| dc.description.abstract | Energy demand increases every year in line with economic and population growth. Fossil fuels, such as crude oil, natural gas, and coal, have become the primary sources of energy worldwide. One renewable energy source is biodiesel. The use of biodiesel can reduce greenhouse gas emissions and air pollution compared to fossil fuels. Biodiesel is synthesized from used cooking oil, which has a free fatty acid value of 0.658%, suitable for processing through transesterification. The biodiesel synthesis involves the use of KOH catalyst with both stirring at 1500 rpm and ultrasonication at a frequency of 20 kHz, conducted at a temperature of 60 °C. The mass ratio of used cooking oil to methanol is 2:1, with a catalyst mass of 2% relative to the mass of used cooking oil, and a reaction time of 90 minutes. The physical properties of the synthesized biodiesel include density, viscosity, flash point, and acid value. The density is 0.88907 g/mL, viscosity is 7.68962, cetane number is 66.3, and the flash point is 179°C. In terms of these properties, the biodiesel quality is superior to that of the stirring method variation. Although the calorific value is lower at 39.362 MJ/kg, the difference is not significant. Both methods yield biodiesel of good quality that meets the Indonesian National Standard (SNI) for alternative fuel use. | en_US |
