Biodiesel Production From High FFA Raphia vinifera Oil as a Potential Non-edible Feedstock: Process Optimization Using Response Surface Methodology

Herein, Raphia vinifera is explored as an excellent potential feedstock. This study focused on exploring the potential of Raphia vinifera oil (RVO) as a viable feedstock for biodiesel production. Due to the high free fatty acid content in RVO (6.76% FFA), pretreatment was performed. Then, the actual conversion to biodiesel was predicted and optimized using response surface methodology (RSM) based on a Box Benhken design (BBD). Using an oil/methanol molar ratio of 6:1, H2SO4 at 1% wt/wt, a reaction period of 60 min, and a temperature of 65 C-degrees after previous esterification of free fatty acids, the acid value of RVO was significantly reduced to 1.54 mg KOH/g. Four operating conditions were investigated to optimize the %yield of Raphia vinifera oil biodiesel (RVO_B). The operating conditions were methanol/RVO ratio 6:1-12 :1 (mol/mol), catalyst concentration 0.7-1.7 (Wt.%), reaction temperature 48-62 (C-degrees) and reaction time 50-90 (min) for transesterification. Analysis of variance (ANOVA) was used to evaluate the linear and non-linear parameters that were derived from the models. A molar methanol/RVO ratio of 8.82:1, a catalyst concentration of 1.22% (by oil weight), a reaction time of 87.26 min, and a temperature of 62 C-degrees allowed a maximum conversion of 96.13%. The model's determination coefficient (R-2) was found to be 0.9153, indicating its relevance and accuracy in the forecast of results. The methyl esters obtained were analyzed using nuclear magnetic resonance (H-1, C-13 NMR), Fourier transformation infrared spectroscopy (FT-IR), Thermal gravimetry (TG), Elemental analysis CHNS, and Gas Mass Chromatography (GC-MS). The fuel characteristics of RVO_B were also determined, and the measured values were found to comply with the requirements of ASTM D6751 for biodiesel.