Page 327 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

312 Environmental Applications of Nanomaterials

Figure 8.7 Truck-mounted Geo-
®
Probe for creating direct push
wells for nanoiron injection.
Photo is courtesy of GeoProbe ®
Systems, Inc., Salina, Kansas.

in diameter that can then be used for injecting reactive nanoparticles.
A nanoparticle slurry can be injected along part of all of the vertical
range of the probe (Figure 8.8) to provide treatment to specific regions
in the aquifer. This helps to target the reactive nanoparticles to the
contaminated regions of the subsurface where they are needed.

Transport
The effectiveness of remediation, as well as the potential for unwanted
exposure of humans and other biota to these reactive nanoparticles,
depends on how easily these materials transport in porous media.
Uncertainties regarding the fate, transport, and potential toxicity of
engineered nanomaterials have prompted investigations on the fate
and transport of various nanoparticles (very fine colloids) ranging in size
from 1.2 nm to 300 nm (Lecoanet et al. 2004; Lecoanet and Wiesner 2004;
Royal Academy of Engineering 2004; Saleh et al. 2007; Schrick et al.
2004). These studies have demonstrated that nanoiron and many other
types of engineered nanomaterials do not transport easily in saturated
porous media. Transport distances range from a few centimeters for