Physico-Chemical and Fuel Performance Assessment of Biodiesel Produced from Hevea Brasiliensis Rubber Seed Oil via Catalytic Transesterification

Abstract

: The escalating global energy crisis and environmental degradation necessitate sustainable alternatives to petroleum-based fuels. This study investigates the comprehensive characterization and performance evaluation of biodiesel produced from Hevea brasiliensis (rubber) seed oil through catalytic transesterification. Rubber seeds were collected, dried, and mechanically processed, followed by solvent extraction using n-hexane in a Soxhlet apparatus. The extracted oil exhibited physicochemical properties including specific gravity of 0.804 g/cm³, density of 0.8201 g/cm³, acid value of 39.30 mg KOH/g, free fatty acid content of 19.65%, peroxide value of 33.84 meq/kg, saponification value of 171.91 mg KOH/g, and iodine value of 131.42 g I₂/100g. Biodiesel production was achieved through base-catalyzed transesterification using ethanol as the alcohol donor and potassium hydroxide as the catalyst, yielding 90% conversion efficiency. The produced biodiesel demonstrated favorable fuel quality parameters: flash point of 110°C, cloud point of 4°C, pour point of 1°C, kinematic viscosity of 4.32 mm²/s, density of 915.56 kg/m³, and calculated cetane number of 93.33. Comparative analysis with ASTM D6751 biodiesel standards and ASTM D975 diesel specifications revealed that the rubber seed oil biodiesel meets most critical fuel quality requirements, with superior flash point characteristics ensuring enhanced safety during storage and handling. The elevated acid value (89.76 mg KOH/g) and free fatty acid content (44.88%) suggest the necessity for pre-treatment optimization to minimize catalyst consumption and soap formation during transesterification. The study demonstrates that H. brasiliensis seed oil represents a viable non-edible feedstock for sustainable biodiesel production, offering advantages in terms of availability, renewability, and compatibility with existing diesel engine infrastructure. The findings contribute to the expanding knowledge base on alternative fuel sources and support the transition toward energy independence and environmental sustainability in tropical regions where rubber cultivation is prevalent.