Kinetics, thermodynamics and process parameter impact on solvent extraction of oil from Colocynthis vulgaris Shrad (melon) seeds

The effects of process parameters (temperature, time and particle size) on the oil yield as well as their effects on the kinetic and thermodynamic (enthalpy, entropy and free energy) parameters of oil extraction from Colocynthis vulgaris Shrad [melon seed (MS)] were investigated. The highest oil yield of 53.86% (by weight) was obtained at 55 °C, 0.5 mm and 150 min. Results of the physicochemical properties indicated that the viscosity, acidity and flash point were 7.64 Cp, 1.66 mg KOH/g oil and 230 °C, respectively, indicating the potential industrial utilisation of the oil. Chemical composition analysis of MS oil showed that it is composed of 61.89% and 37.99% unsaturated and saturated fatty acids, respectively. The kinetics of MS oil extraction was best described by pseudo second-order model, followed by hyperbolic, Elovich's and parabolic models. However, the power law model failed to give adequate fitting to the experimental data. ΔH, ΔS and ΔG values of the MS oil extraction process were 333.40 kJ/mol, 1.22 J/mol/K and −64.82 kJ/mol, respectively, indicating an endothermic, irreversible and spontaneous process.