The synthesis of novel amphiphilic GOJS-Cn nanoparticles and their further application in stabilizing pickering emulsion and enhancing oil recovery

Mixed nanoparticle stabilized Pickering emulsion is a novel research topic, which has been attracted more attention. In the present study, the novel amphiphilic GO-Janus SiO2-Cn nanoparticles (GOJS-Cn, n represents the number of carbon atoms in the modified alkyl chain) were successfully fabricated for the first time and investigated their ability in stabilizing Pickering emulsions for enhancing oil recovery. Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) were employed to determine the successful fabrication of the GOJS-Cn. The optical microscopy was utilized to directly observe the GOJS-Cn (n = 0, 3, 8, and 12) stabilized emulsions and the static multiple light scattering was employed to further evaluate its stability quantitatively. It was found that the GOJS-C12 displayed the greatest ability to stabilize emulsions, even in high salinity (104 mg/L NaCl/MgCl2/CaCl2/AlCl3) and temperature (90 °C). Then, the interfacial tension, water contact angle, and dilatational measurements were conducted to reveal the mechanism of the GOJS-C12 superior emulsifying ability. The amphiphilic GOJS-C12 with great amphiphilicity spontaneously adsorbed at oil-water interface to promote the formation of rigid interfacial film, which was essential for the long-term stability of emulsion. Moreover, the core flooding tests reflected the GOJS-C12 stabilized emulsion could significantly enhance oil recovery (∼14.8%), then based on microscopic visualization experiments the potential EOR mechanism was proposed.