Co-solvent transesterification of bitter almond oil into biodiesel: optimization of variables and characterization of biodiesel

Abstract

The influence of co-solvent on transesterification of one of non-edible feedstocks, Bitter Almond Oil (BAO) with methanol was investigated. Hexane and potassium hydroxide (KOH) were chosen as the co-solvent and the catalyst, respectively. The variables included in the optimization process were concentration of KOH, methanol to oil molar ratio, hexane to methanol volume ratio, temperature, time, type of co-solvent and type of alkali catalyst. BioDiesel (BD) with yield of 97.88…98.50 ester content % w/w were obtained using 0.60% KOH w/w, 5:1 methanol to oil molar ratio, 1:1 hexane to methanol volume ratio, 32 °C reaction temperature and 45 minutes of reaction. The Fourier Transform InfraRed (FTIR) spectroscopy and Thin Layer Chromatography (TLC) were used to ensure the conversion of BAO into BD. The fuel properties of the prepared BD were determined and found within the acceptable limits prescribed by ASTM D6751-15ce1 and EN 14214:2017. Moreover, properties of (biodiesel + petro-diesel) blends complied with the limits prescribed in the ASTM D7467-17 standards as well. It was concluded that the presence of co-solvent reduced the concentration of the catalyst, temperature, methanol to oil molar ratio and time required to produce maximum yield of BD comparing to non-solvent process. As a result, co-solvent transesterification is recommended for further application.

Keywords

• bitter almond oil
• co-solvent transesterification
• biodiesel
• fuel properties
• analysis of biodiesel
• blending evaluation