Thermodynamic models for Alloxan solubility in various solvents at different temperatures

The solubility of Alloxan in methanol, ethanol, ethane-1, 2 diol, water, acetone and tetrahydrofuran was measured by gravimetric method over a temperature range (293.15 to 323.15) K at atmospheric pressure. The solubility increases non-linearly with temperature in all the studied solvents. Further, in protic solvents, solubility is maximum in methanol and minimum in ethane-1, 2 diol whereas in the selected non protic solvents, solubility is greater in tetrahydrofuran than in acetone. The experimental data were correlated with modified Apelblat and Buchowski-Ksiazczak equations. The calculated results show good agreement with the experimental data. Some apparent thermodynamic parameters such as dissolution enthalpy, Gibb's free energy, and entropy of mixing have also been calculated. The evaluated thermodynamic parameters are found to be positive. The positive enthalpy and Gibb's free energy indicate endothermic and spontaneous dissolution of compounds. The positive entropy suggests entropy-driving dissolution process.