demulsifiers

Demulsifiers, also known as emulsion breakers, are chemical additives used to promote the separation of emulsified water droplets from oil or other immiscible liquid phases. They are used in refinery streams, produced water treatment, lubrication oil processing, and wastewater treatment to improve phase separation and reduce water content in the oil.

Demulsifiers work by altering the interfacial film and the electrical double layer at the oil–water interface, reducing interfacial tension or shifting surface charge to promote droplet coalescence. Some act by flocculating small droplets, others by bridging droplets with polymer chains, or by displacing natural emulsifiers that stabilize the emulsion. They are often formulated to reach the interface through oil solubility or dispersibility and may be chosen to target specific emulsion types, temperatures, and salinities.

Common formulations include oil-soluble or oil-dispersible polymers and resins, polyether or polyamine systems, alkylphenol formaldehyde resins, and cationic or nonionic surfactants. Many products are tailored for high salinity, high temperature, or particular oil chemistries. In practice, demulsifiers are selected to optimize water removal, reduce downtime, and meet oil-water separation specifications.

Applications and performance are influenced by temperature, pH, salinity, water-cut, droplet size distribution, mixing energy, and residence time. Routine testing includes bottle tests and dynamic emulsion or compatibility assessments to evaluate separation efficiency and final oil-water content.

Safety and environmental considerations include handling, storage, toxicity, biodegradability, and proper disposal of spent demulsifier liquids and separated water.