demulsifying

Demulsifying is the process of destabilizing emulsions to promote separation of a dispersed liquid from a continuous phase, typically removing water from oil or separating oil and water in industrial streams. Emulsions are stabilized by interfacial films formed by adsorbed surface-active substances, including asphaltenes, resins, and various surfactants, which hinder droplet coalescence.

Demulsification aims to break these films and encourage droplet coalescence and gravity or centrifugal separation. Approaches include chemical demulsification, where demulsifying agents are added to alter interfacial properties; thermal treatment, which reduces viscosity and promotes coalescence; and physical methods such as electrostatic coalescence and centrifugation. Adjusting temperature, salinity, and pH can also affect stability and separation rate.

Industrial applications are broad. In the petroleum industry, demulsification is used to remove water from crude oil and other process streams to meet pipeline and refinery specifications and to prevent corrosion and processing problems. In water treatment, demulsification aids in separating oil-bearing streams to produce water suitable for discharge or reuse. Demulsifiers are often polymeric or small-molecule surfactants that destabilize the interfacial film by charge neutralization, dehydration of droplets, or bridging between droplets. Selection depends on oil type, emulsion severity, and downstream processing requirements.

Performance is typically assessed by break time, residual water content in oil, and emulsion stability indices. Practical considerations include compatibility with other process chemicals, the presence of heavy constituents such as resins or asphaltenes, and operational constraints of separation equipment.