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A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam
Foam

The most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam....
 in industrial process liquids. The terms anti-foam agent and defoamer are often mixed up since these often are the same products. It depends on where it is in use which term is the most common.

A defoamer is used to normally used to increase process speed and reduce other problems that foam may cause in industrial processes.






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Encyclopedia


A defoamer or an anti-foaming agent is a chemical additive that reduces and hinders the formation of foam
Foam

The most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam....
 in industrial process liquids. The terms anti-foam agent and defoamer are often mixed up since these often are the same products. It depends on where it is in use which term is the most common.

A defoamer is used to normally used to increase process speed and reduce other problems that foam may cause in industrial processes. It addresses both problems with surface foam and entrained/entrapped air. A wide variety of chemical formulas are available to promote coalescence
Coalescence

Coalescence may refer to:* Coalescence , the merging of genetic lineages backwards time to a most recent common ancestor* Coalescence , the merging of two or more words into one...
 of foam.

Properties

Generally a defoamer is insoluble in the foaming medium and have surface active properties. An essential feature of a defoamer product is a low viscosity
Viscosity

Viscosity is a measure of the Drag of a fluid which is being deformed by either shear stress or extensional stress. In everyday terms , viscosity is "thickness"....
 and a facility to spread rapidly on foamy surfaces. It has affinity to the air-liquid surface where it destabilizes the foam lamella
Lamella

Lamella is a term for a platelike structure, appearing in multiples, that occurs in various situations, such as biology or materials sciences. It implies a thin layer , the same derivation as for `laminate'....
s. This is causing rupture of the air bubbles and break down of surface foam. Entrained/entrapped air bubbles is agglomerated, becomes bigger and goes faster to the surface of the bulk liquid.

History

The first defoamers where aimed at breaking down visible foam at the surface. Kerosene
Kerosene

Kerosene, sometimes spelled kerosine in scientific and industrial usage, also known as paraffin, is a combustible hydrocarbon liquid....
, fuel oil
Fuel oil

Fuel oil is a fractional distillation obtained from petroleum distillation, either as a distillate or a residue. Broadly speaking, fuel oil is any liquid petroleum product that is burned in a furnace or boiler for the generation of heat or used in an engine for the generation of power, except oils having a flash point of approximately and oi...
 and other light oil products was much used to break down foam
Foam

The most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam....
. Other vegetable oils also found some use. Fattyalcohol
Alcohol

In chemistry, an alcohol is any organic compound in which a hydroxyl Functional group is bound to a carbon atom of an alkyl or substituted alkyl group....
s (C7 - C22) was effective but expensive antifoams. They were added to oil products to boost the efficiency. Milk
Milk

Milk is an opaque white liquid produced by the mammary glands of female mammals . It provides the primary source of nutrition for newborn mammals before they are able to digestion other types of food....
 and cream
Cream

Cream is a dairy product that is composed of the higher-butterfat layer skimmed from the top of milk before homogenization. In un-homogenized milk, over time, the lighter fat rises to the top....
 was forbears for modern day emulsion type defoamers.

During the 1950s experiments with silicone
Silicone

Silicones are largely inert, man-made compounds with a wide variety of forms and uses. Typically heat-resistant, nonstick, and rubberlike, they are commonly used in cookware, medicine, sealants, adhesives, lubricants, and insulation....
 based defoamers started. These ware based on polydimethylsiloxane
Polydimethylsiloxane

Polydimethylsiloxane belong to a group of polymeric organosilicon compounds which are commonly refered to as silicones. PDMS is the most widely used silicon-based organic compound polymer, and is particularly known for its unusual rheology properties....
 (silicone oil) dispersed in water or light oil. Silicone oils worked well, but gave much surface disturbances in many applications like paint
Paint

Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
s and papermaking
Papermaking

Papermaking is the process of making paper, a substance which is used ubiquitously today for writing and packaging.In papermaking a dilute suspension of fibers in water is drained through a screen, so that a mat of randomly interwoven fibers is laid down....
. In 1963 the first antifoams with hydrophobic particles in light oil
Light oil

Light oil may refer to:*Light fuel oil produced through distillation.*Light crude oil, which is less viscous than intermediate and heavy crude oil....
 was patented. The particle was hydrophobic silica
Hydrophobic silica

Hydrophobic silica is a silica that have hydrophobic groups chemical bond to the surface. Hydrophobic silica can be made both from silica fume and precipitated silica....
. In the early 1970s was hydrophobic waxes like ethylene bis stearamide
Ethylene bis stearamide

Ethylene bis stearamide is derived from stearic acid and ethylenediamine. It is a waxy white solid and is also found as powder or beads....
 dispersed in oils developed. These types of defoamers where very efficient, but the oil crisis of 1973
1973 oil crisis

The 1973 oil crisis started on October 15, 1973, when the members of Organization of Arab Petroleum Exporting Countries or the OAPEC proclaimed an oil embargo "in response to the U.S....
 made these too expensive and resulted in a push for reduction of the oil content. The solution was adding water
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
. So water extended (water in oil emulsion) and water based (oil in water emulsion) defoamers appared.

The developent of silicone based defoamers have gone further by using different emulsifiers and modified silicone oils. In the early 1990s was silicone emulsion defoamers that caused less surface disturbances used in the wood pulp
Wood pulp

Pulp is a dry fibrous material prepared by chemically or mechanically separating fibers from wood or fiber crops.Pulp can be either fluffy or formed into thick sheets....
ing industry with great success. These caused better washing, reduced biological oxygen demand (BOD) in effluent
Effluent

Effluent is an outflowing of water from a natural body of water, or from a man-made structure.Effluent in the man-made sense is generally considered to be water pollution, such as the outflow from a sewage treatment facility or the wastewater discharge from industrial facilities....
 and reduced deposits.

Chemistry


Oil based defoamers

Have an oil carrier. The oil might be mineral oil
Mineral oil

Mineral oil or liquid petroleumis a by-product in the distillation of petroleum to produce gasoline and other petroleum based products from crude oil....
, vegetable oil, white oil
White oil

White oil is a home made insecticide spray used for controlling a wide range of insect pests in the garden. The spray works by blocking the breathing pores of insects causing suffocation and death....
 or any other oil that is insoluble in the foaming medium, except silicone oil
Silicone oil

Silicone oils are silicon analogues of carbon based organic compounds, and can form long and complex molecules based on silicon rather than carbon....
. An oil based defoamer also contains a wax
Wax

Wax has traditionally referred to a substance that is secreted by bees and used by them in constructing their honeycombs.It is an imprecisely defined term generally understood to be a substance with properties similar to beeswax, namely...
 and/or hydrophobic silica
Hydrophobic silica

Hydrophobic silica is a silica that have hydrophobic groups chemical bond to the surface. Hydrophobic silica can be made both from silica fume and precipitated silica....
 to boost the performance. Typical waxes are ethylene bis stearamide
Ethylene bis stearamide

Ethylene bis stearamide is derived from stearic acid and ethylenediamine. It is a waxy white solid and is also found as powder or beads....
 (EBS), paraffin
Paraffin

In chemistry, paraffin is the common name for the alkane hydrocarbons with the general formula CnH2n+2. Paraffin wax refers to the solids with n=20–40....
ic waxes, ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
 waxes and fatty alcohol
Fatty alcohol

Fatty alcohols are aliphatic alcohols derived from natural fats and oils, originating in plants, but also synthesized in animals and algae. Their significance in nutrition and health has historically been overlooked, and is only now being realized, as they are closely related to fatty acids, including the well-documented omega 3 fatty acids....
 waxes. These products might also be added surfactants to improve emulsification and spreading in the foaming medium.

These are heavy duty defoamers and are normally best at knocking down surface foam.

Powder defoamers

Are in prinsipal oil based defoamer on a pariculate carrier like silica. These are added to powdered products like cement
Cement

In the most general sense of the word, a cement is a binder, a substance which sets and hardens independently, and can bind other materials together....
, plaster
Plaster

The term plaster can refer to plaster of Paris, lime plaster, or cement plaster. This article deals mainly with plaster of Paris.Plaster of Paris is a type of building material based on calcium sulfate Hydrate, nominally CaSO4?0.5H2O....
 and detergent
Detergent

A detergent is a material intended to assist cleaning. The term is sometimes used to differentiate between soap and other surfactants used for cleaning....
s.

Waterbased defoamers

These are different types of oils and waxes dispersed in a water base. The oils are often white oil
White oil

White oil is a home made insecticide spray used for controlling a wide range of insect pests in the garden. The spray works by blocking the breathing pores of insects causing suffocation and death....
s or vegetable oils and the waxes are long chain fatty alcohol
Fatty alcohol

Fatty alcohols are aliphatic alcohols derived from natural fats and oils, originating in plants, but also synthesized in animals and algae. Their significance in nutrition and health has historically been overlooked, and is only now being realized, as they are closely related to fatty acids, including the well-documented omega 3 fatty acids....
, fatty acid
Fatty acid

In chemistry, especially biochemistry, a fatty acid is a carboxylic acid often with a long unbranched aliphatic tail , which is either saturation or Unsaturated compound....
 soap
SOAP

SOAP, originally defined as Simple Object Access Protocol, is a protocol specification for exchanging structured information in the implementation of Web Services in computer networks....
s or ester
Ester

An ester is an often Aroma compound organic chemistry or partially organic compound formed by the reaction between an acid and an alcohol or aromatic alcohol with the elimination of water....
s. These are normally best as deaerator
Deaerator

A deaerator is a device that is widely used for the removal of air and other dissolved gases from the feedwater to steam generating boilers. In particular, dissolved oxygen in boiler feedwaters will cause serious corrosion damage in steam systems by attaching to the walls of metal piping and other metallic equipment and forming oxides ....
s, which means they are best at releasing entrained air.

Silicone based defoamers

Have a silicone
Silicone

Silicones are largely inert, man-made compounds with a wide variety of forms and uses. Typically heat-resistant, nonstick, and rubberlike, they are commonly used in cookware, medicine, sealants, adhesives, lubricants, and insulation....
 compound
Compound

Compound may refer to:* Chemical compounds, combinations of two or more elements* Compound , a cluster of buildings having a shared purpose, usually inside a fence or wall...
 as the active component. These might be delivered as an oil or a water based emulsion. The silicone compound consists of an hydrophobic silica
Hydrophobic silica

Hydrophobic silica is a silica that have hydrophobic groups chemical bond to the surface. Hydrophobic silica can be made both from silica fume and precipitated silica....
 dispersed in a silicone oil
Silicone oil

Silicone oils are silicon analogues of carbon based organic compounds, and can form long and complex molecules based on silicon rather than carbon....
. Emulsifiers are added to ensure that the silicone are spreading fast and well in the foaming medium. The silicone compound might also contain silicone glycols and other modified silicone
Silicone

Silicones are largely inert, man-made compounds with a wide variety of forms and uses. Typically heat-resistant, nonstick, and rubberlike, they are commonly used in cookware, medicine, sealants, adhesives, lubricants, and insulation....
 fluids.

These are also heavy duty defoamers and are good at both knocking down surface foam and releasing entrained air.

EO/PO based defoamers

Containing EO/PO copolymers. They are delivered as oils, water solutions, water based emulsions. EO/PO copolymers have normally good dispersing properties and are often suited when deposit problems also is an issue.

Industrial Problems

The most noticeable form of foam is foam floating on the stock surface. It is easy to monitor and relatively easy to handle. Surface foam may cause problems with liquor levels and give overflow. This might reduce the process speed and availability of process equipment.

Mechanical problem factors

Mechanical factors that may generate foam and entrapped air:
  • Leaky seals on pumps
  • High pressure pumps
  • Poor system design (tank, pump inlet, outlet and manifold
    Manifold

    In mathematics, more specifically topology, a manifold is a topological space in which every point has a neighborhood which "resembles" Euclidean space....
     design)
  • Pressure
    Pressure

    Pressure is the force per unit area applied to an object in a direction surface normal to the surface. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure....
     release


The main classes of air that are of concern to the mechanical systems are
  • Dissolved air behaves as part of the water phase, except that it can come out of solution as small bubbles (entrained air)
  • Entrained air consists of bubbles that are small enough to collect on top of a fluid
  • Bubbles that have sufficient buoyancy
    Buoyancy

    In physics, buoyancy is the upward force that keeps things afloat. The net upward buoyancy force is equal to the magnitude of the weight of fluid displaced by the body....
     to rise to the surface and are described as foam


Foam in process and coolant liquids

Foam, entrained and dissolved air that are present in coolants and processing liquids, may cause various kinds of problems, including:
  • Reduction of pump
    Pump

    A pump is a device used to move fluids, such as gases, liquids or Slurry. A pump displaces a volume by physical or mechanical action. One common misconception about pumps is the thought that they create pressure....
     efficiency (cavitation
    Cavitation

    Cavitation is defined as the phenomenon of formation of vapour bubbles of a flowing liquid in a region where the pressure of the liquid falls below its vapour pressure....
    )
  • Reduced capacity of pumps and storage tank
    Storage tank

    A storage tank is a container, usually for holding liquids, sometimes for compressed gases . The term can be used for reservoirs , and for manufactured containers....
    s
  • Bacteria
    Bacteria

    The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
    l growth
  • Dirt flotation
    Flotation process

    Flotation process is a method of separation process widely used in the wastewater treatment and mineral processing industries.Various flotation processes include the following:...
     / Deposit
    Deposit

    Deposit may refer to:*Deposit account, the liability owed by the bank to its depositor*Deposit , material added to a landform*Damage deposit taken in relation to rental or an item or property...
     formation
  • Reduced effectiveness of the fluid solution(s)
  • Eventual downtime to clean tanks
  • Drainage problems in sieve
    Sieve

    In general, a sieve separates wanted/desired elements from unwanted material using a tool such as a mesh, net or other filtration or distillation methods, but it is also used for classification of powders by particle size, or for size measurement as an analytical technique....
    s and filter
    Filtration

    Filtration is a mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium to fluid flow through which the fluid can pass, but the solids in the fluid are retained....
    s
  • Formation
    Formation

    'Formation' can refer to:* Formation flying, aerobatics performed with several aircraft* Formation , a high-level military organization* Formation , defining the fibre distribution within the paper sheet...
     problems (i.e in a paper mill
    Paper mill

    A paper mill is a factory devoted to making paper from Wood_pulp and other ingredients using a Fourdrinier Machine or similar apparatus. It is a common misconception that paper mills are sources of odors....
     it may cause the fibers to form an inhomogeneous sheet
    Sheet

    Sheet may refer to:* Sheet, a village in Hampshire* Bed sheet, a piece of cloth used to cover a mattress* Sheet , a rope, cable or chain used to control a sail...
    )
  • Cost of replenishing the liquid
  • Cost of entire material rejection due to imperfections


Test methods

There are several ways to test defoamers.

The easiest is looking at the surface foam. All that is needed is a system for generating foam. This might be done with a round pumping system with a nossle and a cylinder or an air injection system into a cylinder. The cylinder is fitted with a scale to measure the foam height. This equipment may have a heater to control the temperature.

Entrained air can be tested with a similar equipment that have a density
Density

The density of a material is defined as its mass per unit volume. The symbol of density is ....
 meter that can record changes of the liquor density over time.

Drainage can be tested with a filter
Filtration

Filtration is a mechanical or physical operation which is used for the separation of solids from fluids by interposing a medium to fluid flow through which the fluid can pass, but the solids in the fluid are retained....
 system for measuring the time to drain a liquid through the filter. The filter might be pressurized or have a vacuum
Vacuum

A vacuum is a volume of space that is essentially empty of matter, such that its gaseous pressure is much less than atmospheric pressure. The word comes from the Latin term for "empty," but in reality, no volume of space can ever be perfectly empty....
.

Applications


Detergents

Anti-foams are added in certain types of detergent
Detergent

A detergent is a material intended to assist cleaning. The term is sometimes used to differentiate between soap and other surfactants used for cleaning....
s to reduce foaming
Foam

The most general definition of foam is a substance that is formed by trapping many gas bubbles in a liquid or solid. It can also refer to anything that is analogous to such a phenomenon, such as quantum foam....
 that might decrease the action of the detergent. For example dishwasher
Dishwasher

A dishwasher is a mechanical device for cleaning dishware and cutlerys. Dishwashers can be found in restaurants and private homes....
 detergents have to be low foaming for the dishwasher to work properly.

Food

When used as an ingredient in food
Food

Food is any substance, usually composed of carbohydrates, fats, proteins and water, that can be Eating or Drinking by an animal or human for nutrition or pleasure....
, antifoaming agents are intended to curb effusion
Effusion

In chemistry, effusion is the process in which individual molecules flow through a hole without collisions between molecules. This occurs if the diameter of the hole is considerably smaller than the mean free path of the molecules....
 or effervescence
Effervescence (chemistry)

Effervescence is the escape of gas from an aqueous solution. The term is used to describe the foaming or fizzing that results from a release of gas....
 in preparation or serving. The agents are included in a variety of foods such as Diet Pepsi
Diet Pepsi

Diet Pepsi is a low-calorie carbonation cola, introduced in 1964 as a variant of Pepsi-Cola with no sugar. Its current formula in the United States contains only the artificial sweetener aspartame....
, Diet Coke
Diet Coke

Diet Coke is a sugar-free soft drink produced and distributed by The Coca-Cola Company. It was introduced in the United States on Independence Day in 1982 as the first new brand since 1886 to use the Coca-Cola trademark....
, Sprite
Sprite (soft drink)

Sprite is a transparent, lemon-lime flavored, caffeine free soft drink, produced by the Coca-Cola Company. It was introduced to the United States in 1961....
, and chicken nuggets in the form of polydimethylsiloxane
Polydimethylsiloxane

Polydimethylsiloxane belong to a group of polymeric organosilicon compounds which are commonly refered to as silicones. PDMS is the most widely used silicon-based organic compound polymer, and is particularly known for its unusual rheology properties....
 (a type of silicone
Silicone

Silicones are largely inert, man-made compounds with a wide variety of forms and uses. Typically heat-resistant, nonstick, and rubberlike, they are commonly used in cookware, medicine, sealants, adhesives, lubricants, and insulation....
).

Silicone oil
Silicone oil

Silicone oils are silicon analogues of carbon based organic compounds, and can form long and complex molecules based on silicon rather than carbon....
 is also added to cooking oil
Cooking oil

Cooking oil is purified fat of plant origin, which is liquid at room temperature.Some of the many different kinds of edible Vegetable fats and oilss include: olive oil, palm oil, soybean oil, canola oil, pumpkin seed oil, corn oil, sunflower oil, safflower oil, peanut oil, grape seed oil, sesame oil, argan oil and rice bran oil....
 to prevent foaming in deep-frying.

Industrial use

Defoamers are used in many industrial processes and products: wood pulp
Wood pulp

Pulp is a dry fibrous material prepared by chemically or mechanically separating fibers from wood or fiber crops.Pulp can be either fluffy or formed into thick sheets....
, paper
Paper

Paper is thin material mainly used for writing upon, printing upon or packaging. It is produced by pressing together moist fibers, typically cellulose pulp derived from wood, rags or grasses, and drying them into flexible sheets....
, paint
Paint

Paint is any liquid, liquifiable, or mastic composition which after application to a Substrate in a thin layer is converted to an opaque solid film....
, industrial wastewater treatment
Industrial wastewater treatment

Industrial wastewater treatment covers the mechanisms and processes used to treat waters that have been contaminated in some way by anthropogenic industrial or commercial activities prior to its release into the environment or its re-use....
, food processing
Food processing

Food processing is the set of methods and techniques used to transform raw ingredients into food or to transform food into other forms for ingestion by humans or animals either in the home or by the food industry....
, oil drilling, machine tool
Machine tool

A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by machining, which is the selective removal of metal....
 industry, oils cutting tools, hydraulics
Hydraulics

Hydraulics is a topic of science and engineering dealing with the mechanical properties of liquids. Hydraulics is part of the more general discipline of fluid power....
, etc

Pharmaceuticals

Antifoaming agents are also sold commercially to relieve bloating
Bloating

Bloating is any abnormal general swelling, or increase in diameter of the abdomen area. As a symptom, the patient feels a full and tight abdomen, which may cause abdominal pain sometimes accompanied by borborygmus....
. A familiar example is the drug Simethicone
Simethicone

Simethicone is an Wiktionary:oral anti-foaming agent used to reduce bloating, discomfort and pain caused by excess gas in the stomach or intestinal tract....
, which is the active ingredient in drugs such as Maalox
Maalox

Maalox is a brand name antacid containing Aluminium hydroxide and Magnesium hydroxide to neutralize or reduce stomach acid.Maalox helps relieve symptoms of excessive stomach acidity in patients with indigestion, heartburn, gastroesophageal reflux disease, or stomach ulcer or duodenal ulcer ulcers....
, Mylanta, and Gas-X.

See also

  • Foaming agent
    Foaming agent

    A foaming agent is a surfactant, which when present in small amounts, facilitates the formation of a foam, or enhances its colloid stability by inhibiting the Coalescence of bubbles....