Conversion of Degummed Soybean Oil to Biodiesel: Optimization of Degumming Methods and Evaluation of Fuel Properties

Biodiesel, known as fatty acid methyl ester, has become increasingly important due to the following advantages: it is renewable, biodegradable, non-toxic, and eco-friendly. At present, the main hurdle for its commercialization is high feedstock price. Crude soybean oil may be a cheap source for biodiesel production. However, it contains high amount of phosphorus, which can inhibit the action of the catalyst during transesterification. The degumming process can remove most of phosphorus in the crude soybean oil. In this paper, different degumming methods were investigated and an optimal method was determined based on phosphorus content, free fatty acid, and bound glycerin tests. Crude soybean oil degummed by the optimal method was further transesterified, and the fuel properties, including acid number, water and sediment, flash point, soap, moisture, methanol content, and free and total glycerin, etc., were further evaluated. It was found that the fuel properties were within ASTM D 6751 specifications.