Troger's base-derived thin film composite membrane for enhanced nanofiltration performance

Nanofiltration (NF) membrane technology serves as an efficient method for separation and purification, playing a vital role in various industrial fields such as water treatment, food processing, and pharmaceutical manufacturing. However, there are still drawbacks, such as limited flux due to densely crosslinked composite layer and poor stability in solvents. In this study, we report the fabrication of the thin-film composite (TFC) NF membrane using Troger's base-derived building block, aiming to manipulate intrinsic pore structures of the assynthesized ultra-thin composite layer by introducing rigid dihedral units. The interfacial polymerization process is employed to enable the polycondensation of Troger's base-based diamine monomer and tri-aldehyde monomer via Schiff base reaction. The effects of monomer concentration, immersion time, interfacial polymerization reaction time, heat treatment time and temperature on the performance of NF membrane were studied. The optimized NF membrane presents a rejection of Methyl blue (MB) above 95.3 % and achieves a high water permeance of 43.4 L.m(-2)center dot h(-1)center dot bar(-1). The water permeance is 2-3 times higher than the reported NF membranes with similar rejection ability. In addition, Troger's base-derived TFC NF membrane exhibits excellent long-term stability and good organic solvent tolerance. Considering the high water permeance and separation efficiency, the present membrane has significance in dye removal and separation processes.