Mixed Matrix Membranes Composed of Graphene-Based Derivatives as Additives in PVAm for CO₂ Capture

Graphene oxide (GO) mixed matrix membranes (MMMs) that employ facilitated transport of carbon dioxide were prepared and tested for use in postcombustion carbon capture. Two graphene hybrids were synthesized using exfoliated graphene (G) and GO as a basis and were then appended with triethylene glycol (TEG) and N-(2-hydroxyethyl)-ethylenediamine (EDAOH) functional groups, respectively. Unfunctionalized GO nanoparticles were commercially obtained for comparison to the synthesized nanoparticles. The three additives were tested as nanofillers with loadings of 0.5 wt % and, in one case, 1 wt % in polyvinylamine (PVAm) matrices for CO₂ and N₂ gas permeability using humidified mixed gas. MMMs using G-TEG filler particles resulted in improved CO₂/N₂ selectivity, while GO-EDAOH fillers improved both the CO₂ permeability and the CO₂/N₂ selectivity compared to neat PVAm. Unfunctionalized GO fillers resulted in no significant change in gas transport properties. Mechanical properties were also tested. The addition of GO or GO-EDAOH filler particles resulted in improvements in storage modulus as well as higher glass transition temperature, while G-TEG filler particles yielded a less significant change compared to neat PVAm.