The effective components in Chinese herbal medicine, such as saponins, flavonoids and alkaloids, are relatively low in content, and a large number of components are ineffective components such as starch, inorganic salts and proteins. The existence of these ineffective components makes the concentration of effective components lower and makes the active ingredients difficult to be absorbed. It also hinders the extraction of effective components and brings about a certain air crash. In order to make better use of effective components, it must be extracted. Most of the effective components, such as saponins, flavonoids and alkaloids, are most of the molecular weight of 200-1000, the molecular weight of the ineffective components is above 50000, and the molecular weight of some inorganic salts is less than 100.
Membrane separation technology is the purpose of separating solute and solvent by membrane pore size at normal temperature. The study shows that the application of membrane separation technology in the separation and purification of Chinese herbal medicine mainly has three major functions, that is, to intercept large molecular impurities, filter small molecules and dehydrate [4]. Shi Qing and others used membrane separation technology to separate and purify the berberine, astragalus polysaccharides and chlorogenic acid in honeysuckle, and found that the removal of solid suspension and the clarity of the liquid were also significant.
3. Application of membrane separation technology in concentration of traditional Chinese medicine extract
Because of the different solubility and diffusion properties of the components in the mixed material, the high density polymer film has the choice of some components in the material solution, and it is easy to adsorb on the surface of the membrane by the solution of the component molecules, and the diffusion passes through the chemical potential gradient of the membrane, so the composition of the upstream side liquid is changed and through the polymer. The component of the membrane permeates the lower side and vaporizes on the surface of the membrane because the vapor pressure is less than its saturated vapor pressure. Then, the condensation product is formed after the condensation system is condensed. This technology can achieve distillation, extraction and absorption of liquid separation by traditional methods with low energy consumption, such as the near boiling point, constant boiling point mixture and the separation [5] of isomers which are difficult to separate or inseparable from the distillation. Compared with the traditional separation technology, it is characterized by high efficiency. As long as the membrane is suitable, the single stage can reach high separation degree. Two is low energy consumption, energy saving 1/2 to 1/3 compared with constant boiling distillation; three is simple process, less additional treatment and convenient operation; four is not introducing other reagents in the whole process, so product and The environment is not polluted; the five is to facilitate amplification and coupling and integration with other processes. This method is mainly used for dehydration of alcohols, ketones, aromatic compounds, amines, esters, ethers, organic acids, nitriles, aliphatic hydrocarbons and organosilicon compounds. Because of the effective ingredients in many medicinal materials, such as total emodin, flavonoids, chlorogenic acid, caryonin, astragaloside, etc., alcohol leaching or precipitation is used, and the alcohol solution needs to be recovered. This technology is simple and quick to achieve the purpose of recovering alcohol.
Compared with the conventional separation and separation process, the advantage of membrane distillation is that it can separate ions, macromolecules, colloids, cells and other non volatile substances in theory, and the operating temperature is lower than the traditional distillation process, the operating pressure is lower than the traditional process, the mechanical properties of the membrane are low, and the separation of special substances is suitable for 100%. Highly concentrated substances can even produce crystals and produce high efficiency. Because it has the characteristics of low temperature concentration, it can be used for the condensation of heat sensitive substances.
4. Application and Prospect of membrane separation technology in pharmaceutical industry
Membrane separation technology is a new and energy saving technology for material separation and concentration. Because its separation process is carried out at normal temperature, no phase change, no chemical change, good selectivity, strong adaptability and low energy consumption, it can replace the traditional technology of evaporation concentration and drilling resin filtration in the current pharmaceutical industry. The rate of effective components of effective chemicals is improved step by step, especially for improving the added value of traditional Chinese medicine, expanding the export of Chinese medicine and the development of the modernization of Chinese medicine.
At present, membrane separation technology has made great progress, but it is still in an upward stage of development, and there is still much work for us to do. Membrane science and technology in twenty-first Century will further improve and improve the existing membrane process, continue to explore and develop new processes and materials, and continue to expand the original application field, making film technology play a greater role.
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