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In this work, the heating profile of water, dimethyl sulfoxide (DMSO), acetonitrile (CH3CN) and ethanol (EtOH) and their solutions containing monocationic (CnMIMBr, n = 4, 6, 8, 10, 12, 14 and 16) and dicationic (di-CnMIMBr, n = 4, 6, 8 and 10) imidazolium-based ionic liquids (ILs) were evaluated under ultrasound irradiation. Similarly, ILs (CnMIMBr, n = 4, 8 and 14) with the BF 4 − anion and inorganic salts, such as NaBr and NaCH3CO2 were also evaluated. The results showed that water and DMSO have a linear heating profile; while CH3CN and EtOH have a logarithmic profile. In general, the IL-containing solutions heated up a little faster than the pure solvents, which indicates that the cationic moiety of the ILs did not cause notable changes in the heating profile of the solvents. The IL concentration and the consequent dissociation effects on this were not observed in any of the experimental conditions tested. The addition of NaBr and NaCH3CO2 changed the heating profile of EtOH, resulting in a linear profile. Additionally, our results confirmed that experimental parameters, such as irradiation amplitude and solution volume, significantly change the heating profile of solvents. Finally, under conventional heating and stirring (silent experiments), the heating profile of the pure solvents and the IL-containing solvents indicated that, under ultrasound, the cavitation process makes the heating faster and more efficient. Determination of the dissipated power reflected the solvent’s heating profile more than its heat capacity; therefore, the heating rate in ultrasound reveals the cavitation effects in the particular medium. These results are important because they show that the catalytic effects of ILs in chemical reactions or the solvent effects in micro extraction processes under ultrasound irradiation can be retained without raising the temperature and without decomposition of the ILs or products.

Graphical abstract, Highlights • US effect on fluconazole emulsion containing imidazolium-based ionic liquids was studied. • US-prepared emulsions had a smaller droplet size and polydispersity than mechanical stirring. • Higher amplitude US improved the encapsulation efficiency more than concentration of surfactant. • US modify the shape of the droplets (spherical or crystalline) of the emulsions with C16MIM[Br]. • An increase in energy was favorable to the encapsulation process., The aim of this work was to evaluate the influence of US on the properties of the fluconazole emulsions prepared using imidazolium-based ILs ([Cn C1im]Br). The effects of the preparation method (mechanical stirring or US), US amplitude, alkyl chain length (of [C12C1im]Br or [C16C1im]Br), and IL concentration on the physicochemical properties were evaluated. Properties such as droplet size, span index, morphology, viscosity encapsulation efficiency, and drug release profile were determined. The results showed that US-prepared emulsions had a smaller droplet size and smaller polydispersity (Span) than those prepared by mechanical stirring. Additionally, the results showed that emulsions prepared with [C16C1im]Br and US had spherical shapes and increased stability compared to emulsions prepared by MS, and also depended on the IL concentration. The emulsion prepared by US at 40% amplitude had increased encapsulation efficiency. US provided a decrease in the viscosity of emulsions containing [C12C1im]Br; however, in general, all emulsions had viscosity close to that of water. Emulsions containing [C16C1im]Br had the lowest viscosities of all the emulsions. The emulsions containing the IL [C16C1im]Br had more controlled release and a lower cumulative percentage of drug release. The IL concentration required to prepare these emulsions was lower than the amount of conventional surfactant required, which highlights the potential synergic effects of ILs and US in preparing emulsions of hydrophobic drugs.