Mechanism-Oriented Review of Crude Oil Emulsion Separation: Interfacial Chemistry and Droplet Dynamics.

الملخص

The persistence of highly stable water-in-oil (W/O) crude oil emulsions with complex interfacial structures presents major challenges for petroleum production and oily wastewater treatment. These emulsions contain dispersed water droplets ranging from submicron sizes (<1 µm) to several tens of micrometers and are stabilized by naturally occurring surface-active components such as asphaltenes, resins, and fine solid particles. Droplets smaller than 10 µm are particularly difficult to separate using conventional gravity-based processes, resulting in reduced separation efficiency, increased energy consumption, equipment corrosion, and higher operational costs. This review provides a mechanistic and comparative analysis of current demulsification technologies with the aim of linking interfacial chemistry and droplet-scale dynamics to separation performance. The study systematically examines conventional and emerging separation approaches, including chemical demulsification, electrostatic coalescence, membrane-assisted separation, ultrasonic treatment, and nanomaterial-based demulsification strategies. Particular attention is given to recent developments reported between 2022 and 2025, including ionic-liquid demulsifiers, bio-based materials, hybrid separation systems, and membrane-assisted coalescence technologies. The reviewed studies indicate that effective destabilization mechanisms promote droplet coalescence, enabling micron-and submicron-sized droplets to grow into larger droplets exceeding 50 µm, which significantly enhances separation efficiency. Laboratory and pilot-scale investigations frequently report oil-water separation efficiencies exceeding 90% when appropriate interfacial conditions are achieved. The analysis further demonstrates that separation performance is primarily governed by interfacial phenomena and droplet interaction dynamics rather than by increasing operational intensity alone. Overall, this review identifies current technological limitations, highlights emerging research directions, and emphasizes the potential of nano-enabled and hybrid demulsification systems for developing cost-effective and environmentally sustainable crude oil emulsion separation technologies suitable for industrial applications