Intensification of mass transfer for zwitterionic amine monomers in interfacial polymerization to fabricate monovalent salt/antibiotics separation membrane

Abstract

Zwitterionic groups are conducive to improve the antifouling performance and water permeability of nanofiltration membranes because of the excellent hydrophilicity and charged property. However, the transport of zwitterionic monomers during interfacial polymerization process is much slower than the reaction, leading to form many defects in the separation layer. In this study, phase transfer catalysts were used to intensify the interfacial mass transfer of zwitterionic amine monomers for fabricating polyamide thin-film composite nanofiltration membranes. The transport process was explored by measuring the diffusion kinetics of monomers to regulate the structures and properties of zwitterionic membranes. Consequently, low concentration of N-aminoethyl piperazine propane sulfonate (AEPPS) as aqueous monomer could be used to prepare membranes with excellent nanofiltration performance. When the concentration of AEPPS was as low as 1 w/v%, the as-prepared zwitterionic membrane possessed a pure water flux of 10.6 L m−2 h−1 bar−1 with a high erythromycin retention of 91.7% and a low NaCl retention of 7.3%, which exhibited great application potential in the separation of monovalent salt/antibiotics. Moreover, the flux recovery ratio of the zwitterionic membrane was still maintained at ∼96.5% after undergoing twice fouling-rinse experiments of bovine serum albumin, exhibiting exceptional antifouling performance.