THE ESTERIFICATION OF TARTARIC ACID WITH ETHANOL - KINETICS AND SHIFTING THE EQUILIBRIUM BY MEANS OF PERVAPORATION

In this study the kinetic parameters have been established for the esterification of tartaric acid with ethanol. Both concentration-based as well as activity-based reaction rate constants and equilibrium constants have been determined. The activity-based data have been determined using UNIFAC activity coefficient estimations. It can be concluded that reaction rate constants determined in dilute solutions are capable of describing the reaction in a concentrated environment. This applies both for the activity-based description as well as for the concentration-based description. Although the activity coefficients involved differ significantly from unity, the effects of the individual activity coefficients are mutually compensated. Therefore, it is also possible to predict the reaction correctly when the concentration-based parameters are used. When pervaporation is used to remove the water produced in this reaction, the equilibrium composition can be shifted significantly towards the formation of the final product diethyltartrate. The membrane surface area to be installed has a clear optimum: when AIV is chosen too low the water removal is too slow and when AIV is chosen too high, too much of the ethanol is removed also.