Nanoscale zerovalent iron particles (NZVI) can rapidly transform a variety of heavy metal and halogenated organic contaminants through chemical reduction processes. In fact, due to its high redox activity and small size, direct injection of reactive NZVI is considered to be a promising approach for <i>in situ</i> remediation of contaminated groundwater. The main objective of this research was to assess the potential of using NZVI for the <i>in situ</i> remediation of perfluorinated surfactants, particularly perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), in groundwater system through sorption and reductive reactions. We tested the sorption capacity and reductive defluorination potential of bare and several surface-modified NZVI towards PFOA and PFOS. The modification methods include sulfidation, doping with inert metals, and coating with vitamin B12. PFOS was found to be strongly sorbed to NZVI with the distribution ratio being around 10,000 L/kg at low concentration range (&lt; 1 mg/L) and up to one order of magnitude higher when the concentration was further increased. The sorption affinity was significantly influenced after NZVI oxidation/passivation in water, or reaction with sulfide ions (sulfidation). The desorption of PFOS bound to NZVI was tested by different aqueous and solvent extraction methods. We also examined the influence of solution chemistry (pH, ionic strength) and aging with reactive species (sulfide ions, humic acids) on the sorptive and reactive behaviour of NZVI towards perfluorinated compounds. Moreover, this study will provide valuable insight to the site remediation strategies using NZVI for aquifers contaminated by perfluorinated surfactants and co-contaminants such as trichloroethylene which have been shown to be degraded extensively by NZVI.

Remediation of perfluorinated surfactants in groundwater by injection of nanoscale zerovalent iron particles

253rd National Meeting (2017)

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