Preparation of PMIA loose nanofiltration membrane with electrostatic layer-by-layer self-assembled for dye/salt filtration

Poly (m-phenylene isophthalamide)-based loose nanofiltration membranes were fabricated by electrospinning and subsequential electrostatic layer by-layer self-assembly methods, and the polyelectrolyte multilayers (PEMs) generated by polyacrylic acid (PAA) and polyethyleneimine (PEI) were adopted to contribute the surface functional layer of nanofiber membranes. The incidences of spraying parameter and nano-SiO2 content on the morphology, chemical constitution and dyes separation performance of PEMs functional layer was investigated, respectively. The results showed that the construction of the PEMs functional layer could obviously enhance the Congo red (CR) filtration efficiency by increasing the rejection from 4.9% to 99.8% and improve the surface hydrophilicity by reducing the water contact angle (WCA) from 90.1° to 51.8°. Nano-SiO2 is introduced as a filler to regulate the assembly density of PEMs functional layers, the prepared PEMs/PMIA/SiO2 membrane achieved a relatively stable permeation flux (22.9 L·m−2·h−1), and maintained high separation efficiency of CR/NaCl solution, revealing the excellent dye desalination performance, which exhibited a potential for the dye/salt wastewater treatment. In particular, we offered a new method to prepare loose nanofiltration (LNF) membranes by electrospinning and electrostatic self-assembly technique with accurate separation of inorganic salts and dye molecules.