Cellulose acetate-graphene oxide loose nanofiltration membrane as pre-treatment for salt rejection in a seawater: Synthesis, characterization and fabrication

Growing global freshwater scarcity has intensified demand for efficient seawater desalination technologies, yet conventional cellulose acetate (CA) membranes remain limited by insufficient hydrophilicity and suboptimal salt rejection performance. In this study, CA was combined with graphene oxide (GO) to produce CA/GO composite membranes, and their salt rejection performance in a seawater loose nanofiltration system was reported. These membranes were synthesized via phase inversion by varying GO concentration to be 0.5, 1.0, and 1.5 wt% into CA polymer as matrices at 15 and 25 wt%. The structural, chemical, and morphological properties of raw materials and the membranes were characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (FESEM-EDX), and water contact angle measurements. The results showed that the CA 15 wt%/GO 1 wt% membrane demonstrated the most favorable balance of performance, achieving a water flux of 11.80 L/m²·h and the highest salt rejection of 37.75%, corresponding to a permeate TDS of 23,033 mg/L, alongside the lowest water contact angle of 74.12° among equivalent CA-concentration membranes, indicating enhanced hydrophilicity. The XRD analysis confirmed increased crystallinity (up to 58.08%) with introduction of GO while the FESEM revealed a uniform GO dispersion within the CA polymer matrix. These findings demonstrate that controlled GO incorporation into CA membranes significantly enhances membrane hydrophilicity and salt rejection efficiency, establishing CA/GO composites as a viable and scalable platform for seawater loose nanofiltration applications as pre-treatment.