What is the ultrasonic defoaming?

What is the ultrasonic defoaming?

Foam is a structure formed by gas wrapped in liquid, and is commonly found in products such as detergents, shampoos, and toothpastes. While foam can provide a good user experience in some products, it can be an undesirable factor in certain industrial processes. For example, in the food, pharmaceutical, chemical and other industries, foam can affect process control, product quality and production efficiency. Therefore, the research and application of foam elimination technology are of great significance.

Principle of ultrasonic defoaming Ultrasonic defoaming is a physical phenomenon that uses ultrasonic vibration to act on foam. Ultrasound refers to sound waves with a frequency exceeding 20kHz. The principle of ultrasonic defoaming is to use the high-frequency vibration of ultrasonic waves to destroy the foam structure through the mechanical action of the foam liquid, causing the bubbles to collapse rapidly, thereby achieving the effect of eliminating foam.

The specific principle is as follows
1. When ultrasonic vibration acts on foam liquid, a large number of tiny bubbles will be generated. These bubbles will rapidly expand and collapse under the action of ultrasonic vibration.

2. The shear force and pressure changes caused by ultrasonic vibration on the liquid reduce the interfacial tension between the gas and the liquid, which is conducive to bubble collapse.
3. The stirring effect of ultrasonic vibration on the liquid can bring the bubbles into better contact with the surrounding liquid, thereby accelerating the collapse of the bubbles.

Ultrasonic defoaming is a method that uses the characteristics of ultrasonic waves to eliminate foam. Its principles mainly involve the following aspects:
1. **Destroy the surface tension of foam**: Foam is formed by a liquid film wrapping a gas. There is surface tension between the molecules on the liquid surface, which keeps the foam in a relatively stable form. Ultrasound is a high-frequency mechanical wave. When ultrasonic waves act on the foam system, high-frequency vibrations will be generated. This vibration will produce strong disturbances in the liquid film of the foam, making the local surface tension distribution of the liquid film uneven. In the case of uneven surface tension, the stability of the foam is destroyed and the film is prone to rupture, resulting in the elimination of the foam.

2. **Cavitation**: When ultrasonic waves propagate in liquids, cavitation will occur. During the negative pressure half cycle of ultrasonic waves, tiny cavitation bubbles will form in the liquid. As these cavitation bubbles form and grow, they absorb gas and energy from the surrounding liquid. When the ultrasonic wave enters the positive pressure half cycle, the cavitation bubbles will quickly collapse and close. When the cavitation bubble collapses, it will produce extremely high pressure and temperature, as well as strong shock waves and micro jets. These energies and forces act on the foam, which can effectively destroy the structure of the foam and cause the foam to burst and disappear.

3. **Accelerate foam drainage**: The vibration effect of ultrasonic waves can accelerate the flow of liquid in the foam system and promote the liquid drainage process between foams. Under normal circumstances, the liquid between the bubbles will slowly drain out under the action of gravity and surface tension, causing the bubbles to gradually collapse. The effect of ultrasonic waves can speed up the discharge of liquid, causing the foam to lose liquid support faster, thereby accelerating the collapse of the foam.

4. **Inhibit foam generation**: In addition to eliminating existing foam, ultrasonic waves can also inhibit the formation of foam to a certain extent. Because the action of ultrasonic waves makes it difficult for the gas in the liquid to gather to form stable bubble nuclei, thereby reducing the possibility of new foam generation. This is because the high-frequency vibration and cavitation of ultrasonic waves will make the gas in the liquid disperse more evenly, making it difficult to form large bubbles that are large enough to develop into foam.