demulsification

Demulsification is the process of separating an emulsion into its constituent immiscible liquids by breaking the stability of the dispersed droplets. It is commonly applied to oil and water mixtures, such as produced crude oil containing produced water, or industrial wastewater containing oil.

Emulsions are stabilized by interfacial films, charged surfaces, and thin boundary layers around droplets. Demulsification aims to destabilize these structures so droplets can coalesce and separate. This is often achieved by chemical means, using demulsants that adsorb at interfaces, neutralize or bridge droplet charges, or alter the interfacial film’s rigidity. Physical factors such as temperature, shear, and mixing energy also influence stability and can aid coalescence. In some cases, salinity or pH adjustments are used to enhance breakup.

Methods used to achieve demulsification include chemical demulsification with specialized breakers or coagulants, as well as physical and combined approaches. Chemical demulsants are typically high- or low-molecular-weight compounds designed to destabilize films and promote droplet aggregation. Physical methods include gravity separation, electrostatic coalescence, centrifugation, and heating, often used in sequence or in tandem with chemical treatment to improve efficiency.

Applications span the oil and gas industry, where dehydration of crude oil and treatment of produced water are common, and wastewater treatment facilities that must separate oil from water before discharge or reuse. Effectiveness depends on emulsion type, droplet size distribution, temperature, pH, salinity, and the chemistry of additives. Performance is evaluated by residual oil content, water breakthrough, and compliance with environmental or product specifications.