Conversion of oils with high %FFAs values to biodiesel: One and two-step chemical reactions

Abstract

In this study, an attempt was made to convert turpentine oil (TO) into biodiesel using one and two step chemical processes. The %free fatty acids (FFAs) value of the supplied TO was determined to be 5.8% by the titration method. The TO was obtained from a company that extracts the oil using the cold press method and sells it for commercial purposes. If the FFA value of the oil is above 5%, the soap formed prevents the separation of methyl esters and glycerol. To observe this situation, without reducing the FFA value of the oil, an attempt was made to synthesize biodiesel (TOTB100) using only the transesterification process. Additionally, an attempt was made to synthesize biodiesel (TOETB100) from the same oil using esterification and transesterification processes. After the esterification process, the %FFAs value of the oil was determined to be 2.24% by the titration method, and it was then converted to biodiesel through the transesterification process. The samples synthesized through single and two step reactions, as well as the raw oil, exhibited a peak at 1461.1 cm-1 in the Fourier Transform Infrared Spectroscopy (FT-IR) spectra. However, only the TOETB100 sample exhibited a peak at 1438.8 cm-1 in the FT-IR spectrum. In the two-step chemical process, the conversion of triglycerides to fatty acid methyl esters resulted in an increase in absorption at 1438.8 cm-1 (methyl CH asymmetric bending) with an increase in the methyl ester ratio in the reaction medium. In summary, the peak at 1438.8 cm-1 has been chosen to track the quantity of the biodiesel synthesis reaction through the peaks obtained from FT-IR spectra. The peak has been indicated in various studies in the literature to be the most sensitive to changes in biodiesel concentrations.