The use of magnesium oxide and magnesium hydroxide synthesis method
1, the properties of nanoscale magnesium hydroxide
Nano-sized magnesium hydroxide molecular formula Mg (OH) 2, white fine powder, non-toxic, tasteless, no corrosion, relative density 2.36, refractive index began to decompose at 1.561350 degrees centigrade, decomposed rapidly at 430 degrees centigrade, decomposed at 490 C, dissolved in strong acid solution and insoluble in salt solution.
(1) optical properties
When the grain size of metal materials is reduced to the nanoscale, the color is changed to black and the particle size decreases. The absorbability of nanoparticles is directly proportional to the color of the nanoparticles. The quantum size effect of the energy level and the surface charge distribution of the grain also affect the process of absorption. The conduction electron energy levels in the grain often coacerate into narrow energy bands and cause narrow absorption bands. The nonlinear optical effect has become another aspect of the study of optical properties of nanomaterials.
(2) electromagnetic properties
The distance between the atoms of a metal material is proportional to the change in particle size. Therefore, when the grain of metal is in the nanometer range, its density will increase as the distance becomes smaller. In this way, the average free path of free electrons in the metal decreases and the conductivity decreases. In magnetic structure, there are great differences between coarse grain materials and nanomaterials. In general, the magnetic structure of magnetic materials is composed of many magnetic domains, separated by domain walls, and magnetized by domain wall motion. In nanomaterials, when the particle size is less than a critical value, all the grains present a single magnetic domain structure, and the coercivity is greatly increased. When the grain size of nanomaterials is reduced, the magnetic ordered state of the core material will change radically. For example, the ferromagnetic material in the rough crystal state can be transformed into a superparamagnetic state when the particle size is less than a certain critical value.
(3) chemical catalytic properties
As the particle size of nanomaterials is smaller, the number of atoms on the surface will occupy a large proportion, the adsorption capacity will be strengthened and the chemical activity will increase. So, at room temperature, many metal nanomaterials burn in the air with intense oxidation. The nonpolar nanomaterials exposed to the atmosphere will adsorb gas and form an adsorption layer. Using this characteristic, the gas sensing original can be made by using nano materials to detect different gases. The catalytic performance of metal nanomaterials shows that the H-H bond, C-C bond, C-O bond and C-H bond can be catalyzed under the suitable conditions. The main advantages of nanomaterials as catalysts include fine pores, no impurities, free selection of components, mild conditions and convenient use.
(4) thermal properties
The changes in the various elastic and thermodynamic parameters in the restricted atomic system will lead to a change in the equilibrium phase when the size of the phase is sufficient for an hour. By the thermogravimetric analysis, it is found that the melting point of nano copper particles with an average particle size of 40nm is reduced from 1053 to 750. The melting point of nanomaterials is less than that of the same kind of coarse-grained material, and the specific heat capacity is larger than the coarse grain material. 2, the use of nanometer magnesium hydroxide
Nano magnesium hydroxide is widely used, and can be used as flame retardant, preservative, food additives, acid-base neutralizer, flue gas desulfurizer, heavy metal remover and so on.
(1) flame retardants
After the decomposition of magnesium hydroxide, Magnesium Oxide and a large amount of steam will be produced. When it decomposes, it will absorb a lot of heat. The water released will reduce the temperature of the substrate, while Magnesium Oxide can be used as a good flame retardant.