Hu, S; Luo, X; Wan, C; Li, Y
Characterization of crude glycerol is very important to its
value-added conversion. In this study, the physical and chemical properties of five biodiesel-
derived crude glycerol samples were determined. Three methods, including iodometric-periodic acid
method, high performance liquid chromatography (HPLC), and gas chromatography (GC), were shown to
be suitable for the determination of glycerol content in crude glycerol. The compositional
analysis of crude glycerol was successfully achieved by crude glycerol fractionation and
characterization of the obtained fractions (aqueous and organic) using titrimetric, HPLC, and GC
analyses. The aqueous fraction consisted mainly of glycerol, methanol, and water, while the
organic fraction contained fatty acid methyl esters (FAMEs), free fatty acids (FFAs), and
glycerides. Despite the wide variations in the proportion of their components, all raw crude
glycerol samples were shown to contain glycerol, soap, methanol, FAMEs, water, glycerides, FFAs,
and ash.