title: ABTS as an Electron Shuttle to Enhance the Oxidation Kinetics of Substituted Phenols by Aqueous Permanganate.
abstract: In this study, it was, interestingly, found that 2,2'-azino-bis(3-ethylbenzothiazoline)-6-sulfonate (ABTS), a widely used electron shuttle, could greatly accelerate the oxidation of substituted phenols by potassium permanganate (Mn(VII)) in aqueous solutions at pH 5-9. This was attributed to the fact that these substituted phenols could be readily oxidized by the stable radical cation (ABTS(•+)), which was quickly produced from the oxidation of ABTS by Mn(VII). The reaction of Mn(VII) with ABTS exhibited second-order kinetics, with stoichiometries of ∼5:1 at pH 5-6 and ∼3:1 at pH 7-9, and the rate constants varied negligibly from pH 5 to 9 (k = (9.44 ± 0.21) × 10(4) M(-1) s(-1)). Comparatively, the reaction of ABTS(•+) with phenol showed biphasic kinetics. The second-order rate constants for the reactions of ABTS(•+) with substituted phenols obtained in the initial phase were strongly affected by pH, and they were several orders of magnitude higher than those for the reactions of Mn(VII) with substituted phenols at each pH. Good Hammett-type correlations were found for the reactions of ABTS(•+) with undissociated (log(k) = 2.82-4.31σ) and dissociated phenols (log(k) = 7.29-5.90σ). The stoichiometries of (2.2 ± 0.06):1 (ABTS(•+) in excess) and (1.38 ± 0.18):1 (phenol in excess) were achieved in the reaction of ABTS(•+) with phenol, but they exhibited no pH dependency.
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Song
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Jiang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Ma
authors.affiliation: Key Laboratory of Green Chemical Engineering and Technology of College of Heilongjiang Province, College of Chemical and Environmental Engineering, Harbin University of Science and Technology , Harbin 150040, China.
authors.forename: Su-Yan
authors.initials: SY
authors.lastname: Pang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Yong-Ze
authors.initials: YZ
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Yang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Cong-Wei
authors.initials: CW
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Jian-Qiao
authors.initials: JQ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Gu
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Qin
mesh_terms: D052160:Benzothiazoles / Q000737:chemistry*; D011756:Diphosphates / Q000737:chemistry; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008345:Manganese / Q000737:chemistry; D017895:Manganese Compounds / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010087:Oxides / Q000737:chemistry*; D010636:Phenols / Q000737:chemistry*; D012996:Solutions; D013451:Sulfonic Acids / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*
chemical_list: D052160:Benzothiazoles; D011756:Diphosphates; D017895:Manganese Compounds; D016877:Oxidants; D010087:Oxides; D010636:Phenols; D012996:Solutions; D013451:Sulfonic Acids; D014867:Water; C048856:permanganic acid; C002502:2,2'-azino-di-(3-ethylbenzothiazoline)-6-sulfonic acid; D008345:Manganese