Proton sponge catalyzes interfacial polymerization in organic phase to enhance nanofiltration membrane performance

Interfacial polymerization (IP) plays a vital role in the manufacturing process of polyamide (PA) nanofiltration (NF), which is of great value in a wide variety of separation processes. In this study, we proposed a catalytic strategy to mix proton sponge/hexane solution and TMC/hexane solution during the interfacial polymerization reaction, thus achieving a facilitative modulating effect on the interfacial polymerization process. The nanofiltration membranes prepared by the catalytic strategy showed reduced thickness of the separation layer, reduced roughness, and more uniform pore size distribution than the blank membrane. As a result, the modified membranes showed nearly double permeate flux (from 8.0 to 15.9 Lm−2h−1bar−1) and slightly increased Na2SO4 retention, as well as improved separation selectivity for monovalent/divalent salts and stronger antifouling ability. At the same time, this strategy also improved the uniformity of membrane pore size distribution while loosening the membrane structure. The illustrated strategy based on the catalytic modulation of interfacial polymerization by proton sponge achieved an enhancement of all aspects of nanofiltration membrane performance through such a simple step, showing good prospects for application in the manufacture of membrane for high performance nanofiltration.