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Types of Anti-Foaming Agents: What They Are and How They Work
Oil-based defoamers
Oil-based defoamers have an oil carrier. The oil might be mineral oil, vegetable oil or any other oil that is insoluble in the foaming medium, except silicone oil. An oil-based defoamer also contains a wax and/or hydrophobic silica to boost the performance. Typical waxes are ethylene bis stearamide (EBS), paraffin waxes, ester waxes and fatty alcohol waxes. These products might also have surfactants to improve emulsification and spreading in the foaming medium.
Powder defoamers
Powder defoamers are in principle oil-based defoamers on a particulate carrier like silica. These are added to powdered products like cement, plaster and detergents.
Water-based defoamers
Water-based defoamers are different types of oils and waxes dispersed in a water base. The oils are often mineral oil or vegetable oils and the waxes are long chain fatty alcohol, fatty acid soaps or esters. These are normally best as deaerators, which means they are best at releasing entrained air.
Silicone-based defoamers
Silicone-based defoamers are polymers with silicon backbones. These might be delivered as an oil or a water-based emulsion. The silicone compound consists of a hydrophobic silica dispersed in a silicone oil. Emulsifiers are added to ensure that the silicone spreads fast and well in the foaming medium. The silicone compound might also contain silicone glycols and other modified silicone fluids.
These are also heavy duty defoamers and are good at both knocking down surface foam and releasing entrained air.
Polydimethylsiloxane is a widely used antifoaming agent.
Silicone-based defoamers are also suitable in non-aqueous foaming systems like crude oil and oil refining. For very demanding applications fluorosilicones may be suitable.
EO/PO-based defoamers contain polyethylene glycol and polypropylene glycol copolymers. They are delivered as oils, water solutions, or water-based emulsions. EO/PO copolymers normally have good dispersing properties and are often well suited when deposit problems are an issue.
Alkyl polyacrylates
Alkyl polyacrylates are suitable for use as defoamers in non-aqueous systems where air release is more important than the breakdown of surface foam. These defoamers are often delivered in a solvent carrier like petroleum distillates.
Applications
How Anti foaming Agent is used Industrially
Defoamers are used in many industrial processes and products:
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wood pulp
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paper
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paint
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industrial wastewater treatment
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food processing
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oil drilling, machine tool industry
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oils cutting tools
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hydraulics, etc.
How Anti foaming Agent is used for industrial waste water treatment
Anti foaming agent or defoamer is used in industrial waste treatment specifically for Steel industry waste water produced is acidic in nature is neutralized with ammonia strong base produces excessive foam during neutralization. Anti foaming agent or defoamer is added to waste water to reduce formation of foam
What is the Difference between Anti-foaming agent and Defoamer
Both antifoams and defoamers are used for foam control. Major difference between defoamer and anti-foam is that anti-foam agents can prevent foam from forming, whereas defoamers can control the amount of existing foam. Therefore, anti-foam agents prevent foam formation while defoamers reduce existing foam.
Anti foaming Agent
A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam in industrial process liquids. The terms anti-foam agent and defoamer are often used interchangeably. Strictly speaking, defoamers eliminate existing foam and anti-foamers prevent the formation of further foam. Commonly used agents are insoluble oils, polydimethylsiloxanes and other silicones, certain alcohols, stearates, and glycols. The additive is used to prevent formation of foam or is added to break a foam already formed.
In industrial processes, foams pose serious problems. They cause defects on surface coatings and prevent the efficient filling of containers. A variety of chemical formulae are available to prevent formation of foams.
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