Enhanced water filtration performance in electrospun cellulose acetate membranes via TEMPO-mediated cellulose nanocrystal incorporation and hot pressing

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 (CNCTEMPO) further improved performance. TEMPO oxidation introduced a carboxyl content of 0.56 ± 0.04 mmol/g, enhancing nanocrystal dispersion and interfacial adhesion within the CA matrix. This reduced the water contact angle from 104° to 37° and filtration time from 100 minutes to under 30 seconds. 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.% CNCTEMPO. This is the first systematic study examining the synergistic effect of electrospinning, hot pressing, and CNCTEMPO functionalization, offering a promising strategy for fabricating high-performance, multifunctional membranes for sustainable water treatment applications.