Multifunctional Nanoparticulate Systems for in-Situ Remediation of Chlorinated Hydrocarbons

The widespread occurrence of dense non-aqueous phase liquids (DNAPLs) in groundwater and in soil is of serious environmental concern. Nanoscale zerovalent iron particles (NZVI) are a preferred option for reductive dehalogenation of TCE due to their environmentally benign nature, high efficiency and low cost. However, it is difficult to transport these particles to the source of contamination due to aggregation. This study describes a novel approach to the preparation of ZVI containing particulate systems that are effectively transported to contaminant sites and serve as targeted delivery agents for remediation. We describe the synthesis of highly uniform colloidal carbon microspheres embedded with zerovalent iron nanoparticles. These materials have multiple functionalities (a) they are reactive and function effectively in reductive dehalogenation (b) they are highly adsorptive thereby bringing the chlorinated compound to the proximity of the reactive sites and also serving as adsorption materials for decontamination (c) they are of the optimal size for transport through sediments (d) they have amphiphilic chemical functionalities that help stabilize them when they reach the DNAPL target zones. These multiple functionalities can be designed at low cost and the materials are environmentally innocuous. The detailed characterization of these multifunctional colloids through high resolution electron microscopy, and their functional properties will be described. The presentation will focus on the fundamental aspects of adsorption, transport and reaction using these materials.