What Is a Demulsifier?

Demulsifier is a surfactant that can destroy emulsions. Demulsifiers destroy emulsions mainly by partially replacing the stabilization membrane. Used as a dehydrating agent, it can remove the water in crude oil and heavy oil, so that the water content can meet the requirements; used in oil wells can reduce the viscosity of crude oil, so that oil wells are not blocked. It is obtained by polymerization of fatty alcohol, propylene oxide and ethylene oxide. Soluble in water, light yellow or milky white viscous liquid. The smell of soap. Freezing point is 25 40 . The hydroxyl value is 60 mg potassium hydroxide / g. , The aqueous solution was milky white. ^[1]

During the flotation process, sometimes

Due to the complexity of the composition of crude oil, oil layer water and natural emulsifiers, it is extremely difficult to study the physical and chemical processes that occur at the oil-water interface. Therefore, the demulsification process and demulsification mechanism of chemical demulsifiers are still under study. But demulsifiers and emulsifiers are both surface-active substances, but their effects are completely opposite. The demulsification mechanism of various demulsifiers is summarized as follows: ^[3]

Demulsifier is a kind of surface active substance, which can destroy the emulsified liquid structure, so as to achieve the purpose of separating the phases in the emulsion. Crude oil demulsification refers to the use of the chemical action of the demulsifier to remove the oil and water from the emulsified oil-water mixture to achieve

According to the current use of demulsifiers, demulsifiers can be divided into two categories: water-soluble demulsifiers and oil-soluble demulsifiers. ^[4]

Demulsifiers can eliminate the factors that stabilize the original emulsion, leading to aggregation, coalescence, delamination and demulsification of the emulsion. The most important reason for the stability of emulsions is the formation of charged (or uncharged) interface films with certain mechanical strength or steric hindrance by emulsifiers. Therefore, the main role of the demulsifier is to eliminate the effective role of the emulsifier. The choice of the demulsifier should be based on the characteristics of the emulsifier. ^[6]

The basic principles for selecting a demulsifier are as follows:

(1) It has good surface activity and can replace the emulsifier in the emulsion from the interface. Emulsifiers have surface activity, otherwise an adsorption film cannot be formed at the interface, and this adsorption is a spontaneous process. Therefore, the demulsifier must also have a strong interfacial adsorption capacity to replace the emulsifier.

(2) The interfacial film formed on the oil-water interface of the demulsifier must not have firmness, and it is easy to rupture under external conditions or when the droplets collide, so that the droplets are likely to coalesce.

(3) Ionic emulsifiers can make the droplets charged and stable. Selecting ionic demulsifiers with opposite charges can neutralize the surface charge of the droplets.

(4) Non-ionic or high molecular demulsifiers with large relative molecular mass are dissolved in the continuous phase, and the droplets can be aggregated due to bridging, and then aggregate, delaminate and demulsify.

(5) The solid emulsion with solid powder emulsifier can choose the wetting agent with good solid powder as the demulsifier to make the powder completely wet into the water phase or oil phase.

It can be seen from these principles that some emulsifiers and demulsifiers often do not have obvious boundaries, which depends on the specific system. Of course, there are some surfactants that are only suitable for use as demulsifiers for certain emulsions, and can not be used as demulsifiers or emulsifiers for other systems.