TiO2/CNC interlayer assisted photocatalytic nanofiltration membrane for enhanced self-cleaning performance

The growing demand for efficient water treatment technologies has driven the development of advanced nanofiltration (NF) membranes capable of tackling multiple challenges, including self-cleaning, effective pollutant removal, and precise ion selectivity. Herein, we fabricated a photocatalytic nanofiltration membrane using in situ grown TiO2 on cellulose nanocrystal (CNC) as an interlayer (TiO2/CNC) via vacuum-assisted interfacial polymerization. The TiO2 catalysts, loaded on the CNC surface, effectively degrade organic matter under ultraviolet (UV) light irradiation. The successful incorporating of TiO2/CNC interlayer resulted in a membrane with rough, hydrophilic, and loosely selective polyamide (PA) layer. The as-prepared membrane (TFC@TiO2/CNC) exhibited high water permeance of 23.3 L/m2 & sdot;h & sdot;bar, along with excellent salt rejection (95.5 % for Na2SO4) and organic matter retention (96.4 % for Congo red and 99.1 % for humic acid). In testing involving the separation of organic and salt mixtures, the membrane demonstrated an average 99 % flux recovery after 30 min of UV irradiation, while the membrane without TiO2/CNC interlayer experienced an average flux recovery of 79 %. Following UV irradiation, the TFC@TiO2/CNC membrane showed no significant decline in water permeance or retention for both Na2SO4 and humic acid, indicating strong anti-fouling properties with a flux attenuation of 9.2 % compared to the initial cycle which had a flux attenuation of 21.6 %. For dye fouling, the membrane with photocatalysts displayed excellent flux recovery. The results indicated that the TiO2/CNC interlayer-enhanced membrane holds great potential for treatment of organic wastewater in the treatment of industrial wastewater.