甲酸对Cr(III)紫外光氧化的抑制作用研究
Inhibitory effect of formate on oxidation of Cr(III) under UV irradiation
环境中Cr(III)氧化至Cr(VI)的过程至今并不清楚，尽管有关铬还原的研究已经有广泛的报道。本文研究了一种小分子有机酸-甲酸对铁催化的Cr(III)光氧化反应的影响规律。为分析机理，实验中检测了Cr(VI), Fe(II)和H2O2浓度。在未添加甲酸的体系中，Cr(III)可较容易的被羟基铁配合物光解产生的羟基自由基(oOH)氧化成Cr(VI)。但当加入甲酸后，未检测到Cr(VI)的存在。可能的原因是甲酸是一种较强的自由基捕获剂可以与Cr(III)竞争氧化剂。另外甲酸分解产生的强还原自由基CO2o-也可以再次还原已生成的Cr(VI)。然而，CO2o-的产率很低，主要由于UV/Fe(III)体系中oOH的量子产量较低。本研究对于理解富碳水环境中铬的氧化还原化学具有重要意义。
化学金属元素无机化合物化学工业环境科学理论
环境科学铁循环氧化还原光化学
王兆慧,肖冬雪,柳建设,刘仁兰.甲酸对Cr(III)紫外光氧化的抑制作用研究[EB/OL].(2013-12-24)[2025-10-31].http://www.paper.edu.cn/releasepaper/content/201312-776.点此复制
The oxidation processes of Cr(III) to Cr(VI) are not well understood, although the reduction of Cr(VI) has been extensively investigated. Here the effects of the small organic acid, formic acid, on the iron-catalyzed photo-oxidation of Cr(III) were examined. The concentrations of Cr(VI), Fe(II) and H2O2 were monitored to elucidate the reaction mechanisms. In the absence of formate, Cr(III) can be readily oxidized to Cr(VI) by photogenerated oOH from photolysis of ferric hydroxyl complex. The presence of formate diminished the production of Cr(VI) due to its strong radical scavenging capacity for oOH and potential re-reduction of Cr(VI) by its secondary reducing CO2o- radical. However, the yield of CO2o- may be very low because of the much lower quantum yield of oOH in UV/Fe(III) systems. The present study has important implication for understanding the redox chemistry of chromium species in carbon-rich aquatic environment.
environmental scienceiron cyclingredoxphotochemistry
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