Molecular dynamics simulation on water/oil interface with model asphaltene subjected to electric field

Hypothesis: The droplet-medium interfaces of petroleum emulsions are often stabilized by the indigenous surface-active compounds (e.g., asphaltenes), causing undesired issues. While demulsification by electric field is a promising technique, fundamental study on the droplet-medium interface influenced by electric field is limited. Molecular dynamics (MD) simulations are expected to provide microscopic insights into the nano-scaled water/oil interface.Methods: MD simulations are conducted to study the adsorption of model asphaltene molecules (repre-sented by N-(1-hexylheptyl)-N0-(5-carboxylicpentyl) perylene-3,4,9,10-tetracarboxylic bisimide (C5Pe)) on a water-toluene interface under various strengths of electric field. The adsorption amount and struc-tural feature of C5Pe molecules at water-toluene interface are investigated, and the effects of electric field and salt are discussed. Findings:C5Pe molecules tend to adsorb on the water-oil interface. As the electric field strength increases, the adsorption amount first slightly increases (or remains constant) and then decreases. The electric field dis-rupts the compact 7C -7C stacking between C5Pe molecules and increases their mobility, causing a dis-persed distribution of the molecules with a wide range of orientations relative to the interface. Within the studied range, the addition of salt ions appears to stabilize the interface at high electric field. These results provide useful insights into the mechanism and feasibility of demulsification under electric field.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

This study investigates the adsorption behavior of model asphaltene molecules at the water-toluene interface using molecular dynamics simulations. It reveals that the electric field strength affects the adsorption behavior, and the addition of salt ions can stabilize the interface.