Aggregation Behavior of Imidazolium-Based Ionic Liquids in Water

Abstract

Ionic Liquids / Aggregation / UV SpectraThe UV absorption spectra of aqueous solutions of [C 4 mim][Br], [C 4 mim][BF 4 ], and [C 8 mim][Br], along with the differential UV spectra of aqueous [C 8 mim][Br] solutions,were measured at room temperature in this work. It is found that three transformations, denoted respectively as α, β and γ , can occur over the interested concentration range of solutions due to ionic liquid aggregation. Further, the content of ionic liquids and the wavelength of absorption maximum at these transformations are determined, and the implications at each transformation are analyzed. As a result, this paper discusses the effects of imidazolium cation, alkyl chain length and counterion type on the aggregation behavior and the contribution of interactions (such as hydrogen bonds, Coulombic, aliphatic and π-π stacking interactions) to the aggregation of 1-alkyl-3-methylimidazolium salts in water. Moreover, the possible structures of both aggregate and bulk phase in the aqueous solutions of ionic liquids are predicted also.

Recovery of Syringic Acid from Industrial Food Waste with Aqueous Solutions of Ionic Liquids

“…With this type of ILs, the enhancement in solubility is more pronounced at low concentrations of IL, close to the CMC, but seems to quickly saturate at low concentrations, above which a much weaker effect on the solubility of the syringic acid is observed. This behavior was observed by Cláudio et al while evaluating the variation of the solubility of vanillin in aqueous solutions of [C n C 1 im]Cl ILs, with 2 ≤ n ≤ 14, concluding that ILs with shorter alkyl chain lengths ([C n C 1 mim]­Cl, n = 2–6) behave as hydrotropes, whereas ILs with longer alkyl side chains ([C n C 1 im]­Cl, n = 8–14) , behave as surfactants. However, the data corresponding to [C 8 C 1 im]­Cl and [Ch]­[Oct] (cf.…”

The peculiar effect of water on ionic liquids and deep eutectic solvents

“…For [Emim][Cl]-H 2 O system, the investigation by using small-angle neutron scattering technique shows that [Emim][Cl] is homogenously dissolved in water, which is mainly caused by a strong hydration of [Cl] À by water. 238 Zhang et al 239 , b and g) at different IL contents occur within the investigated compositional range. In the very dilute IL solutions (x IL from 0 to a), the anions and imidazolium cations are almost ''free'', and H-bonds are dominant among the hydrated ions.…”

Computational studies of room temperature ionic liquid–water mixtures

“…8 Micelle formation in ILs has been well-studied using experimental techniques. [9][10][11] A rapid decrease in the CMC is observed when the length of the chain is increased. 11 Several computational studies on IL/water mixtures [12][13][14][15][16][17][18] complement these experiments.…”