Effect of some imidazolium based ionic liquids on the electrical conductivity of L(+)‒lactic acid in aqueous solutions of poly(ethylene glycol)

In this research, influence of some ionic liquids on the electrical conductivity of L(+)‒lactic acid (LaH) have been investigated in aqueous polyethylene glycol 20000 (PEG) solutions. The molar conductivities of LaH in water, aqueous solutions of PEG and (PEG + ionic liquid,1‒hexyl‒3‒methylimidazoliumbromide[C6mim]Br/1‒octyl‒3‒methylimidazolium bromide[C8mim]Br) were measured at T = (288.15-318.15) K. These data have been analyzed by Quint‒Viallard (QV) conductivity equation and the limiting molar conductivities (Λ0) and dissociation constants (KD) were calculated by this equation. The results demonstrate that the values of Λ0 decrease with increasing concentration and longer alkyl chain length of the ionic liquids. The KDvalues were also used to calculate the dissociation standard thermodynamic functions (ΔGD0,ΔSD0, and ΔHD0). The values of ΔGD0 are positive and become more positive at higher temperatures. This implies that the dissociation of the acid is a non spontaneous process in standard state.