摘要:
研究了稀水溶液中Cr(Ⅵ)的光化学还原过程,考察了·OH自由基俘获剂的种类、结构及溶液pH值对Cr(Ⅵ)还原的影响结果表明稀水溶液中Cr(Ⅵ)的还原过程分化学还原与光化学还原两步进行,前者为直接氧化还原过程,后者则经历自由基反应;·OH自由基俘获剂中羟基的数量和位置对Cr(Ⅵ)的还原均有影响,羟基α位碳上氢原子数量愈多,碳氢键强度愈小,愈有利于Cr(Ⅵ)还原;溶液pH值对Cr(Ⅵ)的还原有重要影响,随着pH值的升高,其还原率和反应速率均下降,当pH≥70时,Cr(Ⅵ)的还原基本停止
Abstract:
In this paper,the experiences of the photochemical reduction of chromium(Ⅵ)were researched and the effects of some factors,such as molecular structure,dose,solution pH,etc.,on Cr(Ⅵ)reduction were explored.The results showed that Cr(Ⅵ)reduction consisted of two steps:chemical reduction and photochemical reduction.In the first step,Cr(Ⅵ)was reduced directly by free radical cleaner,and the second step experienced free radicals reaction.Because the photochemical reduction involved the abstraction of a hydrogen atom from the α position carbon to the radical cleaners the amount and position of hydroxyl affected on the reduction of Cr(Ⅵ).The solution pH affected on the reduction of Cr(Ⅵ)drastically.With the pH increasing,the reduction ratio of Cr(Ⅵ)decreased.When the pH was up to 7.0,the reduction of Cr(Ⅵ)would cease.
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