Rapid demulsification and dehydration characteristics of Pickering emulsions under the action of an electric field

This article aimed to display the stability and demulsification characteristics of oil displacing Pickering emulsions, which have excellent stability and exhibit fast demulsification properties under the action of non-uniform, high-frequency, high-voltage electric fields. The surface of SiO2 nanoparticles was modified by silane coupling agent to obtain hydrophobic modified SiO2 nanoparticles for preparing the Pickering emulsion. Experiments showed that the stability of Pickering emulsions improved with increasing nanoparticles concentration. Applying a non-uniform electric field at high frequency and high voltage for 4 min was shown to successfully demulsify and dehydrate Pickering emulsions. The dehydration efficiency gradually increased when the electric field voltage was increased from 3 to 7 kV, but the growth rate gradually decreased; when the electric field frequency increased from 1 to 5 kHz, the dehydration efficiency increased in a stepwise manner, but the variation was extremely limited. The best dehydration effect was achieved at 7 kV and 5 kHz, with a dehydration efficiency of 63.6%. Based on the electric field distribution characteristics and particle force analysis, it is proposed that the intrinsic cause of emulsion demulsification is the movement and redistribution of nanoparticles along the electric field intensity gradient direction at the droplet interface by dielectrophoretic force.