Porous silica nanosheets in PIM-1 membranes for CO2 separation

PIM-1-based freestanding mixed matrix membranes (MMMs) and thin film nanocomposites (TFNs) were prepared by incorporating porous silica nanosheets (SN) and exfoliated SN (E-SN) derived from natural vermiculite (Verm) in the PIM-1 polymer matrix. In addition, SN were functionalized by sulfonic acid and amine groups (S-SN and N-SN, respectively) and were also used as fillers for the preparation of MMMs. The gas separation performance was evaluated using CO2/CH4 and CO2/N2 (1:1, v:v) binary gas mixtures. Among freestanding membranes, fresh ones (i.e. tested right after preparation) containing 0.05 wt% functionalized SN and E-SN outperformed the neat PIM-1, surpassing the 2008 Robeson upper bound. At the same filler concentration, fresh MMMs with sulfonic acid-functionalized SN (S-SN) exhibited 40% higher CO2 permeability, 20% higher CO2/N2 selectivity and almost the same CO2/CH4 selectivity as neat PIM-1 membranes. Moreover, after 150 days of aging, these membranes were capable of maintaining up to 68% of their initial CO2 permeability (compared to 37% for neat PIM-1). When prepared as TFN membranes, the incorporation of 0.05 wt% of S-SN led to 35% higher initial CO2 permeance and five times higher CO2 permeance after 28 days

Thin film nanocomposite membranes of PIM-1 and graphene oxide/ZIF-8 nanohybrids for organophilic pervaporation

In this work, thin film nanocomposite (TFN) membranes of super-glassy polymer PIM-1 containing zeolitic imidazolate framework-8 (ZIF-8)/graphene oxide (GO) composites (ZG) have been prepared by dip-coating onto water pre-impregnated polyvinylidene fluoride (PVDF) substrates. Higher flux and improved separation factors as compared to bare PIM-1 thin film composite (TFC) membranes have been achieved in organophilic pervaporation; for an aqueous feed solution with 5 wt% of butanol at 65 °C, a total permeate flux of 7.9 ± 0.69 kg m−2h−1 and a separation factor (βBtOH/H2O) of 29.9 ± 1.99 have been obtained with a TFC membrane containing 0.5 wt% of ZG filler. The pervaporation separation index (PSI) of this membrane (228 kg m−2h−1) is amongst the highest values reported in the literature. This excellent performance is attributed to the formation of a defect-free PIM-1 active layer (<1 μm) and the hydrophobic nature of the ZG fillers.Patricia Gorgojo is grateful to the Spanish Ministerio de Economía y Competitividad and the European Social Fund for her Ramon y Cajal Fellowship (RYC2019-027060-I/AEI/10.13039/501100011033). Boya Qiu would like to acknowledge the China Scholarship Council (CSC, file no. 202006240076)and the University of Manchester for the joint PhD studentship to support her research.Peer reviewe