Preparation of thermally stable PMIA loose nanofiltration membrane for dye/salt water separation

Nanofiltration (NF) membrane technology has become a prospective alternative to treat textile dye/salt wastewater. Nevertheless, most textile dye/salt wastewater has a complex composition, high temperature and high salt content, which required the NF membrane to maintain high separation accuracy and thermal stability. In this study, poly(m-phenylene isophthalamide) (PMIA) loose NF membranes were fabricated by coating encapsulation and cross-linking method. The triethylnetetramine (TETA) modified GO nanosheets (AGOs) were introduced into the PVA solution, which is encapsulated inside the PMIA nanofiber membrane and followed by glutaraldehyde (GA) post-crosslink. Effects of polyvinyl alcohol (PVA) content and -NH2 group density of AGOs on the membrane morphology, chemical structure and dyes/salt separation performance were investigated by SEM, XPS, FTIR and filtration test, respectively. The PPN10 membrane with PVA content of 5 wt% and TETA concentration of 10 % showed a denser and more selective functional layer. Compared with PP5 membrane, the PPN10 membrane possessed an approximately 100 % CR rejection and 4.2 % NaCl rejection (50 degrees C) with CR water flux around 68 L center dot m-2 center dot h- 1 . The introduction of AGOs, obviously improved the membrane's thermal stability because the AGOs improved the cross-linking sites of -OH and increased the stability of the PVA cross-linked network, which shows excellent application prospect for dye/salt separation wastewater.