pH-induced mechanistic changeover from hydroxyl radicals to iron(IV) in the Fenton reaction
pH-induced mechanistic changeover from hydroxyl radicals to iron(IV) in the Fenton reaction
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DOI：
10.1039/c2sc20099f
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发表时间：
2012-01-01
期刊：
影响因子：
8.4
通讯作者：
Bakac, Andreja
中科院分区：
文献类型：
--
作者：
Bataineh, Hajem;Pestovsky, Oleg;Bakac, Andreja
Fe（II）和H2 O2在pH 6-7的非配位缓冲液中反应的主要途径表现出对[H+]的逆动力学依赖性，并导致二甲基亚砜（DMSO）氧化成二甲基砜（DMSO 2）。这一步骤使Fe（II）再生，并使DMSO的氧化具有催化作用，这一发现强烈支持Fe（IV）在接近中性的pH下作为芬顿中间体。在pH 6-7下，Fe（IV）对DMSO的氧化效率低于（H2O）（5）FeO 2+，后者是在酸性溶液中由Fe（H2O）（6）（2+）的臭氧氧化产生的。由于Fe（II）和Fe（IV）之间的快速竞争反应导致催化剂的不可逆损失，因此需要高浓度的DMSO以在pH >= 6时实现显著的周转数。在pH 6和
A major pathway in the reaction between Fe(II) and H2O2 at pH 6-7 in non-coordinating buffers exhibits inverse kinetic dependence on [H+] and leads to oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2). This step regenerates Fe(II) and makes the oxidation of DMSO catalytic, a finding that strongly supports Fe(IV) as a Fenton intermediate at near-neutral pH. This Fe(IV) is a less efficient oxidant for DMSO at pH 6-7 than is (H2O)(5)FeO2+, generated by ozone oxidation of Fe(H2O)(6)(2+), in acidic solutions. Large concentrations of DMSO are needed to achieve significant turnover numbers at pH >= 6 owing to the rapid competing reaction between Fe(II) and Fe(IV) that leads to irreversible loss of the catalyst. At pH 6 and