Biodiesel production from rice bran oil soapstock using novozyme 435 catalyst

Abstract

In this study, the fatty acid methyl ester (biodiesel) production from rice bran oil soapstock, acid oil from neutralization of the soapstock, and rice fatty acid using Novozyme 435 as catalyst were optimized. These substrates are by-product from rice bran oil refining. Biodiesel produced by soapstock was obtained only 36% in biodiesel production because it contained high water and soap content. When acid and rice fatty acid were use as substrate, biodiesel was obtained in a good yield. Thus, the acid oil and rice fatty acid were appropriate substrate for biodiesel production and the optimal conditions were a 2:1 molar ratio of methanol to FFA, the reaction temperature of 30 ℃, 10% Novozyme 435 and reaction time for 2 hrs. In the optimal condition, FFA were reduced to less than 2% while triglycerides were remained. Since about 10% of triglyceride (TG) contained in both acid oil and rice fatty acid, it as found that two step catalyzed process (enzyme and base, successively) is the appropriate procedure for biodiesel production from acid oil of rice fatty acid while the biodiesel production using acid-catalyzed process consisted of this process in the first of two steps and base-catalyzed process in the last step. The optimal reactions for base-catalyzed step were a 5:1 molar ratio of methanol to TG, the reaction temperature of 65℃, 0.8% NaOH and reaction time for 1 hr. The chemical and physical properties of biodiesel produced by this process were investigated and the results showed that this biodiesel reached the standard properties with high oxidation stability (10 hrs).