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Preparation Of Nanometer Magnesia And The Study On Their Surfaces Modification

Posted on:2007-11-17Degree:MasterType:Thesis
Country:ChinaCandidate:H X WangFull Text:PDF
GTID:2121360185961838Subject:Inorganic Chemistry
Abstract/Summary:PDF Full Text Request
Nano-sized MgO is a very prosperous material extensively used in high-quality ceramics, electric insulating materials, cosmetics, paint, rubber filler, acid gas adsorbent and catalytic carrier because of the volume efffect, the quantum size effect, the surface effect and the macroscopic quantum tunnel effect. Compared with MgO, nano-MgO have special functions in the properties of light, electricity, magnetism and chemistry and have attracted great attention.The properties and application of nanometer magnesia have be reviewed in this paper . Both the progress in research and the synthesis of nanometer magnesia have been reconsidered. A new preparation techniques named "precipitation with polymer protection method" was put forward. Taking Mg(NO3)·6H2O as a ram material, a product of hexamethylene terra mine decomposition as a precipitating agent, water as a reaction media and the polymer (PEG) as protection reagent, the magnesium hydroxide was obtained. Magnesium oxide nanoparticle were prepared by firing the magnesium hydroxide compound at 873K after being dehydrated by means of multi-freeze centrifugal and vacuum drying at a constant temperature.The reaction was studied by TG-DTA, FI-ER. The particle size and morphology of nano-MgO was characterized by TEM, XRD, AFM and BET. The sample has cubic crystal structure with about 3.1nm of average diameter by the XRD from scherrer formula. The BET curves show that the specific surface of the sample was 26.34 m2/g.According to the experience of synthesis of nanometer-sized magnesia powders, the influence factors to nanometer size and yield have been discussed. Selected five factors and four levels were determined for an orthogonal test. They were the concentration of reactants Mg(NO3)2·6H2O, the molar ratio of reactants (Mg(NO3)2·6H2O:(CH2)6N4), the concentration of surfactant, the reaction temperature and the reaction time. The optimum processing conditions in preparation of nanometer magnesia were obtained: the concentration of reactants Mg(NO3)2·6H2O was 0.3 mol.L-1, the molar ratio of reactants (Mg(NO3)2·6H2O:(CH2)6N4) was 1:2, surfactant was 13.8%, the reaction temperature was 95℃ and the reaction time was 2h. The developed method was simple and inexpensive so that it had potential for further scale-up applcation in industry.With the development of nano technology, the surface modification and dispersion of nanometer particles were given more study. Some surface modification...
Keywords/Search Tags:nano-sized magnesia, magnesium nitrate, hexamethyene tetramine, precitation method, polymer protection, surface modification, octadecoic acid, active exponent, lipophilic degree, settling process
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