The Stability, Toxicity, and Reactivity of Zero Valent Iron Nanoparticles

Zero valent iron nanoparticles effectively remediate groundwater contaminants due to\ud their catalytic properties and enhanced surface area. However, these properties\ud contribute to particle agglomeration, decreasing their effectiveness. In this study, we\ud examined the effect of two stabilizing agents (gum arabic (GA) and sodium\ud carboxymethyl cellulose (CMC)) on particle stability, toxicity, and reactivity.\ud Stability was assessed by measuring particle hydrodynamic diameter (HDD). The\ud HDD of the unstabilized particles was over 1000 nm, while the CMC and GA\ud stabilized particles were around 200 nm. Embryonic zebrafish were used to\ud investigate the sublethal toxicity and mortality resulting from particle solution\ud exposure over 5 days. The CMC stabilized particles and unstabilized particles caused\ud significant mortality at lower concentrations, while lower concentrations of GA\ud stabilized particles only caused hatching delay. Reduction of trichloroethylene (TCE)\ud was assessed using gas chromatography following a 24 hour incubation. The\ud concentration of TCE only decreased when incubated with GA and CMC stabilized\ud particles. The small HDD of the particles synthesized with stabilizers indicated these\ud compounds stabilized the particles. GA stabilized particles had the smallest HDD, led\ud to the greatest decrease in TCE, and were assessed to be the least toxic in this study