When the ultrasonic wave propagates in the liquid, due to the violent vibration of the liquid particles, small voids will be generated inside the liquid. These small cavities quickly expand and close, resulting in a violent impact between the liquid particles, resulting in a pressure of thousands to tens of thousands of atmospheres. This violent interaction between the particles will cause the temperature of the liquid to rise suddenly and play a good role in stirring, thereby emulsifying the two incompatible liquids (such as water and oil), and accelerating the dissolution of the solute and accelerating the chemistry. reaction. The various effects caused by the action of ultrasonic waves in liquids are called cavitation of ultrasonic waves.
Using ultrasonic waves in chemical reactions can increase the rate of chemical reactions, shorten the reaction time, improve reaction selectivity, and can stimulate chemical reactions that cannot occur without the presence of ultrasonic waves. Because of its unique reaction characteristics, ultrasonic chemistry is currently receiving extensive attention and is one of the most important and very active research fields such as synthetic chemistry.
Ultrasonic chemistry has been widely used in every field of chemistry, such as: organic synthetic chemistry, nanomaterial preparation, biochemistry, analytical chemistry, polymer chemistry, polymer materials, surface processing, biotechnology and environmental protection.
There is an alternating period of positive and negative pressure during the propagation of ultrasonic waves in the medium. In the positive pressure phase, the ultrasonic wave squeezes the molecules of the medium, increasing the original density of the liquid medium, while in the negative pressure phase, the density of the medium decreases.
Ultrasonic chemistry should have the characteristics of accelerating the chemical reaction, reducing the reaction conditions, shortening the reaction induction time, and being able to carry out chemical reactions that are difficult to perform with some traditional methods.
The phenomenon of cavitation using power ultrasound to accelerate and control chemical reactions, increase the reaction rate and initiate new chemical reactions is called ultrasonic chemistry. Sonochemistry can be applied to almost all chemical reactions, such as extraction (extraction) and separation, synthesis and degradation, biodiesel production, sewage treatment, cell crushing, dispersion and coagulation, extraction of bio-nano and so on.
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