Green Concept in Preparation of Biodiesel by Decarboxylation of Fatty Acids Derived from Waste Coconut and Rubber Seed Oils

Green production of diesel was carried out using waste coconut oil and rubber seed oil. Experiments were carried out using preliminary apparatus constructed in house as well as using a high temperature pressure reactor. Acid values of oil samples were determined before and after the decarboxylation process. Decarboxylation of hydrolysed waste coconut oil produced the hydrocarbons, nonane (15.60% w/w), decane (46.38% w/w), undecane (23.2%w/w), dodecane (1.34%w/w) and tridecane (0.36% w/w). Decarboxylation of non-hydrolysed waste coconut oil when reacted at 350 °C using Pd/C catalyst resulted in hexadecane, undecane, tridecane and pentadecane. Decarboxylation of non-hydrolysed rubber seed oil resulted in 6-dodecene, 5-undecene and tridecane, while hydrolysed rubber seed oil resulted in tetradecane, 2-tetradecene, 1-hexadecene, pentadecane and 6-tetradecyne. Many hydrocarbon compounds produced are corresponding to the diesel range of C₁₀-C₂₂ indicating the possibility of using these products in diesel fuel applications after further testing. The decrease in the acid value of reaction mixtures containing waste oils after decarboxylation was used as an indicator for the conversion or the decarboxylation. The process employed in the production of biodiesel was a simple and environmentally friendly green method supported by catalysis and did not involve any toxic chemicals, derivatizing agents or harmful solvents.