Characterization of Glycerol-Ester Emulsions from Transesterification with Different Alcohols Using the CLSM Technique

Abstract

Confocal laser scanning microscopy (CLSM) was applied in order to observe the apparent characteristics of glycerol-ester emulsions in transesterification with methanol, ethanol, and mixtures of methanol/ethanol in the present study. The CLSM operated with an XY mode using a laser combiner, which featured a red helium-neon (543 nm) and Nile blue A that was used as dye. The confocal images show significant differences involved in the distribution of glycerol in ester obtained from different alcohol systems. In the case of methanolysis, drops of glycerol clearly separated from fatty acid methyl ester (FAME), which made phase separation easier between glycerol and FAME. In ethanolysis, an unclear formation of glycerol drops in fatty acid ethyl ester (FAEE) was visualized. When the amount of ethanol in mixtures of methanol/ethanol increased, the shape of glycerol drops became unstable. This resulted in a flock of glycerol being dispersed in ester, which made phase separation difficult. The confocal images strongly support the notion that alcohol type is a crucial factor in the formation of glycerol drops in ester, which can affect phase separation between glycerol and ester in biodiesel production.

Keywords

• CLSM; FAME; FAEE; Glycerol; Emulsions

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