Effect of Time on the Quality of Biodiesel from Cooking Oil Used Using Lignite Coal Catalyst with Assistance Ultrasonic

Waste from used cooking oil can cause harm to various aspects of our lives. Efforts to reduce used cooking oil waste are by producing biodiesel. Biodiesel production is carried out using the transesterification method of oil and methanol with the help of a heterogeneous catalyst. One alternative material that can be developed as a heterogeneous catalyst is low-rank coal. This research aims to determine the quality of biodiesel produced from used cooking oil by varying the transesterification time using a lowrank coal catalyst with the help of ultrasonic waves. Used cooking oil and methanol (1:2) were transesterified at a temperature of 60°C with varying times of 25 minutes, 30 minutes, 35 minutes, and 40 minutes using 2 grams of low-rank coal catalyst with the help of ultrasonic waves with a frequency of 47 kHz. This research produced biodiesel with the highest yield of 77.78% at a transesterification time variation of 35 minutes with characteristics of a density of 40°C of 859.5 kg/m3, a kinematic viscosity of 40°C of 4.01 cSt, a water content of 0.026% and a number acid 0.44 mgKOH/g. In general, the biodiesel produced meets SNI 7182:2015.