A novel PAN-GO-SiO₂ hybrid membrane for separating oil and water from emulsified mixture

In this article, we report the development of a polyacrylonitrile-graphene oxide-silicon dioxide (PAN-GO-SiO₂) hybrid membrane for separation of oil and water from their emulsified mixture. The membrane was successfully fabricated using a one-step electrospinning process. GO and SiO₂ nanofillers were added in PAN in different concentrations to determine the optimized composition for the PAN-GO-SiO₂ hybrid membrane. A scanning electron microscopy (SEM) examination showed that the nanofillers were uniformly embedded in the nanofibrous structure of the electrospun hybrid membrane. The GO was mainly embedded inside the PAN nanofibers, causing knots while SiO₂ nanoparticles were found embedded on the nanofiber surface, resulting in the formation of micro-nano protrusions on the fiber surface. The formation of these hierarchical structures, together with enhanced hydrophilicity due to oxygen containing groups on both SiO₂ and GO, resulted in a high rejection ( > 99%) of oil from oil-water emulsion. Membrane performance evaluation under gravity separation tests showed that the separation flux and phase rejection was enhanced with the incorporation of nanofillers. The inclusion of nanofillers also enhanced the mechanical properties of the membrane. The best flux and phase separation performance was obtained for an optimized concentration of 7.5 wt % SiO₂ and 1.5 wt % GO in PAN. The flux of separated water was enhanced from 2600 L m^-2 h^-1 for pristine PAN to 3151 L m^-2 h^-1 for PAN-GO-SiO₂. The hybrid membrane also showed good mechanical and chemical stability, and antifouling propensity.