Fabrication of thin-film composite nanofiltration membranes with improved performance using β-cyclodextrin as monomer for efficient separation of dye/salt mixtures

Complete separation of dye/salt mixtures through nanofiltration (NF) membranes is of great significance for the sustainable development of salt-containing dye wastewater treatment. Herein, a novel hydrophilic thin-film composite NF membrane was fabricated using β-cyclodextrin (β-CD) and trimesoyl chloride (TMC) via interfacial polymerization on a commercial ultrafiltration membrane. The performance of the resultant β-CD/TMC membranes was optimized by altering the variables. The results showed that the optimized β-CD4.0/TMC membrane (4.0 wt% β-CD, 0.2 wt% TMC, and 0.5 mol L-1 NaOH) possessed a pure water flux of 207.8 L m-2h−1 at 2.0 bar. Meanwhile, the membrane exhibited efficient dye/salt separation with high rejection of dyes (e.g. 100.0% for congo red and 99.1% for rose bengal) and low salt rejection (e.g. 8.5% for NaCl). Congo red/NaCl mixtures achieved similar removal rates to those of dye or salt solutions (the congo red rejection over 99.0% and the rejection of NaCl was below 10.6%). Furthermore, the membrane showed desirable stability, the flux remained at 82.9% of the initial value after filtration for 16 h. We believe that the fabricated NF membrane has a great potential for application in the treatment of salt-containing dye wastewater with improved selectivity for dye/salt separation.