title: Non-photochemical production of singlet oxygen via activation of persulfate by carbon nanotubes.
abstract: The reaction between persulfate (PS) and carbon nanotubes (CNTs) for the degradation of 2,4-dichlorophenol (2,4-DCP) was investigated. It was demonstrated that CNTs could efficiently activate PS for the degradation of 2,4-DCP. Results suggested that the neither hydroxyl radical (OH) nor sulfate radical (SO4-) was produced therein. For the first time, the generation of singlet oxygen (1O2) was proved by several methods including electron paramagnetic resonance spectrometry (EPR) and liquid chromatography mass spectrometry measurements. Moreover, the generation of the superoxide radical as a precursor of the singlet oxygen was also confirmed by using certain scavengers and EPR measurement, in which the presence of molecular oxygen was not required as a precursor of1O2. The efficient generation of1O2using the PS/CNTs system without any light irradiation can be employed for the selective oxidation of aqueous organic compounds under neutral conditions with the mineralization and toxicity evaluated. A kinetic model was developed to theoretically evaluate the adsorption and oxidation of 2,4-DCP on the CNTs. Accordingly, a catalytic mechanism was proposed involving the formation of a dioxirane intermediate between PS and CNTs, and the subsequent decomposition of this intermediate into1O2.
authors.affiliation: College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
authors.forename: Xin
authors.initials: X
authors.lastname: Cheng
authors.affiliation: College of Architecture and Environment, Sichuan University, Chengdu 610065, China; National Engineering Laboratory for Clean Technology of Leather Manufacture, Sichuan University, Chengdu 610065, China. Electronic address: hgguo@scu.edu.cn.
authors.forename: Hongguang
authors.initials: H
authors.lastname: Guo
authors.affiliation: College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
authors.forename: Yongli
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: College of Historical Culture and Tourism, Sichuan Normal University, Chengdu 610068, China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Wu
authors.affiliation: College of Architecture and Environment, Sichuan University, Chengdu 610065, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D017665:Hydroxyl Radical / Q000737:chemistry; D037742:Nanotubes, Carbon / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry*; D013481:Superoxides / Q000737:chemistry
chemical_list: D037742:Nanotubes, Carbon; D013481:Superoxides; D026082:Singlet Oxygen; D017665:Hydroxyl Radical; D010100:Oxygen
keywords: Carbon nanotubes; Kinetics; Non-radical mechanism; Persulfate; Singlet oxygen