Sulfonated Orange Peel Catalysts for Biodiesel Production: Recent Advances and Future Directions

Abstract This study explores sustainable sulfonated orange peel catalysts (SOPCs) for biodiesel production. The carbonization‐sulfonation process used to manufacture SOPC, which is made from leftover orange peels, produces high‐density sulfonic acid groups that increase SOPC's catalytic activity. Under optimal conditions, using oleic acid as feedstock, SOPC achieved a biodiesel conversion of 96.51 %. The catalyst demonstrated excellent reusability, maintaining high conversion rates over multiple cycles with minimal efficiency loss. Compared to conventional homogeneous catalysts like sodium hydroxide and sulfuric acid, SOPC's heterogeneous nature facilitates simple separation from the reaction mixture, lowering purification expenses and environmental impact. Its ability to process feedstocks with high free fatty acid content further enhances its versatility for biodiesel production from various oil sources. This highlights SOPC's potential as a cost‐effective, environmentally friendly, and sustainable catalyst for biodiesel production. Continued research and optimization could accelerate its adoption, supporting the transition to cleaner, renewable energy solutions.