Influence of temperature on the liquid–liquid equilibria containing two pairs of partially miscible liquids: Water+furfural+1-butanol ternary system

In order to show the influence of the temperature on the liquid–liquid equilibria for water+furfural+1-butanol ternary system, the solubilities and equilibrium data starting at 298.15 K have been measured. Between 298.15 K and 376.6±0.5 K, binodal band type curves are present, but above this last value, two separate binodal curves appear. The solubility data for water+furfural binary system is also reported. From the solubility curve, the upper critical solution temperature (UCST) was interpolated: 396 K and mass fraction of water equal to 0.49. When the temperature is decreased below the lower CST, the ternary system presents two binodal curves expanding toward each other until they meet with a common plait point at the lowest point on the ridge (saddle point, or col), which is situated at 376.6±0.5 K with a ternary composition: w1=0.64; w2=0.21 and w3=0.15. Tie-line data were satisfactorily correlated by the Othmer and Tobias method on a mass fraction basis, and their plait point coordinates were estimated when two separate binodal curves were present. From experimental distribution coefficients and selectivities, 1-butanol appears to be a good solvent for extraction purposes, particularly when the process is carried out at room temperature.