Supercritical Methanol Extraction and Transesterification of Jatropha Curcas L. Seeds for the Production of Biodiesel – Process Parameters Study

In this work, optimization of supercritical methanol extraction and transesterification for the production of biodiesel was investigated using Jatropha curcas L. seeds. Several important process parameters including heat pre-treatment (45°C-105°C for 12 and 24 hours), particle size (0.5 mm-2.0 mm) and temperature (200°C-300°C) were being studied by varying one factor at a time. The experiment was carried out in a high pressure batch reactor and supercritical methanol served both as the oil-extraction solvent as well as esterification/transesterification reagent which proceed simultaneously in the reactor. Co-solvent was required to accelerate the initial oil extraction phase and to improve the overall kinetic of the reaction. Fatty acid methyl ester (FAME) or biodiesel yield was calculated in relation to the total extracted oil obtained from n-hexane Soxhlet extraction for 24 hours. The highest efficiency for the process to obtain the highest biodiesel yield was at 108.5% with the following optimized conditions: 90°C heat pre-treatment temperature for 12 hours, ≤1.0 mm particle size, 300°C temperature, 60 min reaction time, 10.0 ml/g solvent to solid ratio and 2.5 ml/g co-solvent to solid ratio. Optimization of the process was important to compare its process intensity with other biodiesel production methods to produce biodiesel. The results from this experimental work proved that the above catalyst-free biodiesel production method had high potential to be further investigated for commercialization.