Multi-phase interfacial phenomenon of demulsification by the solid particles on a view of phase behavior

Demulsification over solid materials is a promising technique to remediate the emulsified oily wastewater but the important interface phenomenon has yet not been well understood by the common simulation at a molecular level. In this work, this interface phenomenon of demulsification over solid particles was investigated by the molecular dynamics (MD) simulation with a view of phase behavior. It was firstly demonstrated that the migration of oil-molecule and evolution of oil-phase interface were qualified to explore the oil-water interface activity of solid materials according to the simulations on Fe2O3, SiO2, graphene and graphene oxide. Subsequently, the interfacial activity of metal-organic frameworks (MOFs) was investigated using this MD simulation. Among different MOFs, MIL-100(Fe) could adsorb the oil-molecule and improve the migration of oil-phase, causing a strong fusion as like as graphene. However, although MIL-53(Al) could strongly adsorb the oil-molecule, it inhibits the migration of oil-phase around itself, then stabilizing it as a solid emulsifier. Furthermore, the distinct interface phenomenon of MIL-100(Fe) and MIL-53(Al) has been verified by morphology of oil droplets in oil-in-water emulsion. These findings can provide a new view on revealing the demulsification mechanism and direct us to an effective approach to develop potentially useful insoluble demulsifiers.