Nanoparticles Embedded in Amphiphilic Membranes for Carbon Dioxide Separation and Dehumidification.

Abstract

Polymers containing ethylene oxide (EO) groups have gained significant interest as the EO groups have favorable interactions with polar molecules such as H2 O, quadrupolar molecules such as CO2 , and metal ions. However, the main challenges of poly(ethylene oxide) (PEO) membranes are their weak mechanical properties and high crystallinity nature. The amphiphilic copolymer made from PEO terephthalate and poly(butylene terephthalate) (PEOT/PBT) comprises both hydrophilic and hydrophobic segments. The hydrophilic PEOT segment is thermosensitive, which facilities gas transports whereas the hydrophobic PBT segment is rigid, which provides mechanical robustness. This work demonstrates a new strategy to design amphiphilic mixed matrix membranes (MMMs) by incorporating zeolitic imidazolate framework, ZIF-71, into the PEOT/PBT copolymer. The resultant membrane shows an enhanced CO2 permeability with an ideal CO2 /N2 selectivity surpassing the original PEOT/PBT and Robeson's Upper bound line. The nanoparticles-embedded amphiphilic membranes exhibit characteristics of high transparency and mechanical robustness. Mechanically strong composite hollow fiber membranes consisting of PEOT/PBT/ZIF-71 as the selective layer were also prepared. The resultant hollow fibers possess an excellent CO2 permeance of 131 GPU (gas permeation units), CO2 /N2 selectivity of 52.6, H2 O permeance of 9300 GPU and H2 O/N2 selectivity of 3700, showing great potential for industrial CO2 capture and dehumidification.