Synthesis of the novel symmetric buckypaper supported ionic liquid membrane for the dehydration of ethylene glycol by pervaporation

• Synthesis of SILM by using BP as porous support to form a so-called BP-SILM.
• The use of BP increase the amount of the immobilized [Bmim][BF4]–PVA.
• The [Bmim][BF4] significantly improve BP-SILM pervaporation performance.

In this study, a novel symmetric supported ionic liquid membrane (SILM) was prepared by infiltrating 1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4] into a buckypaper (BP) to form a so-called buckypaper supported ionic liquid membrane (BP-SILM). The [Bmim][BF4] was blended with polyvinyl alcohol (PVA) prior to the infiltration. The role of BP as a support can effectively entrap the infiltrated [Bmim][BF4]–PVA in the interstitial pores and supply the necessary mechanical stability for the resulting BP-SILM. The BP-SILM structure, in which the membrane and support phases were merged into a single layer, was found to be different from that of conventional asymmetric membranes. The BP-SILM structure allows the formation of a thinner symmetric membrane without compromising its mechanical properties. During the application of the BP-SILM in the pervaporation process to dehydrate ethylene glycol aqueous solution, the presence of BP and [Bmim][BF4] was observed to significantly enhance the separation performance and enhance the intrinsic membrane permeability. The BP-SILM exhibited high pervaporation performance with a permeation flux of 102 g m−2 h−1, a separation factor as high as 1014, and a water permeance of 9046 gpu. The BP-SILM also demonstrated a robust pervaporation performance over an operation of 120 h.