Liquid–liquid
equilibrium study was performed on the eight
ternary systems containing binary azeotrope mixtures (n-heptane + n-amyl alcohol or isoamyl alcohol) and
deep eutectic solvents at 298.15 K and 101 kPa. In order to evaluate
the influence of structure of the constituent components on the phase
equilibria, the ternary systems were systematically analyzed. In this
research, four choline chloride based deep eutectic solvents (ChCl-DESs)
were synthesized for separation of the amyl alcohols from a hydrocarbon
(n-heptane). The prepared DESs were choline chloride
+ ethylene glycol (DES1; 1:2 mol ratio), choline chloride + propylene
glycol (DES2; 1:3 mol ratio), choline chloride + 1,4-butylene glycol
(DES3; 1:4 mol ratio), and choline chloride + diethylene glycol (DES4;
1:4 mol ratio). The Othmer–Tobias equation was applied to check
the reliability of the tie-line compositions. The measured equilibrium
data were correlated by the NRTL model, and the binary interaction
parameters were determined. The consistency of the model parameters
was validated by topological analysis connected to the Gibbs tangent
principle. Distribution coefficients and separation factors were obtained
from the tie-line data in order to evaluate the capacity of the studied
deep eutectic solvents. The obtained solute distribution coefficients
were found to be almost similar for all the studied ternary systems.