Demulsifiers, or emulsion breakers, are a class of specialty chemicals used to separate emulsions (e.g. water in oil). They are commonly used in the processing of crude oil, which is typically produced along with significant quantities of saline water. This water (and salt) must be removed from the crude oil prior to refining. If the majority of the water and salt are not removed, significant corrosion problems can occur in the refining process.

Demulsifiers are active chemical intermediates that – when formulated into blends and applied in the field – reduce the interfacial tension between hydrocarbon and water, allowing for rapid coalescence, dehydration and separation of the liquid phases, which leads to improved quality of the separated hydrocarbon.