Page 23 - Environmental Nanotechnology Applications and Impacts of Nanomaterials

Nanotechnology and the Environment 9

properties of nanoparticles that might affect their potential for aggre-
gation [17] and little evaluation of the transport properties of these new
materials in aqueous systems. In Chapter 7, the chemistry of nanopar-
ticles is examined from a colloid science perspective, considering fac-
tors that may be different at the nanoscale in determining the
nanoparticle stability and transport.

Environmental applications
of nanomaterials
The products of nanochemistry are being been used to create new gen-
erations of technologies for curing environmental maladies and pro-
tecting public health. Water pollution control, groundwater remediation,
potable water treatment, and air quality control are being advanced
through nanomaterial-based membrane technologies, adsorbents, and
catalysts. The use of nanomaterials as photocatalysts is discussed in
Chapter 5. Nanomaterials are also inspiring new solutions for provid-
ing and using energy that are more environmentally neutral than con-
ventional approaches, as introduced in Chapter 2. Advances in fuel
cells, photovoltaics, and electrical transmission, as well as solutions for
managing air and water pollution generated by fossil fuels, have been
enabled through developments in new materials.
Groundwater remediation, water treatment, and fuel cell development
are among the applications in which nanomaterials are finding their way
into environmental engineering practice. The remediation of contami-
nated groundwater is a costly problem that has been approached in
environmental engineering using both pump-and-treat and in situ tech-
nologies. In most cases, pumping contaminated groundwater to the sur-
face to remove contaminants and reinjecting the treated water has proven
to be both cost-prohibitive and incapable of meeting cleanup goals. As a
result, in situ treatments such as biodegradation have been explored
extensively. Physical chemical approaches to in situ treatment have
included the use of zero valent iron and catalysts to promote redox reac-
tions that degrade contaminants. Nanomaterials have been developed to
promote such reactions at high rates; however, successful application of
this technology will require a high degree of control of nanoparticle mobil-
ity, reactivity, and ideally, specificity for the contaminant of interest.
Background on groundwater remediation and the development of nano-
materials for in situ treatment is presented in Chapter 8.
Membrane technologies are playing an increasingly important role as
unit operations for environmental quality control, resource recovery,
pollution prevention, energy production, and environmental monitoring.
In water treatment they can be used for a wide spectrum of applications,
ranging from particle removal to organic removal and desalination.
Membranes are also at the heart of fuel cell technologies. Fuel cells can