Sulfonated Graphene Oxide Nanofluid: Potential Applications for Enhanced Oil Recovery

Graphene oxide (GO)-based materials have been extensively evaluated in emulsification processes due to their amphiphilic properties, thermal stability, and high reactivity that allow for chemical functionalization with polymers, nanoparticles, and organic compounds, which can modify physicochemical properties and improve the recovery of crude oil. In this work, the effect of a sulfonated graphene oxide (SGO) nanofluid on interfacial properties in a light and medium crude oil–water system was evaluated. GO sulfonation was performed by amidation reactions with carboxyl groups present in GO flakes. GO and SGO were characterized by infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectronic spectrometry (XPS), and scanning electron microscopy (SEM). The thermal stability of GO and SGO was evaluated by thermogravimetry technique (TGA). The interfacial activity of SGO was evaluated by interfacial tension measurements performed by the pendant drop method, and the stability of emulsions was analyzed by ζ potential measurements. Results show that the sulfonation process improves the surfactant effect of GO, decreases the IFT up to a 93% for the light-crude-oil/water system at low concentrations of nanofluid, and can improve the thermal stability with respect to GO in a wide range of temperatures, favoring the formation of stable emulsions.