Waste cooking oil biodiesel and petroleum diesel soot from diesel bus: A comparison of morphology, nanostructure, functional group composition and oxidation reactivity.

• Morphology, nanostructure, functional group composition, and oxidation reaction of soot particles with different fuels are analyzed. • Soot particles from WCO biodiesel combustion exhibit more disordered nanostructure. • The surface functional group content and sp3/sp2 of biodiesel soot particles are higher. • Soot particles from WCO biodiesel is easier to be oxidized than fossil diesel soot particles. • The nanostructure definite correlations with soot particles reactivity. Biodiesel is one of carbon neutral fuels for diesel engine and waste cooking oil (WCO) would be the most viable source for biodiesel production in China. This paper studied the micromorphology, nanostructure, surface functional group composition, and oxidation activity characteristics of particles emitted from a China V bus fueled by pure WCO biodiesel and petroleum diesel, respectively. Compared with petroleum diesel, the results showed that particle mass (PM) and particle number (PN) of WCO biodiesel decreased by 38.66% and 38.12%, respectively, while the proportion of nucleation mode particles increased by about 10%. The soot particles of WCO biodiesel have higher disordered nanostructure, smaller primary particle size and fringe length, larger fringe separation distance and tortuosity, and lower graphitization degree than those of petroleum diesel. Moreover, the oxygen-containing surface functional groups content and carbon atom hybrid ratio of soot particles of WCO biodiesel were higher than those of petroleum diesel under the same oxidation temperature. And then the activation energy of soot particles from WCO biodiesel which contained more lattice defect structures was 38.43 kJ/mol, 37.8% lower than petroleum diesel, which is easier to be oxidized. [ABSTRACT FROM AUTHOR]