Activated Lignin for Biodiesel Formation

Current biodiesel production is costly, in part due to the catalysts added during transesterification and later washed out. We have previously shown that intact rapeseed shells can be ball-milled with an alcohol to produce biodiesel without an added catalyst. Here, we report on the activation and identity of the complexing agent within the shells of rapeseeds and sunflower seeds. Lignin, present in the cell walls of plant matter, complexes with iron and manganese within metallic media, such as in a ball mill, and acts as a catalyst support in a transesterification reaction with oil and methanol. When ball-milled with methanol, rapeseed and sunflower seeds produce up to 90% biodiesel, similar to yields produced by industrial methods. However, this new method for producing biodiesel is a greener alternative, as it requires fewer organic solvents, may reduce the time and energy required for synthesis, and may reduce the effort required for product purification.