Trichloroethylene (TCE) is one of the most frequently found chlorinated organic compounds in contaminated soil and groundwater systems. TCE is widely known to be toxic, likely to be carcinogenic, and mutagenic to humans and animals. The reductive dehalogenation of TCE using nanoscale zerovalent iron (nZVI) represents a promising approach for remediation due to its environmentally benign nature, high efficiency, and low cost. However, due to high surface energies and intrinsic magnetic interactions between nZVI particles, the dispersion of bare nZVI is poor in multiphase environments. The coating of nZVI surface with polymers or polyelectrolytes has shown to enhance their colloidal dispersion in the environments and decrease adhesion to porous media due to steric and/or electrostatic repulsion between the nanoparticles. However, reactivity of polymer coated nZVI was lower than that of bare nZVI due to the reactive surface of the nZVI particles was occupied by polymer molecules and unavailable for direct reductive reaction with TCE. To enhance the reactivity of polymer stabilized nZVI nanoparticles toward chlorinated compounds, a general strategy is to incorporate a second, catalytic metal such as Pd onto the nZVI particles to form bimetallic nanoparticles. Although Pd exhibits highest catalytic activity, the high expense of Pd, excessively fast corrosion of Pd-Fe complex in water and strong deactivation of Pd by groundwater constituents may restrict its wide application. In contrast, non-noble metals show a distinct advantage over noble metals such as their low cost and abundance. The objective of this research was to investigate the feasibility of using CMC as a stabilizer for preparing more reactive and stable non-noble metal containing bimetallic particles for the degradation of TCE in water. The reactivity of CMC-nZVI-Ni was found superior as compared to Cu and Sn, while no chlorinated byproducts were observed during TCE reduction.

Polymer stabilized nZVI nanoparticles for enhanced TCE degradation

251st National Meeting (2016)

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