Cellulose acetate and polycaprolactone based photoactive ultrafiltration membrane: A novel approach with UV-switchable photocatalytic activity

The development of self-cleaning, biodegradable polymer-based membranes with anti-fouling properties has gained significant attention. Herein, a novel ultrafiltration membrane made of cellulose acetate blended with polycaprolactone (PCL) was fabricated using a straightforward, non-solvent-induced phase-separation technique. The optimized membrane showed a high clean water flux of up to 71.3 ± 3.25 L/m2/h. It also displayed high mechanical tensile strength with a Young's Modulus of 41.05 MPa, which can be attributed to PCL. A smooth surface was observed from scanning electron microcopy (SEM) and atomic force microscopy (AFM) analysis. The optimized membrane demonstrated 88.8%, 95.4% and 96.8% rejection for 50 mg/L methyl red, crystal violet and eriochrome black T dyes, respectively, with an average flux of 53.3 ± 1.6 L/m2/h. The optimized membrane was encased and immobilized with 2% TiO2 to demonstrate TiO2-assisted UV-switchable photocatalytic properties, as confirmed by x-ray diffraction (XRD) analysis. The membrane rejected the dyes without UV-LED light and exhibited self-cleaning ability in the presence of UV-LED light (at λmax = 365 nm) and 20 mg/L H2O2 within 2 h. Anti-fouling, self-cleaning biodegradable membranes exhibit potential for sustainable water treatment due to their excellent anti-fouling characteristics from balanced hydrophilic-hydrophobic moieties in the polymeric matrix and the smooth surface.