DISQUAC CALCULATION OF THERMODYNAMIC PROPERTIES OF ETHER PLUS 1-ALKANOL SYSTEMS - COMPARISON WITH UNIFAC CALCULATION

The experimental data available in literature on vapour-liqued equilibrium (VLE), excess molar Gibbs energies (G(E)), excess molar enthalpies (H-E), activity coefficients at infinite dilution (gamma(i)(infinity)) and excess molar heat capacities (Cp(E)) of binary mixtures of monoethers or polyethers + 1-alkanols are examined on the basis of the DISQUAC group contribution model. The components in the mixture are characterized by three types of groups of surfaces: aliphatic (CH3 or CH2 groups); hydroxyl (OH group) and oxygen (O group). Interaction parameters for aliphatic/oxygen and aliphatic/hydroxyl contacts have been estimated previously from n-alkane + ether parameters between the oxygen and hydroxyl groups in ether + 1-alkanol systems behave as follows: the dispersive coefficients C-eh,1(DIS) remains constant;the quasi-chemical coefficients C-eh,1(DIS), increase with the size of the monoethers, C-eh,2(DIS) decrease regularly with the alkyl chain length in monoethers and 1-alkanols. The interaction parameters for diethers + 1-alkanols are different but, vary in a similar way; they can be used for describing other polyether +1-alkanol systems. The DISQUAC calculations are compared to those obtained with the modified UNIFAC model (Dortmund). These comparisons show that DISQUAC has more flexibility for correlation and prevision.