Purification of Crude Glycerol using Acidification: Effects of Acid Types and Product Characterization

Research Article

Austin J Chem Eng. 2014;1(1): 1004.

Purification of Crude Glycerol using Acidification: Effects of Acid Types and Product Characterization

Nanda MR1, Yuan Z1, Qin W2, Poirier MA3 and Chunbao X1*

1Department of Chemical and Biochemical Engineering, Western University, Canada

2Department of Biology, Lake head University, Canada

3Imperial Oil Products Division, Sarnia Technology Applications and Research, Canada

*Corresponding author: Xu Chunbao (Charles), Department of Chemical and Biochemical Engineering, Institute for Chemicals and Fuels from Alternative Resources (ICFAR), Western University, London, ON, Canada, N6A 5B9

Received: May 25, 2014; Accepted: July 09, 2014; Published: July 14, 2014


Purification of crude glycerol is essential for its applications for high-value products. In this study, crude glycerol was purified by acidification using sulfuric, hydrochloric or phosphoric acid, and the results were compared. Phosphoric acid was found to be the best purifying agent among the others. Acidification of a biodiesel plant waste crude glycerol (containing approximately 13 wt% glycerol and 6 wt% ash) for a total processing time of 1 h, produced a purified product containing approximately 96 wt% glycerol, and 0.7 wt% ash. Effects of pH values on the purification efficiency were investigated. The crude glycerol and the purified products were extensively characterized.

Keywords: Crude glycerol; Purification; Sulfuric acid; Hydrochloric acid; Phosphoric acid


With the increased concern over the depletion of fossil fuels worldwide, the search for alternative energy/chemical sources has been becoming urgent more than ever before. Biodiesel produced from renewable animal or plant oil has been one of two most commonly explored bio-fuels (the other is bio-ethanol) that could effectively reduce the global dependence on the fossil fuels and the greenhouse gas emission.

Biodiesel is mainly produced by the transesterification of animal fats or vegetable oils (triglyceride) with methanol in presence of an alkali or acid catalyst [1,2]. During the transesterification process in a biodiesel plant, crude glycerol is the primary byproduct, accounting for about 10 wt% of the biodiesel product [3,4].

With the rapid growth of biodiesel industry all over the world, a large surplus of glycerol has been created [5], leading to the closure of several traditional glycerol production plants [6]. This huge amount of glycerol, once it enters into the market, would significantly affect the glycerol price. The current market value is US$ 0.27- 0.41 per pound of pure glycerol [7] and as low as US$ 0.04 - 0.09 per pound of crude glycerol (80% purity) [8]. The world scenario of glycerol production is given in Figure 1. It is predicted that by 2020 the global production of glycerol will reach 41.9 billion liters [9]. Thus, crude glycerol disposal and utilization has become a serious issue and a financial and environmental liability for the biodiesel industry. Economic utilizations of glycerol for value-added products are critically important for the sustainability of biodiesel industry.