chemistry*; D007700:Kinetics; D010100:Oxygen / Q000737:chemistry; D010795:Phthalic Acids / Q000737:chemistry*; D013482:Superoxide Dismutase / Q000378:metabolism; D013481:Superoxides / Q000737:chemistry
chemical_list: D005609:Free Radicals; D010795:Phthalic Acids; C540010:biochar; D013481:Superoxides; D002606:Charcoal; D017665:Hydroxyl Radical; D006861:Hydrogen Peroxide; D002374:Catalase; D013482:Superoxide Dismutase; D010100:Oxygen; C007379:diethyl phthalate
keywords: Biochar suspensions; Diethyl phthalate degradation; Free radicals in biochar; Hydroxyl radical