Valorization of Almond Fruit Residue in Eco-friendly Biodiesel Production

Abstract The increasing global demand for renewable energy solutions brings the need to explore alternative bio-fuel sources to reduce dependency on fossil fuels and mitigate environmental pollution. This study investigated the valorization of almond fruit biomass (Prunus dulcis) as a sustainable feedstock for biodiesel production. The physicochemical properties of the extracted oil were evaluated, and advanced analytical techniques, including Fourier Transform Infrared Spectroscopy (FTIR) and Gas Chromatography-Mass Spectrometry (GC-MS), were used to characterize the chemical composition. The oil content of almond nut, almond kernel, and almond hull was analyzed, with the almond nut yielding the highest bio-oil at 34%, followed by the hull (27.05%) and kernel (25.5%). The findings revealed the presence of significant functional groups such as esters, alcohols, and hydrocarbons, with methyl palmitate (8.06%), n-hexadecanoic acid (30.09%), and oleic acid (17.27%) identified as dominant compounds. Comparative analysis of physicochemical properties demonstrated that esterified almond-derived bio-fuels exhibit improved fuel characteristics, including a reduction in kinematic viscosity from 22.4 mm²/s to 2.63 mm²/s, an increase in oxidative stability, and an enhanced calorific value of 30.87–34.73 MJ/kg. Furthermore, engine test bed evaluations indicated improved combustion efficiency and reduced emissions when compared to conventional diesel. These results highlight the potential of almond fruit residue as a viable and eco-friendly biodiesel source, contributing to the advancement of sustainable energy solutions.