title: Kinetics and mechanism of 2,6-dimethyl-aniline degradation by hydroxyl radicals.
abstract: This research investigated the intrinsic second-order rate constant between 2,6-dimethyl-aniline (2,6-DMA) and hydroxyl radicals (OH) using Fenton's reactions under both batch and continuous operations. The competitive kinetics technique with aniline as a reference compound was employed. In the batch study under various conditions, the second-order rate constants of 2,6-DMA with OH were between 1.59 x 10(10) and 1.80 x 10(10)M(-1)s(-1) with a mean of 1.71 x 10(10)M(-1)s(-1) which equals the average value obtained from the continuous study as well. The concentrations of OH at the steady state under the continuous mode were estimated to be between 4.85 x 10(-10) and 6.82 x 10(-10)mM. 2,6-dimethyl-nitrobenzene, 2,6-dimethyl-phenol, 2,6-dimethyl-nitrophenol, 2,6-dimethyl-hydroquinone, 2,6-dimethyl-p-benzoquinone, and 2,6-dimethyl-3-hydroxy-p-benzoquinone were identified as the aromatic by-products indicating that the methyl group on the aromatic ring was not susceptible to OH attack. Maleic, lactic, oxalic, acetic, and formic acids were found as generated carboxylic acids. An oxidation pathway of 2,6-DMA by OH is also proposed.
authors.affiliation: International Postgraduate Programs in Environmental Management, Graduate School, Chulalongkorn University, Bangkok 10330, Thailand.
authors.forename: Nonglak
authors.initials: N
authors.lastname: Boonrattanakij
authors.forename: Ming-Chun
authors.initials: MC
authors.lastname: Lu
authors.forename: Jin
authors.initials: J
authors.lastname: Anotai
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D002264:Carboxylic Acids; D006861:Hydrogen Peroxide; D017665:Hydroxyl Radical / Q000737:chemistry*; D007501:Iron; D007700:Kinetics; D010084:Oxidation-Reduction
chemical_list: D000814:Aniline Compounds; D002264:Carboxylic Acids; C045076:Fenton's reagent; D017665:Hydroxyl Radical; C007766:2,6-xylidine; D006861:Hydrogen Peroxide; D007501:Iron