Sustainable reverse osmosis thin-film composite membranes based on cellulose acetate and recycled acrylic fiber waste

Thin-film composite reverse osmosis (RO) membranes were developed using recycled acrylic fiber waste as a sustainable support material and cellulose acetate (CA) as the selective layer. Acrylic fiber wastes were transformed into nanofiltration support membranes by using the phase inversion technique, followed by dip-coating with CA/acetone solutions to form RO composite membranes. The effects of CA concentration, pore former (methanol) content, and evaporation time prior to immersion precipitation on membrane structure and RO performance were systematically investigated. Membrane morphology and physicochemical properties were characterized using Fourier transform infrared, scanning electron microscopy, X-ray diffraction, thermal gravimetric analysis and water uptake analysis. Desalination performance was evaluated using a 2000 ppm NaCl solution in a dead-end RO system at 15.5 bar. Increasing evaporation time enhanced salt rejection but reduced water flux due to the formation of a denser CA selective layer. The optimized membrane, prepared using 5 wt% CA with 5 wt% methanol and an evaporation time of 5 min, achieved high salt rejection (85–92%) with acceptable water permeability. The results demonstrate the feasibility of utilizing recycled acrylic fiber waste for the fabrication of efficient RO membranes, offering a cost-effective and environmentally sustainable approach for water desalination applications.