Design an in-situ anti-bacterial structure of nanofiltration membrane with a novel bisimidazoline aqueous monomer

Bio-fouling is a key issue for the nanofiltration operation. In this study, 1, 2-bis (N-aminoethyl imidazoline) ethane (BAIE) firstly was used as a novel bisimidazoline aqueous monomer to prepare the anti-bacterial nanofiltration (NF) membranes. A novel nanofiltration (BAIE-TMC NF) membrane with in-situ anti-bacterial structure and anti-fouling property was fabricated via interfacial polymerization (IP) with trimesoyl chloride (TMC), basing on a polyethersulfone (PES) substrate. Protonated imidazole endowed the surface of BAIE-TMC NF membrane with weak electronegativity, and its salt rejection sequence was MgSO₄ > Na₂SO₄ > MgCl₂ > NaCl > LiCl. Meantime, the BAIE-TMC NF membrane with 0.5 wt% BAIE (M-0.5) exhibited a high rejection for bivalent ions, with a high MgSO₄ rejection (94.7 %). Notably, BAIE-TMC NF membrane containing an in-situ anti-bacterial imidazole structure showed significant anti-fouling and anti-bacterial properties. After BSA or HA filtration process, the flux recovery rates of all BAIE-TMC NF membranes were higher than 95 %, and M-0.5 exhibited high inhibition performance against Escherichia coli (98.5 %) and Staphylococcus aureus (98.4 %). Furthermore, M-0.5 exhibited excellent long-term separation stability during the three weeks separation experiment. BAIE can serve as an effective aqueous monomer for fabricating in-situ anti-bacterial and anti-fouling NF membrane to achieve the rejection of organic pollutant and bivalent ions.