Lignin nanoparticles-intercalated reduced graphene oxide/glass fiber composite membranes for highly efficient oil-in-water emulsions separation in harsh environment

The low water permeability of reduced graphene oxide (RGO) membranes limit their wide applications in water treatment. Herein, a new route to fabricate a lignin nanoparticles-intercalated RGO composite membrane with high flux is reported. The addition of alkali lignin (AL) not only contributed to the reduction of graphene oxide (GO) in the hydrothermal reduction process, but also intercalated between RGO nanosheets. The AL/RGO nanosheets were further cross-linked with polydopamine (PDA) to stabilize the interlayer structure and finally assembled onto a glass fiber (GF) membrane by a vacuum filtration process. The AL/RGO@PDA membrane shows a large pure water flux up to 2410.3 L/m 2 h, which increased by 297.3% than that of the RGO composite membrane (810.7 L/m 2 h) without nanoparticles intercalated. Even after 10 cycles, the AL/RGO@PDA membrane remained high separation efficiency (above 99.10%) for n-hexadecane emulsion. In addition, such a membrane maintained the original performance at high temperature (98 °C) and in highly corrosive environments (pH=1, pH=14). Overall, this study provides a facile and eco-friendly method to fabricate high flux RGO composite membrane, showing promising application for water purification and separation. • Alkali lignin can avoid excessive reduction of graphene oxide. • The intercalated lignin nanoparticles increased the flux of the composite membrane. • The membrane exhibited high separation efficiency and flux by gravity-driven. • The membrane can maintain stability under multi-kinds external stimulations. • The membrane showed excellent antifouling property and reusability.