Views:13 Author:Site Editor Publish Time: 2019-07-15 Origin:Site
what's the relationship bewteen Chemical and the magical sonochemistry
What is sonochemistry?
The so-called sonochemistry mainly refers to the use of ultrasound to accelerate chemical reactions and improve the chemical yield.
Interdisciplinary. The sonochemical reaction is not from the direct interaction of sound waves with matter molecules because in liquids
The commonly used acoustic wave wavelength is 10 cm ~ 0.015 cm (corresponding to 15 kHz ~ 10 MHz), much larger than the molecular ruler.
Degree. The sonochemical reaction is mainly due to acoustic cavitation - the formation, oscillation, growth, shrinkage to collapse of the cavity in the liquid
Collapse, and the physical and chemical changes caused by it. The process of liquid acoustic cavitation is to concentrate the sound field energy and release it quickly.
the process of. When the cavitation bubble collapses, the extremely small space (between nanoseconds and microseconds) is around the cavitation bubble.
Inside, it produces a high temperature of 5000 K or more (so high temperature is enough to cause the liquid medium and cavitation bubbles to be emitted
Pyrolysis occurs, which triggers a series of free radical reactions. And a high pressure of about 5 × 107Pa, the temperature changes
The rate of up to 109K/s is accompanied by a strong shock wave and/or a jet with a speed of 400 km per hour.
A chemical reaction that is difficult or impossible to achieve under normal conditions provides a new, very special
The environment has opened up a new chemical channel. Therefore, the cavitation effect can directly cause chemistry in liquid media.
Reaction. A discipline related to these chemical reactions is called sonochemistry, and some literatures are also called soundification.
Learning Ultrasonic Chemistry or High Energy Chemistry is the last independent chemistry discipline in the catalogue of chemistry.
The main content of sonochemistry is to use ultrasonic cavitation energy to turn on or accelerate chemical reactions to improve chemical production.
Amount. In sonochemistry, power ultrasonic waves of 20 kHz to 50 kHz are mainly used, and the usual sonochemical reactor scale
The degree is close to the wavelength of the acoustic wave, so that the low-frequency ultrasonic wave propagates little attenuation in the medium, on the wall of the container.
Almost all-reflection occurs, and sufficient sound intensity causes the surface of the liquid medium to be severely disturbed, so that a reverberant field is easily established in the reactor.
Ultrasonic cavitation provides a form of energy, such as time of action, pressure, and energy available to each molecule.
The surface is completely different from some traditional energy sources such as light energy, heat energy and ionizing radiation energy.
There are four types of sonochemical reactions, which are: common chemical reactions, redox reactions in aqueous solutions.
Should, the degradation of the polymer and the decomposition of the organic solvent. If we discuss the mechanism of the sonochemical reaction, then
Often all sonochemical reactions are separated into ultrasonic waves to accelerate the chemical reaction of the reaction, and only the application of ultrasonic waves
There are two major types of chemical reactions that can occur.
There are many examples of sonochemical reactions belonging to the former type, such as hydrolysis of esters, hydrogenation of acetylene and acetaldehyde.
Originally, a reaction of calcium carbonate with an acid, decomposition of a diazo compound, and a reaction using a solid catalyst.
Examples of the latter type of sonochemical reaction are: degradation and polymerization of polymers, in tetrachlorination
Iodine is released from iodide under carbon conditions, H2O2, HNO2 and HNO3 are formed in water saturated with air, and a hydroxyaromatic compound or the like is formed in an aqueous solution of an aromatic hydrocarbon.
Second, the application of sonochemistry
Sonochemistry is one of the frontiers of current chemical research. Its development is attracting the attention of the chemical academic community on an international scale. Sonochemical technology is expected to bring major changes to the industries such as pesticides, synthetic drugs, plastics and microelectronic devices, and is therefore receiving great attention from the chemical production industry. At present, the international chemical community believes that one of the cutting-edge projects that should be given priority in chemical research is the chemical behavior of substances under extreme conditions of high temperature and ultra-high pressure, which helps to understand chemical reactions, open up new ways, and seek new materials. It is certain that the development of sonochemical science will surely have new contributions.
Experimental chemists can perform power ultrasound in a range of applications and expect to derive one or several benefits from these benefits, which are generally expressed as:
1. Accelerate the chemical reaction or soften the required reaction conditions.
2. Sonochemical reactions The requirements for reagent specifications are often reduced compared to general techniques.
3. The reaction is often initiated by ultrasound without the need to add reagents.
4. The steps normally required in the synthesis procedure are reduced.
5. In some cases, the reaction may be carried out completely in accordance with another route.
The following is a list of applications of power ultrasound in the chemical industry.
1. Electroplating. Applying ultrasonic irradiation to the plating bath increases the plating rate and prevents the plating current from dropping.
In general, this current drop phenomenon due to polarization always occurs. Power ultrasound for electrochemistry
The benefits of the process are as follows:
(1) Ultrasonic irradiation can remove bubbles appearing on the surface of the electrode at any time to ensure unimpeded current flow.
(2) The jet produced by ultrasonic cavitation can continuously purify the electrode surface to maintain its chemical activity.
(3) Ultrasonic cavitation can continuously perturb the diffusion layer to prevent ion depletion.
(4) Ultrasonic perturbation causes more ions to pass through the electrode bilayer during the entire electrochemical reaction.
2. Precipitation, crystallization and atomization. The commonality of the three processes of precipitation, crystallization and atomization is that they are all
Power ultrasound acts on the liquid medium to produce a manifestation of a particular form of material. In several industrial productions,
It is often necessary to process particularly small and uniform particles of matter. A lot of facts prove that ultrasound is processing such micro
A very effective tool for tablets. For example, in pharmaceutical factories, for the production of oral or subcutaneous injection suspension agents, it is required to add
The work is very small and uniform material particles, one can get a stable suspension, and the other is easy to absorb.
3. Separation and filtration. Conventional filtration methods often have filter plugging, so the filter membrane has to be replaced periodically. It goes without saying that if you avoid filtering blocking and keep working continuously, it will bring obvious economic benefits. The facts show that applying power ultrasound can provide an ideal solution to this problem. Ultrasonic irradiation is used to improve the filtration process mainly in two aspects: one is that ultrasonic irradiation will cause the fine particles to agglomerate, thereby speeding up the filtration; secondly, the ultrasonic irradiation provides sufficient vibration energy to the system, so that Part of the particles remain suspended, providing more free passage for solvent separation.
Third, the future of sonochemistry
In the 1920s, at the Chemical Laboratory of Princeton University, the first time that ultrasound was discovered
The hydrolysis of dimethyl sulfate and the reaction of sulfite to reduce potassium iodate, but did not cause the weight of chemists
Vision. In the mid-1980s, sonochemistry became the same as thermochemistry, photochemistry, and electrochemistry.
The new branch of chemistry has sprung up in the international arena and has developed rapidly.
On April 8-11, 1986, the first International Symposium on Acoustic Chemistry was called at the University of Warwick, UK.
Open, marking that sonochemistry has occupied a field of modern science and technology after a short period of revival
Place of the land. On April 14, the same year, the British "Times" wrote: "A new industrial revolution is in sight.
It will revolutionize the traditional production techniques of plastics, detergents, pharmaceuticals and agrochemicals, and it will be unparalleled.
The advantages are safety (not requiring high temperature and high pressure conditions in current production) and low cost (only the minimum amount of energy is consumed)
the amount). ... This is called a new branch of science in sonochemistry."
The rise of sonochemistry has not only aroused great concern in the chemical industry, but also inspired the deepening of the chemical industry.
Interesting. In 1986, at the American Chemical Society (ACS) National Conference in Anaheim, "Organic Metals
The main content of the topic of high-energy technology in chemistry is sonochemistry; in 1987, the Royal Society of Chemistry
Specialized in the group of sonochemistry; in the same year at the University of Savoie in France, on "New Synthesis in Organic Chemistry"
The EUCHEM Special Study Group of the Methodology takes sonochemistry as an important part of it;
20 state-owned companies signed a contract to establish a “sound chemistry club” to support sonochemical research economically.
Sonochemistry is gaining more and more attention from chemists in the 21st century. This emerging chemistry discipline is
The value is young and has expanded to the industrial application field. The magical sound chemistry will definitely round our dreams.