Hydrophilic hierarchical carbon with TiO2 nanofiber membrane for high separation efficiency of dye and oil-water emulsion

Abstract

Hierarchical carbon hybrid materials have gained more attention in recent times especially in the separation of pollutants from wastewater. In this study, a novel ternary composite of graphitic carbon nitride (G-C3N4) decorated on reduced graphene oxide (RGO) with titanium dioxide (TiO2) nanohybrids was synthesized using hydrothermal approach to modify the electrospun PVDF membranes for the separation of oil and dye in wastewater. The characteristic functional groups of G-C3N4, RGO and TiO2 (G-C3N4,/RGO/TiO2) nanohybrids were confirmed by X-ray diffraction (XRD) and X-ray photon electron spectroscopy. Moreover, the prepared membranes were also studied using field emission scanning electron microscope and X-ray photoelectron spectroscopy. Interestingly, the PVDF modified membranes displayed excellent thermal stability with lower contact angle, increased surface roughness and surface charges. It was due to the tunable covalent π-π interfaces among G-C3N4 and RGO 2D hierarchical structured nanosheets. Besides due to the reasonable hierarchical structure formation of chemical and physical defense mechanism, the modified membranes exhibited outstanding antifouling performance and different oil water emulsion rejections. The pure water flux for GT-4 membrane was around 1261.2 ± 2 L/m2.h and exhibited high oil water removal efficiency above 95.4 ± 0.1% for different oils. The modified PVDF membranes also exhibited higher rejection rate of about 94.2 ± 0.5% for methylene blue dye removals. These studies confirm the formation of hydration layer and hierarchical structure for membranes which can be employed in oil water emulsion separation and dye rejection studies.