Optimization of Nanoscale Zero-Valent Iron for the Remediation of Groundwater Contaminants

Nanoscale zero-valent iron (nZVI) is an emerging tool for the remediation of groundwater contaminants. The nanoparticles are capable of reductively destroying or immobilizing a wide range of contaminants. Their small size results in a high surface area to mass ratio, making them much more reactive compared to their more-coarse predecessors. Small particle size also allows nZVI particles to be injected directly into contaminated areas via a well, limiting the above-ground footprint and allowing access to contaminated areas that are beyond the reach of some conventional methods. nZVI technology has the potential to facilitate remediation in difficult situations, improve remediation outcomes, and reduce remediation costs. Using bench-scale laboratory experiments, this research investigates three methods for improving the reactivity and transport characteristics of nZVI, including: optimizing the nanoparticle synthesis process, addition of a polyelectrolyte stabilizer, and amendment of the particles with a palladium catalyst. Optimizing the synthesis method improved reactivity by 72%. Addition of a polyelectrolyte stabilizer further increased nZVI reactivity by 452%, while decreasing mean particle size from 29.3 to 4.6 nm and inhibiting aggregation. Finally, amendment with an optimized amount of 3.3% (w/w) palladium catalyst increased reactivity by another 375% while decreasing the formation of toxic byproducts during contaminant degradation