Kinetics of nitrate, nitrite, and Cr(VI) reduction by iron metal
Kinetics of nitrate, nitrite, and Cr(VI) reduction by iron metal
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DOI：
10.1021/es011000h
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发表时间：
2002-02-01
影响因子：
11.4
通讯作者：
Scherer, MM
中科院分区：
文献类型：
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作者：
Alowitz, MJ;Scherer, MM
在间歇反应器中研究了三种铁金属 (Fell) 还原硝酸盐、亚硝酸盐和 Cr(VI) 的动力学，研究了一系列 Fell 表面积浓度和溶液 pH 值 (5.5-9.0)。在 pH 7.0 时，所研究的三种 Fe-0 类型（Fisher、Peerless 和 Connelly）中每种污染物的一阶速率系数 (k(obs)) 仅存在适度差异 (2-4x)。 pH 7.0 时亚硝酸盐和 Cr(VI) 还原的 k(obs) 值相对于 Fell 表面积浓度而言是一阶的，并且亚硝酸盐和 Cr(VI) 的平均表面积归一化速率系数 (k(SA)) 分别为 9.0 X 10(-3) 和 2.2 x 10(-1) L m(-2) h(-1)。与亚硝酸盐和 Cr(VI) 不同，Fell 表面积浓度对硝酸盐还原速率几乎没有影响（Connelly Fe-0 除外，它在较高 Fall 表面积下以较慢的速率还原硝酸盐）。 Fisher Fell 还原硝酸盐、亚硝酸盐和 Cr(VI) 的速率随着 pH 值的增加而降低，硝酸盐的表观反应级数为 0.49 +/- 0.04，亚硝酸盐为 0.61 +/- 0.02，Cr(VI) 为 0.72 +/- 0.07。缓冲液类型对还原率的影响很小，表明 pH 值是造成还原率差异的主要原因。在高 pH 值下，Cr(VI) 还原在短时间内停止，并且在 48 小时内观察到可忽略不计的亚硝酸盐还原。
The kinetics of nitrate, nitrite, and Cr(VI) reduction by three types of iron metal (Fell) were studied in batch reactors for a range of Fell surface area concentrations and solution pH values (5.5-9.0). At pH 7.0, there was only a modest difference (2-4x) in first-order rate coefficients (k(obs)) for each contaminant among the three Fe-0 types investigated (Fisher, Peerless, and Connelly). The k(obs) values at pH 7.0 for both nitrite and Cr(VI) reduction were first-order with respect to Fell surface area concentration and average surface area normalized rate coefficients (k(SA)) of 9.0 X 10(-3) and 2.2 x 10(-1) L m(-2) h(-1) were determined for nitrite and Cr(VI), respectively. Unlike nitrite and Cr(VI), Fell surface area concentration had little effect on rates of nitrate reduction (with the exception of Connelly Fe-0, which reduced nitrate at slower rates at higher Fall surface areas). The rates of nitrate, nitrite, and Cr(VI) reduction by Fisher Fell decreased with increasing pH with apparent reaction orders of 0.49 +/- 0.04 for nitrate, 0.61 +/- 0.02 for nitrite, and 0.72 +/- 0.07 for Cr(VI). Buffer type had minimal effects on reduction rates, indicating that pH was primarily responsible for the differences in rate. At high pH values, Cr(VI) reduction ceased after a short time period, and negligible nitrite reduction was observed over 48 h.