초록
<P><B>Abstract</B></P> <P>The enzymatic route for biodiesel production is environmentally attractive, but costs need to be reduced and reaction times shortened. Costs can be reduced by producing lipases by solid-state fermentation and using the fermented solids directly to catalyze the ethyl-esterification of fatty acids in solvent-free media. However, the esterification studies done to date with fermented solids have involved 12g or less of fermented solids and reaction times greater than 30h. The aim of the current work was therefore to increase the scale of the process by an order of magnitude, while also decreasing the reaction time, using bi-distilled olein as the source of fatty acids. The best result was obtained with a molar ratio of ethanol to fatty acids of 1.5:1, in a process in which 245g of ethanol and 1000g of olein were circulated in a closed-loop system through a column containing 120g of dry fermented solids. A two-compartment reservoir was used, with the water in the outflow of the column being decanted in the first compartment. The organic phase that passed to the second compartment was agitated and fed back to the column. This system gave 88% conversion in 24h. This system was used in 6 successive 48-h batches with the same dry fermented solids, in which a total of 4.6kg of ester was produced. These are promising results that lay the basis for further scale-up studies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We scaled-up the ethyl-esterification of fatty acids in a solvent-free medium. </LI> <LI> 120g dry fermented solid with 1000g olein and 245g ethanol gave 88% conversion in 24h. </LI> <LI> A new two-compartment reservoir allowed removal of water and mixing of the organic phase. </LI> <LI> The same lot of dry fermented solids was used in six 48-h cycles, producing a total of 4.6kg of esters. </LI> <LI> We obtained the highest productivity for biodiesel synthesis using fermented solids to date, 333mgg<SUP>−1</SUP> h<SUP>−1</SUP>. </LI> </UL> </P>