New Review Paper: Characterizing the Results of nZVI Injection
PGT
This paper is a review—with a lot of new results mixed in—on the challenges involved in characterizing the results of emplacing nZVI into the subsurface for remediation. Many of most commonly used characterization methods are not as diagnostic as is widely assumed. The advantages of a number of alternative methods are described. Currently, this paper is featured as the Most Download Journal of Contaminant Hydrology article.
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Shi, Z., D. Fan, R. L. Johnson, P. G. Tratnyek , J. T. Nurmi , Y. Wu, and K. H. Williams. 2015. Methods for characterizing the fate and effects of nano zerovalent iron during groundwater remediation. J. Contam. Hydrol. 181: 17-35.
The emplacement of nano zerovalent iron (nZVI) for groundwater remediation is usually monitored by common measurement such as pH, total iron, and oxidation-reduction potential (ORP) by potentiometry. However, the interpretation of such measurements can be misleading because of the complex interactions between the target materials (e.g., suspensions of highly reactive and variably aggregated nanoparticles) and aquifer materials (sediments and groundwater), and multiple complications related to characterization methods (sampling and detection). This paper reviews current practice for both direct and indirect characterization of nZVI during groundwater remediation and explores prospects for improving these methods and/or refining the interpretation of these measurements. To support our recommendations, results are presented based on laboratory batch and column studies of nZVI detection using chemical, electrochemical, and geophysical methods. Chemical redox probes appear to be a promising new method for specifically detecting nZVI, based on laboratory tests. The potentiometric and voltammetric detection of iron nanoparticles, using traditional stationary disc electrodes, rotating disc electrodes, and flow-through cell disc electrodes, provides insight on interpreting ORP measurements, which are affected by solution chemistry conditions and the interactions between iron nanoparticles and the electrode surface. The geophysical methods used for characterizing ZVI during groundwater remediation are reviewed and its application for nZVI detection is assessed with results of laboratory column experiments.