title: Electron-beam treatment of aromatic hydrocarbons that can be air-stripped from contaminated groundwater. 1. Model studies in aqueous solution.
abstract: As a model for the electron-beam degradation of volatile aromatics (benzene, toluene, ethylbenzene, xylenes, BTEX) in groundwater strip gas, to be reported in Part 2, the gamma-radiolysis of benzene has been studied in aqueous solutions. Addition of *OH to the aromatic ring gives rise to hydroxycyclohexadienyl radicals which either dimerize or disproportionate. The various dimers undergo acid-catalyzed water elimination yielding biphenyl. Phenol is formed upon disproportionation directly, but also via dihydroxycyclohexadiene which subsequently undergoes acid-catalyzed water elimination. Co-radiolysis of benzene with nitrite generates *NO2 in addition to the hydroxycyclohexadienyl radical. These not only interact with one another (product: nitrobenzene via nitro-hydroxycyclohexadienes) but the *NO2 radical is also capable of abstracting cyclohexadienylic hydrogens. This reaction leads to the formation of 2- and 4-nitrophenol and to further nitrated products that were not identified. These are suggested to be formed in an analogous reaction of *NO2 with the hydroxycylohexadienyl dimers. The effect of O2 on these reactions and the relevance for the gas-phase radiolysis of BTEX is discussed.
authors.affiliation: Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, P.O.Box 101365, 45413 Mülheim, Germany.
authors.forename: Gertraud
authors.initials: G
authors.lastname: Mark
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Schuchmann
authors.forename: Man Nien
authors.initials: MN
authors.lastname: Schuchmann
authors.forename: Lutz
authors.initials: L
authors.lastname: Prager
authors.forename: Clemens
authors.initials: C
authors.lastname: von Sonntag
mesh_terms: D004583:Electrons; D004787:Environmental Pollution / Q000517:prevention & control*; D005740:Gases; D006841:Hydrocarbons, Aromatic / Q000737:chemistry*; D017665:Hydroxyl Radical / Q000737:chemistry; D008956:Models, Chemical; D016877:Oxidants / Q000737:chemistry; D012989:Soil Pollutants; D014835:Volatilization
chemical_list: D005740:Gases; D006841:Hydrocarbons, Aromatic; D016877:Oxidants; D012989:Soil Pollutants; D017665:Hydroxyl Radical