Kinetics, thermodynamics and characterization of neem seeds (Azadirachta indica) oil extraction: Extensive study of the processes

Kinetic and thermodynamics studies and the effect of process parameters such as seed average particle size, extraction time and temperature on the extraction of neem seed oil were investigated. Solvent extraction method was used with n-hexane as the solvent. The plot of percentage yield versus time showed that percentage yield increased with increase in time and temperature and decrease in seed average particle size. The highest percentage yield of 54.14% was obtained at optimum conditions of 0.5 mm average particle size, 55 °C temperature and 150 min extraction time. Kinetic study showed that pseudo second order model and Elovich’s model both described the extraction of neem seed oil based on least RMS and SD values. However, pseudo 2nd order gave highest R² value and calculated oil yield at aforementioned optimum conditions. Therefore, pseudo 2nd order model was chosen as best kinetic model for the process. Hyperbolic model, conversely gave no fit to the process. Thermodynamics parameters results $\Delta$H (428.11 KJ/mol), $\Delta$S (1.82 KJ/mol), and $\Delta$G (-168.63 KJ/mol) for extracting oil from neem seed indicate that the process was endothermic, irreversible and spontaneous, respectively. The physiochemical properties show that neem oil has potential in biodiesel application. Fatty acid composition showed that neem seed oil is saturated.