Experimental measurement and correlation of the solubility of aloe-emodin in seven pure solvents

• Aloe-emodin is a bioactive anthraquinone compound.
• The solubility of aloe-emodin increases with an increase in temperature.
• 1-Pentanol is a suitable solvent for industrial preparation of aloe-emodin.
• Two models were well correlated the solubility data.

The solubility of aloe-emodin in seven pure solvents namely water, methanol, ethanol, 1-propanol, 1-butanol, 2-butanol, and 1-pentanol was measured by a static analytic method. The measurements were carried out over the temperature range from (278.15 to 318.15) K at 5 K intervals under atmospheric pressure using a UV/vis spectrophotometer analysis. The effects of experimental temperature and solvent type on the solubility are discussed. The relative solubility of aloe-emodin in seven solvents was determined in elevated order to be xwater < xmethanol < xethanol < x2-butanol < x1-propanol < x1-butanol < x1-pentanol. The experimental result shows that 1-pentanol could be a suitable solvent for industrial preparation of aloe-emodin. The experimental solubility values were correlated with the modified Apelblat and λh models. It was found that the two empirical thermodynamic models can satisfactorily correlate the solubility of aloe-emodin in the seven solvents over the range of temperature studied.

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