Study On The Liquid-Liquid And Solid-Liquid Equilibria For Recovery Of Maleic Anhydride Using Organic Solvent

In this paper, the liquid-liquid equilibrium data for the binary systemswater+di-n-butyl phthalate (DBP), water+di-n-ethyl phthalate (DEP) andwater+di-isobutyl hexahydrophthalate(DIBE) from 298.2K to 348.2K were measuredby equilibrium method. The mutual solubility of each binary system at eachtemperature was correlated by the NRTL and UNIQUAC models and the correlationaccuracy was very high. Moreover, the NRTL and UNIQUAC models, of which theinteraction parameters were expressed as a function of the temperature from 298.2Kto 348.2K, were respectively used to correlate the LLE data in the range of 298.2K to348.2K for each binary system. The results show that the correlation accuracy of theUNIQUAC model is better than that of the NRTL model and is satisfactory. TheUNIFAC model provided in Pro/â…¡software (version 5.61) was used to predict theLLE data for water with di-n-butyl phthalate, or di-n-ethyl phthalate. Predicted resultswere compared with the experimental results.The solubilities of trans-butenedioic or o-phthalic acid in DBP or DIBE solvent at298.2K, 313.2K, 318.2K, 333.2K and 343.2K were determined by synthetic method.These solubilities were also predicted by using thermodynamic equations. The resultspredicted with the exact melting heat show a good agreement with the experimentalvalues, whereas that predicted using estimated melting heat have large deviation fromthe experimental values.In addition, the distribution equilibria of trans-butenedioic or o-phthalic acid inthe two solvents, water and DBP, at 298.2K, 318.2K and 333.2K were investigated bythe experiments. The distribution coefficients and the distribution constants of them atthese temperatures were obtained by the reduction of the experimental data, while thedissociation constants of them in water at 318.2K and 333.2K were determined.