Preparation of COF-TpPa1 membranes by chemical vapor deposition method for separation of dyes

Covalent organic frameworks (COFs) exhibit potentials in adsorption, separation, heterogeneous catalysis, and energy storage due to low density, high thermal stability and inherent porosity. In this work, p-phenylenediamine (PDA) and 2,4,6-trihydroxy-benzene-1,3,5-tricarbaldehyde (TFP) were simultaneously evaporated onto modified poly(1,1-difluoroethylene) (PVDF) membrane in a chemical vapor deposition reactor to prepare COF-TpPa1 membranes for the separation of dyes. The effects of evaporation temperature, evaporation time, amount of Fe powder and pores size of PVDF membranes were studied, and the long-term operation was evaluated. The membranes showed an excellent water permeance (up to 400 L m−2 h−1 MPa−1) with high rejection (>90%) for different dyes (Mw 450–800), and low rejection (<8.2%) for salts. The COF-TpPa1 membrane also displayed considerable long-term operation stability. This facile approach can be extended to the preparation of a broad range of COFs membranes.