Low pressure UV-cured CS–PEO–PTEGDMA/PAN thin film nanofibrous composite nanofiltration membranes for anionic dye separation

Abstract

Novel low pressure UV-cured chitosan–polyethylene oxide–polytriethylene glycol dimethacrylate/polyacrylonitrile (CS–PEO–PTEGDMA/PAN) thin film nanofibrous composite nanofiltration membranes for anionic dye separation are demonstrated. Firstly, a double-layer mat containing an ultrathin electrosprayed CS–PEO–triethylene glycol dimethacrylate (TEGDMA) hydrophilic nanobeaded top layer and an electrospun PAN nanofibrous substrate layer was manufactured. Then the hydrophilic top layer was acidic moist-cured followed by hot pressing to form an integrated barrier film on the supporting layer. Here, acidic moisture was utilized to soften the nanobeads and facilitate the CS melting process. Finally, the top layer was UV-cured to form CS–PEO–PTEGDMA semi-interpenetrating polymer networks to physically crosslink CS. Different conditions were selected to achieve an optimized integrated barrier layer on PAN nanofibrous substrate. The optimized membrane possessed high nanofiltration performance for anionic dye separation with superior permeate flux (∼117.5 L m⁻² h⁻¹) and high rejection (∼99.9%) to Direct Red 80 solutions under low applied pressure of 0.2 MPa for energy saving purposes. An adsorption-assisted nanofiltration process was proposed for the CS–PEO–PTEGDMA membranes to separate anionic dyes. Moreover, the resultant CS–PEO–PTEGDMA nanofiltration membranes exhibited excellent antifouling properties (the flux recovery ratio reached 96.0% after 3 runs for 18 h), and they also possessed good reusability over repeated operations with a simple regeneration process. This work may pave the way for other intriguing polymer materials and provide a practical feasibility for water purification.