Setiyo Gunawan, Arief Widjaja, Tri Widjaja : The Effect of Acid Catalyst Concentration on The Purity and Yield of Biodiesel Produced from in-situ Esterification of Rice Bran
Setiyo Gunawan S.T., Ph.D
Prof.Dr.Ir. Arief Widjaja M.Eng.
Prof. Dr. Ir. Tri Widjaja M.Eng.
Biodiesel is biodegradable, renewable, non-toxic and environmentally friendly energy. The cost of the raw materials comprises 60-88% of the production cost in commercial biodiesel (fatty acid methyl esters, FAMEs) production. Therefore, due to the economic reasons, the use of low cost raw materials as substrats for biodiesel production is being preferred. In this case, rice bran, which contents 13.5% oil, is an interesting substrat. In-situ esterification of high-acidity rice bran with methanol and sulfuric acid catalyst was investigated.The effects of sulfuric acid catalyst concentration and reaction time on purity and yield of biodiesel were discussed. The compositions of produced methyl esters due to the conditions were also determined. Increasing the sulfuric acid catalyst concentration from 1.5 to 5% decreased the FAMEs yield by about 84%. Using larger sulfuric acid catalyst concentration resulted in bran darkening and an increase in bran stickiness that interfered with separation operations. This was probably due to bran cell wall disruption by the acid. It was found that the ratio between saturated and unsaturated fatty acids of the isolated FAMEs was 1.08.