A comparison of diesel engine soot with carbon black

A range of analytical techniques has been used to characterise the chemistry and morphology of a diesel-engine and an exhaust soot, and a comparison made with a selection of commercial carbon blacks. Significant differences have been observed in the chemical composition of exhaust and engine soots, particularly in their surface chemistry and the presence of adsorbed lubricant components on the engine soot. Both forms of soot differ from carbon black -particularly their elemental composition and surface chemistry. In terms of morphology, at the primary particle level, there is a high degree of similarity between both forms of soot and typical carbon blacks in so far as they all show very similar primary particle sizes, and virtually indistinguishable perturbed graphitic or turbostratic internal structure. A hypothesis is proposed to account for these observations based on the similarities in the soot and carbon black generation process, but differences in the quenching and postquenching environment of soots and carbon blacks. Nevertheless there appears to be potential for certain blacks to mimic the aggregation behaviour of soots in used lubricating oils. (C) 1999 Elsevier Science Ltd. All rights reserved.