Robust carbon nitride nanosheet interlayered thin-film nanocomposite membrane for enhanced organic solvent nanofiltration

The integration of a nanomaterial interlayer within a thin-film composite membrane can markedly enhance its performance in organic solvent nanofiltration (OSN). However, this enhancement often comes at the expense of membrane integrity due to differential swelling behaviors in diverse solvents. In this study, we present an interlayered thin film nanocomposite (TFNi) membrane that demonstrates both high permeance and robust stability, utilizing green, porous, and reactive crystalline carbon nitride (CCN) nanosheets as the functional interlayer. The results revealed that ascribed to the presence of the CCN interlayer, the membranes retained their rejection towards organic dyes even after 10 h of DMF exposure, while the organic solvent permeance was significantly improved by the DMF treatment. The methanol permeance of the CCN-TFNi-DMF membrane reached an impressive 8.77 L m⁻² h⁻¹ bar⁻¹, sustaining stable performance throughout a 72 h test period under a pressure of 10 bar. We attributed this performance enhancement to the extra nanochannels introduced by the CCN nanosheets that bolstered the permeance of the TFNi membrane, as well as the formation of a stable polyamide film resulting from the reaction between the amino groups on the CCN nanosheet surface and trimesoyl chloride during the interfacial polymerization process. This work provides valuable insights into the development of structurally reinforced TFNi membranes with exceptional performance for OSN separation applications.