Recovery and Purification of Crude Glycerol from Vegetable Oil Transesterification

摘要

This article reviews the purification techniques involved in producing high-purity glycerol in the biodiesel industry. Utilization of glycerol by-products (contains less than 50 wt.% of glycerol and the remaining contents are water, salts, unreacted alcohol and catalyst) in biodiesel production affords greener and less costly processes. Research has focused on several purification steps that are capable of producing high-purity glycerol. Various new techniques for purifying glycerol promise better quality and lower cost and technologies are required to fulfil increasing worldwide demand. Neutralization, ultrafiltration, the use of ion exchange resins, vacuum distillation and other methods have been utilized in single or multiple stages. Recent studies have demonstrated that the combination of more than one technique produces high-purity glycerol (>99.2%). Purifications cost can be as low as 0.149 USD$/kg. For many applications, high-purity glycerol is more useful. In some cases, it is even necessary, particularly in the fields of hydrogen production, methanol production, pharmaceuticals and food additives.