Purification of Crude Glycerol

The glycerol obtained from transesterification is separated from biodiesel by gravity. The concentration of this type of glycerol is ~50% (wt),which is so-called raw glycerol and contains the contaminants such as alcohol, soap, base catalyst, salts, and untreated organic materials.

Crude glycerol can be obtained through the following purification of raw glycerol:

1. Acidification of the soaps with HCl and separation of formed free acids by gravity
2. Neutralization with caustic soda
3. Evaporation for methanol recovery and water removal. The methanol recovered can be reused for biodiesel production. The the crude glycerol with 80-85% (wt.) can be obtained.

Crude glycerol purification:

1. Crude glycerol can be purified by vacuum distillation to a purity of 99.5% (wt).
2. Crude glycerol with diluted salt can be refined with ion-exchange
3. Crude glycerol with high salt content can be purified with ion exchange chromatography and thin film distillation.