A high performance magnetically responsive Janus nano-emulsifier: Preparation, emulsification characteristics, interfacial rheology, and application in emulsion flooding

Recently magnetic nanomaterial has become a research hotspot in many areas due to its environment friendly, low-toxicity, magnetic responsiveness, and excellent reusability. This paper aims to study a novel amphipathic Janus magnetic nanoparticle (MJNP) applied for emulsion flooding, including preparation, emulsification characteristics, interface rheology, and enhanced oil recovery performance. X-ray diffraction (XRD), Fourier transform Infrared spectrometer (FT-IR), Transmission electron microscopy (TEM), Scanning electron microscope (SEM), Thermal gravimetric analyzer (TGA), and vibrating sample magnetometer (VSM) are employed to observe the crystal structure, shape, size, surface components of Janus nanoparticle, and magnetic responsiveness. Results show this high performance MJNP fabricated by Pickering emulsion method has coupled carboxyl and octyl chemical groups on both ends of its surface. What's more, MJNPs have not only sufficiently small particle size for ensuring free flow in reservoir but outstanding magnetic responsiveness for efficient reusability. This hydrophilic MJNP owns excellent emulsion performance to prepare high internal phase O/W emulsion without any additive. Results show 0.3% of MJNP has prepared stable O/W emulsion with 90% of oil content, and 80% emulsion is even stabilized by 0.02% of MJNP and fails to phase inversion. Furthermore, these emulsions fabricated by higher concentration of MJNP own finer stability and anti-temperature. The intensity of interfacial film is evidently enhanced with the aggregation of MJNPs on oil-water interface. When concentration of MJNP is equal to 0.2%, the interfacial dilational modulus has increased to 34.24 mN/m. Moreover, the MJNP interfacial film shows remarkably elasticity. Salinity has a significant effect to the stability of MJNP interfacial film, and this effect is more distinct in the higher concentration of MJNP. 0.08% of MJNP fluid has the best anti-salt performance. Meanwhile, this novel Janus nanoparticle shows an excellent oil recovery capacity for emulsion flooding. • A high performance magnetic Janus nanoparticle has been successfully synthesized by Pickering emulsion method. • This magnetic Janus nanoparticle owns excellent emulsion performance to prepare stable 90% of oil-in-water emulsion. • This high internal phase emulsion has good stability on 130 °C. • The anti-salt has reached to 2% for this magnetic Janus nanoparticle stabilizing oil-water interface film. • This magnetic Janus nanoparticle shows remarkable oil recovery performance.