Covalent organic framework membranes with limited channels filling through in-situ grown polyaniline for efficient dye nanofiltration

Due to the high porosity and ordered channels, covalent organic framework (COF) membranes with ultrathin selective layer and high permeance have gained increasing attention in the field of nanofiltration (NF). However, it remains a challenge to fabricate ultrathin and dense COF NF membranes with both high permeance and high rejection. This work presents a facile and efficient method to fabricate COF membrane with limited channel filling through in-situ growth of polyaniline (PANI) layer. Specifically, interfacial polymerized COF-TpPa membrane was fabricated with ~ 1.8 nm pore channel, and then the in-situ grown PANI layer could fill the partial of channels and reduce the effective pore size of COF-TpPa. The obtained PANI-TpPa composite membrane exhibited excellent performance with pure water permeance up to 85.2 L·m−2·h−1·bar−1, congo red rejection above 99.4%, and acid fuchsin rejection above 81.0%. The whole membrane fabrication just cost 3 h and took place at room temperature, which was much more efficient than other membranes with similar performance. Besides, the PANI-TpPa composite membrane showed excellent stability in acidic environment and organic solvent, and maintained great performance in long-term test.