Rates of hydroxyl radical generation and organic compound oxidation in mineral-catalyzed Fenton-like systems
Rates of hydroxyl radical generation and organic compound oxidation in mineral-catalyzed Fenton-like systems
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DOI：
10.1021/es020874g
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发表时间：
2003-03-15
影响因子：
11.4
通讯作者：
Voelker, BM
中科院分区：
文献类型：
--
作者：
Kwan, WP;Voelker, BM
氧化铁催化过氧化氢（H2 O2）生成羟基自由基（.OH）已被用于氧化土壤和地下水中的有机污染物。本研究的目标是确定哪些因素控制.OH（V-OH）的生成速率，并表明如果V-OH和.OH与系统成分的反应速率常数是已知的，则可以预测溶解的有机化合物的氧化速率。使用C-14-标记的甲酸作为探针，我们测量V-OH在pH 4的H2 O2和合成的水铁矿，针铁矿，赤铁矿或天然氧化铁涂层石英含水层砂浆料。在我们的所有实验中，V-OH与氧化铁和H2 O2的表面积浓度的乘积成比例，尽管不同的固体以不同的速率产生.OH。我们使用这些结果来开发一个模型的甲酸的分解率作为初始的甲酸和过氧化氢的浓度和氧化铁的类型和数量的函数。我们的模型成功地预测了在我们的含水层砂实验和其他一些研究中观察到的V-OH和有机化合物的氧化速率，但在其他情况下高估了V-OH和氧化速率，这可能表明未知的反应物在这些系统中干扰.OH的产生或消耗.OH。
The iron oxide-catalyzed production of hydroxyl radical (.OH) from hydrogen peroxide (H2O2) has been used to oxidize organic contaminants in soils and groundwater. The goals of this study are to determine which factors control the generation rate of .OH (V-OH) and to show that if V-OH and the rate constants of the reactions of .OH with the system's constituents are known, the oxidation rate of a dissolved organic compound can be predicted. Using C-14-labeled formic acid as a probe, we measured V-OH in pH 4 slurries of H2O2 and either synthesized ferrihydrite, goethite, or hematite or a natural iron oxide-coated quartzitic aquifer sand. In all of our experiments, V-OH was proportional to the product of the concentrations of surface area of the iron oxide and H2O2, although different solids produced .OH at different rates. We used these results to develop a model of the decomposition rate of formic acid as a function of the initial formic acid and hydrogen peroxide concentrations and of the type and quantity of iron oxide. Our model successfully predicted the V-OH and organic compound oxidation rates observed in our aquifer sand experiment and in a number of other studies but overpredicted V-OH and oxidation rates in other cases, possibly indicating that unknown reactants are either interfering with .OH production or consuming .OH in these systems.