Recovery of byproducts from the rice milling industry for biofuel production

Abstract

In this study, the efficiency of enzymatic esterification and homogenous acid esterification for the reduction of Free Fatty Acid (FFA) content of acid rice bran oil (47 mg KOH g−1 ) was studied. Further, alkaline transesterification of the pretreated oil mixed with sunflower oil (to achieve FFA content ≤2%) was conducted to maximize fatty acid methyl esters (FAME) production. Homogeneous acid esterification was conducted at respectively 65◦ C and 45◦ C, using 2 wt.% and 4 wt.% of H2 SO4 as catalyst and 9:1 methanol:oil molar ratio. Enzymatic esterification was performed at 35◦ C using a 6:1 molar ratio of methanol:oil and 5 wt.% of catalyst. Homogenous acid esterification allowed to achieve the highest acid value reduction (92%), although enzymatic pretreatment alone allowed to obtain the highest FAME content (86 wt.%) compared to acid catalyzed process (41 wt.%). The obtained results show potential of this alternative raw material for bioenergy purposes. (c) 2020 Taylor & Francis Group, London, UK.