Environmental Engineering Reference
In-Depth Information
enable novel applications” (National Nanotechnology Initiative [NNI]
2008). Encompassing nanoscale science, engineering, and technology, nan-
otechnology involves imaging, measuring, modeling, and manipulating
matter at this length scale. Although industrial sectors involving semicon-
ductors; memory and storage technologies; display, optical, and photonic
technologies; energy; biotechnology; and health care produce the most
products containing nanomaterials, there are increasing ef orts to use nan-
otechnology as an environmental technology to protect the environment
through pollution prevention, treatment, and clean up of long-term prob-
lems such as hazardous waste sites. h e technology could be a benei cial
replacement of current practices for site remediation. However, potential
risks are poorly understood and might lead to unintended consequences.
Nanoremediation has the potential not only to reduce the overall costs
of cleaning up large-scale contaminated sites, but also to reduce clean-up
time, eliminate the need for treatment and disposal of contaminated soil,
and reduce some contaminant concentrations to near zero—all
in situ
.
Proper evaluation of nanoremediation, particularly full-scale ecosystem-
wide studies, needs to be conducted to prevent any potential adverse envi-
ronmental impacts. In addition to remediating pollution, nanoparticles
can be used as sensors to monitor toxins, heavy metals and organic con-
taminants in land, air and water environments, and have been found to be
more sensitive and selective than conventional sensors. In this chapter, we
present a background and overview of current practice, research i ndings
related to nanotechnology, issues surrounding the use of nanotechnology
for environmental remediation, and future directions.
7.2
Nanoremediation Using TiO
2
Nanoparticles
Tiny particles of titanium dioxide are found as key ingredients in wall
paints, sunscreens, and toothpaste; they act as rel ectors of light or as abra-
sives. However with decreasing particle size and a corresponding change
in their surface-to-volume ratio, their properties change so that crystal-
line titanium dioxide nanoparticles acquire catalytic ability; activated by
the UV component in sunlight, they break down toxins or catalyze other
relevant reactions.
Titanium oxide photocatalyts have been widely studied for solar energy
conversion and environmental applications in the past several decades
because of their high chemical stability, good photoactivity, relatively low
cost and nontoxicity. However, the photocatalytic capability of TiO
2
is lim-
ited to only ultraviolet light; to overcome this problem both chemical and
Search WWH ::
Custom Search