Molecular dynamics approach to interfacial manipulation and dehydration enhancement of crude oil emulsions: a case study on plasma pre-treatment

Abstract

The current efficiency of crude oil dehydration is significantly influenced by the strength and stability of the oil–water interfacial film. To break through this bottleneck, this study first combined plasma pre-treatment with an electric field for the synergistic dehydration of crude oil emulsions. Experimental results indicated that plasma pre-treatment generated oxygen-containing derivatives, which significantly weakened the interfacial film, reducing interfacial tension by up to 43% and improving dehydration efficiency by 66.7%. Furthermore, combined with molecular dynamics simulations, we provided unprecedented mechanistic insights into the microscopic process. The simulations revealed that the oxygen-containing derivatives preferentially adsorb at the oil–water interface, reducing the electrostatic attraction and hydrogen bonding between water molecules inside the droplet, while simultaneously generating dispersion attraction with the oil phase. This dual action compromises the droplet's dynamic stability and facilitates severe deformation under the electric field. This study bridges a critical gap in the application of plasma technology to crude oil dehydration and establishes a theoretical framework for synergistic dehydration mechanisms involving multi-physical fields.