中文摘要：

通过分析酸性条件下（pH为1—3），Fe^3＋催化氧化S（Ⅳ）过程中溶液吸光度变化的趋势，对Fe^3＋催化氧化S（Ⅳ）的反应机理进行了初步推导．实验证明。液相中该反应机理主要是催化氧化与自由基反应相结合，O2的存在对于反应有重要作用，O2^-的生成是S（Ⅳ）被氧化的关键；当水中溶解氧接近耗尽时，反应进程发生改变．当Fe^3＋、S（Ⅳ）浓度增加，自由基生成量增加时，有利于反应进行；作为反应产物，Fe^2＋、S（Ⅵ）浓度增加，反应推动力减小，反应速率降低；同时Fe^2＋、SO4^2-可以与溶液中的其它物质形成配合物，影响了Fe^3＋-S（Ⅳ）配合物的生成与分解，不利于S（Ⅵ）的氧化．

英文摘要：

The mechanism of the catalyzed oxidation reaction of S（Ⅳ ） with Fe^3 ＋ was studied by analyzing variation trend of the absorbance of the mixed solution under acidic condition （ pH = 1 - 3）. It was found that the mechanism of the reaction in aqueous solution was the combination of catalyzed oxidation and radical reaction, and the O2- produced from the oxygen in solution played a very important role for the oxidation of S（ Ⅳ ）. As a result, when the oxygen in solution was approached exhausted, the reaction path was changed as well. The studies also showed that the increase of the concentration of Fe^3＋ and S（Ⅳ） was beneficial to the reaction due to the increase amount of radical; however, the increase of the concentration of Fe^2 ＋ and S （Ⅵ） results iu the reduced reaction rate due to the chemical equilibrium and the complexes formation of Fe^2 ＋ and SO4^2- with other spices in the solution, which impede the formation and decomposition of Fe^3＋ -S（ Ⅳ ） complexes.