Enhanced desulfurization performance and stability of Pebax membrane by incorporating Cu+ and Fe2+ ions co-impregnated carbon nitride

In this study, Cu+ and Fe2+ ions were co-impregnated onto carbon nitride nanosheets via polydopamine chelating, and then incorporated into a Pebax matrix to fabricate the facilitated transport hybrid membranes. The homogeneously dispersed nanosheets disturb the packing of Pebax chains and render the hybrid membrane an appropriate free volume property. The existence of stabilizer Fe2+ on Cu+Fe2+@CNs prevents the disproportionation and oxidation of Cu+, which is an efficient facilitated transport carrier for thiophene via π-complexation in gasoline desulfurization. Accordingly, the hybrid membranes exhibit superior desulfurization performance along with good stability even at high operation temperature. Especially, when the content of Cu+Fe2+@CNs is 5 wt%, the membrane achieves the optimum desulfurization performance with a permeation flux of 13.42 kg/(m2 h) (18.76% higher than that of pure Pebax membrane) and an enrichment factor of 7.11 (28.80% higher than that of pure Pebax membrane) under 60 °C for octane-thiophene model gasoline with thiophene content of 1312 ppm. Besides, the membrane shows good stability in the long-term desulfurization under high operation temperature of 60 °C for 10 days and keeps the stability of incorporated Cu+ for six months. The study offers a facile approach to enhance the carrier stability in high-performance facilitated transport membranes.