Optimization of biodiesel synthesis by esterification using a fermented solid produced by Rhizopus microsporus on sugarcane bagasse

Abstract

A fermented solid containing lipases was produced by solid-state fermentation of Rhizopus microsporus on sugarcane bagasse enriched with urea, soybean oil, and a mineral solution. The dry fermented solid produced using R. microsporus (RMFS) was used to catalyze the synthesis of alkyl-esters by esterification in a solvent-free system containing ethanol and oleic acid (as a model system) or a mixture of fatty acids obtained from the physical hydrolysis of soybean soapstock acid oil (FA-SSAO) in subcritical water. The conversions were 93.5 and 84.1%, for oleic acid and FA-SSAO, respectively, at 48 h and 40 °C, at a molar ratio (MR) of ethanol to fatty acid of 5:1. A further increase in the MR to 10:1 improved the production of ethylic-esters, giving conversions at 48 h of 98 and 86% for oleic acid and FA-SSAO, respectively. The results obtained in this work foster further studies on scaling-up of an environmentally friendly process to produce biofuels.

Valorization of a high-acidity residual oil generated in the waste cooking oils recycling industries

“…Valorization of a high-acidity residual oil generated in the waste cooking oils recycling industries • 7 with respect to RO, which was not removed from the reaction medium to minimize operational costs, thus reducing the yield of the subsequent esterification by 3%. In a study conducted on the influence of water on the esterification of fatty acids, it was observed that when the concentration of water was 5% wt., the conversion in the esterification reaction decreased by 30% (Botton et al, 2018). On the contrary, when the percentage of water in the reaction medium was greater, about 10-30% wt., the reduction in conversion was lower.…”

“…Eq. 2Finally, one last procedure consists of hydrolyzing the triglycerides with an enzyme (lipase) in aqueous medium thus transforming the triglycerides into FFA, then esterifying the FFA with methanol and an acid catalyst into FAME (Botton et al, 2018).…”

“…water). As aforementioned, water is the product of esterification and causes equilibrium to shift towards the formation of reactants which inhibit the reaction (Botton et al, 2018).…”

Esterification of Free Fatty Acids with Glycerol within the Biodiesel Production Framework

“…One proposed solution is the previous esterification of the FFA with methanol to obtain FAME [5], i.e., biodiesel, using an acid catalyst (usually sulfuric acid), as shown in Equation (2). This reaction is reversible, so an excess of water can displace the equilibrium towards the formation of FFA [6], thus water should be removed during the process. The most suitable conditions found by several authors for this procedure when treating oils with high acidity were 5% H 2 SO 4 (wt.)…”

“…Another alternative consists of firstly hydrolyzing the triglycerides with an enzyme (lipase) in aqueous medium to obtain FFA (Equation 3), and then esterifying the resulting FFA with methanol, in the presence of an acid catalyst, into FAME. Lipases from the yeast Candida rugose [4] and from the fungus Rhizopus microsporus [6] have been assayed in the hydrolysis step, none of them achieving high FFA yields.…”