Ultrasonic extraction

Introduction to Ultrasonic Extraction Technology and Equipment for Traditional

Ultrasonic extraction (also known as ultrasonic extraction) has been adopted by innovators for the extraction of effective components from traditional Chinese medicinal materials and various animals and plants due to its unique advantages of low extraction temperature, high extraction rate, and short extraction time. It is a modern high-tech means to replace traditional shearing process methods and achieve efficient, energy-saving and environmentally friendly extraction. Ultrasonic extraction utilizes the mechanical effect, cavitation effect and thermal effect of ultrasonic waves to increase the movement speed of medium molecules and the penetration of the medium to extract the effective components of biological materials.

I.The Principle of Ultrasonic Extraction of Chinese Herbal Medicines
(1) The principle states that when waves (including vibrations from both super sources and wave sources) propagate through a continuous medium, they cause movement of the medium's particles at their wavefronts, and every point reached by the wave source in the medium induces vibration in adjacent particles, turning them into new wave sources. The wave disturbances created by such sources will impart acceleration and kinetic energy to every particle along their propagation path. Ultrasonic waves can accelerate medium particles to more than a thousand times the acceleration due to gravity. Under the influence of ultrasonic waves, medium particles undergo high-frequency oscillations tens of thousands of times per second and exhibit massive speeds and kinetic energies greater than 100 m/s, rapidly exciting the solution molecules. (2) Ultrasonic waves create a unique 'cavitation effect' in liquid media, generating countless micro-bubbles with internal pressures reaching thousands of atmospheres, and continuously producing micro-explosions that generate strong shock waves on a microscopic scale, impacting solid-liquid or liquid-liquid molecules, causing the air in the medium to be 'bombarded' and promoting the rupture and deformation of medium cells, accelerating the release of substances from the medium molecules. (3) The physical characteristics of ultrasonic waves during propagation in the medium induce mechanical vibrations, micro-jets, micro-flows, and other multi-level effects, all facilitating the diffusion of active ingredients in the solution.

II. Advantages of Ultrasonic Extraction

1. Advantages of ultrasonic extraction
　　(1) High ultrasonic extraction efficiency. The unique extreme physical characteristics of ultrasound can promote the wall breakage or deformation of plant tissues, so that the extraction of the active ingredients of the material is more sufficient, and the extraction rate is significantly increased by 50-500% compared with the traditional process.
　　(2) Short ultrasonic extraction time. The extraction rate of ultrasonically enhanced materials can usually be obtained in 24-40 minutes, and the extraction time is shortened by more than 2/3 compared with traditional processes, so the raw material processing volume is large.
　　(3) The ultrasonic extraction temperature is low. The optimal temperature for ultrasonic extraction of materials is 40-60 degrees Celsius, so there is no need to equip a boiler to provide steam heating, which is conducive to saving energy and improving environmental pollution. More importantly, it is unstable in the heat and has a protective effect on the active ingredients.
　　(5) There are few liquid impurities extracted by ultrasound, and the active ingredients are easy to separate and purify.
　　(6) Ultrasonic extraction is simple and easy, and the maintenance and maintenance of the equipment are convenient.

2. Ultrasonic enhanced extraction

(1) Solid liquid extraction is commonly referred to as extraction, which involves extracting useful components from a material using a suitable solvent. The traditional process involves heat treatment or mechanical stirring to enhance the process. It has been found that the application of power ultrasound can significantly enhance and improve the extraction process. The perturbation effect of ultrasound increases the permeability of solvent into the extracted cells and enhances the mass transfer process; Another function of ultrasound is that the strong shear force generated by ultrasound cavitation can cause the cell wall of the medium to rupture, making it easier for the cell to release its contents. Ultrasonic enhanced solid-liquid extraction is the main cause of effective mass transfer and cell rupture, surpassing any feasible technology in the past and achieving efficient extraction. Ultrasonic extraction is more effective than conventional thermal extraction in permanent institutions and shortens the extraction time, with most substances being extracted within the first 10 minutes of the process.

(2) Liquid liquid extraction involves the mass transfer process between two immiscible organic and aqueous phases. The interface effect caused by the cavitation effect of ultrasound increases the interfacial area between the two phases, while the turbulence effect caused by the shock wave during cavitation collapse eliminates the obstruction of the two-phase interface, thereby increasing the liquid-liquid extraction speed. For liquid-liquid extraction systems that are generally controlled by mass transfer rates, the effect of ultrasound is very significant.

3、Introduction to Ultrasonic Extraction Equipment

1. Model Classification: Ultrasonic extraction equipment is divided into small-scale models, pilot models, and large-scale production models.

(1) Small trial model: generally used in laboratories, with ultrasonic power ranging from 1K to 2KW and extraction tank or tank volume ranging from 5 to 10L.

(2) Pilot model: Generally used for intermediate experiments, the pilot machine adopts a single ultrasonic circulation system with an ultrasonic power of 3KW and an extraction tank volume of 1 to 2L. The material is pumped into a separate ultrasonic treatment tank for circulation treatment using a material pump (as shown in Figure 1).

(3) Scale production model: mainly used for mass production of traditional Chinese medicine extraction. The principle is the same as (2), except that multiple sets of high-power ultrasonic waves are combined in series on the basis of the original (as shown in Figure 2). The materials will be affected by ultrasonic waves when they enter each tank, and the processing effect can be achieved by entering from one tank and exiting from one tank at the back, in order to increase processing capacity and efficiency.

Ultrasonic extraction is based on the working principle of ultrasonic cavitation and is a purely mechanical treatment. Similar to high-shear mixers, ultrasonicators generate only mechanical shear forces in the process medium. Ultrasonic extraction itself is a non-thermal, chemical-free extraction technique.
Ultrasonic cavitation is the occurrence of sound waves or ultrasonic cavitation at high power and is based on repeated high and low pressure cycles. Alternating high and low pressure cycles of 20,000 ultrasonic treatments per second create strong shear forces and liquid jets. This extreme stress overcomes the selectivity of the membrane, perforates and destroys the cell wall, and results in high-quality transfer between the inner cell and the surrounding solvent. With ultrasonic extraction, higher yields and shorter extraction times can be achieved. Since ultrasonic extraction is a reproducible process, the extraction results can be repeated to obtain a standardized extraction quality.

Ultrasonic cavitation can locally lead to extreme conditions such as very high differential pressure and high shear forces. When cavitation bubbles burst onto the surface of solids such as particles, plant cells, tissues, etc., microejection and interparticle collisions can produce effects such as particle rupture, acoustic perforation (perforation of cell walls and cell membranes), and cells. Additionally, the bursting of cavitation bubbles in the liquid medium creates turbulence and agitation, facilitating mass transfer between the cell interior and the surrounding solvent. Ultrasonic radiation is a highly effective way to enhance the mass transfer process, as ultrasound causes cavitation and its associated mechanisms, such as micromotion caused by liquid jets, compression and decompression in materials, and subsequent cell wall destruction.

Cavitation
Ultrasonic extraction reduces solvent usage and makes solvent usage gentler. This means that ultrasonic extraction increases the extraction rate and produces healthier extracts. This is due to its ability to operate at low temperatures, which both reduces heat loss caused by temperature factors and avoids vaporization of substances due to low boiling points and maintains bioactive substances. Ultrasonic extraction is simple, safe to use, and precisely controllable applications. As a non-thermal extraction method, sonication can be performed at low temperatures, thus avoiding the degradation of heat-sensitive and thermally unstable substances. Ultrasonic extraction is also able to significantly reduce production time, as the traveling ultrasound breaks the cell wall, reducing the transfer time of active ingredients from the plant material to the solvent.

Effects of ultrasonic extraction
Ultrasound Cell rupture and increased mass transfer Ultrasound can assist in the extraction process by rupturing cells and enhancing mass transfer in the boundary layer around the solid matrix. As a perforation of the cell wall and cell membrane, ultrasound enhances the permeability of the cell wall and cell membrane and is usually an intermediate step before the cell is completely destroyed by ultrasound. The mechanical effects of ultrasound-induced cavitation, such as heat and pressure differences, shock waves, shear forces, liquid jets, and microflows, enhance the penetration of solvents into the cells and improve mass transfer between cells and solvents, allowing the transfer of intercellular substances into the solvents.

Ultrasonic extraction is based on the working principle of ultrasonic cavitation and is a purely mechanical treatment. Similar to high-shear mixers, ultrasonicators generate only mechanical shear forces in the process medium. Ultrasonic extraction itself is a non-thermal, chemical-free extraction technique.

Ultrasonic cavitation is the occurrence of sound waves or ultrasonic cavitation at high power and is based on repeated high and low pressure cycles. Alternating high and low pressure cycles of 20,000 ultrasonic treatments per second create strong shear forces and liquid jets. This extreme stress overcomes the selectivity of the membrane, perforates and destroys the cell wall, and results in high-quality transfer between the inner cell and the surrounding solvent. With ultrasonic extraction, higher yields and shorter extraction times can be achieved. Since ultrasonic extraction is a reproducible process, the extraction results can be repeated to obtain a standardized extraction quality.

Ultrasonic cavitation can locally lead to extreme conditions such as very high differential pressure and high shear forces. When cavitation bubbles burst onto the surface of solids such as particles, plant cells, tissues, etc., microejection and interparticle collisions can produce effects such as particle rupture, acoustic perforation (perforation of cell walls and cell membranes), and cells. Additionally, the bursting of cavitation bubbles in the liquid medium creates turbulence and agitation, facilitating mass transfer between the cell interior and the surrounding solvent. Ultrasonic radiation is a highly effective way to enhance the mass transfer process, as ultrasound causes cavitation and its associated mechanisms, such as micromotion caused by liquid jets, compression and decompression in materials, and subsequent cell wall destruction.

Cavitation
Ultrasonic extraction reduces solvent usage and makes solvent usage gentler. This means that ultrasonic extraction increases the extraction rate and produces healthier extracts. This is due to its ability to operate at low temperatures, which both reduces heat loss caused by temperature factors and avoids vaporization of substances due to low boiling points and maintains bioactive substances. Ultrasonic extraction is simple, safe to use, and precisely controllable applications. As a non-thermal extraction method, sonication can be performed at low temperatures, thus avoiding the degradation of heat-sensitive and thermally unstable substances. Ultrasonic extraction is also able to significantly reduce production time, as the traveling ultrasound breaks the cell wall, reducing the transfer time of active ingredients from the plant material to the solvent.

Effects of ultrasonic extraction
Ultrasound Cell rupture and increased mass transfer Ultrasound can assist in the extraction process by rupturing cells and enhancing mass transfer in the boundary layer around the solid matrix. As a perforation of the cell wall and cell membrane, ultrasound enhances the permeability of the cell wall and cell membrane and is usually an intermediate step before the cell is completely destroyed by ultrasound. The mechanical effects of ultrasound-induced cavitation, such as heat and pressure differences, shock waves, shear forces, liquid jets, and microflows, enhance the penetration of solvents into the cells and improve mass transfer between cells and solvents, allowing the transfer of intercellular substances into the solvents.