Ultrasonic extraction (also known as ultrasonic extraction) is applied to the extraction of effective contents of Chinese medicinal materials and various animals and plants by innovative people with its unique advantages of low extraction temperature, high extraction rate and short extraction time. It is a modern technical means to replace the traditional shear process to achieve high-efficiency, energy-saving and environmental protection extraction.

Ultrasonic extraction has two meanings: the application of ultrasonic technology and the extraction of chemical components in drugs. It is a new extraction technology that uses the cavitation and other special effects produced by ultrasound to extract the chemical components contained in drugs quickly and efficiently.

principle

Ultrasonic extraction is to use the mechanical effect, cavitation effect and thermal effect of ultrasonic wave to extract biological effective components by increasing the movement speed of medium molecules and the penetration force of medium.

Mechanical effect

The propagation of ultrasonic wave in the medium can make the medium particles vibrate in its propagation space, thus strengthening the diffusion and propagation of the medium, which is the mechanical effect of ultrasonic wave. The ultrasonic wave generates a kind of radiation pressure in the process of propagation, which propagates along the direction of the acoustic wave and has a strong destructive effect on the material, which can make the cell tissue deform and the plant protein denatured; At the same time, it can also give different accelerations to the medium and the suspension, and the motion speed of the medium molecule is much greater than that of the suspension molecule. Thus, friction is generated between the two. This friction can depolymerize biomolecules and make the effective components on the cell wall dissolve in the solvent faster.

Cavitation effect

Usually, some micro bubbles are more or less dissolved in the medium, and these bubbles vibrate under the action of ultrasonic waves. When the sound pressure reaches a certain value, the bubbles increase due to directional diffusion, forming a resonant cavity, and then suddenly close. This is the cavitation effect of ultrasonic waves. When this bubble is closed, it will generate a pressure of several thousand atmospheres around it to form a micro shock wave, which can cause the cell wall of the plant and the whole organism to break. Moreover, the whole breaking process is completed in an instant, which is conducive to the dissolution of the active ingredients.

heat effect

Like other physical waves, the propagation process of ultrasonic wave in the medium is also a process of energy propagation and diffusion, that is, during the propagation process of ultrasonic wave in the medium, its acoustic energy is continuously absorbed by the particles of the medium, and the medium converts all or most of the absorbed energy into heat energy, which leads to the rise of the temperature of the medium itself and the tissue of medicinal materials, and increases the dissolution rate of the effective ingredients of the drug. Since the increase in the internal temperature of the drug tissue caused by the absorption of acoustic energy is instantaneous, the biological activity of the extracted component can be kept unchanged.

The application of ultrasound in extraction at present, the application of ultrasound in extraction has been increasingly widespread, and it has been industrialized in the extraction of traditional Chinese medicine. The extraction of traditional Chinese medicine in China has the disadvantages of large solvent consumption, long extraction time, high extraction temperature, long process route and low extraction efficiency, which lead to the main problems such as high residual solvent content, low content of effective components, difficult to control quality and unclear efficacy in traditional Chinese medicine products, low product price and weak competitiveness in the international market, which greatly restricts the process of modernization of traditional Chinese medicine in China. Ultrasonic extraction of Chinese medicine can obviously reduce the solvent consumption and shorten the extraction time. High extraction rate can be achieved at a lower temperature without damaging the effective components of Chinese medicine. It can be widely used for the extraction of saponins, alkaloids, flavonoids, anthraquinone, organic acids and polysaccharides in Chinese medicine. The ultrasonic wave is caused by ultrasonic cavitation. The strong ultrasonic wave emitted from the end of the horn activates the cavitation bubble in the liquid in the reaction vessel. When the bubble collapses, the shock wave or jet acts on the cell wall and breaks it. At present, supercritical CO2 extraction has become the focus of research in recent years because of its advantages such as green and pollution-free, less or no solvent residue, low inactivation of active ingredients and high product quality. But at the same time, this technology has the disadvantages of high extraction pressure, long time, low extraction rate, large amount of entraining agent and high energy consumption, which greatly limits its industrial application. If ultrasound is applied to supercritical fluid extraction, the pressure and temperature of the extraction system can be significantly reduced, the amount of entraining agent and the extraction time can be reduced, and the extraction rate can be significantly improved.