Polydopamine-anchored Polyether on Fe3O4 as Magnetic Recyclable Nanoparticle-Demulsifiers

Abstract Environmentally friendly and cost-efficient recyclable demulsifiers are critical for dewatering of water-in-oil (W/O) emulsions. Here, a novel facile synthesis of magnetic-recyclable demulsifiers is reported. Three kinds of commercial polyether demulsifiers (AE1910, SP169, and AR321) are used and anchored onto Fe3O4 nanoparticle surfaces using mussel-inspired polydopamine as an adhesive. Infrared spectra, transmission electron microscopy imaging, dynamic light scattering, thermogravimetric analysis, and X-ray diffraction are employed. The results confirm successful polydopamine coating on nanoparticle surfaces (Fe3O4@PDA) and follow the binding of polyether demulsifiers (Fe3O4@PDA@AE1910). A water contact angle of 91.3° measured on Fe3O4@PDA@AE1910 indicates particle amphiphilicity for promising interfacial activity. A low interfacial tension (∼1.0 mN⋅ m−1) and a rapid adsorptive behavior are observed for the oil-water interface with the presence of Fe3O4@PDA@AE1910. The three kinds of nanoparticles report high demulsification efficiency of 98.00 %, 91.63 %, and 94.33 % for crude oil emulsions. They also record 98.25 %, 90.27 %, and 98.66 % for water/n-decane emulsions for Fe3O4@PDA@AE1910, Fe3O4@PDA@SP169, and Fe3O4@PDA@AR321, respectively. These nanoparticles can be magnetically recovered and reused. As high as 77.81 % remaining demulsification efficiency is reached after eight cycles of treating water/n-decane emulsion and three cycles of treating crude oil emulsions by using Fe3O4@PDA@AE1910. The findings indicate a promising application of polydopamine-coated Fe3O4 nanoparticle to prepare various magnetic recyclable nanoparticle demulsifiers in dewatering of W/O emulsions. Compared with previous reports, the synthetic process is simple, and the synthetic condition is temperate and environmentally friendly, which may advance the application of recyclable nano-demulsifiers in the oil field.