Foam And Defoaming Agent

Date:Jun 21, 2019

Foam and defoaming agent

I. overview of bubbles

Foam consists of three components (gas, liquid, surfactant) and two phases (gas and liquid)

Causes of bubbles:

Produced by agitation

Stable foams are formed from surfactants, such as nonionic, anionic surfactants, proteins, fine solid particles, etc.

But most of the time it's a problem:

Reduced productivity

Reduces pumping efficiency

Adiabatic, difficult to control temperature

Solid floating

Reduce container capacity

Prevention of distillation

Increase filling time

How to eliminate and suppress bubbles?

Foam is a natural product of many manufacturing processes, for which effective foam control is essential, otherwise many processes are severely limited or do not work at all. General methods to control foam include:

Physical control

Change the temperature

Reduce the pressure

Adjust stirring speed, etc

Chemical control

Silicone defoaming agent

Non - silicon defoaming agent

Classification of foam control

Defoaming: removing existing bubbles

Bubble suppression: inhibiting the formation of bubbles

Degassing: gathering fine bubbles into large ones

How to choose defoaming agent?

Generally speaking, effective defoaming agents must meet the following conditions:

• it must have a higher surface activity than the foaming surfactant, that is, it must have a lower surface tension.

• easy dispersion in the system

• it must be insoluble (at least partially insoluble) in a foaming medium, or it will act on its own as a surfactant, thus stabilizing the foam.

• the droplet size of the defoamer should be within the foam thickness range.

• chemical inertia

• no residue or odor