Identification of Sulfate and Hydroxyl Radicals in Thermally Activated Persulfate
Identification of Sulfate and Hydroxyl Radicals in Thermally Activated Persulfate
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DOI：
10.1021/ie9002848
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发表时间：
2009-06-03
影响因子：
4.2
通讯作者：
Su, Hsin-Wey
中科院分区：
文献类型：
--
作者：
Liang, Chenju;Su, Hsin-Wey
热激活可诱导过硫酸盐(S(2)O(8)(2-))降解生成硫酸根(SO(4)(-)中心点)，在碱性条件下可发生自由基相互转化形成羟基自由基(Ho中心点)。在过硫酸盐氧化体系中，自由基SO(4)(-)中心点/Ho中心点可以单独或同时存在。为了鉴定活性自由基物种，建立了一种化学探针法。在体系中加入过量的探针化合物，观察到探针的反应性与潜在的自由基物种之间的差异。研究了叔丁醇、苯酚和硝基苯(NB)等多种探针同时识别SO(4)(-)中心点/HO中心点的方法。NB只能与自由基反应：它不能与过硫酸盐反应。Nb与Ho中心点的反应速率是Nb与SO(4)(-)中心点的反应速率的3000-3900倍，这是区分SO(4)(-)中心点/Ho中心点反应性的一个很好的候选探针。此外，通过不同pH值下Nb的降解动力学，证明了pH对SO(4)(-)中心点/Ho中心点形成的影响。结果表明，在pH值下，SO(4)(-)中心点是主要的自由基
Thermal activation can induce persulfate (S(2)O(8)(2-)) degradation to form sulfate radicals (SO(4)(-)center dot) that can undergo radical interconversion to form hydroxyl radicals (HO center dot) under alkaline conditions. The radicals SO(4)(-)center dot/HO center dot can be present either individually or simultaneously in the persulfate oxidation system. To identify the active radical species, a chemical probe method was developed. An excess of probe compounds was added to the system, and differences between the reactivity of the probes and the potential radical species were observed. The usage of various probes, including tert-butyl alcohol, phenol, and nitrobenzene (NB), for simultaneously identifying SO(4)(-)center dot/HO center dot was investigated. NB can only react with radicals: it cannot react with persulfate. The reaction rate of NB with HO center dot is 3000-3900 times greater than that of NB with SO(4)(-)center dot, which is a good candidate for use as a probe for differentiating between SO(4)(-)center dot/HO center dot reactivity. Furthermore, the effects of pH on the formation Of SO(4)(-)center dot/HO center dot were demonstrated by the degradation kinetics of NB at varying pH values. The results indicated that SO(4)(-)center dot is the predominant radical at pH