Principle introduction:
When ultrasonic waves propagate in liquid media, they produce a series of effects such as mechanics, heat, optics, electricity and chemistry through mechanical action, cavitation action and thermal action. In particular, high-power ultrasound will produce strong cavitation, thereby forming instantaneous high temperature, high pressure, vacuum and micro jets locally.
As a physical means and tool, ultrasonic technology can produce a series of extreme conditions in the medium commonly used in chemical reactions. This energy can not only stimulate or promote many chemical reactions, accelerate the speed of chemical reactions, and even change some The direction of the chemical reaction produces some unexpected effects and miracles. It is generally believed that the occurrence of the above phenomenon is mainly due to the mechanical action and cavitation of ultrasound, which are the result of changing the reaction conditions and environment.
1. Sonochemistry is an emerging interdisciplinary subject, which mainly refers to the use of ultrasound to accelerate chemical reactions or trigger new reaction channels to increase the yield of chemical reactions or obtain new chemical reaction products. The main power of sonochemical reaction comes from acoustic cavitation, which comes from extreme physical conditions such as high temperature (greater than 5 000K), high pressure (greater than 2.03×108Pa), shock wave or micro jets that accompany the implosion of cavitation bubbles.
2. The application of sonochemistry The application range of sonochemistry is very wide, which can be roughly summarized into 9 categories,
They are: biochemistry, analytical chemistry, catalytic chemistry, electrochemistry, photochemistry, environmental chemistry, mineral chemical treatment, extraction and separation, synthesis and degradation.
 
Mechanical action-the introduction of ultrasonic waves into the chemical reaction system, ultrasonic waves can make the substance make a violent forced movement, and produce unidirectional force to accelerate the transfer and diffusion of the substance, and it can replace mechanical agitation in a suitable range, because ultrasonic agitation is produced from a microscopic point of view , Which greatly increases the probability of contact and collision between the reactants, so it greatly accelerates the rate of chemical reactions.
Cavitation-In some cases, the generation of ultrasonic effects is related to the cavitation mechanism. Acoustic cavitation refers to a series of dynamics generated by tiny bubbles (cavities) existing in the liquid under the action of sound waves. Learning process: oscillation, expansion, contraction and even collapse. Where cavitation occurs, the local state of the liquid changes greatly, resulting in extreme high temperature and high pressure. Provides a new and very special physical and chemical environment for chemical reactions that are difficult or impossible to achieve under general conditions
 Catalyze chemical reactions——
 ①The conditions of high temperature and high pressure facilitate the cracking of the reactants into free radicals and divalent carbon, forming more active reaction species;
②Shock wave and microjet have desorption and cleaning effects on solid surfaces (such as catalysts), which can remove surface reaction products or intermediates and the passivation layer on the catalyst surface;
③The shock wave may destroy the structure of the reactant;
④ Dispersion reactant system;
⑤Ultrasonic cavitation corrodes the metal surface, and the shock wave causes the deformation of the metal lattice and the formation of internal strain zones, which improves the chemical reaction activity of the metal;
⑥Promote the solvent to penetrate deep into the solid and produce the so-called inclusion reaction;
⑦Improve catalyst dispersion.