Characterization of crude glycerol from biodiesel production from multiple feedstocks.

Glycerol is the principal by-product of biodiesel production. For each gallon of biodiesel produced, approximately 0.3 kg of crude glycerol accompanies. Such crude glycerol possesses very low value because of the impurities contained. As the demand and production of biodiesel grow exponentially, the utilization of the glycerol becomes an urgent topic. The make-up of crude glycerol varies depending on the parent feedstock and the biodiesel production process. Before the crude glycerol could be considered for possible value-added utilizations, it is necessary to characterize it on its physical, chemical, and nutritional properties. This article reports the characterization of crude glycerol obtained from different seed oil feedstocks of mustard, rapeseed, canola, crambe, soybean, and waste cooking oils. Batch processes of biodiesel production were used as the means of crude glycerol preparation using unrefined vegetable oils, methanol, and sodium methylate as the catalyst. After separation from biodiesel, the crude glycerol from each of the oils was analyzed using ASTM and other standard test methods. Elemental impurities, nutritional value, and other chemical properties were tested.