Graduated characterization method using a multi-well microplate for reducing reactivity of nanoscale zero valent iron materials

• Published in: Applied catalysis. B, Environmental Vol. 181; pp. 314 - 320
• Main Authors: Hwang, Yuhoon, Salatas, Apostolos, Mines, Paul D., Jakobsen, Mogens H., Andersen, Henrik R.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-02-2016
• Subjects: Assaying; Color; Colorimetric assay; Colorimetry; Dehalogenation reactivity; Indophenol reaction; Iron; Laboratory apparatus; Multi-well microplate; Nanoscale zero valent iron; Nanostructure; Reagents; Reduction; Indophenol reaction; Colorimetric assay; Multi-well microplate; Dehalogenation reactivity; Nanoscale zero valent iron
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2015.07.041

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•Color assays using five substrates characterized a graduated reactivity order of nZVI.•The assays quantified reduction products to avoid interfering reactions.•Three reaction products were quantified using both the same wavelength and reagents.•Assay was adapted to a 96-well microplate, thus minimizing sample and reagent use.
Even though nanoscale zero valent iron (nZVI) has been intensively studied for the treatment of a plethora of pollutants through reductive reaction, quantification of nZVI reactivity has not yet been standardized. Here, we adapted colorimetric assays for determining reductive activity of nZVI and its composites with other metals. The assay quantifies reduction products to avoid interfering reactions, such as sorption and volatilization. Three different reaction products, ammonium, phenol, and aniline, generated as the result of reduction of nitrate, p-halophenols, and nitrobenzene, respectively, could be quantified using the same reagent for all reactions. The colorimetric assays were further adapted to the 96-well microplate format, thus minimizing sample and reagent use, as well as lowering color development time to 2h. The substrates showed graduated reactivity, and thus, reduction potency and kinetics of different materials and reaction mechanism was distinguished. The applicability was successfully proven by determining the reactivity of a commercial nZVI sample, and investigating the effect of nickel content on dehalogenation. Therefore, the suggested reactivity test with different compounds, combined with the use of a multi-well microplate based color assay, promises to be a useful and simple tool in various nZVI related research topics.