Reactive Nanoparticles for Groundwater Remediation: Optimizing the Benefits and Mitigating the Risks with Surface Coatings

Title:	Reactive Nanoparticles for Groundwater Remediation: Optimizing the Benefits and Mitigating the Risks with Surface Coatings
Category:	Miscellaneous
Date:	26. June 2009, 14:00 -
Venue:	Eawag Dübendorf
	Forum Chriesbach D24
Speaker:	Gregory V. Lowry, Associate Professor, Carnegie Mellon University, Pittsburgh, Pennsylvania (USA)
Download:	as calendar event

Novel reactive nanomaterials, such as Fe0 nanoparticles (NZVI), offer the potential for highly efficient targeted delivery of remedial agents to subsurface contaminants.  The primary challenge to application of reactive nanoparticles is selecting appropriate surface modifiers that enable emplacement in the contamination zone, but do not adversely impact the particle’s reactivity with the contaminant.  Surface coatings can also enhance the particle’s interaction with the contaminant of interest and decrease the potential toxicity of the particles. Concomitant optimization of mobility, reactivity, while minimizing toxicity requires a fundamental molecular level understanding of the surface modifiers properties and how they affect nanoparticle deposition. Dynamic light scattering and electrophoretic mobility measurements, along with Ohshimas’s analysis are used to characterize the layer conformation and properties of different types of common synthetic and natural polyelectrolytes adsorbed onto NZVI.  Batch reactivity studies and column and 2-D flow cell studies under a variety of hydrogeochemical conditions and heterogeneities were then conducted on polyelectrolyte-modified NZVI to determine the effect of the adsorbed layer properties and injection conditions on reactivity and mobility.  Surface coatings decreased particle reactivity with TCE by up to a factor of 20, and eliminated the particles bactericidal properties.  The magnitude of the effect depended on the adsorbed layer conformation of the polyelectrolyte as explained using the Scheutjens and Fleer train-loop-tail conceptual model for homopolymer sorption.  This study emphasizes the important role of surface coatings on the sustainable development of nanotechnologies, a significant theme of a newly funded NSF Center of Environmental Implications of NanoTechnology (CEINT).