Title:DFT Study of the Possible Reaction Path for Radical Promoted Esterification
Mechanism of Free Fatty Acids of Soapnut Oil for the Production of
Biodiesel
Volume: 19
Issue: 11
Author(s): Naila Ghani, Naveen Kosar, Sana Sadaf*, Tariq Mahmood, Muhammad Khalid, Khurshid Ayub*, Javed Iqbal*Sadia Noor
Affiliation:
- Department of Chemistry, University of Agriculture, Faisalabad-38000, Pakistan
- Department of Chemistry, COMSAT University, Abbottabad Campus, KPK 22060, Pakistan
- Department of Chemistry, University of Agriculture, Faisalabad-38000, Pakistan
- Punjab Bio-energy Institute, University of Agriculture, Faisalabad-38000, Pakistan
Keywords:
Esterification, density functional theory (DFT), reaction mechanism, soaf nut, biodiesel, photocatalyst.
Abstract:
Esterification of higher free fatty acids content by using a photo-catalyst has recently been
proved as the most efficient method for the pretreatment of non-edible oil to synthesize biodiesel.
Methods: In the current study, mechanistic details of photo-catalyzed esterification reaction for four
different fatty acids through density functional theory (DFT) calculations are explored and compared
with un-catalyzed esterification reaction.
Results: Revealed that the presence of photo-catalyst lowers the activation barrier and the structure of
fatty acid has no significant effect on its reactivity. Thermodynamic data also revealed that the presence
of photo-catalyst lowered the activation energy from 51.67 kcal/mol to 0.7495 kcal/mol. Furthermore,
Gibbs free energy changes (ΔrGm
Ø) and molar enthalpy changes (ΔrHm
Ø) of the photo-catalyzed
esterification reaction are negative, indicating that it is a spontaneous exothermic reaction. On the other
hand, free fatty acids esterification in the absence of a catalyst is a kinetically unfavorable process with
positive values of ΔrGm
Ø and ΔrHm
Ø.
Conclusion: Our findings theoretically clarify the mechanism of the photo-catalyzed esterification
reaction of FFA present in non-edible oil, which facilitates the process of biodiesel production.