Capsaicin mimic-polyethyleneimine crosslinked antifouling loose nanofiltration membrane for effective dye/salt wastewater treatment

Loose nanofiltration membranes (LNMs) based on the crosslinking of polyphenol and polyamine continue to receive tremendous attention for dye/salt separation owing to their high dye rejection and salt transmission. Herein, a novel antifouling LNM was fabricated by the crosslinking of polyphenol-inspired capsaicin-mimic N-(5-methyl acrylamide-2,3,4 hydroxy benzyl) acrylamide (AMTHBA) and polyethyleneimine (PEI) on hydrolyzed polyacrylonitrile (HPAN) substrate via green rapid coating (GRC) approach. The environmental-friendly GRC process based on Schiff-base reaction and electrostatic interaction could be achieved within 10 min, and the surface properties of the LNMs could be precisely tailored by adjusting the coating parameters. As a result, the AM-PEI/HPAN LNMs, which possessed superior hydrophilic and weak negatively charged surface, exhibited excellent separation performance. The optimal AM-PEI/HPAN LNM presented high dye rejections (i.e., 99.2% for Methyl Blue, 98.6% for Congo Red and 75.8% for Crystal Violet) and low salt rejections (i.e., R (NaCl, 4.4%) < R (MgCl2, 15.6%) < R (MgSO4, 17.7%) < R (Na2SO4, 36.3%)), meanwhile it presented a desirable permeance as high as 42.9 L m−2 h−1 bar−1. As excepted, the capsaicin-containing LNMs also exhibited dramatically improved resistance to organic fouling (flux recovery ratio was up to 98%) and bacteria growth (sterilization ratio of E. coli was approximately 90%). Moreover, the separation performances remained stable during 24-h filtration process of dye/salt aqueous mixture. All these indicate that the as-prepared AM-PEI/HPAN LNMs have great potential in practical applications.