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Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron.
Environmental Science: Processes & Impacts ( IF 4.3 ) Pub Date : 2020-03-03 , DOI: 10.1039/c9em00592g
Feng He 1 , Li Gong , Dimin Fan , Paul G Tratnyek , Gregory V Lowry
Affiliation  

The efficiency and selectivity of zerovalent iron-based treatments for organohalide contaminated groundwater can be quantified by accounting for redistribution of electrons derived from oxidation of Fe0. Several types of efficiency are reviewed, including (i) the efficiency of Fe(0) utilization, εFe(0), (ii) the electron efficiency of target contaminant reduction, εe, and (iii) the electron efficiency of natural reductant demand (NRD) involving H2O, O2, and co-contaminants such as nitrate, εNRD. Selectivity can then be calculated by using εe/εNRD. Of particular interest is εe and the key to its determination is measuring the total quantity of electrons provided by Fe0 oxidation, which can be based on either the loss of Fe(0), the formation of Fe(ii)/Fe(iii), or the composition of the total reaction products. Recently, many data have accumulated on εe for the treatment of various chlorinated solvents (esp. trichloroethylene, TCE) by zerovalent iron (ZVI), and analysis of these data shows that ZVI particle properties (e.g., stabilization with polymers, bimetallic modification, sulfidation, etc.) and other operational factors have variable effects on εe. Of particular interest is that pre-exposure of ZVI to reduced sulfur species (i.e., sulfidation) consistently improves the εe of contaminant reduction, mainly by suppressing the reduction of water.

中文翻译:

定量零价铁对有机卤化物脱氯的效率和选择性。

零价铁基处理有机卤化物污染的地下水的效率和选择性可以通过考虑源自Fe0氧化的电子的重新分布来量化。综述了几种类型的效率,包括(i)Fe(0)利用效率,εFe(0),(ii)目标污染物减少的电子效率,εe和(iii)天然还原剂需求的电子效率( NRD)涉及H2O,O2和共污染物,例如硝酸盐εNRD。然后可以使用εe/εNRD计算出选择性。εe特别令人感兴趣,其确定的关键是测量Fe0氧化提供的电子总量,这可以基于Fe(0)的损失,Fe(ii)/ Fe(iii)的形成,或总反应产物的组成。最近,εe上已经积累了许多数据,用于通过零价铁(ZVI)处理各种氯化溶剂(尤其是三氯乙烯,TCE),对这些数据的分析表明,ZVI的颗粒性质(例如,用聚合物稳定,双金属改性,硫化等) 。)和其他操作因素会对εe产生不同的影响。特别令人感兴趣的是,主要通过抑制水的还原,将ZVI预先暴露于减少的硫种类(即,硫化)可始终提高污染物减少的εe。
更新日期:2020-04-24
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