Because glycerol distillation residue contains a lot of salt, organic impurities and pigments, there are few reports about direct utilization.
For glycerol distillation residues containing a large amount of salt, according to the literature, glycerol distillation residues were extracted with alcohols and other organic solvents in 1940, and decolorized with activated carbon to produce polyglycerol.
The recovery of glycerol is mainly lost in distillation residue. The main component of distillation residue is polyglycerol, which can be used as raw material of polyglycerol ester as food additive if recovered.
Glycerol is a kind of high boiling point substance with high thermal sensitivity. Glycerol itself will decompose and polymerize at 204 C. The degree of polymerization and the amount of polymerization will accelerate with the increase of temperature and increase with the extension of time. And distillation residue also contains a lot of salt, alkali, organic impurities, pigments and so on. So it is not easy to recover glycerol from distillation residue. It is difficult to purify by chemical method alone.
Short-range distillation is suitable for distillation and purification of high molecular weight and thermosensitive substances. At present, the domestic pharmaceutical industry, spices and other industries have been used. For example, the distillation of vitamin A and E, and the distillation of mono-fatty acid glycerides by short-range distillation equipment.
