Enhanced Water Filtration Performance in Electrospun Cellulose Acetate Membranes via TEMPO-Mediated Cellulose Nanocrystal Incorporation and Hot Pressing

Abstract Access to clean water is increasingly critical due to escalating pollution from industrialization and population growth. This study presents the development of advanced cellulose acetate (CA)-based membranes for water filtration through an integrated approach combining electrospinning, hot pressing, and cellulose nanocrystal (CNC) functionalization. A 12 wt% CA solution in a 4:1 acetone/acetic acid mixture was electrospun under optimized conditions (1 mL/h, 15 cm, 35–70% relative humidity) to produce uniform, bead-free nanofibrous mats. Subsequent hot pressing at 100 °C and 20 bar yielded denser membranes with enhanced mechanical durability and reduced pore size. Functionalization with CNCs and TEMPO-oxidized CNCs (CNC TEMPO ) further improved performance. Structural characterization confirmed the successful TEMPO oxidation of CNCs, as evidenced by FTIR bands at 1730 and 1604 cm⁻¹ and a carboxyl content of 0.56 ± 0.04 mmol/g, enhancing nanocrystal dispersion and interfacial adhesion within the CA matrix. Moreover, SEM images showed denser and more homogeneous fiber morphology after hot pressing and CNC TEMPO incorporation, as well as higher tensile strength values, indicating structural reinforcement. These changes led to a reduction in water contact angle (from 104° to 37°) and filtration time from 100 min to under 30 s. Filtration tests showed improved rejection of 2.0 μm particles (92%) and efficient methylene blue dye removal (up to 95%) in membranes with 3 wt% CNC TEMPO . To the best of our knowledge, this is the first study to combine electrospinning, hot pressing, and TEMPO-oxidized cellulose nanocrystals in cellulose acetate membranes to simultaneously enhance wettability, mechanical stability, and filtration performance using a fully bio-based system. This integrated strategy offers a promising route for fabricating high-performance, multifunctional membranes for sustainable water treatment applications. Graphical Abstract