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Environmentally friendly alternatives have been recently developed focusing on the search for less aggressive, more innovative, and sustainable chemical processes and products. Regarding this, two green options─biobutanol, as the next generation of renewable fuel better than ethanol, and protic ionic liquids (PILs), a class of ionic liquids (ILs), as green design solvents with easier recovery and purification processes─are attracting widespread interest. Looking forward to a more economically feasible and sustainable process, this study mainly investigated biorefinery byproduct-based PILs (acetate and butyrate anions) for n-butanol recovery. For that, liquid–liquid equilibrium (LLE) data of ternary systems composed of water + butanol/acetone + PIL using the cloud-point titration method were determined at different temperatures (293.15 and 323.15 K), and the data were fitted to the nonrandom-two-liquid (NRTL) model to obtain the model binary interaction parameters, yielding RMSD below 1.91%. The PILs studied were 2-hydroxyethylammonium acetate (HEAA), bis(2-hydroxyethyl)ammonium acetate (BHEAA), tris(2-hydroxyethyl)ammonium acetate (THEAA), 2-hydroxyethylammonium butyrate (HEAB), bis(2-hydroxyethyl)ammonium butyrate (BHEAB), and tris(2-hydroxyethyl)ammonium butyrate (THEAB).

In this study, the potential of alkanolammonium-based protic ionic liquid (PIL) aqueous solutions as solvents of Kraft lignin was evaluated. The results showed that the PILs’ anion plays a key role in lignin dissolution, while the cation plays a secondary role. The presence of extra hydroxyl groups in the anion structure negatively affects lignin solubility, while the increase of the cation alkyl chain favors this process. Using mechanical agitation, all tested PILs required 8 h to reach saturation, except for lactate-based PILs (at least 24 h). The efficiency of lignin dissolution was improved with ultrasounds achieving saturation in less than 4 h. Finally, the recyclability of two PILs was herein demonstrated for at least three cycles. Tris(2-hydroxyethyl)ammonium lactate presented the best ability to dissolve Kraft lignin (>47 wt %) among the tested PILs. This result shows the capacity of PILs as excellent media to dissolve lignin.