Analysis of soot particles derived from biodiesels and diesel fuel air-flames

► Soot morphology and nanostructure of several biodiesel and diesel fuel air-flames. ► We examine soot particle diameter, degree of particle agglomeration and nanostructure. ► Tested biodiesels have smaller soot particle diameters compared to diesel. ► Diesel fuel soot has an internal structure consisting of stacked graphene layers. ► Biodiesel fuel soot contains circular carbon rings, similar to carbon onion ring structure.