Conversion of by-products from the vegetable oil industry into biodiesel and its use in internal combustion engines: a review

Biodiesel produced from by-products and waste materials can be an economical way of reducing traditional oil consumption and environmental problems. The by-products from the vegetable oil refining industry such as soapstock, acid oil and fatty acid distillates are suitable for producing biodiesel. The present work is a survey related to the use of these by-products to obtain biodiesel, covering not only the traditional and most widely used acid/base catalysis, but also solid and enzymatic catalysis. Details of the techniques are presented and compared. The advantages and drawbacks of the diffe...