Electron-Beam Treatment of Aromatic Hydrocarbons That Can Be Air-Stripped from Contaminated Groundwater. 2. Gas-Phase Studies
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- 作者：Lutz Prager ; Gertraud Mark ; Hartmut Mä ; tzing ; Hanns-Rudolf Paur ; Jü ; rgen Schubert ; Fritz H. Frimmel ; Sebastian Hesse ; Heinz-Peter Schuchmann ; Man Nien Schuchmann ; and Clemens von Sonntag
- 刊名：Environmental Science & Technology
- 出版年：2003
- 出版时间：January 15, 2003
- 年：2003
- 卷：37
- 期：2
- 页码：379 - 385
- 全文大小：104K
- 年卷期：v.37,no.2(January 15, 2003)
- ISSN：1520-5851
文摘
The electron-beam (EB) degradation of volatile aromatics(benzene, toluene, ethylbenzene, xylenes: BTEX) ingroundwater strip gas, which in the present work hasbeen modeled by the introduction of the desired aromatic(s) to a stream of air or another gas, such as oxygen, isinitiated essentially by the addition of 
OH radicals tothe aromatic ring, giving rise to hydroxycyclohexadienylradicals, which form the corresponding peroxyl radicalsupon addition of oxygen. As studied in some detail withbenzene as a BTEX representative, various reactions of theselead to numerous oxidation products in a cascade ofreactions, including the decomposition of products underthe prevailing conditions of high turnover of the initial aromatic.Importantly, hydroxycyclohexadienylperoxyl radicalformation is partly reversible, and the reactions of thehydroxycyclohexadienyl radicals, which thus have a significantpresence in these systems, must therefore also be takeninto consideration. In the gas phase, in contrast to the aqueousphase (see Part 1), the reactions of the hydroxycyclohexadienyl radicals lead to oligomeric products that appearto contribute, in addition to ionic clusters, to nucleationfor the aerosols observed. Various nitrated products, amongthem nitrophenols, are observed when air is used forthe stripping. However, these studies did not clear thepilot plant stage, since BTEX degradation using a bioreactorcarried out in parallel was so successful that the EBtechnology was judged to be noncompetitive. As for thelatter, expensive equipment consisting of a stripper, the EBmachine, and an aerosol precipitator would be required.The condensed aerosols are biorefractory and would requirefurther treatment for detoxification.
OH radicals tothe aromatic ring, giving rise to hydroxycyclohexadienylradicals, which form the corresponding peroxyl radicalsupon addition of oxygen. As studied in some detail withbenzene as a BTEX representative, various reactions of theselead to numerous oxidation products in a cascade ofreactions, including the decomposition of products underthe prevailing conditions of high turnover of the initial aromatic.Importantly, hydroxycyclohexadienylperoxyl radicalformation is partly reversible, and the reactions of thehydroxycyclohexadienyl radicals, which thus have a significantpresence in these systems, must therefore also be takeninto consideration. In the gas phase, in contrast to the aqueousphase (see Part 1), the reactions of the hydroxycyclohexadienyl radicals lead to oligomeric products that appearto contribute, in addition to ionic clusters, to nucleationfor the aerosols observed. Various nitrated products, amongthem nitrophenols, are observed when air is used forthe stripping. However, these studies did not clear thepilot plant stage, since BTEX degradation using a bioreactorcarried out in parallel was so successful that the EBtechnology was judged to be noncompetitive. As for thelatter, expensive equipment consisting of a stripper, the EBmachine, and an aerosol precipitator would be required.The condensed aerosols are biorefractory and would requirefurther treatment for detoxification.