Preparation Of Aminosilane Modified Graphene Oxide Membrane And Study On CO₂ Separation Performance

In recent years,due to the continuous improvement of global industrialization,the greenhouse effect caused by the huge amount of CO2 emissions has become more and more severe.Therefore,developing efficient carbon capture technology has become a hot spot in the field of scientific research.Membrane separation technology is now considered as a promising approach to capture CO2 owing to the advantages of low cost,low energy consumption and small ecological footprint.The development of separation membrane materials with high permeability,high selectivity and high stability is the key to the successful application of membrane technology.In this study,graphene oxide(GO)was used as the major material to construt mixed matrix membranes and nanochannel composite membranes respectively.The research results are as follows:Membrane interface regulation and transport mechanism intensification:Mixed matrix membranes(MMMs)are restricted by the non-ideal interfacial morphologies which lead to the weakened gas separation performances and mechanical strength.We fabricated MMMs by introducing aminosilane functionalized graphene oxide(f-GO)nanosheets into Pebax(?)1657 matrix.The introduction of f-GO decreased the crystallinity and increased chain mobility of Pebax matrix.And benefiting from the improved filler dispersion,semi-interpenetrating network structure formed by Pebax chains and the Si-O-Si network in the interface,and the high intrinsic mechanical strength of GO,the MMMs exhibit a 1.7-times higher Young’s modulus and 1.1-times higher break strength.The amino groups on GO help to construct a facilitated transport pathway along the polymer-filler interface.With greatly improved CO2 separation performances in dry state,the membranes exhibited even higher performances in humidified state.Particularly,Pebax/f-GO-0.9%membrane showed a high CO2 permeability of 934.3 Barrer,and a CO2/CH4 selectivity of 40.9,a CO2/N2 selectivity of 71.1,surpassing the 2008 Robeson upper bound.Interlayer transport channel regulation and transport mechanism intensification:The construction of efficient and stable transport channel in gas separation membrane is one of the key factors to improve membrane performance.The ideal channel should have good CO2 affinity and appropriate size to achieve synergistic strengthening of the CO2 transport mechanisms.We assembled the graphene oxide nannosheets and organicsilanes layer by layer on polyethersulfone(PES)microporous membranes by vacuum filtration.The mixture of APTS and TEOS was introduced as intercalation molecules between the layers of GO nanosheets.On the one hand,the introduction of organosilane can effectively regulating the size of transport channels,enhancing the diffusion of the membrane;on the other hand,amino groups from APTS can provide CO2-philic sites,enhancing the solubility of the membranes.Both of the permeability and selectivity of the composite membrane were significantly improved.Particularly,GO-APTS-TEOS(4)/PES membrane showed a CO2 permeability of 74.2 GPU and a CO2/CH4 selectivity of 30.1,which is quite promising in carbon capture.