Highly permeable ionic liquid 1-butyl-3-methylimidazoliumtetrafluoroborate (BMIMBF4)/CuO composite membrane for CO2 separation

Abstract

An ionic liquid (IL) 1-butyl-3-methylimidazoliumtetrafluoroborate (BMIM⁺BF₄⁻)/CuO composite was prepared for CO₂ transport membranes. CuO nanoparticles (NPs) were successfully generated in BMIM⁺BF₄⁻. The formation of CuO NPs was ascribed to the favorable interaction between the ions of BMIM⁺BF₄⁻ and the surface of the CuO particles. To confirm the coordination behavior of the BMIM⁺BF₄⁻/CuO membrane, TGA and FT-Raman spectroscopy were employed. The ideal CO₂/N₂ selectivity in the case of the composite material was 21.0, with a CO₂ permeance of 52.4 GPU, while the neat BMIM⁺BF₄⁻ membrane showed a selectivity of 5.0 and a CO₂ permeance of 17.0 GPU. The enhanced separation performance was attributed to (1) the synergistic effect of well-dispersed CuO nanoparticles, resulting in enhanced CO₂ solubility due to the increased surface of the oxide particle layer and (2) the abundant free ions in BMIM⁺BF₄⁻.