CO₂-facilitated transport through Poly(N-vinyl-γ-sodium aminobutyrate-co-sodium acrylate)/polysulfone composite membranes

Poly(N-vinyl-γ-sodium aminobutyrate-co-sodium acrylate) (VSA-SA)/polysulfone (PS) composite membranes were prepared for the separation of CO₂. VSA-SA contained secondary amines and carboxylate ions that could act as carriers for CO₂. At 20°C and 1.06 atm of feed pressure, a VSA-SA/PS composite membrane displayed a pure CO₂ permeation rate of 6.12 × 10^-6 cm³(STP)/cm ² s cmHg and a CO₂/CH₄ ideal selectivity of 524.5. In experiments with a mixed gas of 50 vol % CO₂ and 50 vol % CH₄, at 20°C and 1.04 atm of feed pressure, the CO₂ permeation rate was 9.2 × 10^-6 cm³ (STP)/cm ²s cmHg, and the selectivity of CO₂/CH₄ was 46.8. Crosslinkages with metal ions were effective for increasing the selectivity. Both the selectivity of CO₂ over CH₄ and the CO₂ permeation rate had a maximum against the carrier concentration. The high CO₂ permeation rate originated from the facilitated transport mechanism, which was confirmed by Fourier transform infrared with attenuated total reflectance techniques. The performance of the membranes prepared in this work had good stability.