Surface grafting of a zwitterionic copolymer onto a cellulose nanofiber membrane for oil/water separation

Abstract

Numerous oil/water mixtures are produced by industrial processes and residential activities, leading to the need for effective separation technologies for wastewater treatment and environmental remediation. In the present study, we report a cellulose-based nanofiber membrane with exceptional hydrophilicity and oleophobicity that rejects organic solvents and allows the penetration of water, thus avoiding fouling by organic residues, which has been a serious issue for conventional oil/water separation membranes. The cellulose-based nanofiber membrane was fabricated through the electrospinning of cellulose acetate and subsequent deacetylation. The resulting surface hydroxyl groups were utilized to bind with the zwitterionic copolymer poly(sulfobetaine methacrylate-r-glycidyl methacrylate) via a ring-opening reaction with the epoxy groups in the copolymer. The resulting copolymer-grafted cellulose nanofiber membrane allowed the highly selective penetration of the water phase from three different oil/water mixtures. The average filtration efficiency was higher than 98% with outstanding reusability and stability over at least 20 cycles following decontamination by washing the membrane with water. The proposed material platform expands the potential use of cellulose materials to a wide range of applications in which hydrophilic coating is required.