Redox Interactions of Cr(VI) and Substituted Phenols: Kinetic Investigation.
Redox Interactions of Cr(VI) and Substituted Phenols: Kinetic Investigation.
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Cr(VI) 和取代酚的氧化还原相互作用：动力学研究。
DOI：
10.1021/es00061a026
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发表时间：
1994
影响因子：
11.4
通讯作者：
W. Fish
中科院分区：
文献类型：
--
作者：
M. Elovitz;W. Fish
在与环境相关的反应物浓度、pH、温度和离子强度范围内，研究了取代苯酚在水溶液中将Cr（V1）还原为Cr（II1）的动力学。在一定pH下，苯酚还原剂浓度和单体Cr（V1）总浓度均为一级反应。从pH 5到pH 1，反应速率提高了4个数量级。在相同的pH范围内，相对于[H+l]的表观反应顺序在0.2 ~ 2之间变化，但也取决于苯酚的结构。对14种取代酚的反应性进行了比较，发现取代基效应明显。当pH值为2时，14种酚类化合物的反应速率跨越了5个数量级以上，随着取代基（甲氧基>甲基>氯，醛>硝基）的给电子性质的增加，反应活性普遍增加。取代基效应用二阶速率常数（~ a ~ o H）与苯酚半波电位（Elp）的线性关系来描述。代表性的反应半衰期落在主要环境运输过程的时间尺度内，并表明这些相互作用的动力学在评估铬和酚类化合物污染的地点时具有重要意义。
The kinetics of the reduction of Cr(V1) to Cr(II1) by substituted phenols in aqueous solution were studied over environmentally relevant ranges of reactant concentrations, pH, temperature, and ionic strength. At a fixed pH, the reaction was first order with respect to both the concentration of phenol reductant and the total concentration of monomeric Cr(V1). Reaction rates increased as much as 4 orders of magnitude from pH 5 to pH 1. The apparent reaction order with respect to [H+l varied between 0.2 and 2 over this same pH range, but also depended on the structure of the phenol. Comparison of the reactivities of 14 substituted phenols revealed a strong substituent effect. A t pH 2, rates for the 14 phenols spanned more than 5 orders of magnitude with reactivity generally increasing with the electron-donating character of the substituent (methoxy > methyl > chloro, aldehyde > nitro). Substituent effects are described by a linear correlation of the second-order rate constants ( ~ A ~ o H ) with the phenol half-wave potential (Elp). Representative reaction half-lives fall within the time scales of major environmental transport processes and suggest that the kinetics of these interactions are of significant concern in assessing sites contaminated with chromium and phenolic compounds.