Biodiesel Preparation from Aleurites Moluccanus and Croton Megalocarpus Oils

This project was based on preparation of biodiesel by conventional method using oils from croton megalocarpus and aleurites moluccanus (candlenut) and determination and comparison of physicochemical properties of the oils and their resultant biodiesels. The need for large scale production of biodiesel is driven by significant harmful emission of fumes by burning petrol for road transport diminishing crude oil reserves and soaring prices of petroleum based fuels.

The objective of this study was to prepare biodiesel from candlenut and croton oils and determine and compare physicochemical properties of the biodiesels. Oil extraction was carried out using Soxhlet solvent extraction apparatus and mechanical screw oil press machine at Kenya Industrial Research and Development Institute (KIRDI). Oil yields were in range of 48-59% and 30-38% for candlenut and Croton megalocarpus, respectively.

Preliminary tests on oil which include specific gravity, saponification value, viscosity and acid value were done to ascertain the quality and suitability of the above oils for biodiesel production. The neat candlenut oil was found to have a high acid value of 19.71mgKOH /g while that of croton oil was found to be relatively lower at 6.19 mg KOH/g. The saponification values were 126 and 196 mgKOH/g for croton and candlenut respectively.

Transesterification of heated croton oil was carried out using methanol and 1%wt/wt KOH as the catalyst in a jacketed reactor for 1 hr at the reaction temperatures of 60 degree Celsius, the yield was 81.4%. Biodiesel of candlenut was prepared using a two stage process which involved both esterification (pre-treatment stage) and transesterification processes and gave a yield of 77.3.

The physical properties studied for the neat biodiesel for both candlenut and Croton megalocarpus were within the range specified by American society for testing of materials (ASTM) and Kenya Bureau of Standards (KEBS). The tests included calorific value using bomb calorimeter, flash point using pensky matern closed-cup apparatus, kinematic viscosity using Ostwald viscometer, specific gravity using density bottle, cloud point and pour point using cloud point and pour point apparatus and acid value using volumetric titration.

The calorific values of the B100 were 35.28 and 36.19 MJ/kg for croton and candlenut respectively against 43.38 MJ/Kg for Diesel fuel (DF). The Acid numbers of the B100 were 0.42 and 0.56 mg KOH/g for croton and candlenut respectively which were below the 0.8 mgKOH/g set by ASTM. Kinematic viscosities of Fatty acids methyl esters (FAME) at 40 °C were 4.8702 and 4.56 mm2/s for Croton and candlenut which were close to that of DF at 2.56 mm2/s and were within range of 1.9-6 mm2/s set by ASTM. The neat oils had higher flash point which significantly reduced to 150 and 159 °C for candlenut and croton respectively while that of DF was found to be 68 °C. The cloud points and pour points of the neat biodiesels were also found to be within acceptable limits as set by ASTM.  This study shows that biodiesel of candlenut and croton oil has similar physicochemical properties compared to those of diesel fuel hence can be used as a blend with the diesel fuel without need of modification of the engine.

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