SUSTAINABLE BIODIESEL PRODUCTION: ENZYMATIC CONVERSION OF MORINGA OLEIFERA

Abstract

This study investigates the sustainable production of biodiesel from mature Moringa oleifera seeds, a non-edible and underutilized biomass that does not compete with food resources, thereby supporting food-energy balance and circular bioeconomy goals. Biodiesel was produced via transesterification using Candida antarctica lipase immobilized on functionalized activated carbon (FAC) as a green biocatalyst. Moringa oil was extracted through Soxhlet extraction using hexane, and its physico-chemical properties including acid value, iodine value, density, moisture content, viscosity, and saponification value were characterized to assess its suitability as a sustainable biodiesel feedstock. To enhance enzymatic efficiency and reusability, Candida antarctica lipase was purified and immobilized on FAC treated with various acids (HCl, HNO₃, H₂SO₄), with hydrochloric acid-functionalized FAC (HCl-FAC) showing the highest immobilization capacity (6.022 U/g). Immobilization conditions (time, temperature, pH, agitation) were optimized using One-Factor-at-a-Time (OFAT) screening and Face Centered Composite Design (FCCCD) under Response Surface Methodology (RSM), yielding optimal conditions of 40°C, pH 6, and 24 hours. Further optimization of biodiesel synthesis was performed, considering methanol-to-oil ratio, temperature, catalyst concentration, and reaction time. Maximum biodiesel yield (94.01%) was achieved under optimal sustainable conditions: methanol-to-oil ratio of 4:1, 40°C, 4% catalyst loading, and 24 hours reaction time. The kinetic analysis indicated a pseudo-first order reaction with an activation energy of 43.126 kJ/mol and a frequency factor of 1.758 × 10⁸ min^-¹. Post-reaction, the biodiesel was characterized by its iodine value, acid composition, kinematic viscosity, density, cloud point, and pour point. The fuel properties conformed to ASTM D6751 and EN 14214 standards, confirming their high quality and environmental compatibility. Overall, this study demonstrates a sustainable, efficient, and eco-friendly approach to biodiesel production from Moringa oleifera, reinforcing its potential role in renewable energy strategies and low-carbon fuel alternatives.