The 鈥?/sup>OH Radical Yield in the H2O2 + O3 (Peroxone) Reaction
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- 作者：Alexandra Fischbacher ; Justus von Sonntag ; Clemens von Sonntag ; Torsten C. Schmidt
- 刊名：Environmental Science & Technology
- 出版年：2013
- 出版时间：September 3, 2013
- 年：2013
- 卷：47
- 期：17
- 页码：9959-9964
- 全文大小：321K
- 年卷期：v.47,no.17(September 3, 2013)
- ISSN：1520-5851
文摘
The peroxone process is one of the AOPs that lead to 鈥?/sup>OH. Hitherto, it has been generally assumed that the 鈥?/sup>OH yield is unity with respect to O3 consumption. Here, experimental data are presented that suggest that it must be near 0.5. The first evidence is derived from competition experiments. The consumption of 4-chlorobenzoic acid (4-CBA), 4-nitrobenzoic acid (4-NBA) and atrazine present in trace amounts (1 渭M) has been followed as a function of the O3 concentration in a solution containing H2O2 (1 mM) and tertiary butanol (tBuOH, 0.5 mM) in excess over the trace compounds. With authentic 鈥?/sup>OH generated by 纬-radiolysis such a competition can be adequately fitted by known 鈥?/sup>OH rate constants. Fitting the peroxone data, however, the consumption of the trace indicators can only be rationalized if the 鈥?/sup>OH yield is near 0.5 (4-CBA: 0.56, 4-NBA: 0.49, atrazine: 0.6). Additional information for an 鈥?/sup>OH yield much below unity has been obtained by a product analysis of the reactions of tBuOH with 鈥?/sup>OH and dimethyl sulfoxide with 鈥?/sup>OH. The mechanistic interpretation for the low 鈥?/sup>OH yield is as follows (Mer茅nyi et al. Environ. Sci. Technol. 2010, 44, 3505鈥?507). In the reaction of O3 with HO2鈥?/sup> an adduct (HO5鈥?/sup>) is formed that decomposes into O3鈥⑩€?/sup> and HO2鈥?/sup> in competition with 2 O2 + OH鈥?/sup>. The latter process reduces the free-radical yield.