Cloud point or ionic liquid extraction of furfural from aqueous solution: a comparative study based upon experimental design

The goal of the present work was to compare cloud point extraction and extraction using ionic liquid for the separation of furfural from a dilute aqueous solution. Aqueous solutions of the biodegradable non-ionic surfactant Dehydol LT 7 (equivalent to C15E7) and the pure ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate ([C4C1im]PF6) were investigated as extraction solvents. Phase diagrams of binary (water/surfactant) and pseudo-binary (water/surfactant/solute) systems were plotted. The extraction results were expressed by the following responses: percentage of solute extracted, E (%), residual concentrations of solute and surfactant in aqueous phase (Xs,w and Xt,w, respectively), and volume fraction of coacervate at equilibrium (ϕC). For each parameter, the experimental results were fitted to empirical equations in three dimensions. The aim of this study was to find the best compromise between E and the other parameters (Xs,w, Xt,w, and ϕC, as low as possible). The comparison betw...