Ultrafast loose nanofiltration membrane intercalated by in-situ grown nanoparticles for dye purification and reuse

Abstract

Loose nanofiltration membrane is regarded as an effective separation technology for dye purification and reuse, but is still restrained by the trade-off between the permeance and the dye/salts selectivity. Herein, we report the fabrication of an ultrafast loose polyamide nanofiltration (NF) membrane on the nanofibrous support layer with uniform in-situ grown ZnO nanoparticles. It was found that embedding ZnO nanoparticles provides more water channels and increased effective filtration area, thus enhancing the water permeation without trading off the dye/salt selectivity. The fabricated NF membrane with an in-situ formed ZnO-nanoparticle interlayer exhibits an ultrahigh water permeance up to 375 L m−2 h−1 bar−1, which increased by approximate seven-fold than that of virgin NF membrane (54 L m−2 h−1 bar−1) without nanoparticles intercalated, and attains high rejection of organic dyes (>91 % for Congo red, >92 % for Methyl blue, and >98 % for Victoria blue B) but low rejection of inorganic salts (<5 %). The synergy of steric exclusion and charge effect dominate the high selectivity of dye and salts. This study unlocks a new avenue to synthesize ultrahighly permeable-selective loose NF membranes.