Download Nano Particles - Sk. Ruksana - Hindu college

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SK Ruksana
M.Sc. Chemistry
Introduction
– Nano technology is the creation of new materials,
devices and systems through the control of matter
on the nanometer length scale, at the level of
atoms and molecules. The essence of
nanotechnology is the ability to work at these
levels to generate nanostructures with
fundamentally new molecular organization.
Types of nano-particles
– Nano particles are available commercially in the
form of dry powders or liquid dispersions. The
latter is obtained by combining nanoparticles with
an aqueous or organic liquid to form a suspension
or paste. It may be necessary to use chemical
additives to obtain a uniform and stable
dispersion of particles.
• Pure metals:
Gold: Gold nanoparticles are produced in a
liquid by reduction of hydrogen
tetrachloroaurate (HAuCl4).
Silicon :in an effect to assess the potential for
future nano-electronic devices, silicon
nanoparticles field effect transistors with
nanoparticles as the active channel have been
fabricated.
• Silver: A n umber of metal nanoparticles can
be fabricated within a narrow size distribution
and shape through solution phase methods.
• Cobalt: The synthesis of cobalt nanoparticles
with controllable sizes and shapes via thermo
decomposition has been reported.
Metal oxide
• Silca: The hydrolysis and polymerization of
tetraalkoxysialnce (TEOS) in ethanol solution
containing water and ammonia allows
preparation of mono-dispersed silica powders.
• Zinc Oxide: ZNO nanowires were successfully
synthesized by simply heating the desired metal
powder to a temperature above its melting
point in a flow of mixed gases(20% oxygen, 80%
Ar with the total flow rate of 120 sccm).
• Iron oxide: Magnetic nanoparticles have
been proposed for use as biomedical
purposes to a a large extent.
• Alumina: Alumina metal has been hydrolysed
at 1000C to synthesize boethmite. Gelatinous
and dry boehmite were used to prepare stable
sol.
• Titania: Titanium dioxide is an imporatnt
catalyst for oxidation of hazardous
compounds in air and water particularly for
photo catalysis.
Methods using solid precursors
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Inert gas condensation
Pulsed laser ablation
Spark discharge generation
Iron sputtering
Methods using liquid or vapour
precursors
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Chemical vapor synthesis
Spray pyrolysis
Laser pyrolysis
Thermal plasma synthesis
Flame synthesis
Flame spray pyrolysis
Application
• Nanostructures and nanoparticles are being
developed to help cure the diseases.
• Liquid perfluorocarbon, has long been the
basis of experimental blood substitutes.
• For particularly dangerous cancers that have
spread or metastasized to several or many
locations, the nanoparticles presumably
would find their way to all of the cancerous
locations.
Toxic effects of nanomaterials
• Toxic effects of nanometerails will be very
specific to the type of base material, size,
legends, and coatings. One of the earliest ob
servations was that nanomaterials, also
called ultrafine particles (<100nm) showed
greater toxicity than fine particulars (<2.5um)
of the same material on a mass basis.
Significance of nano particles
• Nanoparticles made of semiconducting
material are also labeled quantum dots.
Nanospheres, nanorods and nanocups are
just a few of the shapes that have been
grown.
• Nanoparticle research is currently an area of
intense scientific research due to a wide
variety of potential applications in
biomedical, optical and electronic fields.
• Natural sources include volcanic activity,
natural fires, chemical reactions in the
atmosphere, or sea spray leading to sait
particles.
• Human activity produces nanoparticles
mostly by combustion of fossil fuels. Staring
from wood fire, humans have developed
industrial scale nanoparticles sources with
more or less continuous operation.
• Stationary sources such as waste incinerators
or power stations have largely eliminated
their nanoparticle emissions following
environmental legislation.
• One of the major sources of nanoparticles
are on and off road vehicles, with the largest
contribution of carbonaceours soot
stemming from diesel engines.