Chemical Engineering Journal, Vol.358, 869-877, 2019
Novel Fe3O4 based superhydrophilic core-shell microspheres for breaking asphaltenes-stabilized water-in-oil emulsion
Stabilization and destabilization of emulsions play an important role in a wide range of engineering and environmental processes (e.g., oil-water separation, waste water treatment). The destabilization of water-in-oil (W/O) emulsions in the presence of asphaltenes, which form a protective interfacial layer to prevent the coalescence of emulsions, is a well-known challenging issue in oil production. In this study, a novel type of core-shell microspheres with magnetic core functionalized with a superhydrophilic zwitterionic polyelectrolyte shell has been developed and characterized, which shows excellent capability in breaking asphaltene-stabilized W/O emulsions and releasing considerable amount of water with the assistance of an external magnetic field. Surface force measurements using drop probe atomic force microscope (AFM) demonstrated the strong attraction between zwitterionic polyelectrolytes and emulsion droplets. The water-oil interfacial tension was found to increase with the addition of the microspheres, contributing to the coalescence of emulsions. Quartz crystal microbalance with dissipation monitoring (QCM-D) tests demonstrated that asphaltenes could be adsorbed on the polyelectrolyte surface, suggesting that the polyelectrolyte could interact and disrupt the protective asphaltene layer at oil-water interfaces to facilitate the demulsification. The adsorbed asphaltenes on the polyelectrolyte shell can be released when the microsphere was treated in water, showing a reversable asphaltene adsorption/desorption behavior, which has great potential for cyclic reuse. Our results provide useful insights into the fundamental interactions between emulsions in the presence of polyelectrolytes, with implications for the development of new demulsification methods in water-oil separation and other environment related processes.