Activation process of air stable nanoscale zero-valent iron particles
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Date
2017
Journal Title
Journal ISSN
Volume Title
Publisher
ELSEVIER SCIENCE SA
Abstract
Nanoscale Zero Valent Iron (nZVI) represents a promising material for subsurface water remediation
technology. However, dry, bare nZVI particles are highly reactive, being pyrophoric when they are in contact with air. The current trends of nZVI manufacturing lead to the surface passivation of dry nZVI particles with a thin oxide layer, which entails a decrease in their reactivity. In this work an activation
procedure to recover the reactivity of air-stable nZVI particles is presented. The method consists of exposing nZVI to water for 36 h just before the reaction with the pollutants. To assess the increase in nZVI reactivity based on the activation procedure, three types of nZVI particles with different oxide shell
thicknesses have been tested for Cr(VI) removal. The two types of air-stable nZVI particles with an oxide
shell thickness of around 3.4 and 6.5 nm increased their reactivity by a factor of 4.7 and 3.4 after activation, respectively. However, the pyrophoric nZVI particles displayed no significant improvement in reactivity. The improvement in reactivity is related mainly to the degradation of the oxide shell, which
enhances electron transfer and leads secondarily to an increase in the specific surface area of the nZVI
after the activation process. In order to validate the activation process, additional tests with selected chlorinated compounds demonstrated an increase in the degradation rate by activated nZVI particles.
Description
Subject(s)
ZEROVALENT IRON, AQUEOUS-SOLUTION, TCE DECHLORINATION, BOROHYDRIDE REDUCTION, CHROMIUM(VI) REMOVAL, NITRATE REDUCTION, WATER-TREATMENT, SUPPORTED NZVI, H-2 EVOLUTION, WASTE-WATER
Citation
ISSN
1385-8947