A synergistic demulsification method based on electric-field polarization and ultrasonic cavitation/mechanical effects: Theory and experiment

• Proposed a new electro-ultrasonic synergistic demulsification method. • Systematically analyzed two electro-ultrasonic synergistic demulsification routes. • Quantitatively assessed performance gains of ultrasound-electric demulsification. • Proposed synergistic demulsification strategies for emulsions of varied properties. Chemical flooding agents significantly alter droplet interfacial properties and bulk rheology, reducing droplet size and strengthening interfacial films, thereby stabilizing oil–water emulsions and reducing the effectiveness of conventional electrical demulsification. To overcome this bottleneck, this work proposes an electro-ultrasonic synergistic demulsification method using a model water-in-oil (W/O) emulsion as the research subject, and systematically analyzes two electro-ultrasonic synergistic demulsification routes based on experimental investigation and theoretical analysis, namely the synergy between ultrasonic cavitation and electric-field polarization, and the synergy between ultrasonic mechanical effects and electric-field polarization. On this basis, we quantitatively evaluated its performance advantages and proposed practical control strategies. The results suggest that the synergy between the electric polarization effect and the ultrasonic cavitation effect is beneficial for interfacial-film weakening, raising the demulsification efficiency of complex interfacial emulsions by over 13%. The synergy between electric polarization and ultrasonic mechanical effects drives rapid droplet aggregation, achieves efficient coalescence in low-viscosity systems, and increases demulsification efficiency by over 20%. This study not only systematically analyzes two electro-ultrasonic synergistic demulsification routes, but also provides new theoretical support and engineering application ideas for the development of electric-acoustic synergistic demulsification technology.