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

Abstract 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.