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Nanofiltration membranes for water purification provide dramatically improved removal of fine-particle
contaminants, compared to conventional methods of using sedimentation basins and wastewater clarifiers.
Nanoparticles with designed catalysis are capable of absorbing and removing impurities. By using magnetic
separation, these nanomaterials can be reused, which prevents them from becoming contaminants themselves.
As one of many examples, consider nanoscale aluminosilicate molecular sieves called zeolites, which are being
developed for controlled oxidation of hydrocarbons (for example, converting toluene to nontoxic
benzaldehyde).
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This method requires less energy and reduces the volume of inefficient photoreactions and
waste products.
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Extensive research is under way to develop nanoproduced crystalline materials for catalysts and catalyst
supports in the chemical industry. These catalysts have the potential to improve chemical yields, reduce toxic
by-products, and remove contaminants.
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For example, the material MCM-41 is now used by the oil industry to
remove ultrafine contaminants that other pollution-reduction methods miss.
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It's estimated that the widespread use of nanocomposites for structural material in automobiles would reduce
gasoline consumption by 1.5 billion liters per year, which in turn would reduce carbon dioxide emissions by
five billion kilograms per year, among other environmental benefits.
•
Nanorobotics can be used to assist with nuclear-waste management. Nanofilters can separate isotopes when
processing nuclear fuel. Nanofluids can improve the effectiveness of cooling nuclear reactors.
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Applying nanotechnology to home and industrial lighting could reduce both the need for electricity and an
estimated two hundred million tons of carbon emissions per year.
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Self-assembling electronic devices (for example, self-organizing biopolymers), if perfected, will require less
energy to manufacture and use and will produce fewer toxic by-products than conventional semiconductor-
manufacturing methods.
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New computer displays using nanotube-based field-emission displays (FEDs) will provide superior display
specifications while eliminating the heavy metals and other toxic materials used in conventional displays.
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Bimetallic nanoparticles (such as iron/palladium or iron/silver) can serve as effective reductants and catalysts
for PCBs, pesticides, and halogenated organic solvents.
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Nanotubes appear to be effective absorbents for dioxins and have performed significantly better at this than
traditional activated carbon.
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This is a small sample of contemporary research on nanotechnology applications with potentially beneficial
impact on the environment. Once we can go beyond simple nanoparticles and nanolayers and create more complex
systems through precisely controlled molecular nanoassembly, we will be in a position to create massive numbers of
tiny intelligent devices capable of carrying out relatively complex tasks. Cleaning up the environment will certainly be
one of those missions.
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