| Abstract
| - The technique of high-temperature oxidation tandemdifferential mobility analysis has been applied to the studyof diesel nanoparticle oxidation. The oxidation rates inair of diesel nanoparticles sampled directly from the exhauststream of a medium-duty diesel engine were measuredover the temperature range of 800−1140 °C using onlineaerosol techniques. Three particle sizes (40, 90, and 130 nmmobility diameter) generated under engine load conditionsof 10, 50, and 75% were investigated. The results showsignificant differences in the behavior of the 10% load particlesas compared to the 50 and 75% load particles. The 10%load particles show greater size decrease at temperaturesbelow 500 °C and significant size decrease at temperaturesbetween 500 and 1000 °C in a non-oxidative environment,indicating release of adsorbed volatile material or thermallyinduced rearrangement of the agglomerate structure.Activation energies determined are 114, 109, and 108 kJmol-1 for the 10, 50, and 75% load particles, respectively.These activation energies are lower than for flame soot(Higgins et al. J. Phys. Chem. A2002, 106, 96), but thepreexponential factors are lower by 3 orders of magnitude,and the overall oxidation rates are slower by up to afactor of 4 over the temperature range studied. Possiblereasons for the differences are discussed in the text.
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