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How ultrasonic extractors work

Article source:LAWSON Author:Lawson Popularity: 374 Issuing Time:2020/4/8 9:01:11

Ultrasonic extractor, also known as ultrasonic extractor, mainly uses fast mechanical vibration waves generated by piezoelectric transducers to reduce the force between the target extract and the sample matrix to achieve solid-liquid extraction separation. In industrial applications, the use of ultrasonic waves for cleaning, drying, sterilization, atomization and non-destructive testing is a very mature and widely used technology.

Ultrasound refers to mechanical waves with a frequency of about 20 kHz to 50 MHz, and requires an energy carrier - a medium - to propagate. The alternating period of positive and negative pressure in the ultrasonic transmission process, in the positive phase, squeezes the medium molecules, increasing the original density of the medium; in the negative phase, the medium molecules are sparse and discrete, and the medium density decreases. That is to say, the ultrasonic wave does not polarize the molecules in the sample, but produces acoustic cavitation between the solvent and the sample, resulting in the formation, growth and explosive compression of bubbles in the solution, thereby dispersing the solid sample and increasing the The contact area between the sample and the extraction solvent increases the mass transfer rate of the target from the solid phase to the liquid phase.

The superiority of ultrasonic extraction of Chinese medicinal materials is based on the special physical properties of ultrasonic waves.

(1) Accelerate the motion of medium particles. When ultrasonic waves with a frequency higher than 20 KHz are propagated in a continuous medium (such as water), according to the Huygens wave principle, the movement of the medium particles (including the particles of the important effective components of the medicinal materials) will be caused on the wavefront of its propagation. The movement of the medium particles can obtain huge acceleration and kinetic energy. The acceleration of a particle is generally calculated to be more than 2,000 times the acceleration of gravity. Since the medium particles act on the particles of the medicinal ingredients in the medicinal materials, the ultrasonic energy is applied to them, so that they obtain huge acceleration and kinetic energy, and quickly escape from the base of the medicinal materials and dissociate in the water.

(2) Cavitation. The propagation of ultrasonic waves in the liquid medium produces a special "cavitation effect", and the "cavitation effect" continuously generates numerous micro-cavities with internal pressures reaching thousands of atmospheres and constantly "blasts" powerful shock waves on the microscopic scale. Acting on the Chinese medicinal materials, the components of the Chinese medicinal materials are "bombarded" to escape, and the matrix of the medicinal materials is continuously eroded, and the medicinal components that do not belong to the plant structure are continuously separated. Accelerate the extraction and extraction of plant active ingredients.

(3) Ultrasonic vibration homogenization (Sonication) makes the effect of each point in the sample medium consistent, so that the entire sample extraction is more uniform. To sum up, under the action of ultrasonic field, the medicinal substances in Chinese medicinal materials not only obtain their own huge acceleration and kinetic energy as medium particles, but also obtain strong external force impact through "cavitation effect", so the energy rate is fully separated. .



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