Free Fatty Acid Reduction in a Waste Cooking Oil as a Raw Material for Biodiesel with Activated Coal Ash Adsorbent

Abstract

The development of globalization era which was followed by industry and the economy and also the increasing number of people caused an increase in amount of energy consumption and issues of environmental problems. Therefore, further research is needed on energy conservation in order to reduce non-renewable energy consumption. One of the alternative energy source that can be used as fuel and environmentally friendly is biodiesel. Biodiesel through two stages, the first one is esterification process aims to convert fatty acids from triglycerides in the form of esters. And the second one is transesterification process. It is the conversion of triglycerides or vegetable oils into alkyl esters. In this study coal ash waste and cooking oil as raw material are used for making biodiesel. Coal ash is used as an adsorbent to bind free fatty acids (FFA) toward cooking oil because coal ash has a high silica content. This research was conducted in several stages, namely activation of coal ash, characteristics of coal ash, free fatty acid test (FFA), waste cooking oil adsorption process. Coal ash is activated physically with time and temperature as the variabels. From the activation process, the best coal ash iodine value was obtained at 60 minutes warm up time and 140 °C temperature was 682,173 mg / g. The adsorption process is carried out with a period of 1 gram of adsorbent, 2 grams, and 3 grams. Coal ash can reduce the levels of free fatty acids in used cooking oil by 87.44% in the adsorption process with a time variable of 60 minutes and a temperature of 150°C.