Oxygen−Sulfur Species Distribution and Kinetic Analysis in the Hydrogen Peroxide−Thiosulfate System

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• 作者：Yongchao Lu ; Qingyu Gao ; Li Xu ; Yuemin Zhao ; Irving R. Epstein
• 刊名：Inorganic Chemistry
• 出版年：2010
• 出版时间：July 5, 2010
• 年：2010
• 卷：49
• 期：13
• 页码：6026-6034
• 全文大小：834K
• 年卷期：v.49,no.13(July 5, 2010)
• ISSN：1520-510X

文摘

We have carried out species determination and kinetic analysis in the hydrogen peroxide−thiosulfate reaction by means of capillary electrophoresis and high performance liquid chromatography. In addition to thiosulfate, dithionate, trithionate, and tetrathionate, other polythionates such as pentathionate and hexathionate were detected during the oxidation process. The polythionates found are sensitive to the pH, with the average length of the sulfur chain decreasing with increasing pH. By varying the pH and the concentrations of the reactants, we find that the reaction is first order with respect to each of the reactants with rate constant k = 0.025 M⁻¹ s⁻¹. With HOS₂O₃⁻, HSO₃⁻/SO₃²⁻, S₃O₆²⁻, S₄O₆²⁻, and S₅O₆²⁻ as key intermediates that are eventually oxidized to sulfate, a proposed 14-step kinetic model simulates the reaction process, including the evolution of the thiosulfate and tetrathionate concentrations at various pHs.