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Solubility and thermodynamics of vitamin C in binary liquid mixtures involving water, methanol, ethanol and isopropanol at different temperatures
Abstract Vitamin C also known as ascorbic acid is an important compound for different fields of knowledge and applications. The development of separation processes and reaction media requires experimental information concerning solid-liquid equilibrium of the organic acid in different pure substances and mixtures. With the intention of raising solubility data, this research aims to perform a study of phase equilibrium involving vitamin C in mixtures formed by water/ethanol, water/isopropanol, methanol/ethanol, methanol/isopropanol and ethanol/isopropanol. The experiment was conducted throughout the molar composition range of the binary solution at the temperatures of 293.15 K, 303.15 K, 313.15 K and 323.15 K. The Jouyban-Acree model was applied in order to correlate the experimental solubility data and the adjustable parameters were calculated as a function of temperature. The experimental results were applied to thermodynamic relations to determine standard functions of dissolution. The increase of temperature leads to a larger amount of dissolved vitamin C. The solubility is also dependent on the solution concentration and that is interconnected with the dielectric constant of the binary solution. The Jouyban-Acree model is able to correlate the experimental data satisfactorily and the standard thermodynamic quantities of dissolution agree with the interpretation of the behavior experimentally observed.
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