Evaluation of the Modified Margules Model for Calculation of Activity Coefficient for Acetylsalicylic Acid Solutions in Some Organics Solvents

Monday, November 8, 2010
Hall 1 (Salt Palace Convention Center)
Gustavo D. Maia Sr., Sciences, Federal University of Alfenas - UNIFAL, Alfenas, Brazil and Marco Giulietti, Chemical Engineering, Federal University of Sao Carlos- UFSCar, Sao Carlos-SP, Brazil

As one of the most regularly traded-in medicines in the world, the acetylsalicylic acid has been scarcely researched when in solution. This study is aimed at determining parameters for the modified Margules thermodynamic model for acetylsalicylic acid solutions in ethanol, acetone, propylene glycol, and 2-propanol, in addition to comparing the values of activity coefficient with experimental data. The modified Margules equation for a binary system promotes a good representation for manifold simple liquid mixtures, where the species involved present similar shape, size, and chemical nature. Through adjustments it is possible to conclude that the modified Margules model represents the experimental data more accurately when applied to the binary system acetylsalicylic acid/acetone. The model show good agreement to predict the activity coefficient for the binary system acetylsalicylic acid/ethanol. When binary systems acetylsalicylic acid/2-propanol and acetylsalicylic acid/propylene glycol are studied, the model was not able to predict, with good agreement, the experimental values of activity coefficient as good as for the first ones.

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