Abstract

This study addresses the escalating demand for sustainable energy by investigating biodiesel production
from the non-edible oil of Balanites aegyptiaca (Desert Date) seeds, using a novel bifunctional catalyst
derived from the seed shells. Physicochemical analysis of the extracted oil revealed an acid value of
51.9 mg KOH/g, saponification value of 88.3 mg KOH/g, iodine value of 3.55 g I₂/100 g, peroxide value
of 526.7 meq O₂/kg, moisture content of 7.16%, specific gravity of 0.48, and free fatty acid (FFA)
content of 30.55%, confirming its non-edible, low-cost feedstock suitability. Due to high FFA, a two-step conversion process was employed: acid-catalyzed pre-esterification using a sulfated shell catalyst (H₂SO₄/DDSS), followed by base-catalyzed transesterification using KOH-impregnated DDSS. Gas Chromatography-Mass Spectrometry and Fourier Transform Infrared spectroscopy (notably the
carbonyl peak at ~1740 cm⁻¹) confirmed successful conversion to fatty acid methyl esters. Key fuel
properties, kinematic viscosity (5.3 cSt), cetane number (68.1), flash point (240°C), pour point (12°C),
density (0.85 g/ml), copper strip corrosion (1b), sulfated ash (0.6%), and higher heating value (42.4 MJ/kg), all met ASTM D6751 standards. The study concludes that Desert Date seed oil biodiesel, produced via a waste-derived catalyst, represents a viable, closed-loop valorization strategy for
agricultural residues, offering a compliant renewable energy source.

Key words: Biodiesel, Balanites aegyptiaca, Heterogeneous Catalyst, Transesterification, Fuel Characterization