Highly selective and permeable β-cyclodextrin based polyester nanofiltration membranes maintaining good chlorine resistance

Possessing high chlorine resistance is an important consideration for membranes to be applied for water treatment. In this study, the superior chlorine resistant β-cyclodextrin (β-CD) based polyester membranes were developed via interfacial polymerization (IP) with the β-CD and glycerol or mannitol as the aqueous phase monomers. By adjusting the compositions of the aqueous phase, the pore size and distribution of the resultant membranes were accurately controlled, thus improving the separation efficiency of the membranes. The optimized membrane (β-CD/Ma3) had the higher water flux (60.4 L‧m-2‧h-1 at 2.0 bar) and Na2SO4 retention (95.6%). After immersed in 10 ppm sodium hypochlorite (NaClO) solution for 360 h, the membrane performance in terms of water flux and salt retention was almost unaltered, mirroring a good long-term stability. In another test, the Na2SO4 retention of membrane remained at 91.7%, which was only 4.1% lower than the original value, after exposure to a high concentrated NaClO solution (2000 ppm) for 72 h. Fouling cycling test was also performed, and the flux was maintained as high as 97.2% of the original value after examination of three cycles. All these observations clearly indicate that the optimized membrane has outstanding chlorine resistance and superior antifouling property.