Mixed matrix membranes incorporated with reduced graphene oxide (rGO) and zeolitic imidazole framework-8 (ZIF-8) nanofillers for gas separation

Mixed matrix membranes (MMMs) were successfully fabricated by incorporating reduced graphene oxide (rGO) and zeolitic imidazole framework-8 (ZIF-8) nanofillers into the polyethersulfone (PES) matrix. The synthesized nanofillers were characterized using XRD, FTIR, TGA and BET before being embedded into PES-based membranes. Their effects on the membrane morphology and gas separation performances at various operating pressure were studied. It was found that the addition of nanofillers led to a significant enhancement in gas permeabilities, particularly when a combination of rGO-ZIF-8 nanofillers was used. However, the CO2 and CH4 permeabilities for 2.0rGO-ZIF-8 MMMs were observed to decrease with increasing operating pressure. This work suggests that the formation of interface voids and membrane defects in the MMMs might lead to the high gas permeabilities and low gas selectivity. The membranes were then coated with polyether block amide (PEBAX) and the O2/N2 and CO2/CH4 selectivities were observed to improve significantly.