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Abstract
ABSTRACTThe global energy crisis and environmental concerns have intensified the search for sustainable fuels like biodiesel. This study presents a systematic optimization of sulfuric acid (HSO) catalyst concentration for biodiesel production from used palm oil. The effect of HSO concentration within the range of 0.25% to 2.0% (ww) on biodiesel yield and key fuel properties was investigated. Results demonstrated that the biodiesel yield increased significantly with catalyst concentration, reaching a maximum of 96.44 0.38% at an optimum of 1.5% (ww) HSO. A further increase to 2.0% resulted in no significant yield improvement, indicating a plateau effect. The biodiesel produced at this optimum condition was analyzed for critical quality parameters. The measured values, acid value (0.20 mg KOHg), flash point (235 C), water content (0.04%), and density (0.89 gcm), were found to be in full compliance with the ASTM D6751 standard. The study conclusively establishes that a 1.5% (ww) HSO catalyst concentration is optimal for the efficient and economical production of high-quality, standard-compliant biodiesel from used palm oil, offering a viable waste-to-energy pathway for regions with abundant palm oil waste.Keywords: Biodiesel, Palm Oil, Transesterification, CatalystINTRODUCTIONThe escalating global demand for energy, driven by population growth and rapid industrialization, continues to exert immense pressure on finite fossil fuel reserves. This, coupled with the volatile economics of petroleum-based fuels and their well-documented environmental impacts, has underscored the urgent need for sustainable and renewable energy alternatives (Changmai et al., 2020, Lamba et al., 2024). Among these alternatives, biodiesel has emerged as a promising substitute for conventional diesel due to its renewability, biodegradability, and superior emission profile, including significant reductions in carbon monoxide, unburned hydrocarbons, and particulate matter (Maulidiyah et al., 2021, Abdulkareem & Nasir, 2024).Biodiesel is chemically defined as fatty acid alkyl esters, primarily Fatty Acid Methyl Esters (FAME), produced via the transesterification of triglycerides derived from vegetable oils, animal fats, or waste cooking oils with a short-chain alcohol, typically methanol, in the presence of a catalyst (Changmai et al., 2020, Cern Ferrusca et al., 2023). The American Society for Testing and Materials (ASTM D6751) standard provides stringent specifications to ensure biodiesel quality and engine compatibility. While feedstocks like soybean, rapeseed, and sunflower oil are commonly used, the high productivity and widespread cultivation of oil palm make it a significant resource. In this context, used palm oil presents a particularly attractive, low-cost, and sustainable feedstock. Its utilization not only reduces production costs but also addresses waste disposal issues, especially in regions with high palm oil consumption (Lamba et al., 2024, Ooi et al., 2024).The transesterification process is critically influenced by several parameters, among which the type and concentration of the catalyst are paramount. Homogeneous acid catalysts, such as sulfuric acid (HSO), are highly effective for feedstocks with high Free Fatty Acid (FFA) content, as they simultaneously catalyze both esterification of FFAs and transesterification of triglycerides, thereby minimizing soap formation (Asaad et al., 2023, Obidike et al., 2022). However, the catalyst concentration must be meticulously optimized. An insufficient amount leads to incomplete conversion and low yields, while an excess can foster side reactions, cause equipment corrosion, increase production costs, and complicate downstream purification (Asaad et al., 2023, Onyia et al., 2024).Although extensive research exists on biodiesel production from various waste cooking oils, a review of the literature reveals a distinct knowledge gap. While many studies compare different catalyst types (e.g., NaOH vs. HSO or homogeneous vs. heterogeneous), few have undertaken a systematic, quantitative investigation of the effect of incremental HSO catalyst dosage specifically on the conversion of used palm oil, a feedstock often characterized by high FFA content (Maulidiyah et al., 2021, Obidike et al., 2022). Moreover, many studies report yield outcomes without a concurrent, comprehensive evaluation of how these incremental changes impact multiple critical fuel properties as per international standards.This study is therefore designed to address this gap. The primary objective is to rigorously investigate the impact of varying sulfuric acid catalyst concentrations (0.25% to 2.0% ww) on both the yield and the quality of biodiesel produced from used palm oil. The specific aims are:1. To determine the optimal HSO concentration that maximizes biodiesel yield.2. To evaluate key fuel properties (acid value, flash point, water content, and density) of the biodiesel produced at the optimal condition against the ASTM D6751 standard.3. To provide a clear, empirical correlation between catalyst dosage and process efficiency for this specific feedstock, contributing to the development of cost-effective and sustainable biodiesel production protocols relevant to regions with abundant palm oil waste.
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Copyright © 2025 Umunnakwe Christian Emeka. This is an open access article distributed under the Creative Commons Attribution License.
