Extraction of Crude Rubber Oil from Rubber Seed and Production of Biodiesel

Abstract

Biodiesel is a mono alkyl ester of long chain fatty acids derived from renewable feed stocks, such as vegetable oils or animal fats, for using in compression ignition engine. Studies were carried out to extract non-edible crude rubber oil from rubber seed and to produce potential biodiesel from it. Crude rubber oil was extracted by Soxhlet extraction process with n-hexane solvent and also mechanically extracted by using continuous screw expeller. Due to its high free fatty acid (3.89% FFA) content, the crude rubber oil was processed in two steps. The acid-catalyzed esterification and followed by the base catalyzed transesterification. The acid-catalyzed esterification reaction was carried out with concentrated H2SO4 acid and ethanol-to-oil ratio. The production of biodiesel involved the transesterification of treated rubber oil with ethanol in the presence of a base catalyst (KOH) to yield ethyl ester as a product and glycerine as a by-product. The first step reduces the FFA level from 3.89% to 1.1% in one hour at 50oC for 40% w/w ethanol-to-oil ratio with 1% w/w H2SO4. After the reaction the mixture was stagnated for an hour and ethanol-water upper layer was discarded. The second step convert the product into biodiesel and glycerol through transesterification using 30% w/w ethanol-to-oil and 0.8% w/w KOH to oil at 65oC. The maximum biodiesel yield achieved at rate of 89.36% within one hour and the glycerol concentration in the by-product (glycerol layer) obtained after duel step transesterification was found 18.82%.