Electron-beam treatment of aromatic hydrocarbons that can be air-stripped from contaminated groundwater. 1. Model studies in aqueous solution.
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.
Mark
Gertraud
G
Max-Planck-Institut für Strahlenchemie, Stiftstrasse 34-36, P.O.Box 101365, 45413 Mülheim, Germany.
Schuchmann
Heinz-Peter
HP
Schuchmann
Man Nien
MN
Prager
Lutz
L
von Sonntag
Clemens
C
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
D005740:Gases; D006841:Hydrocarbons, Aromatic; D016877:Oxidants; D012989:Soil Pollutants; D017665:Hydroxyl Radical