In-situ growth of zeolitic imidazolate framework-67 nanoparticles on polysulfone/graphene oxide hollow fiber membranes enhance CO2/CH4 separation

Zeolitic imidazolate frameworks (ZIFs) are attracting membrane-based gas separation researchers because of their exceptional and tunable physicochemical properties. In this study, a novel approach has been demonstrated to modify hollow fiber membranes (HFMs) by in-situ growth of ZIF-67 nanoparticles on the lumen side of polysulfone/graphene oxide (Psf/GO) HFMs. The formation of ZIF-67 nanoparticles on the HFMs was confirmed by different spectroscopy and microscopy techniques. The gas separation performance was measured by conducting experiments with pure gas and an equimolar mixture of CO2 and CH4, at 25 °C and 1–5 bar pressure. In the single gas permeation studies, ZIF-67 coated HFMs showed CO2/CH4 selectivity of 22.38 ± 0.30, which was almost 3.4 times the selectivity of the pristine HFMs. Furthermore, for equimolar CO2/CH4 mixture, though a slight decrease in CO2 permeance was measured, ZIF-67 coated HFMs exhibited CO2/CH4 selectivity of 44.94 ± 3.00, which was 3.3 times the selectivity of the uncoated HFMs. Interestingly, ZIF-67 coated HFMs maintained their gas separation performance over a long duration. Thus, the novel in-situ grown ZIF-67 on Psf/GO HFMs showed improved CO2/CH4 separation performance, making these modified membranes potentially useful for the practical gas separation applications.