Resumen
Homogeneous acidic catalyst was mostly utilized in the conventional biodiesel production process. However, the production cost of the whole process was high due to the separation of liquid biodiesel and liquid catalyst. Hence, acid heterogeneous catalyst would offer a promising solution to this problem. The research objectives were to synthesis an efficient heterogeneous acidic catalyst for biodiesel production using monk fruit biomass and to characterise the catalyst produced. The experimental study was conducted by impregnating the biomass with phosphoric acid as the activating agent. Impregnation ratio of 1.0, 1.5, 2.0 and 2.5 g of weight of activating agent/biomass were tested. The biomass was then calcinated and carbonized to form activated carbon. Calcination temperature with the range of 300? to 600? were also tested. The activated carbon was then sulfonated and phenyl functionalized to increase its active sites for better catalytic activity. The performance of the catalysts was tested in the esterification process between palmitic acid and methanol. Highly porous carbon materials were observed under the scanning electron microscope (SEM). Acid functional group -SO3H was proven and found in the catalyst from the energy-dispersive X-Ray Spectroscopy (EDX) and Fourier Transform-infrared Spectroscopy (FT-IR). The catalyst was found to be stable under the temperature 250? from the thermogravimetric analysis (TGA). The catalyst exhibited highest acid density of 4.04 mmol/g. The biodiesel yield obtained were calculated quantitatively through the gas chromatography (GC). The highest yield of biodiesel obtained was found to be at 87.40 %, under the operating conditions of 10:1 malar ratio of palmitic acid to methanol, 120?, 10 wt.% catalyst loading and 4 h duration of reaction. The study had proven that monk fruit biomass could be synthesized into acid heterogeneous catalyst for biodiesel production through a greener and more sustainable route.