Foam can cause a issue in some industries. Products to overcome this are used across the wide spectrum of different markets, ranging from paper pulp processing, paints and water treatment. Surfactants that generate foam are added to a wide range of applications for various reasons but in some applications, foam generation can cause issues. Also, in some applications such as sugar beet and pulp processing, foam is generated naturally during processing. The addition of an additive to suppress the generation of foam levels is therefore required, and such foam control agents are known as either antifoams or defoamers.
Both antifoam or defoamer is the same in many respects but the term antifoam suggests the prevention of foam and a defoamer operates by causing the collapse of the foam that has already been generated.
How an antifoam works
Antifoams operate by the migration toward the air–water interface. The antifoam then substitutes the surfactant at the surface which prevents the foaming agents from interaction with air to form foam.
The following depicts how an antifoam prevents foam generation at the air-water interface:
How a defoamer works
A defoamer operates by the breakdown of foam that has already been generated. The following schematic illustrates how they work:
There are a number of foam control products in the marketplace. The most common types are either silicon based or mineral oil types.
Mineral oil type
Lankem have developed two types based on a mixture of mineral oils, complex esters and hydrophobic particles. In some applications, use of silicone oil can cause problems due to the substantive nature of silicone, which can have a detrimental effect. In these application, such as coatings, mineral oil based defoamers are the preferred option.
For low to medium foam
Such as emulsion polymerisation, coatings and applications of medium to low agitation we recommend the use of Dfoam AX1.
For high foam
For applications where foam is a issue, such as applications of high and continuous agitation we recommend the use of Dfoam AR2.
Silicone oil types
Polydimethylsiloxane PDMS (INCI name: Dimethicone is the simplest and most widely used form of silicone that is used in defoamer systems. The oil is emulsified in water to produce a very effective defoamer.
For more details, please view the blog.