Transesterification Kinetics, Thermodynamic Modeling, and Emission Profiles of Biodiesel from Hevea brasiliensis Seed Oil

International Journal of Chemistry | Vol. 6, No. 9, September 2015 | pp. 65–72

DOI: 10.46882/2015/IJC/000084

Article Type: Original Research Paper

Title: Transesterification Kinetics, Thermodynamic Modeling, and Emission Profiles of Biodiesel from Hevea brasiliensis Seed Oil

Names of Authors: M. C. Okonkwo¹, L. H. Nguyen²*

Authors’ Affiliations:
¹Department of Industrial Chemistry, Enugu State University of Science and Technology, Enugu, Nigeria.
²Department of Chemical Engineering, Ho Chi Minh City University of Technology, Ho Chi Minh City, Vietnam.

Abstract: Utilizing non-edible agricultural waste seeds as chemical feedstocks for alternative fuel synthesis promotes green energy targets without competing with food supplies. This study investigates the transesterification kinetics and chemical properties of biodiesel synthesized from rubber (Hevea brasiliensis) seed oil. Because of an elevated initial free fatty acid content (6.12 mg KOH/g), a two-step acid-base catalyzed transesterification route was deployed. The first step reduced the acid value below 1.0 mg KOH/g using 1.5% v/v sulfuric acid in methanol, followed by standard base-catalyzed transesterification with potassium methoxide. Fatty acid methyl ester (FAME) yield was optimized at 94.2% using a 6:1 methanol-to-oil molar ratio, a catalyst concentration of 1.0 wt% KOH, and a process temperature of 60°C for 90 minutes. Kinetic analysis confirmed that the transesterification process followed pseudo-first-order reaction mechanics with an activation energy of 42.6 kJ/mol. Fuel properties of the prepared biodiesel, including kinematic viscosity (4.25 mm²/s at 40°C), flash point (162°C), and cetane number (51), matched international ASTM D6751 regulatory specifications. Diesel engine tests using a B20 blend showed a 14.5% reduction in particulate emissions compared to conventional diesel.

Keywords: Hevea brasiliensis; Biodiesel; Transesterification; Reaction kinetics; Activation energy; Kinematic viscosity

Manuscript Timeline: Received: March 04, 2015; Revised: May 11, 2015; Accepted: June 20, 2015; Published: September 09, 2015.

Citation: Okonkwo, M. C., & Nguyen, L. H. (2015). Transesterification Kinetics, Thermodynamic Modeling, and Emission Profiles of Biodiesel from Hevea brasiliensis Seed Oil. International Journal of Chemistry, 6(9), 65–72.

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