Preparation of Modified Composite Nanofiltration Membrane Synergistically Using Carboxylic Multi-walled Carbon Nanotube and β-cyclodextrin

A new modified blend ultrafiltration (UF) membrane with good hydrophilicity, high porosity and excellent anti-fouling performance was developed by using carboxylic multi-walled carbon nanotube (CMWCNT) as casting solution additive. Furthermore, a composite nanofiltration (NF) membrane with large water flux and good retention rate was fabricated by using the PVDF/CMWCNT blend UF membrane as the substrate, and polyvinyl alcohol (PVA), β -cyclodextrin ( β -CD) and polyethylenimine (PEI) as the coating solution. The results show that with the appropriate addition of CMWCNT in the casting solution, the surface roughness, porosity and recovery rate of the PVDF/CMWCNT blend UF membrane is obviously increased. The water flux of blend UF membrane is significantly improved when the CMWCNT content increases from 0 wt% to 0.2 wt%. The water flux of blend UF membrane with 0.2 wt% CMWCNT is 162.7 L/(m 2 ·h), which is 44.3% higher than that of the pure PVDF membrane. When β -CD content is 0.8 wt%, the retention rate of Congo red by PVDF/CMWCNT/ β -CD composite NF membrane reaches 98.7%, which is 28.3% higher than that of single PVA/PEI modified membrane. This research will provide a new idea and simple method for developing novel high-performance composite NF membranes.