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

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.

Automated summary

In this study, a cellulose-based nanofiber membrane with exceptional hydrophilicity and oleophobicity is reported, which allows the penetration of water and rejects organic solvents, avoiding fouling by organic residues. The membrane is fabricated through electrospinning of cellulose acetate and subsequent deacetylation, followed by binding with a zwitterionic copolymer. The resulting membrane exhibits highly selective penetration of the water phase from various oil/water mixtures, with high filtration efficiency and reusability.