Novel CO2 separation membranes with functionalized nanofillers
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In this work, a series of GO-based and nanocellulose-based nanoparticles were successfully functionalized through the EDC-catalyzed amide forming reaction, which confirmed by the new generated amide bond on FTIR spectrums and the concentrated nitrogen content on the EDX mapping. The similar morphology of nanoparticles before and after functionalization can be observed from STEM images. Dry samples of polymer-functionalized nanocellulose possess obvious ductile tactility compared with the brittle nanocellulose. Significantly improved thermal stability and decreased crystallinity also have been observed from those polymer-functionalized nanocellulose, suggesting the potentially superior processing properties on a larger scale. Above functionalized nanoparticles were blended into two kinds of polymer matrix, 3% PVA and 1% SHPAA respectively and successfully coated as ultra-thin membranes on PVDF support. The gas separation performance of nanocomposite membranes in our work were compared with Robeson upper bond.Compared with neat PVA membrane, both CO2 permeance and CO2/N2 selectivity of neat SHPAA/PVA membrane approached the Robeson upper bond considerably, owing to the facilitated transport mechanism. The best separation performance (the point nearest to Robeson upper bond) among all kinds of hybrid membranes was observed from the SHPAA/PVA matrix containing 1 wt% GO-PEG, thanks to the extraordinary CO2/N2 selectivity. GO-based nanocomposite membranes exhibit the tendency of moving the membrane performance up and down along the direction of upper bond line (either high selectivity low permeance or on the contrary), while nanocellulose-based composite membranes generally display the current of moving toward the target region, especially those in the PVA matrix. Therefore, polymer-functionalized nanocelluloses are considered as promising nanofiller materials for producing high performance, defect-free hybrid membranes.