Characterization and application of a thin-film composite nanofiltration hollow fiber membrane for dye desalination and concentration

NF hollow fiber membrane was fabricated and was applied to the process of dye desalination and concentration using an X-BR and NaCl mixed aqueous solution as the pollutant. NF hollow fiber membrane possessed a molecular weight cut-off (MWCO) of approximately 520 Da and a pure water flux of 47.5 L/m2 h at 0.4 MPa. Rejections of different salts followed in the order of MgSO4 > Na2SO4 > MgCl2 > NaCl, with up to 96.20% rejection for MgSO4 and rejections of the anionic dyes reactive brilliant blue X-BR and acid red B were 99.99% and 99.90%, respectively. The dye rejection and permeate flux were affected by the dye concentration as well as the presence of NaCl in the X-BR aqueous solutions. After finishing the process of dye desalination and concentration, the volume of retentate was concentrated 6.25 times, and the dye concentration in the retentate reached 2854.8 mg/L. Moreover, the recovery rate of dye was up to 91.4%, and over 95.3% NaCl was removed from the dye/salt mixtures. The results indicated that NF hollow fiber membrane could be successfully applied to the dye desalination and concentration process.