Physicochemical Characterization of Diesel Engine’s Soot and Metal Oxide Ash Nanoparticles Using Electron Microscopy, EDS and TGA

Abstract

Physicochemical characteristics of metal oxide ash derived from engine oil additives on particulate matter (PM) from a diesel direct injection compression ignition (DDI-CI) engine, in terms of nanostructure and oxidation kinetics, were investigated through electron microscopy, energy dispersive X-ray spectroscopy and isothermal thermogravimetric analysis. Diesel and synthetic biodiesel were used as the baseline fuel. Engine performance and combustion characteristics of neat diesel and synthetic biodiesel fuel were initially reported. To enhance the formation of ash derived from lubricant additives, an accelerated ash loading method was used by dosing 10% by mass directly into the fuels. Different single primary particle nanostructures of soot and metal oxide ash were clearly observed. Single primary particle nanostructure of soot was a spherical shape composed of curve line carbon crystallites, while nanostructure of metal oxide ash was a spherically round outline shape comprised with parallel straight-line lattice fringes. Soot oxidation kinetics was significantly enhanced due to the presence of metal oxide ashes in the engine’s PM. In addition, the elemental analysis of metal oxide ash, derived from engine oil additives, was investigated using electron dispersive X-ray spectroscopy.