Issue 3, 2020

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

Abstract

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.

Graphical abstract: Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

Supplementary files

Article information

Article type
Critical Review
Submitted
19 דצמ 2019
Accepted
12 פבר 2020
First published
03 מרץ 2020
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Processes Impacts, 2020,22, 528-542

Quantifying the efficiency and selectivity of organohalide dechlorination by zerovalent iron

F. He, L. Gong, D. Fan, P. G. Tratnyek and G. V. Lowry, Environ. Sci.: Processes Impacts, 2020, 22, 528 DOI: 10.1039/C9EM00592G

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