Abstract

The present study emphasizes the development of a solid alkali catalyst acquired from a ternary blend of agrowastes, Heteropanax fragrans (Roxb.) Seem (Kesseru), Sesamum indicum L. (Sesame) and Vigna mungo (L.) Hepper (Black Gram). Potassium carbonate was added to the agrowastes mixture in the ratio of 1:1:1:0.5 (Kesseru : Sesame : Black Gram : K2CO3). The final material was named Kesseru Sesame Black Gram-K2CO3 (KSBG-K2CO3) which was calcined at 550 °C for 1 h. The resultant catalyst was then utilized in the transesterification of a binary mix of Jatropha curcas (jatropha) and Pongamia pinnata (pongamia) for efficient biodiesel synthesis. Various analysis techniques such as X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET), Field emission scanning electron microscope (FESEM), Energy-dispersive X-ray spectroscopy (EDX), High-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and Thermogravimetric analysis (TGA) were employed for characteristics analysis of the catalyst. It was indicated from the study that the developed catalyst consists of carbonates and oxides of certain metal elements as the major active components. Potassium was revealed to be the predominant metal element with 25.29 wt.% followed by Ca (6.55 wt.%) and Mg (4.31 wt.%). The BET surface area and pore volume of the calcined KSBG-K2CO3 catalyst were 7.242 m2 g-1 and 0.024 cm3 g-1, respectively. The basicity of the catalyst was measured as 0.24 mmol/g and the reaction showed 4.42 h-1 turnover frequency. The calcined KSBG-K2CO3 catalyst efficiently produced biodiesel with a 94.92 ± 0.06 % yield under optimized parameters viz. catalyst load of 15 wt.%, 9:1 methanol to oil molar ratio (MOMR), 65 °C reaction temperature in 2.66 ± 0.12 h reaction time. Additionally, the kinetic study of the reaction was conducted and the value of activation energy was determined as 28.44 kJ mol-1. The resultant biodiesel was analyzed by Proton nuclear magnetic resonance (1H NMR), FT-IR and Gas chromatography-mass spectrometry (GC-MS) and the assessment of their properties were done which conformed to the international standards.