A review on the production of biodiesel from waste cooking oil: a circular economy approach

Biodiesel is mainly produced from various bio-based sources, including vegetable oils, waste cooking oil, and more, by esterification and transesterification processes using a suitable catalyst - preferably a heterogeneous catalyst as it is more beneficial in terms of reusability, recovery, product purity, and production cost. Different feedstocks are used for the production of biodiesel, with waste cooking oil emerging as a promising feedstock. Biodiesel offers several advantages, including reduced viscosity, higher flash point, elevated cetane number, biodegradability, non-toxicity, and lower greenhouse gas emissions. Additionally, it exhibits shorter ignition times and greater combustion efficiency, making it favorable for prolonging engine lifespan. However, concerns regarding the use of biodiesel have primarily revolved around its quality and potential long-term impacts on diesel vehicles. Therefore, various chemical modification methods have been explored to address this issue, with esterification and transesterification being the most commonly utilized approaches. This review comprehensively examines the current state of knowledge and recent advancements in the production of biodiesel from waste cooking oil and synthesizes findings from a wide range of research articles, focusing on key aspects such as feedstock selection, conversion technologies, and the environmental and economic viability of biodiesel production from waste cooking oil toward a circular economy in Ghana.