Improving the Selectivity of ZIF-8/Polysulfone-Mixed Matrix Membranes by Polydopamine Modification for H(2)/CO(2) Separation

Gas separation membranes are essential for the capture, storage, and utilization (CSU) of CO(2), especially for H(2)/CO(2)separation. However, both glassy and rubbery polymer membranes lead a relatively poor selectivity for H(2)/CO(2) separation because the differences in kinetic diameters of these gases are small. The present study establishing the mixed matrix membranes (MMMs) consist of a nano-sized zeolitic imidazolate frameworks (ZIF-8) blended with the polysulfone (PSf) asymmetric membranes. The gas transport properties (H(2), CO(2), N(2), and CH(4)) of MMMs with a ZIF-8 loading up to 10 wt% were tested and showing significant improvement on permeance of the light gases (e.g., H(2) and CO(2)). Moreover, the depositional polydopamine (PDA) layer further enhanced the ideal H(2)/CO(2) selectivity, and the PDA-modified MMMs approach the Robeson upper bound of H(2)/CO(2) separation membranes. Hence, the PDA post-modification strategy can effectively repair the defects of MMMs and improved the H(2)/CO(2)selectivity.