ABSTRACT
This study aimed to produce biodiesel from waste vegetable oil (WVO) using the acid transesterification method, addressing the challenges associated with the alkaline transesterification method due to the presence of free fatty acids (FFA). The WVO used in the experiment had a free fatty acid content of 0.7% w/w and an acid value of 1.5 mg KOH/g. The transesterification process was carried out using sulfuric acid (H₂SO₄) as the catalyst at a reaction temperature of 60°C, with a molar ratio of methanol to oil of 6:1, and a catalyst concentration of 1% (v/v). The reaction mixture was stirred at 600 rpm for 2 hours to ensure complete conversion. The physicochemical properties of the resulting biodiesel, including flash point, cloud point, pour point, viscosity, saponification value, and acid value, were determined and found to be 120°C, 13°C, -5°C, 1.5 mm²/s, 0.92 mg KOH/g, respectively. These properties were in accordance with the ASTM 6751-02 standard for biodiesel. The analysis of the biodiesel using Fourier Transform Infrared (FT-IR) spectrometer confirmed the presence of characteristic functional groups such as C=O, OCH₃, and CH₃. Based on the obtained results, it can be concluded that waste vegetable oil has the potential to be used as an alternative source for biodiesel production, providing a sustainable alternative to conventional diesel fuel.
