Problem Statement and Motivation

1. REMEDIATION OF CONTAMINATED SUBSURFACE USING NANOSCALE IRON PARTICLES Investigators: Krishna Reddy & Amid Khodadoust, Department of Civil and Materials Engineering Prime Grant Support: National Science Foundation Problem Statement and Motivation • Nanoscale zerovalent iron (nZVI) particles have the potential to be superior to iron filings, both in terms of initial rates of reduction and total moles of contaminants reduced per mole of iron. • Instead of waiting for the contaminants to pass through the permeable reactive barriers, the nZVI particles can be injected into the contaminated source zones for rapid and effective detoxification of the contaminants. • The delivery of nZVI particles into the contaminated zones uniformly and in required amounts in a controlled manner is essential for effective remediation. Key Achievements and Future Goals Technical Approach • Different soil types and commercial nZVI particles are being characterized and used for the experiments • . Enhanced treatments are being achieved through the use of novel dispersants, pressurized system, and the simultaneous use of dispersant-pressurized systems. • The commercial nZVI particles possess magnetic properties; therefore, a real-time transport of the nZVI particles in porous media is being monitored using an electromagnetic susceptibility sensor system. • Experiments are being conducted to evaluate the effects of soil heterogeneities on the transport of nZVI particles. The reactivity of nZVI particles is being quantified before and after transport in contaminated soils. • Our hypotheses are that: (1) as a result of aggregation, nZVI particles can be transported only to limited distances in subsurface; and (2) enhancement strategies such as use of dispersants and pressurized system have potential to enhance transport of nZVI particles in subsurface. • Research scope includes conducting (1) bench-scale column experiments to determine transport of nZVI particles in different gradation soils without and with enhancement strategies, and (2) bench-scale tank experiments to determine transport of nZVI particles in homogeneous and heterogeneous soils under the optimal conditions determined from the column experiments. Preliminary mathematical modeling will be performed to predict the transport of nZVI particles in porous media under laboratory and simulated field conditions.