Abstract:
Two-dimensional covalent triazine framework material (2D-CTF) is a kind of covalent organic framework material with triazine ring structure consisting of C and N elements, which is considered to be a type of ideal membrane material due to its excellent structural stability and adjustable in-plane nanopore. In this study, few-layers 2D-CTF-1 nanomaterials were prepared using a micro-interface method based on the polymerization of 1,4-dicyanobenzene. The resulting few-layers 2D-CTF-1 nanosheets were used as building blocks to construct 2D-CTF-1 membrane via a layer-by-layer assembly method. The structure and morphology of the prepared 2D-CTF-1 nanosheets and membrane were characterized by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, transmission electron microscopy and scanning electron microscopy. The pure water flux under different pressures and the separation performances of 2D-CTF-1 membrane for small organic dye molecules were tested. The results show that 2D-CTF-1 membrane possesses high pure water flux(153.7 L/(m
2·h)) (25 ℃, 0.1 MPa), and the in-plane nanopores of 2D-CTF-1 are proposed as the main transport channels for water molecules. Besides, the 2D-CTF-1 membrane exhibits high flux (132.5 L/(m
2·h)) (25 ℃, 0.1 MPa) and high rejection rate (98.3%) for separation of organic dye (Congo red). The membrane still shows high flux and rejection after a long-term operation. Thus, 2D-CTF-1 is a promising 2D separation membrane material for high efficient molecular separation.