Surface Polarity-Regulated Hydrogen Bond Reconstruction in Superparamagnetic Fe3o4 Nanoparticles for Ultra-Fast Demulsification of Water-in-Heavy Oil Emulsions at Room Temperature

Abstract

The demulsification of water-in-heavy oil emulsions (W/HO-Es) is frequently required considering the production and environmental issues in the petroleum industry. Magnetic Fe3O4 nanoparticles (NPs) have emerged as a new generation of green demulsification materials and have been commonly employed to demulsify W/HO-Es. However, they face the technical bottleneck of low demulsification efficiency, limiting their industrial application. Herein, the novel amphiphilic polymer-modified superparamagnetic Fe3O4 NPs (ap-Fe3O4) were prepared using interface engineering strategies. These ap-Fe3O4 NPs exhibit ultra-high demulsification efficiency for interfacially active asphaltenes (IAA)-stabilized W/HO-Es. Bottle tests demonstrated that ap-Fe3O4 could completely remove water from W/HO-Es at 2000 ppm within 30 seconds at room temperature, achieving a demulsification efficiency of 100%. Microscopic visual characterization and multi-scale theoretical calculations demonstrate that the outstanding demulsification performance of ap-Fe3O4 is due to the "surface polarity enhanced hydrogen bond reconstruction" effect at the heavy oil-water interface. This enhancement allows ap-Fe3O4, with its high interfacial activity, to effectively disrupt the hydrogen bonds and π-π stacking of IAA at the heavy oil-water interface. This disruption breaks down the IAA films, promotes the coalescence and aggregation of water molecules, and ultimately achieves efficient demulsification of W/HO-Es. This research provides a new approach for regulating the surface hydrogen bonding of magnetic Fe3O4 NPs and establishes a solid theoretical foundation for the further development of revolutionary new magnetic demulsification materials.

Keywords: Fe3O4 NPs, Interface engineering, Demulsification, Water-in-heavy oil emulsions