The effect of common groundwater anions on the aqueous corrosion of zero-valent iron nanoparticles and associated removal of aqueous copper and zinc

This work has investigated the influence of common groundwater anions (Cl , NO3 , SO4 and HCO3 ) on the corrosion behaviour and associated removal of copper (Cu) and zinc (Zn) ions onto nanoscale zerovalent iron particles (nZVI). After 16 week exposure to solutions containing each anion at 10 mM concentrations, nZVI was observed to corrode into different iron (hydr)oxide phases (determined using XRD), depending upon the anion present: HNO3 produced goethite particles; NO3 produced predominantly magnetite/maghemite particles; both SO4 and Cl produced a mixture of phases, including magnetite/maghemite, lepidocrocite and goethite. For solutions containing the different anions and 0.3 mM concentrations of Cu or Zn, near-total metal removal onto nZVI was recorded in the initial stages of the reaction (e.g. <24 h) for all systems tested. However, when Cl and SO4 were also present significant subsequent desorption was recorded and attributed to the influence of anionic pitting corrosion. In contrast, no Cu or Zn desorption was recorded for batch systems containing NO3 , which was attributed to the enmeshment of Cu or Zn in a mixed-valent iron oxide shell. Results herein therefore demonstrate that NO3 could be utilised alongside nZVI to improve its long-term performance for in situ water treatment applications. Crown Copyright © 2017 Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).