Ultrasonic Nano Dispersion
Ultrasonic Nano Dispersion – Ultrasonic Dispersion of Nanomaterials – Cheersonic
Nanoparticles have small particle size, high surface energy, and have a tendency to spontaneously aggregate, and the existence of agglomeration will greatly affect the exertion of the advantages of nano-powders. Therefore, how to improve the dispersion and stability of nano-powders in liquid media is very important. research topic.
Particle dispersion is an emerging fringe discipline developed in recent years. The so-called particle dispersion refers to the engineering in which the powder particles are separated and dispersed in the liquid phase medium and uniformly distributed in the entire liquid phase. It mainly includes three stages of wetting, deagglomeration and stabilization of dispersed particles. Wetting refers to the process in which the powder is slowly added to the vortex formed in the mixing system, so that the air or other impurities adsorbed on the surface of the powder are replaced by the liquid. Deagglomeration refers to the dispersing of larger particle size aggregates into smaller particles by mechanical or supersonic methods. Stabilization refers to ensuring long-term uniform dispersion of powder particles in liquids. According to the different dispersion methods, it can be divided into physical dispersion and chemical dispersion. Ultrasonic dispersion is one of the physical dispersion methods.
Ultrasonic dispersion method: Ultrasound has the characteristics of short wavelength, approximate straight line propagation, and easy concentration of energy. Ultrasound can increase the rate of chemical reactions, shorten the reaction time, and improve the selectivity of the reaction; it can also stimulate chemical reactions that cannot occur in the absence of ultrasonic waves. Ultrasonic dispersion is to place the particle suspension to be treated directly in the supersonic field and treat it with ultrasonic waves of appropriate frequency and power. It is a high-strength dispersion method. The mechanism of ultrasonic dispersion is generally believed to be related to cavitation. The propagation of ultrasonic waves is carried by the medium, and there is an alternating cycle of positive and negative pressure during the propagation of ultrasonic waves in the medium. The medium is squeezed and pulled under alternating positive and negative pressures. When an ultrasonic wave with a sufficiently large amplitude is used to act on the critical molecular distance of the liquid medium that remains unchanged, the liquid medium will rupture to form microbubbles, and the microbubbles will further grow into cavitation bubbles. On the one hand, these bubbles can be redissolved in the liquid medium, or they can float up and disappear; they can also collapse out of the resonance phase of the ultrasonic field. Practice has proved that for the dispersion of suspensions, there is an optimal super-generation frequency, and its value depends on the particle size of the suspended particles. For this reason, it is best to stop for a certain period of time after the super birth, and then continue the super birth to avoid overheating. It is also a good method to use air or water for cooling during the super birth.
Although ultrasonic dispersion is used for the dispersion of ultrafine powder suspensions, although ideal dispersion effects can be obtained, due to the large energy consumption and the high cost of large-scale use, it is currently used in laboratories. It is entirely possible for the super-dispersion to be applied in industrial production.
