Influence of acid catalyst on two step transesterification of Karanja oil with high free fatty acids

Abstract

Karanja oil methyl ester (KOME) was produced by the two step transesterification of oil with an alcohol in the presence of various acid catalysts and base catalysts. The best result was obtained with H₂SO₄ as acid catalyst and KOH as base catalyst; the yield was 97% at 60°C after 150 min. The high yield was observed due to the reduction of free fatty acids (FFA) % by using an acid catalyst in the first step of transesterification. HCl and H₃PO₄ was less active than H₂SO₄ during the process as it presented very low ester yields for the various molar ratios of fatty acid to alcohol studied. The fatty acid profile of the oil (palmitic acid: 11.64%; stearic acid: 7.70%; docosanoic acid: 4.46%; tetracosanoic acid: 1.08%; linolenic acid: 16.66%; oleic acid: 51.61%; eicosanoic acid: 1.33) and the different reactive actions of the acids were responsible for the observed differences in conversion to methyl esters. The result attained by this study might contribute to the economic utilization of a nonedible feedstock.

Keywords:

• Karanja oil
• free fatty acids
• FFA
• acid catalysts
• two step transesterification
• KOME

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors thankfully acknowledge the financial support provided by The Institution of Engineers (India), Kolkata, India [grant number PG2015023] for carrying out Research and Development work in this project.