pH and electrical conductivity measurements of aqueous solutions of amino acid-based ionic

Abstract

Ionic liquids are promising materials for several applications. Amino acid based ionic liquids (AAILs) as a sort of a new generation of ionic liquids are recently proposed taking advantage of hydrogen bonding group and low toxicity. Three types of AAILs are examined in this work; namely 1-Octyl-3-Methylimidazolium Glycine [OMIM][Gly], 1-Octyl-3-Methylimidazolium Alanine [OMIM][Ala] and 1-Octyl-3-Methylimidazolium Proline [OMIM][Pro]. The pH and molar conductivity are measured at ambient conditions for AAILs aqueous solutions at different concentrations; specifically 1, 10, 20, and 30 wt.%. The experimental results show that all AAILs solutions are alkaline (pH>7) where [OMIM][Pro] has the highest pH compared to its counterparts. The trend is reversed for molar conductivity as [OMIM][Gly] showed the highest molar conductivity. These results are attributed to the smaller size of [Gly] compared to [Pro] and [Ala]. However, adding AAILs increases the molar conductivity of the water.