Solvent-free enzymatic esterification of free fatty acids with glycerol for biodiesel application: Optimized using the Taguchi experimental method

Ramkrishna Singh, Bruce S. Dien, Vijay Singh

Research output: Contribution to journalArticlepeer-review

Abstract

Presence of free fatty acids along with glycerides poses a technical difficulty for biodiesel production. This work used a Taguchi L9 design to optimize the solvent-free enzymatic process to result in the esterification of oleic acid with glycerol. Under optimal conditions the esterification reaction temperature of 60°C, enzyme dose of 5 wt%, glycerol: oleic acid molar ratio of 5:1, and reaction time of 3 h, a 75.235 ± 2.19% conversion of oleic acid to esters was achieved. With the addition of molecular sieves, the conversion increased to 86.73% ± 1.09%. However, using the parameters predicted by Taguchi design (60°C, 5 wt%, 5:1, and 4.5 h), 88.5% ± 1.11% of oleic acid could be converted to esters derivative. Diglycerides were the major product, and the reaction equilibrium was attained after 4 h. The immobilized enzyme could be used up to seven times with only a 10% reduction in the conversion. Thus, the process can efficiently reduce the free fatty acid content of oil to make it suitable for biodiesel production.

Original languageEnglish (US)
Pages (from-to)781-790
Number of pages10
JournalJAOCS, Journal of the American Oil Chemists' Society
Volume99
Issue number9
DOIs
StatePublished - Sep 2022

Keywords

  • biodiesel
  • esterification
  • fatty acids
  • immobilized lipase
  • Taguchi design

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Organic Chemistry

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