The high flux poly (m-phenylene isophthalamide) nanofiltration membrane for dye purification and desalination

The aromatic poly (m-phenylene isophthalamide) (PMIA) nanofiltration (NF) membrane with polyvinyl pyrrolidone (PVP) and LiCl as additives was fabricated by phase inversion. The effects of additive content in the casting solution, solvent evaporation temperature and evaporation time during membrane fabrication on the performance of the PMIA NF membrane were investigated. The rejection of the PMIA NF membrane for dyes Eriochrome black T, Eriochrome blue black B and Alizarine red were all over 98%, with a flux about 80 L/m(2)h, while the rejection for NaCl was only about 5.5% when tested at 0.4 MPa. The PMIA NF membrane was applied in the desalination and purification process of Eriochrome black T and NaCl mixed solution. The flux increased largely with the increase of the operation pressure and the temperature, while the rejection for dye remained over 99%. The flux decreased with the increase of the concentration of dye and salt in the feed solution while the rejection for dye and salt remained relative stable. The desalination and purification experiment exhibits that the rejection for the dye remained over 99% throughout the whole experiment which indicated that the PMIA-NF membranes could be successfully applied in the dye purification and desalination process. (C) 2011 Elsevier B.V. All rights reserved.