Solubility of l-asparagine monohydrate in water and water-isopropanol mixed solvents: Measurements and thermodynamic modelling

• Solubility data of l-asparagine monohydrate in pure water and various water –isopropanol mixtures are presented.
• The experimental solubility data are correlated well by both NRTL and UNIQUAC models.
• Heat of fusion is considered as additional adjustable parameter for both the models.

The solubility of l-asparagine monohydrate (LAM) in pure water and various water-isopropanol mixtures is determined in the temperature range from 298.15 K to 333.15 K using gravimetric method. The solubility of LAM increases with increasing temperature at a given solvent composition within the temperature range studied, and decreases with increasing isopropyl alcohol(IPA) ratio over the same temperature range for water-IPA mixture. The NRTL and UNIQUAC framework with adjustable binary parameters were used to correlate the experimental solubility data and the computed solubilities are in good agreement with experimental observations. The heat of fusion for LAM was considered as an additional parameter for both the models and was estimated along with binary parameters using experimental solubility data and a nonlinear regression method. The dissolution enthalpy and dissolution entropy of the solution of LAM in pure water and water-IPA mixtures were also obtained using van't Hoff equation.

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