A new modification of the UNIQUAC equation including temperature dependentparameters

The UNIQUAC equation was modified by introduction of a linear temperature d ependence of the volume and surface area parameters, r(i) and q(i). The slo pe of r(i) and q(i) functions were found to be the same for hydrocarbons an d pyridine. The modified equation was used for prediction of vapor-liquid e quilibria (VLE) in binary mixtures of hydrocarbons and pyridine with hydroc arbons as well as for the prediction of the excess enthalpy (H-E) in binary mixtures formed by pyridine with aliphatic alkanes. The results obtained w ere compared with predictions by UNIFAC and further with UNIQUAC equation a nd its modification involving temperature dependant coordination number z. The proposed temperature dependence of the r(i) and q(i) parameters enables prediction of the VLE at various temperatures and leads to reasonable valu es of H-E. The necessary input reduces to one set of isothermal VLE data. O ne set of UNIQUAC interaction parameters u(ij) is sufficient for representa tion of VLE in a wide range of temperature and to obtain a reasonable predi ction of H-E. (C) 2001 Published by Elsevier Science B.V.