Transport and reactivity of engineered iron nanoparticles in natural porous media

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This grant application will support research investigating potential improvements to in situ remediation technologies for contaminated groundwater. Nanoparticles of zero valent iron (reduced iron) are reactive and are able to rapidly eliminate a number of toxic and potentially carcinogenic pollutants commonly encountered in groundwater, such as trichloroethylene, chromium and arsenic. This makes the nanoparticles of zero valent iron an excellent reactant for remediation of groundwater at contaminated sites. Furthermore, the zero valent iron is converted to iron oxides, which are ubiquitous in soil and naturally present. Through controlled laboratory studies, the proposed research will investigate the transport and reactivity of nanoiron particles in model aquifer sands. Groundwater and soil mineral chemistry can have a strong influence on the transport and reactivity of zero valent iron nanoparticles, and thus impact the efficiency of remediation operations. In particular, the research will investigate the effects of natural organic molecules such as humic acids and microbial polymers that are commonly encountered in groundwater environments, as they have the potential to significantly alter transport and reactivity of naniron particles. The knowledge of these effects will help identify required operating parameters for remediation. The research will also investigate the reactivation of spent or oxidized nanoparticles of zero valent iron for continued pollutant degradation with the help of common soil microorganisms that can produce hydrogen, sulfides or reduce iron. The application of microorganisms for regeneration of oxidized nanoparticles in remediation operation is novel, and can lead to reductions in the amount of iron nanoparticles required for remediation.