Reduction of nitro aromatic compounds by zero-valent iron metal
Reduction of nitro aromatic compounds by zero-valent iron metal
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DOI：
10.1021/es950211h
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发表时间：
1996-01-01
影响因子：
11.4
通讯作者：
Tratnyek, PG
中科院分区：
文献类型：
--
作者：
Agrawal, A;Tratnyek, PG
铁金属的特性使其可用于氯代溶剂的补救，也可减少其他地下水污染物，如硝基芳族化合物（NACs）。硝基苯在厌氧条件下被铁还原为苯胺，中间产物为亚硝基苯。偶氮苯和氧化偶氮苯等偶联产物未检出。硝基苯和亚硝基苯的一级还原速率相似，但苯胺的出现更慢（在存在33 g/L酸洗的18-20目Fluka铁屑的情况下，典型的伪一级速率常数分别为3.5 x 10（-2）、3.4 x 10（-2）和8.8 x 10（-3）min（-1））。硝基还原速率随铁表面积浓度线性增加，得到比反应速率常数（3.9 +/- 0.2 x 10（-2）min（-1）m（-2）L）。溶液pH值或环取代对硝基还原速率的影响最小，硝基苯还原稀有常数与混合速率（rpm）的平方根之间的线性相关性表明，所观察到的反应速率是由NAC向金属表面的传质控制的。随着溶解的碳酸盐浓度的增加和金属对特定碳酸盐缓冲液的延长暴露，硝基苯的还原速率降低，这表明金属上的副产物沉淀抑制了硝基还原。
The properties of iron metal that make it useful in remediation of chlorinated solvents may also lead to reduction of other groundwater contaminants such as nitro aromatic compounds (NACs). Nitrobenzene is reduced by iron under anaerobic conditions to aniline with nitrosobenzene as an intermediate product. Coupling products such as azobenzene and azoxybenzene were not detected. First-order reduction rates are similar for nitrobenzene and nitrosobenzene, but aniline appearance occurs more slowly (typical pseudo-first-order rate constants 3.5 x 10(-2), 3.4 x 10(-2), and 8.8 x 10(-3) min(-1), respectively, in the presence of 33 g/L acid-washed, 18-20 mesh Fluka iron turnings). The nitro reduction rate increased linearly with concentration of iron surface area, giving a specific reaction rate constant (3.9 +/- 0.2 x 10(-2) min(-1) m(-2) L). The minimal effects of solution pH or ring substitution on nitro reduction rates, and the linear correlation between nitrobenzene reduction rare constants and the square-root of mixing rate (rpm), suggest that the observed reaction rates were controlled by mass transfer of the NAC to the metal surf:ace. The decrease in reduction rate for nitrobenzene with increased concentration of dissolved carbonate and with extended exposure of the metal to a particular carbonate buffer indicate that the precipitation of side rite on the metal inhibits nitro reduction.