One and a half decades after the first field demonstration of bimetallic zerovalent iron nanoparticles, in situ groundwater remediation with nZVI technology has witnessed limited field success due to two important technological barriers: hampered particle transport through the underground porous media and rapid material deactivation in environmental matrices. In this study, we investigated the deactivation mechanisms of two widely studied bimetallic nZVIs, nickel or palladium-amended nZVI (Ni-Fe or Pd-Fe) in aqueous media containing various common groundwater constituents. With trichloroethylene as a model contaminant, we identified that the deactivation of Ni-Fe and Pd-Fe were triggered by different groundwater solutes, suggesting the two bimetallic systems possess distinctive electrochemical properties and catalytic chemistry. Furthermore, the relative importance of catalyst poisoning (chemical deactivation) and surface passivation by iron oxide deposits (physical deactivation) in different media was analyzed using carbon isotope fractionation measurements. While these results suggest the reactivity of the bimetallic nZVI in field conditions is subject to considerable attenuation by the groundwater matrices, the use of alternative non-metal catalyst additives is being evaluated to improve nZVI stability and reaction selectivity.

Promise and pitfalls of catalyzed zero-valent iron nanoparticles: Mechanistic investigations into material deactivation and an alternative path forward

248th National Meeting (2014)

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