Efficient dye desalination of nanofiltration membrane prepared by multi-arm amine-rich compound via interfacial polymerization

Abstract

Membrane separation is a highly adaptable technology for dye wastewater treatment yet existing polymeric membranes face critical limitations in simultaneously achieving high dye rejection and salt penetration. Conventional amine monomers typically produce dense separation layers through interfacial polymerization, resulting in compromised permeability and inadequate selectivity for low molecular weight dyes. To address these challenges, this work designed and prepared a four-arm amine-rich compound (TTa) to serve as the aqueous monomer for preparing nanofiltration membranes via interfacial polymerization. TTa's four amine groups showed high reactivity with TMC and formed multidimensional crosslinking for creating regulatable thickness, pore size and surface charge. The membrane exhibited high salt penetration (rejection rate of 12.3% for Na₂SO₄ and 10.4% for NaCl) and high rejection of various dyes (96.2% for congo red, 99.3% for methylene blue and 99.5% for direct red 80). In addition, the membrane exhibited a good anti-fouling property against BSA. The resultant membrane has great potential applications in wastewater treatment and separation of dyes and salts.