Search

The incorporation of functionalized graphene oxide (GO) in mixed matrix membrane (MMM) is expected to greatly increase the permeability and selectivity for O2/N2 separation. In the present study, GO functionalized with 3- (Trimethoxysilyl) propyl methacrylate (TMOPMA) was used as inorganic filler and incorporated in to a PVC/pAMPS based MMM to increase the separation efficiency. Membranes of different compositions were synthesized and the best morphology was achieved with 0.5 g of PVC, 1.0 g of pAMPS and 0.015 g of filler. The synthesized membrane and inorganic filler were characterized using SEM, EDS, FTIR, Raman and XRD spectroscopy. Moreover, the gas permeation studies were performed to check the separation factor of synthesized membrane for O2/N2. The maximum permeability achieved for O2 and N2 was 4097 and 3373 barrers, respectively at 5 bar pressure. For the selectivity, a gradual increasing trend was observed with the increase in permeability. The maximum selectivity achieved was 1.215 at 5 bar pressure. The results revealed an increasing trend in selectivity with the increase in permeability of gases across the membrane with the increase in feed gas pressure.

To increase permeability in O2/N2 separation without compromising selectivity, Cu3BTC2 (or HKUST-1) nanocrystals, which possess well-defined channels and high surface area, were used as the filler for mixed-matrix membrane fabrication. The Cu3BTC2 nanocrystals, which were synthesized at room temperature with a facile method, showed desirable physical properties and porosity comparable to those of a commercial Cu3BTC2 adsorbent (Basolite C300). High-quality mixed-matrix membranes without appreciable defects were successfully fabricated with both Matrimid and polysulfone, which are commercial membrane polymers that suffer from poor permeability. Gas permeation testing revealed that 20 wt% Cu3BTC2 nanocrystals loading dramatically improved the O2 permeability of both polymer membranes (106% for Matrimid and 379% for polysulfone), with modest increases in O2/N2 selectivity. A detailed analysis of diffusivity and solubility showed that the overall O2/N2 diffusion selectivity was improved substantially over that of a neat polymeric membrane with the incorporation of Cu3BTC2 nanocrystals. A comparative study with literature data demonstrated that Cu3BTC2 nanocrystals are far more effective than other metal-organic framework fillers tested to increase permeability in O2/N2 separation.

Membrane-based air separation (O2/N2) is of great importance owing to its energy efficiency as compared to conventional processes. Currently, dense polymeric membranes serve as the main pillar of industrial processes used for the generation of O2- and N2-enriched gas. However, conventional polymeric membranes often fail to meet the selectivity needs owing to the similarity in the effective diameters of O2 and N2 gases. Meanwhile, mixed-matrix membranes (MMMs) are convenient to produce high-performance membranes while keeping the advantages of polymeric materials. Here, we propose a novel MMM for O2/N2 separation, which is composed of Matrimid&reg, 5218 (Matrimid) as the matrix, cobalt(II) phthalocyanine microparticles (CoPCMPs) as the filler, and Pluronic&reg, F-127 (Pluronic) as the compatibilizer. By the incorporation of CoPCMPs to Matrimid, without Pluronic, interfacial defects were formed. Pluronic-treated CoPCMPs, on the other hand, enhanced O2 permeability and O2/N2 selectivity by 64% and 34%, respectively. We explain the enhancement achieved with the increase of both O2 diffusivity and O2/N2 solubility selectivity.