Highly Permeable Polyaniline–Graphene Oxide Nanocomposite Membranes for CO2 Separations AITranslate

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DOI：https://doi.org/10.1021/acsapm.9b00426

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Carbon dioxide (CO2) capture from fossil-fuel-based power plants requires scalable membranes with high CO2 permeability and reasonable CO2/N2 selectivity. Conventional membranes based on polyaniline (PANi) feature a CO2 permeability of 1 Barrer or less, which is unviable for industrial applications such as separating the massive scale of CO2 emissions produced by power plants. Here, we report nanocomposites comprised of the conjugated polymer polyaniline with graphene oxide at different oxidation levels that are blended and drop-cast to form freestanding membranes for gas separations. The added graphene oxide is shown to effectively enhance the gas permeability. These hybrid membranes are characterized by Fourier-transform infrared spectroscopy to indicate clearly the presence of well-dispersed GO in the polyaniline matrix; vertical scanning interferometry and field emission scanning electron microscopy to illustrate the film homogeneity, morphology, and thickness; and thermogravimetric analysis to assess thermal stability. The outcomes highlight composited membranes that are readily scalable, tolerant to slightly elevated temperatures (up to 170 °C), and that feature CO2 permeabilities >700 Barrers and reasonable CO2/N2 selectivities. By applying a doping/dedoping/redoping process using hydrochloric acid (HCl) and ammonium hydroxide (NH4OH), the membrane selectivities can be considerably enhanced. This work thus reports the first synthesis of PANi-based nanocomposite membranes whose permeability begins to approach the upper bound indicated on a Robeson plot.