Desalination behavior of composite membrane with petal shaped pore- formed by superimposition of covalent organic framework with large aperture difference

MJ Guan and DF Yang and Q Li and HT Zhang and JA Xu and MM Cai and WK Lin and SQ Ma and QZ Liu, APPLIED SURFACE SCIENCE, 616, 156441 (2023).

DOI: 10.1016/j.apsusc.2023.156441

Covalent organic frameworks (COFs) are promising materials for developing the new generation of reverse -osmosis membranes owing to their unique structure with well-defined nanoporosity and highly tunable pore -wall chemistry. In this work, a new separation membrane was developed using the molecular dynamics (MD) simulation method by superimposing two COF-based films: HPB-COF (0.577 nm) and TpPa-1 (1.582 nm), with a large difference in aperture. The results showed that the new double-layer superimposition membrane could overcome the trade-off effect, and achieve a high water flux and salt rejection rate. According to the membrane model microanalysis, the HPB-COF divided TpPa-1 into six "petals", thus endowing the first layer and second layer of the membrane with a larger accessible surface area and smaller effective pore diameter, respectively. As a result, the new composite membrane simultaneously had combined advantages of the two COF materials. The water permeance of the TpPa-1/HPB-COF composite membrane was 1.85 times higher than that of the AB -stacked HPB-COF membrane, which was two orders of magnitude higher than that of other conventional reverse- osmosis membranes. The salt rejection rate was 100%, which was higher than that of AB-stacked TpPa-1 membrane (39.42%). Furthermore, the microanalysis revealed that the hydrophilic C--O in TpPa-1 positively improved the water flux.

Return to Publications page