Modulations in surface and aggregation properties of non-ionic surfactant Triton X-45 on addition of ionic liquids in aqueous media

Abstract

The effect of hydrophilic ionic liquids (ILs), 1-butyl-2,3-dimethylimidazolium bromide [bdmim][Br] and 1-butyl-3-methylimidazolium bromide [bmim][Br] on the aggregation and surface active properties of non-ionic surfactant, Triton X-45 (TX-45) has been investigated in aqueous media. The surfactant properties such as critical micelle concentration (cmc), aggregation number (Nagg), surface and adsorption parameters were determined by surface tension and fluorescence techniques in TX-45 + IL/water systems. The cmc values were found to be varying at different wt% of IL than in water. The cmc value of TX-45 slightly decreases at lower (0.1) wt% of IL [bdmim][Br] in the medium. In general, with increasing concentration of both ILs in the solution the cmc of surfactant solution increases, thus the surface activity decreases. The surface activity is much lower in aqueous TX-45/IL than in water. The IL [bmim][Br] is found to increase the cmc of surfactant more rather than IL [bdmim][Br]. The aggregation number of aqueous TX-45 solution decreases with increase in wt% of IL. The hydrogen bonding interactions prevailed in presence of IL [bmim][Br] than IL [bdmim][Br], this led to better solubilisation of surfactant monomers in the former. It is demonstrated that ILs [bdmim][Br] and [bmim][Br] can be judiciously used at different wt% for modifying the aggregation properties of TX-45.