High-flux composite nanofiltration (NF) membrane with electrical double layer (EDL), and preparation method and use thereof

A composite nanofiltration (NF) membrane with an electrical double layer (EDL), wherein the NF membrane with the EDL is formed by a support membrane having a negatively-charged sulfonic acid group and a separation layer having a negatively-charged sulfonic acid group;

• wherein
• the support membrane is formed on a non-woven fabric by a casting solution that is formed by mixing polyvinylidene fluoride (PVDF) and sulfonated PVDF, such that the support membrane is negatively-charged, wherein a sulfonation degree of the sulfonated PVDF is 51.9%;
• the separation layer is formed by coating sulfonated polyethersulfone (PES) on a surface of the support membrane and is negatively-charged, wherein a sulfonation degree of the sulfonated PES is 31.6%,
• the zeta potential of the surface of the composite NF membrane is in a range from −73.6 mV to −77.1 mV at a pH from 1 to 13, the zeta potential is −75.5 mV at pH 1, the zeta potential is −73.6 mV at pH 3, the zeta potential is −74.7 mV at pH 5, the zeta potential is −77.1 mV at pH 7, the zeta potential is −76.3 mV at pH 9, the zeta potential is −76.5 mV at pH 11, the zeta potential is −73.9 mV at pH 13, wherein the water flux is 59 LMH at an operating pressure of 0.1 MPa.