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首页> 外文期刊>Environmental toxicology and chemistry >KINETICS OF THE REDUCTION OF CHROMIUM(VI) BY VITAMIN C
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KINETICS OF THE REDUCTION OF CHROMIUM(VI) BY VITAMIN C

机译：维生素C还原铬（VI）的动力学

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摘要

The kinetics of the reduction of Cr(Ⅵ) to Cr(Ⅲ) by vitamin C was studied using potassium dichromate solution as the model pollutant. Effects of the concentration of vitamin C, pH, temperature, and irradiation on the reduction of Cr(Ⅵ) were examined. The kinetics of Cr(Ⅵ) reduction by vitamin C can be described as -d[Cr(Ⅵ)]/dt = 0.0156 (μM s~(-1))·[Cr(Vl)][vitamin C] (pH 5), where dt is the differential function (d) of time (t). The activation entropy (ΔS) and enthalpy (ΔH) are 42.4 kJ mol~(-1) and -71.0 J mol~(-1) K~(-1), respectively, and the activation energy at 298 K is 63.5 kJ mol~(-1). The advantages of vitamin C as a reductant are as follows: It is an important biological reductant in humans and animals, and it is not toxic. Toxic Cr(Ⅵ) can be reduced by vitamin C not only in acidic conditions but also in alkaline solutions (pH 9); furthermore, the reduction was shown to occur both under the irradiation and in the dark. The present results suggest that vitamin C could be used effectively in the remediation of Cr(Ⅵ)-contaminated soil and groundwater in a wide range of pH, with or without sunlight.
机译：以重铬酸钾溶液为模型污染物，研究了维生素C将Cr（Ⅵ）还原为Cr（Ⅲ）的动力学。研究了维生素C的浓度，pH，温度和辐射对Cr（Ⅵ）还原的影响。维生素C还原Cr（Ⅵ）的动力学可以描述为-d [Cr（Ⅵ）] / dt = 0.0156（μMs〜（-1））·[Cr（Vl）] [维生素C]（pH 5 ），其中dt是时间（t）的微分函数（d）。活化熵（ΔS）和焓（ΔH）分别为42.4 kJ mol〜（-1）和-71.0 J mol〜（-1）K〜（-1），298 K时的活化能为63.5 kJ mol 〜（-1）。维生素C作为还原剂的优点如下：它是人和动物中重要的生物还原剂，无毒。维生素C不仅可以在酸性条件下，而且可以在碱性溶液（pH 9）中还原有毒的六价铬。此外，还表明在辐射下和在黑暗中都发生了还原。目前的结果表明，在有或没有阳光的情况下，维生素C均可有效地修复在宽pH范围内受Cr（Ⅵ）污染的土壤和地下水。

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