(351a) Application of Supported-Ionic-Liquid Membranes to a Binary Separation of Nucleobases

Supported-ionic-liquid membranes (SILMs) are an exciting technology due to their use of tunable ionic liquids and their ability to conduct specific separations. In this work, the separation of nucleobases was studied to gain insight on whether SILMs could be used to perform separations via differing hydrogen bonding interactions with solutes. SILMs were fabricated using pressure-driven filtration to fill the pores of a microfiltration membrane with 1-hexyl-3-vinylimidazolium bistriflimide. These membranes were used in a diffusion-cell setup to separate an aqueous mixture of thymine and cytosine (nucleobases); membrane stability in water was also assessed. For a separation of a feed initially containing 21.8 mM of each solute, mass-transfer coefficients of 14.3·10^-9 m/s and 2.7·10^-9 m/s were calculated for thymine and cytosine (separation factor of 4.95). It is likely that differing ionic-liquid/solute hydrogen-bonding interactions accounted for this separation as both solutes and the ionic liquid can hydrogen bond. The mass-transfer coefficients and other experimental parameters were used to model a separation of a different mixture of thymine and cytosine. A stability test indicated significant leaching of ionic liquid from the membrane for the first 115 hours of the test, but the calculated separation factor remained in the range of 4.95-5.82 over the course of 48-hour and 96-hour separation tests. The demonstrated separation suggests the potential of supported ionic liquid membranes to be used for specific separations of nucleobases and similar compounds that can hydrogen bond.