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  • Non-photochemical productio...
    Cheng, Xin; Guo, Hongguang; Zhang, Yongli; Wu, Xiao; Liu, Yang

    Water research (Oxford), 04/2017, Volume: 113
    Journal Article

    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 of 1O2. The efficient generation of 1O2 using 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 into 1O2. Display omitted •Non-radical mechanism for persulfate (PS) activation by using CNTs were demonstrated.•Generation of singlet oxygen (1O2) was proved by quenching experiments, ESR and LC-MS.•Selective oxidation of aqueous organic compounds was observed.•Kinetic model was established with a dynamic cycle proposed for the adsorption-oxidation of 2, 4-DCP.