Surface reconstruction of sulfonated polysulfone ultrafiltration membrane with cellulose nanocrystals for enhancing anti-fouling performance

The fouling issues of ultrafiltration membranes is one of limitations for their long-term effectiveness. Here, we developed an effective and environmentally friendly approach for constructing anti-fouling ultrafiltration membrane, achieved by the surface modification of sulfonated polysulfone (SPSF) ultrafiltration membrane with cellulose nanocrystals (CNCs). The composite ultrafiltration membrane was obtained by only filtering CNC suspension through SPSF ultrafiltration membrane, and showed good hydrophilicity that its water contact angle is only 53° which is much lower than that of SPSF ultrafiltration membrane (74°). Its retention rate for the pollutants with particle size greater than 10 nm is close to 100 %. Its water flux is almost twice that of SPSF ultrafiltration membrane under the sewage condition. After three cycles of filtering severe sewage, its flux recovery rate is still 95 %, far higher than that of SPSF ultrafiltration membrane (60 %). Therefore, the surface modification strategy of SPSF ultrafiltration membrane with CNCs is effective and green for improving the anti-fouling properties of ultrafiltration membranes, which is a valuable reference for enhancing the anti-fouling performance of ultrafiltration membranes from various materials. The as-prepared CNCs/SPSF ultrafiltration membrane has a promising application in the purification of wastewater containing hydrophobic particles.