UNIFAC Parameters Research Articles

Liquid—liquid equilibria for ternary systems of water—phenol and solvents: new UNIFAC parameters for interactions between the groups ACOH/COOH and prediction

The UNIFAC group-contribution method is used to predict ternary liquid—liquid equilibrium data presented in a recent paper (Alvarez Gonzalez et al.) for the systems water/phenol/benzene, water/phenol/ethylbenzene, water/phenol/nonanoic acid, water/phenol/ethyl acetate, water/phenol/isopropyl acetate, water/phenol/n-butyl acetate, water/phenol/isoamyl acetate and water/phenol/cyclohexyl acetate at 25°C and water/phenol/n-hexyl acetate at 25, 35 and 45°C. New UNIFAC interaction parameters between the groups ACOH/COOH have been obtained. A comparison between the experimental and predicted values is presented.

Vapor-liquid equilibrium for the systems ethyl formate-methyl ethyl ketone, ethyl formate-toluene and ethyl formate-methyl ethyl ketone-toluene: new unifac parameters for interactions between the groups ACH/HCOO, ACCH 2/HCOO and CH 2Co/HCOO

Vapor-liquid equilibrium data are presented for the binary systems ethyl formate-methyl ethyl ketone (MEK) at 40°C and 50 °C and ethyl formate-toluene at 48°Cand 51°C and for the ternary system ethyl formate-MEK-toluene at 50°C. The measurements were carried out in a recirculation still similar to that proposed by Röck and Sieg. Vapor pressures of the pure substances were measured and the data correlated using the Antoine equation. The binary data were reduced by means of a maximum-likelihood procedure providing the relevant Margules, NRTL and UNIQUAC parameters. New UNIFAC interaction parameters between the groups ACH/HCOO, ACCH 2/HCOO and CH 2CO/HCOO have been obtained. These parameters have been used to predict the ternary data, and a comparison between the experimental and predicted values is presented.

Vapor-liquid equilibria for three aldehyde/hydrocarbon mixtures

Isothermal vapor-liquid equilibrium (VLE) data were measured for the mixtures n-pentane/propionaldehyde, n-heptane/n-butyraldehyde, and isobutyraldehyde/n-heptane at low pressures (100-1000 mmHg) by using a dynamic still. The data reported here are thermodynamically consistent according to the point-to-point consistency test. These data are correlated with five activity coefficient models with parameters estimated from the maximum likelihood method. Also, UNIFAC parameters were estimated for the aldehyde/hydrocarbon functional-group interactions based on the new data.

UNIFAC and infinite dilution activity coefficients

AbstractThis paper deals with the possibility of estimating UNIFAC parameters from infinite dilution activity coefficients. Such activity coefficients can be obtained from gas chromatographic measurements (GLC).In some cases the original UNIFAC equations do not represent very well the variations of the activity coefficients with the concentration in the very dilute regions. It is then not possible to estimate reliable parameters from infinite dilution activity coefficients alone.It is shown that a recent modification of the combinatorial part of the UNIFAC equations allows for the estimation of UNIFAC parameters from infinite dilution activity coefficients for alkane—‐ketone, alkane—‐alcohol, and other mixtures.

Vapor-liquid equilibrium for the binary systems ethylene glycol-n-amyl alcohol and ethylene glycol-isoamyl alcohol

Vapor-llquld equHMwn data for the blnary 8ystems ethylene glycol (1,?4hanedbl) wlth n-amyl alcohol (1-pentanol) and ethylene glycol wlth Isoamyl alcohol (3-methyi-l-bulanol) have been measured at 100 mmHg (13.33 kPa) by ushg a reclrculatbn stll a8 propowd by Rbck and Sleg. From these data, Uquld-phare activity coetfldents were flttod by wing the MarguJes, van Laar, Wilson, and UNIQUAC equations. Vapor-prereure meawr(MIBnts of the pure substances were carrled out, and the data were correlated wlth the Antolne equatlon. The Wnaty data were used for the determlnatlon of UNIFAC parameters.