| The contamination of soils and groundwater by aromatic organic pollutants (e.g., pesticides, and energetic compounds) has been a major environmental concern, thus requiring the need to develop effective remediation technologies. Nanoscale iron particles (NIP) have shown to have great potential for in-situ dehalogenation of a variety of organic contaminants in the subsurface. NIP can effectively degrade contaminants due to their very small particle size and large reactive surface area. However, NIP transport in subsurface soils is found to be hindered due to their agglomeration and sedimentation; therefore, different types of surface modifications are suggested to improve stability and enhance their transport in porous soils. This study investigated bare NIP and lactate-modified NIP (LMNIP) for their reactivity with organic pollutants, one-dimensional and two-dimensional transport in different porous soils using gravity fed and pressurized systems. The enhanced in-situ delivery of NIP and LMNIP in low permeability soils was studied using electrokinetic systems. Several series of batch and bench-scale column and tank experiments were conducted. During the transport studies, changes in the magnetic susceptibility values across the porous soils were measured, and effluent quantity and quality were also measured at different time periods. The results show that NIP and LMNIP have the potential to degrade organic contaminants, but LMNIP have potential to transport through porous soil while maintaining adequate reactivity. Pollutants, specifically pentachlorophenol and dinitrotoulene, were found to be degraded effectively. Good correlation between magnetic susceptibility (MS) measurements and iron content in the soils was found, thus MS has the potential to be used for field monitoring of NIP and LMNIP. Overall, this study developed an inexpensive and environmentally-benign lactate-modified NIP that is stable and capable of transporting NIP in soils and groundwater and dehalogenating organic pollutants such. We have also developed pressurized flow and electrokinetic systems to deliver lactate-modified NIP into high permeability and low permeability soils, respectively. |
