结晶分离（Crystallization separation）.docVIP

结晶分离（Crystallization separation） General properties of crystals (1) anisotropy: the main difference between crystal and non crystal amorphous material in many properties such as optical and electrical has direction, which has the same properties in the same direction, are different in different directions; but polycrystalline macro has no anisotropy. (2) uniformity: the crystal is a structure formed by the arrangement of the same molecules, atoms and ions in order to form crystals only when they reach a certain degree of purity. (3) crystal (single crystal) has regular geometrical shape and good symmetry. (4) it has a certain melting point. (5) the same kind of material will form different crystalline morphology, homogeneous polycrystalline phenomenon. Crystallization process Crystallization - a substance from a liquid (liquid or molten body) or gas The process by which crystals are formed is called crystallization. ? - crystallization in certain conditions. The crystalline form of the solute precipitation from solution, to achieve the purpose of separation, which is the traditional method of material separation and purification, widely used in chemical industry, biological engineering, food and pharmaceutical industries, such as sugar, monosodium glutamate, various amino acid production. The analysis and determination of crystalline products were carried out by optical microscope, polarizing microscope and X- ray diffraction. Conditions for crystallization (1) material characteristics (internal causes) (2) the purity of the sample (3) the saturation of solution: in a slightly supersaturated state, the crystal formation rate is slightly larger than the rate at which the crystal dissolves, so that the crystal can be obtained (4) the effect of solvent: solvent can react with crystalline substance, can not affect the biological activity of a crystalline substance; with high temperature coefficient, in order to take advantage of the temperature change of crystallization