Sustainable Biofuel Production from Agricultural By-Products: Citrus Peels and Pumpkin Seeds as Feedstocks for Bioethanol and Biodiesel

Abstract

Energy is fundamental to development, and in correlation with the rapid population growth, its demand is escalating. The issues associated with fossil fuels, their depletion, and negative environmental effects have led to the exploration of alternative energy sources. Biofuels such as biodiesel and bioethanol have emerged as promising, renewable, and environmentally friendly alternatives. This study explores the sustainable production of bioethanol from Citrus peels and biodiesel from Pumpkin seed oil, assessing their potential contributions to energy efficiency and societal benefits. Citrus peels, underwent acid hydrolysis (0.5% H₂SO₄, 2 h) to release fermentable sugars, followed by anaerobic fermentation using 10% (v/v) Saccharomyces cerevisiaea. The resulting bioethanol was confirmed through qualitative analysis via Jones reagent. GC-MS of the hydrodistilled Citrus peel revealed 90.53% limonene in Citrus oil Biodiesel was produced via transesterification of pumpkin seed oil with methanol and potassium hydroxide (KOH) catalyst. GC-MS identified 65.9% unsaturated fatty acids (linoleic and oleic acids dominant), with a 97.5% yield, 0.7% ash content, and calorific value of 39,586 kJ/kg, meeting ASTM/EN standards. The study highlights the potential of utilizing agricultural waste and by-products in biofuel production, contributing to a circular economy and reducing environmental impact. The study demonstrates the viability of Citrus peel waste and Pumpkin seed oil as feedstocks, reducing reliance on fossil fuels while valorizing agricultural by-products. Challenges in scaling production require further exploration to maximize societal and environmental benefits, particularly in resource-rich regions.