Application

Defoaming Machanism

The main defoaming mechanisms include bridge-dehumidification, bridge-stretching and diffusion fluid entrainment. For polysiloxane defoamer, the defoamer mechanism are bridge-dehumidification and bridge-stretching mechanism. When the oil droplets of defoamer enter the surface of the foam film to form a lens shape, the bridge-dehumidification effect will occur. As the film thinns, this lens structure enters the opposite surface of the foam film and forms a bridge, which dehumidifies the film from the oil bridge by capillary force, causing the film to break and the bubbles to disappear. Through the bridging tensile action, oil droplets bridge the surface of the foam film to form an oil bridge. The oil bridge has a tensile effect under the traction of the water phase, which destroys the mechanical balance of the liquid film, makes the liquid film become unstable and breaks in the thinnest area, thus destroying the entire foam structure.

Precautions for the use of defoamer

1. Be insoluble or soluble hardly in the foaming liquid

In order to burst the foam, the defoamer should be concentrated and concentrated on the foam. In the case of defoaming agent, it should be concentrated and concentrated in an instant, and in the case of defoaming agent, it should always be maintained in this state. Therefore, the defoamer is supersaturated in the foaming solution, and only being insoluble or soluble hardly is easy to achieve supersaturation. Insoluble or soluble hardly, it is easy to gather at the gas-liquid interface and concentrate on the foam, and it can play a role at a lower concentration. For the defoamer used in the water system, the molecule of the active ingredient must be strong hydrophobic and weak hydrophilic, and the HLB value should be in the range of 1.53 to have a good effect.

2. The surface tension is lower than the foaming solution

Only when the intermolecular force of the defoamer is small and the surface tension is lower than that of the foaming solution, the particles of the defoamer can be immersed and expanded on the foam. It is worth noting that the surface tension of the foaming solution is not the solution's.

3. There is a degree of affinity with the foaming liquid

Since the defoaming process is actually a competition between the foam collapse speed and the foam formation speed, the defoaming agent can be quickly dispersed in the foaming solution in order to quickly play a wider range of roles in the foaming solution. In order to make the defoamer diffusion faster, the active ingredient of the defoamer must have a certain degree of affinity with the foaming solution. The active ingredient of defoamer is too close to the foaming solution and will dissolve. If too sparse, it's difficult to disperse. The effectiveness is good only when the intimacy is right.

4. No chemical reaction with foaming liquid

The defoamer reacts with the foaming solution. On the one hand, the defoamer will lose its effect. On the other hand, harmful substances may be produced, affecting the growth of microorganisms.

Why choose to use defoamer？

1. The inside of the fermenter is not clean, containing residual bacteria and other fermentation products, and foam will appear during the fermentation process;

2. In the fermentation process, due to cell cracking, fermentation protein concentration increasing and other reasons, foam will also appear in the fermenter;

3. During fermentation, due to the mixing and operation of the equipment, the air is mixed and the pressure in the tank is unbalanced, foam is also produced.

4. Affected by the environment in the fermentation process, the temperature continues to rise during fermentation, and some of the components are decomposed by heat to produce foam.

5. Foam in the fermentation process is unavoidable, and what we can do is to solve the foam as soon as possible.

All aerobic fermentations require and use defoamer. Without them, fermentation processors could encounter a lot of foam as organic materials - such as sugars, starches, cellulose, and proteins - ferment and transform into more desirable products.

Too much foam in the fermentation process will limit equipment capacity, increase production time and cost, reduce product quality, and even affect safety. Therefore, in the two stages of fermentation application - fermentation and product separation - anti-foam agents are commonly used to control foam.

During the fermentation phase, defoamers provide excellent foam control for a variety of aerobic fermentation applications, including bacterial and fungal fermentation. Aerobic fermentation processes inject large amounts of air into the fermenter, which naturally produces foam.

The defoamer can also control foam during the downstream separation of the fermentation product from the fermentation solution. Because these antifoam products are very effective at low concentrations, typically between 1 and 10 PPM of fermentation liquid, they produce little or no interference with product separation.

Defoamer is used to remove foam by adding additional defoamer to the fermentation solution. The principle of defoaming is to reduce the mechanical strength of the foam liquid film, or reduce the surface viscosity of the liquid film, or both, and finally achieve the effect of breaking the foam.