Critical coalescence electric intensity of water droplets adsorbing surfactant molecules under electromagnetic synergy field

Electromagnetic synergy is a more effective physical method than a single AC electric field (ACEF) to enhance oil–water separation. However, the critical coalescence conditions and transformation mechanism of droplets adsorbing surfactant molecules in the synergistic electromagnetic field (EMSF) still lack research. Herein, a series of Triton X-100-adsorbed droplets with different surface tensions were prepared, and the critical coalescence electric intensity ( E c ) of the droplets under ACEF and EMSF were compared. Micro high-speed experiments revealed that E c of droplets under EMSF is higher than under ACEF. The electric intensity, E c , increased with the increase in interfacial tension γ under both ACEF and EMSF. This study provides valuable results for designing high-performance devices by introducing electromagnetic synergy in water-in-oil emulsion treatment. For the equipment with electromagnetic synergy to strengthen oil–water separation, the allowable optimal voltage should be higher than that of the electrostatic coalescer, and the adjustment range is 2.99%−9.57%.