Nano-Particle Production

Micro- and Nano-particles Production Using Supercritical Fluids... 

R. Wiithrich, A. Lai, H. Bleuler A table-top set-up for nano-particles production with electrochemical discharges. 5th International Workshop on Microfactories, October 25-27, Besengon, France. 

In the present study the effect of zeolite particle size (micro- vs. nano-particles) and N20 concentrations on ODHP is studied over Fe modified BEA zeolites. The feasibility of periodic reactivation over Fe-BEA catalysts by oxygen pulses for continuous C3H6 production has been also evaluated. 

A review on using sonochemistry for the fabrication of nano-materials has been published by Gedanken (2004). It has been remarked that, in almost all the sono-chemical reactions leading to inorganic products, nano-materials were obtained and it was observed that, in the field of materials science, among the methods developed to prepare nano-particles, the sonochemical techniques are superior to the other methods in the following aspects ... 

Water-insoluble solids are potentized initially by trituration. This process breaks down drugs into nano particles which assume special importance because of their biological activity. Nano particles naturally occur in diseased tissues from which nosodes are prepared. The basis of liberation of dormant medicinal properties of drugs by trituration is the production of nano particles. Ethanol having a large non-polar part usually stabilizes specific water structures obtained during potentization of a drug. 

The pH of the reaction solution has an important influence on the properties and appearance of the nano copper product the escape of ammonia in the form of bubbles during and after the reaction favors the dispersity of the particles the rotary speed of the propellers has no significant influence on the particle size in the product in the range of speed tested. 

The results on the particle sizes in the product calcined at 600°C measured by TEM are listed in Table 15.6, while those calcined at various temperatures are given in Table 15.7. The data listed in Table 15.6 show that the nano Titania product prepared by TiCl4 hydrolyzation-precipitation in the SCISR had very small sizes and a very narrow size distribution, the weighted mean size of which was calculated to be 9.64 nm. 

For nano HAP product, its size and distribution and appearance of the particles are the major quantity indexes. In addition, chemically the mole ratio of Ca/P essentially characterizes the purity of the product. All these are taken as the criteria for comparison and analysis of the experimental results. 

Figure 16.5 shows the TEM photo of a typical nano hydroxylapatite product synthesized in the SCISR following the operation procedure described in Section 16.2. As can be seen, the particles are about 15 nm in diameter and 50-70 nm long, well dispersed, and have a very regular shape and appearance. 

Here, a new method for the preparation of an aqueous, well-dispersed sol of HAp nano particles directly via a mechanochemical route is described. It should be noted, that such products are very suitable for usual ceramic purposes as well. 

Filtration of small (nano) particles from solvent using a filter with extremely small pores (0.001-0.010 micron) finer than ultrafiltration, not as fine as reverse osmosis. Used for the removal of viruses from plasma protein products. See Yaroshchuk, A.E., Dielectric exclusion of ions from membranes, Adv. Colloid Interface Sci. 85,193-230,2000 Rossano, R., D Elia, A., and Riccio, R, One-step separation from lactose recovery and purification of major cheese-whey proteins by hydroxyapatite — a flexible... 

One of the important fields of study opened up by reaction (26) is the production and characterisation of noble and non-noble, mono- and multi-metallic clusters. Nano-particles of many metals have been produced and their catalytic properties investigated in this way [9] (Chapter 7). 

New improved lubricating greases containing ash-free additives, the combination of lithium and calcium soaps to improve water resistance, the incorporation of functional polymers into the thickener matrix to improve spray-off properties and many more customer-specific solutions have been offered. In the pipeline are products containing functional soaps, nano particles (nested spheres) and lyotropic liquid crystals. In scientific terms, the trend is moving from know how to know why as more is understood about the actual mechanisms involved in grease lubrication. 

The properties of materials that are produced from fine (FP) and ultrafine (UFP) or nano particles by agglomeration are critically influenced by the void volume between the particles forming the agglomerate. This product attribute is called porosity and is defined by the presence, size, shape, and distribution of pores. 

The BaO is produced in the form of very small particles of nearly atomic proportions (nano-particles) which react immediately to form the silicate. Actually, the rate of reaction is proportional to the number of nuclei produced per unit volume. A nucleus is a point where atoms or ions have reaeted and begun the formation of the product structure. In the ease of the BaO + SiOa reaction, the number of nuclei formed per unit of time is small and formation of the structure is diffusion limited. In the case of BaCOs decomposition, the atomic-proportioned BaO reacts with Si02 nearly as fast as it is formed so that the number of nuclei per unit volume is enormously increased. It is thus apparent that if we wish to increase solid state reaction rates, one way to do so is to use a decomposition reaction to supply the reacting species. We will further address this type of reaction later on in our discussion. 

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