Iron Oxide Nanoparticles: Reactivity, Fate, and Transport

Lee Penn
University of Minnesota
Thursday, April 11, 2013
Duke University, Schiciano A | 4:30pm

Iron oxides and oxyhydroxides commonly occur as nanoparticles in the 3-10 nm size range and strongly impact the biogeochemical cycle of iron and other species at the Earth's surface. Comparing surface-area normalized rates of reaction of iron oxide nanoparticles enables elucidation of how reactivity changes as a function of nanoparticle properties, such as mineralogy as well as particle size, shape, and composition. Accessible reactive surface area is particularly sensitive to aggregation state, and characterizing it remains a major challenge.  Further, aggregation state is dynamic, and understanding those dynamics is critically important to predicting fate, transport, and reactivity of nanoparticles in environmental systems.  Solution variables like ionic strength and pH, as well as the presence and concentration of other chemical species like natural organic matter, can strongly impact the dynamics of aggregation. Furthermore, aggregation state can and does change dramatically upon reaction with various species, most especially redox-active species.  Results tracking changes in aggregation state as a function of changing solution conditions and reaction progress will be presented.