Experimental Evidence of the Dependence of Oil Extraction Rate on Extraction Time and Structure of Generative Material

Background: Kinetic and thermodynamic studies of the extraction of oils from pumpkin seeds, sesame seeds and Moringa seeds have been carried out at temperatures of 56 and 54°C. The extraction process was found to be exothermic and the kinetic constants in the three cases determined. It was also observed that the rate of extraction was dependent on extraction time and structural organization of the seeds. The kinetic constants are expected to provide information on the structural organization (crystalline, smectic, nematic or amorphous) of the seeds generating these oils. The enthalpies and entropies of extraction were calculated and a comparison of the kinetic and thermodynamic parameters obtained in the 3 cases was made.

Aim and Objective: This work was designed to extract oils from pumpkin, sesame and Moringa seeds and to determine the kinetics and thermodynnamics of the extraction process at the given temperatures using petroleum ether as solvent.

Methodology: Ten grammes of seeds powder have been introduced in cellulose porous cartridge of 33 X 205 mm and all has been put in soxhlet extractor. In a 1000 mL thrice necked bahloon- flash fitted of a thermometer, 450 mL of petroleum ether (40°-60°c, ϱ=0,65 kg/L) have been introduced as solvent. The fitting out of soxhlet has been done on heating skull cap (mark thermo scientific) in fixing temperature at 56°C(or 54°C for sesame) in balloon flask during a given extraction time. To maintain the temperature constant during the experiment, the heating skull cap has been covered of aluminium paper as heat insulating. The ambient temperature has been kept at 22-23°C. After a given extraction time, the cartridge has been taken up to be dried in the drying oven at 50°C during 24 hours in order to get rid of traces of solvent. The oil-solvent mixture collected in the 1000 mL thrice necked balloon-flask is submitted to rotary evaporator to remove the solvent and the balloon flask with extracted oil is introduced in the drying oven at 105°C during 3 hours to eliminate totally all the traces of humidity.

After this step the balloon flask with oil is cooled in a dessicator and weighed. The difference between the balloon flask containing oil and the empty balloon flask determines the extracted oil mass at a t time in gramme.

Results: The kinetic constants, enthalpies and entropies of the extraction process of the oils from the three different seeds were calculated and compared. In all cases, the rate of oil extraction was found to be directly proportional to time of extraction and structure of the seeds.

Conclusion: The kinetic and thermodynamic study of the extraction of oils from pumpkin, sesame and Moringa seeds show that the extraction was an exothermic balanced phenomenon. The energy thus released by this operation can be used to perform mechanical or electrical work. As for the kinetic constants, they are greater in an amorphous body where the entropy is greater. In such a case, the oil extracted was much more under the same temperature and pressure conditions for a given solvent. Under these conditions, the extraction was dependent not only on time, but also on the structural organization of the material generating the oil.