Submitted by SK Ruksana M.Sc. Chemistry HINDU COLLEGE OF PG COURSES Submitted by 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 Inert gas condensation Pulsed laser ablation Spark discharge generation Iron sputtering

Methods using liquid or vapour precursors 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.