Full conversion of oleic acid to estolides esters, biodiesel and choline carboxylates in three easy steps

A new three step process has been developed and optimized in order to demonstrate that is possible to get complete conversion of free fatty acids (FFA) into estolide esters (biolubricant), biodiesel and choline carboxylates (biosurfactants). This new approach consists in the utilization of HClO4, a cheap and industrially available strong acid, to generate the estolides followed by an esterification process with methanol in presence of a cheap ionic liquid to transform them into estolide esters and the unreacted FFA into biodiesel. A final neutralization step with choline hydroxide allowed to obtain biosurfactants. Finally, estolide esters and biodiesel were optimally split by means of molecular distillation. Both products were found to have excellent properties, fulfilling the requirements of international standards SAE J306 and EN 14214 for lubricants and biodiesel, respectively and demonstrating the industrial application of FFA as raw material to produce higher added value products. (C) 2018 Elsevier Ltd. All rights reserved.