Nanocomposite membranes consisting of poly(ethylene oxide)/ionic liquid/ZnO for CO2 separation

Ionic liquid 1-butyl-3-methylimidazoluim tetrafluoroborate (BMIM+BF4−) was used for preparation of composite membranes containing ZnO nanoparticles. A poly(ethylene oxide) (PEO) composite membrane was used for CO2/N2 separation. The high selectivity of ZnO/BMIM+BF4− membrane was already studied. It was found that when ZnO nanoparticles were dispersed with an ionic liquid (BMIM+BF4−), the permeance of CO2 was significantly enhanced to 101 GPU, compared to the neat ionic liquid BMIM+BF4− membrane to show 17.0 GPU. However, the previously studied ZnO/BMIM+BF4− composites separation membrane was the liquid state membrane. In the case of liquid-state membrane, the liquid could be easily penetrated into the membrane support over time. Thus, since the thickness of the membrane becomes thicker, the separation performance of the membrane would be reduced. In order to overcome these problems, the solid-state membranes were required. Therefore, in this study the separation performance of CO2 and N2 by adding ZnO/BMIM+BF4− composites into poly(ethylene oxide) as polymer matrix.