Nanoparticles : Natural and Engineered
Nanoparticles can have unique chemical properties that larger particles of similar elemental or mineralogical composition do not possess, including surface-pH, oxidation/reduction properties, solubility, and reactivity to dissolved solutes. Recent microscopy advances in detecting nanoparticles have significantly enhanced this field of science.
- Colloid facilitated transport of contaminants. Contaminants may exist as nanoparticles, or colloids, which may move more rapidly through porous media than if the contaminant existed in a dissolved state. Here is an example of nano neptunium oxides, which we showed underwent enhance transport through a vadose zone sediment. Not representing the neptunium as a nanoparticle in our transport models leads to underestimating their true human risk (Peruski et al. 2018 Environ. Sci. & Technol.).
Nano-iron oxides on roots: Nano-iron oxides self-organize along plant roots, protecting plants by binding toxic metals so that they are not available for plant uptake. These iron oxides form because the roots release oxygen, promoting the precipitation of ferrous iron in the groundwater. The iron oxides and organic matter released from the plants create an environment that stimulates microbial populations, especially for heterotrophs.
- Uses of nanoparticles for environmental remediation. Our group has engineered several types of nanoparticles to act as super-scrubbers of contaminants from the aqueous phase. They can be used in reactive barriers, barriers put in the path of a contaminant plume and selectively remove the target contaminant, while permitting water and non-targetted solutes to pass through freely. For example, magnetic mesoporous silica nanoparticles (MMSNs) were designed to bind uranium from water. These nanoparticles can recover naturally occurring uranium from the ocean, providing an inexpensive and environmentally friendly alternative to mining uranium from the deep subsurface.