A novel loose nanofiltration membrane constructed by 1, 2-bis (N-aminoethyl imidazoline) ethane as an aqueous monomer for precise dye/salt separation

In dye/salt separation of textile industry wastewater, bio-fouling holds negative effects on separation ability of loose nanofiltration (LNF) membrane. A novel ultra-high in-situ anti-bacterial LNF membrane was firstly fabricated through interfacial polymerization (IP) using a synthetic aqueous monomer of 1,2-bis (N-aminoethyl imidazoline) ethane (BAIE) and a commercial organic monomer of 1,3,5-tris(bromomethyl)benzene (TBB) in this work. Notably, the BAIE-TBB LNF membrane containing anti-bacterial imidazole structures by IP process could prevent the loss of anti-bacterial modifiers and keep the imidazole structures loaded meanly. It showed significant anti-bacterial performance for Escherichia coli and Staphylococcus aureus. Moreover, the fabricated BAIETBB LNF membrane with 0.1 wt% TBB (M-0.1) exhibited an ultra-high water permeance of 157.1 LMH/bar, a high Congo Red (CR, 100 ppm) rejection of 99.6 %, and a low NaCl (1000 ppm) rejection of 1.5 %, due to its relatively loose functional layer. For the salt/dye mixed solution, M-0.1 presented excellent separation performance with a CR/NaCl separation factor (alpha 246.3), and still exhibited good salt/dye separation performance under high salt concentration. With excellent water permeability, dye/salt separation, and anti-bacterial properties, BAIE-TBB LNF membrane holds great application potential in dye/salt separation.