Preparation of nano particles
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This document discusses various techniques for synthesizing nanoparticles, including sol-gel synthesis, colloidal precipitation, co-precipitation, combustion technique, hydrothermal technique, high energy ball milling, and sonochemistry. It provides details on specific methods like the Frens method for synthesizing gold nanoparticles, co-precipitation reaction for iron oxide nanoparticles using FeCl3 and benzene tetracarboxylic acid, combustion synthesis using lithium nitrate and bismuth nitrate with urea and glycerol, and hydrothermal treatment for titanium dioxide nanoparticles. The advantages of these techniques in producing nanoparticles at low temperatures and with good control of properties are highlighted.
Preparation of nano particles
- 2. SOL-GEL SYNTHESIS COLLOIDAL PRECIPITATION CO-PRECIPITATION COMBUSTIONTECHNIQUE HYDROTHERMALTECHNIQUE HIGH ENERGY BALL MILLING SONOCHEMISTRY
- 3. Wet chemical technique Chemical solution deposition For gel like properties particle density shoud be increased by removing significant amount of solvent SOL GEL
- 4. Sedimentation Centrifugation Drying process (shrinkage and densification) Thermal treatment/firing process (favour polycondensation , enhance mechanical properties and structural stability via final sintering,densification and grain growth)
- 5. Densification can be achieved at a much lower temperature Sol-gel approach is a cheap and low temperature technique that allows for the fine control of products’ chemical composition
- 7. Synthesis of nano particles of gold,silver Tetrachloroauric acid trisodium citrate(reductant) Gold particles (purple colour) HAu+3Cl4 Au0 Frens-Turkevich method
- 9. Simple and low cost process Applicable to preparation of magnetic nano particles Iron oxide nano particles are synthesised by co-precipitation reaction of FeCl3 and 1,2,4,5-benzene tetracarboxylic acid
- 10. FeCl3, NaOH and 1,2,4,5-benzene tetracarboxylic acid are dissolved in water and shaked for 10 minutes Filtered and dried in air Obtained powder is calcined at 4500C for 2 hours Iron oxide nanoparticles are obtained
- 11. Morphology of Fe3O4 powder consists of cubic phase with size of 24 nm FT-IR , XRD and SEM are used to characterise the product
- 12. Used for the preparation of nano particle sized LiBiO2 Requirements Lithium Nitrate bismuth Nitrate Urea (igniter-fuel) Glycerol (binding material)
- 13. Lithium Nitrate and Bismuth Nitrate are mixed together to form a uniform mixture Required quantities of urea and glycerol are added to form a homogeneous paste Pre-heated at 150-2000c to form a dried mass Calcined at 4600c for 5 hours Nanoparticles of LiBiO2 are obtained
- 14. Conducted in steel pressure vessels called autoclaves with or without teflon liners Under controlled temperature and/or pressure with the reaction in aqueous solution Widely used for the production of small particles in ceramics industry Used to prepare nanoparticles of TiO2
- 15. AUTOCLAVE
- 16. Hydrothermal treatment of peptized precipitate of a titanium precursor with water Precipitates are prepared by adding 0.5M isopropanol solution of titanium butoxide into deionisde water They are peptized at 700C for 1 hour in the presence of tetraalkyl ammonium hydroxide (peptizer) Filtration and treatment at 2400C for 2 hours Obtained powder are washed with deionised water and absolute alcohol Dried at 600C
- 17. Under the same concentrations of the peptizer,the particle size decreased with increasing alkyl chain length The peptizers and their concentrations influenced the morphology of the particle
- 19. Utilized in industries to perform size reduction Induce structural changes and chemical reactions by mechanical energy rather than thermal energy,reaction are possible at room temperature and so non-equilibrium in nature The milling process embraces a complex mixture of fracturing, grinding, high speed plastic deformation, cold welding,thermalshock, intimate mixing etc . Produced a large range of nanoscaled materials – nanocrystalline materials, nanoparticles, nanocomposites ,nanotubes,nanowires and nanorods
- 20. Mechanical Alloying (MA) Mechanical Milling (MM) Mechanochemical Synthesis (MS)
- 21. Mixtures of powders are milled together Material transfer is involved A homogeneous alloy is obtained
- 22. Only powder with uniform composition is milled No material transfer is involved
- 23. A special MA process Chemical reaction between the powders take place during milling Grain refinement and chemical reactions take place at low temperature under far from equilibrium conditions Cold welding and Agglomeration during milling opposes MA and MM
- 24. Nanocomposite mixtures formed during mechanochemical reaction can be further processed into nanoscale particles Nano composite of Fe and NaCl was obtained by milling FeCl3 and sodium metal FeCl3 + 3 Na → Fe + 3 NaCl Simple washing after milling dissolves NaCl and nanoparticles of Fe can be obtained
- 25. Excellent versatility Scalability Cost effectiveness