Sustainable Biodiesel Production from Tropical Almond Oil: Optimization and Quality Enhancement via Response Surface Methodology
Author
Ogunsola Joseph Temidara Oludahunsi, Peter O. Muwarure
Abstract
The dependence on fossil fuels in developing countries such as Nigeria has prompted the pursuit of sustainable, renewable energy options. This research examines the optimization and quality enhancement of biodiesel derived from tropical almond (Terminalia catappa) seed oil via response surface methodology (RSM). Oil was obtained using Soxhlet extraction with n-hexane, yielding an oil with a low free fatty acid content (0.185%) and negligible water content (0.02%), rendering it suitable for single-stage alkali-catalysed transesterification without acid pre-treatment. A Box-Behnken design was used to assess the effects of temperature (50-70°C), catalyst concentration (0.3-0.7 wt% KOH), and methanol-to-oil ratio (3:1-9:1) on biodiesel yield. The resulting biodiesel was characterized according to ASTM D6751 and EN 14214 standards. Optimal parameters were established at 60.5°C, 0.55 wt% KOH, and a methanol-to-oil ratio of 6.2:1, giving a predicted maximum yield of 94.8%, experimentally confirmed at 94.5 ± 0.3%. The biodiesel demonstrated favorable fuel properties: kinematic viscosity of 3.21 mm²/s, cetane number of 51.77, flash point of 121.6°C, acid value of 0.28 mg KOH/g, and sulphur content below 10 ppm, all within international limits. This study shows that tropical almond seed oil, an underutilized, non-edible resource, is a viable feedstock for high-quality biodiesel synthesis, and that RSM-based optimization provides a robust framework for process scale-up, supporting affordable, clean energy (SDG 7) and climate action (SDG 13).
Keywords
biodiesel; transesterification; tropical almond oil; response surface methodology; Box-Behnken design; non-edible feedstock
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