A high-performance ZIF-8 membrane for gas separation applications: Synthesis and characterization

The demand for green energy sources is increasing rapidly, such as hydrogen, which is mainly produced through regeneration, filtration, and separation from exhaust gas sources. Inspired by the biological adhesion ability of the marine mussel, the H2 separation performance of ZIF-8 membranes was investigated, which were synthesized on polydopamine-functionalized stainless-steel-nets (SSNs). With the polydopamine (PDA) functionalization, the membrane achieves high separation efficiency while maintaining high membrane permeability, as the PDA layer promotes nucleation and continuous development of the ZIF-8 layer based on covalent bond treatment. First, the performances of the membranes prepared on PDA-functionalized SSNs and those prepared without functionalization were compared. For the single gas permeation test, the PDA functionalized ZIF-8 membrane separation abilities of CO2/N2, H2/N2, and H2/CO2 were found to be 1.25, 4.30, and 3.44, respectively. The separation factors of the ZIF-8 membrane without PDA for CO2/N2, H2/N2, and H2/CO2 were found to be 1.25, 4.06, and 3.16. Then, the effect on the separation ability of ZIF-8 solution concentration was conducted. The best efficiency for H2/CO2 was 11.3, respectively, for 0.2 M of the material solution under optimum conditions. Besides, the commercial ZIF-8 particles were used to prepare the membrane with the same method for comparison with the self-synthesized ZIF-8 particles. The performance of both membranes showed similar efficiency, and self-synthesized ZIF-8 particles showed economic and simplicity. The morphological structure and morphological face of the membrane were analyzed using various characterizations. The ZIF-8 membrane for gas separation is expected to apply to air purification and renewable energy sources in the near future.