5-Sulfoisophthalic acid sodium incorporated polyamide nanofiltration membrane with enhanced separation performance

Highly permeable nanofiltration membrane has attracted great attention in energy-efficient liquid separation. However, the preparation of selective membranes with high permeability and good antifouling capability remains challenging. Here we first reported 5-sulfoisophthalic acid sodium (SSIPA) co-deposition for designing crosslinked polymer nanofilm via interfacial polymerization. The composite membranes composed of thinner sulfated polyamide nanofilms (18.0 ± 2.2 nm) had enhanced hydrophilicity and electronegativity as well as smoother surface and enlarger pore size. The SSIPA integrated polyamide nanofiltration membrane presented approximately 4.8 folds pure water flux of the membrane without SSIPA. The prepared membrane suitable for water desalination had 18.0 and 28.3 LHM/bar pure water permeance with the comparable Na2SO4 rejection of 96.3% and 91.8%, respectively. More importantly, the membrane fabricated with a high proportion of SSIPA achieved better dye/salt fraction performance with dye fluxes of 49.3 LMH/bar as well as superior CR rejection (99.0%) and NaCl passage (97%). At the same time, the natural organic matter (BSA, SA) could be almost completely removed. Significantly, the SSIPA-integrated membrane exhibited excellent long-term stability and antifouling capacity. These novel loose TFC membranes with outstanding separation performance provide potential applications for water desalination and organic separation.