What is a Demulsifier?

Felicia Dye

An emulsion is a mixture of two or more substances that cannot blend. A demulsifier is a substance that can cause emulsified substances to separate. For this reason, such chemicals are often referred to as emulsion breakers. There are many chemicals that can serve this purpose. Choosing the correct one depends upon the substances in the emulsion.

Oil booms being used to limit the spread of an oil spill. Demulsifiers can be used to help clean up spilled oil.
Oil booms being used to limit the spread of an oil spill. Demulsifiers can be used to help clean up spilled oil.

Generally, the proportions of the substances in an emulsion are not equal. There are two common types of emulsions in an industrial setting. These are oil in water or water in oil mixtures. The substance that is most prevalent can be referred to as the matrix. The substance that is in the matrix usually exists in droplets.

Demulsifiers can be used to clean up oil spills.
Demulsifiers can be used to clean up oil spills.

In some cases, emulsions are unstable, and the substances will readily separate. In other cases, separation requires a great deal of intervention. This is when a demulsifier may be used.

When the right chemical is chosen, it works by causing a chemical reaction that is like clumping. Adding a demulsifier to a mixture causes the droplets to break away from the other substances in that mixture. Once the droplets break away, they tend to merge together forming bigger structures. This matter often takes on a foamy consistency that can easily be separated.

Normally, when the correct demulsifier is used, control can be exercised over the other substances in the mixture. Since substances react differently to certain chemicals, the adverse effects on the matrix can be limited. If this type of control were not exercised, all of the substances in a mixture could be compromised in an attempt to demulsify it.

The use of demulsifiers is commonly used in the production of crude oil. This is because water is normally present in oil in the beginning stages. Water can drastically change the properties of oil. It is important, however, for the majority of that water to be separated from the mixture before the crude oil is refined.

Demulsifiers are also used to clean oil spills, such as those that may occur at sea. This tactic has shown mixed results. In some cases, such as those where the emulsions are not too stable, using a demulsifier works well.

In other cases, the results of using demulsifiers for open water spills have been disappointing. Some stable emulsions can be very difficult to break. These may require a large amount of demulsifier. Even if such a breaking chemical is introduced, some emulsions may still not respond. The success is believed to be based largely on the type of oil or substance that needs to be eliminated. Theories based on laboratory testing suggest that demulsifiers are most effective when used in closed containers.

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