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Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron.
Citation:
Phenrat, T., THOMAS LONG, G. V. LOWRY, AND B. VERONESI. Partial oxidation (“aging”) and surface modification decrease the toxicity of nano-sized zero valent iron. Presented at International Environmental Nanotechnology Conference: Applications and Implications, Chicago, IL, October 07 - 09, 2008.
Impact/Purpose:
Nanosize zero-valent iron (nZVI) is used as a redox-active catalyst for in situ remediation of contaminated ground waters. In aqueous environments, nZVI oxidizes over time (i.e., “ages”) to magnetite and other oxides. For remediation, high concentration nZVI slurries are injected directly into the ground near the source of contamination. However, nZVI particles do not readily disperse in aqueous or organic environments, rather they form large aggregates with limited mobility. To remedy this, ”second generation” nZVI materials have been developed that are surface-modified (SM) with polymers or surfactants that facilitate their migration and proximity to the pollutant materials. This added mobility and nZVI’s direct application to ground waters increase the likelihood that nZVI materials will distribute through the environment and raises the possibility that at low concentrations, nZVI could enter the ecosystem and food chain, and impact biological systems. Since nZVI can generate reactive oxygen species (though Fenton chemistry), toxicity experiments were conducted on nervous system cells which are especially sensitive to oxidative stress. Immortalized rodent microglia (BV2) and dopaminergic neurons (N27) were exposed (1,2, 5,10, 20 ppm) to fresh nZVI, “aged” (>11 mo) nZVI, magnetite, and two polymer surface-modified (SM) products (i.e., poly AA-nZVI, MRNIP).
Description:
Nanosize zero-valent iron (nZVI) is used as a redox-active catalyst for in situ remediation of contaminated ground waters. In aqueous environments, nZVI oxidizes over time (i.e., “ages”) to magnetite and other oxides. For remediation, high concentration nZVI slurries are injected directly into the ground near the source of contamination. However, nZVI particles do not readily disperse in aqueous or organic environments, rather they form large aggregates with limited mobility.