The aqueous degradation of butylated hydroxyanisole by UV/S2O82-:: Study of reaction mechanisms via dimerization and mineralization
The aqueous degradation of butylated hydroxyanisole by UV/S2O82-:: Study of reaction mechanisms via dimerization and mineralization
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DOI：
10.1021/es061395a
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发表时间：
2007-01-15
影响因子：
11.4
通讯作者：
Graham, Nigel J. D.
中科院分区：
文献类型：
--
作者：
Lau, Tim K.;Chu, Wei;Graham, Nigel J. D.
研究了BHA在酸性、中性和碱性pH范围内对UV/S2O82-的三种不同相的反应性，在254 nm照射1小时内观察到80-100%的矿化。在反应过程中，溶液pH值的降低主要是由于S2O82-完全转化为硫酸盐离子以及质子的生成。在所有测试的pH值水平下，通过氧化和二聚化过程发现了七种可测量的中间体。在酸性条件下和其他pH值下，BHA的衰变机制有很大不同。有三种独特的中间体只能通过另外两种途径在pH值为3时检测到。这是由于产生较弱的氧化剂或自由基，导致BHA的降解较慢，因此，这些中间体的积累达到可检测的水平。底部钻具组合（BHA）的衰变速率通常从低pH值到高pH值增加；然而，在较高的pH下，由于自由基的无效重组过程和中间体的参与，相应的矿化被延缓。因此，中性pH是矿化和去除BHA效率适中的最佳条件。
Three distinctive phases of BHA reactivity toward UV/S2O82- at acidic, neutral, and basic pH range were examined, where 80-100% mineralization has been observed within an hour of irradiation under 254 nm. A reduction in solution pH during the reaction was observed mainly due to the complete conversion of S2O82- to sulfate ion together with proton generation. Seven measurable intermediates were found via an oxidation and dimerization process at all tested pH levels. The BHA decay mechanisms are quite different in acidic condition and at other pH levels. There are three unique intermediates that are only detectable at pH 3 via two additional pathways. This is due to the generation of weaker oxidants or radicals which results in a slower degradation of the BHA, and therefore, the accumulation of these intermediates to detectable levels. The rate of BHA decay generally increases from low to high pH levels; however, the corresponding mineralization at higher pH is retarded due to the futile process of recombining radicals and involvement of intermediates. Therefore, neutral pH was suggested to be the optimum condition in terms of mineralization and moderate efficiency in removing BHA.