Smart Antifouling and Self-Cleaning Membrane for Effective Oil/Water Separation

A novel membrane consisting of cellulose acetate (CA) nanofibers and poly(N-isopropylacrylamide) (PNIPAM) microparticles is successfully fabricated by simultaneous electrospinning and electrospraying. The CA/PNIPAM membrane has highly effective gravity-driven separation performances for both oil/water mixtures and oil-in-water emulsions. It separates oil droplets from oil-in-water mixtures and oil-water emulsions with rejection rates of 99.83% and 96%, respectively. In order to examine the contribution of PNIPAM particles, the performance of the CA/PNIPAM membrane is compared with the CA membrane. Increased hydrophilicity due to the inclusion of the PNIPAM particles between CA nanofibers results in a higher rejection ratio and superior antifouling performance. While the CA membrane becomes unusable after 10 cycles during the separation of the oil-water emulsion, the CA/PNIPAM membrane is still in good shape after 20 cycles. The self-cleaning ability of the membrane is examined through the permeation flux below and above the lower critical solution temperature (LCST) of PNIPAM. The reversible thermo-responsive flux variation proves that the pore sizes increase at temperatures above the LCST of PNIPAM. Moreover, when the lubricating oil-water emulsion is filtered through the membrane, the permeate changes from clear to turbid due to the nonretained oil particles as the temperature passes through the LCST.

A novel cellulose acetate/poly(N-isopropylacrylamide (CA/PNIPAM) membrane, created by simultaneous electrospinning and electrospraying, effectively separates oil/water mixtures and emulsions. It demonstrates rejection rates of 99.83% and 96% for oil droplets in oil-in-water mixtures and emulsions, respectively. Additionally, the membrane's self-cleaning ability is proven by reversible thermo-responsive flux changes above PNIPAM's lower critical solution temperature, indicating pore expansion.image