Oxidation Activity Restoration of Diesel Particulate Matter by Aging in Air

Abstract

Diesel particulate matter (PM) was collected at different tailpipe positions where the sampling temperature was different. The PM samples were pre-treated in air at high temperature until 40% mass loss. Then, the partially oxidized PM samples were aged in air for 40 days, and the physicochemical properties of partially oxidized PM before and after aging in air were tested. The results showed that the oxidation activity of partially oxidized PM was appreciably restored by aging in air. The morphology, diameter distribution of primary particles and nanostructures of partially oxidized PM changed slightly after aging in air. The amorphous carbon adsorbing on PM surface were faintly observed through high resolution transmission electron microscope (HRTEM) images. The adsorption of oxygen-containing functional groups (carbonyl and hydroxy) and organic compounds were evidenced through Fourier transform infrared spectroscopy (FTIR) and Raman parameter A D3 /A G. The crystallite size calculated using Raman parameter decreased slightly after aging in air.

Limited developmental neurotoxicity from neonatal inhalation exposure to diesel exhaust particles in C57BL/6 mice

“…Although Tween 80 has been shown to enhance nanomaterial uptake into the nasal epithelium [91] and blood-brain barrier membranes [92, 93], it is worth noting those particles were placed in solutions with a concentration ≥ 0.5% Tween 80, about 1000x the concentration of the SRM 1650b solution. Aging of diesel particulate matter has been shown to alter its oxidative potential which, could also influence its capacity to induce neurotoxic effects [94]. The insoluble fraction of NIST SRM 1650b, which could contain harmful organic and metal content, can settle across the exposure period and thus be lost in the inhalation exposure.…”

Physicochemical property changes during oxidation process for diesel PM sampled at different tailpipe positions

“…Oxidation activity mentioned in the section was mainly referred to ignition temperature and burn out temperature. Some part of the physicochemical property changes after partial oxidation were discussed in reference [28]. to the lowest sampling temperature for sample 4, mass loss was remarkable when temperature was lower than 400 °C and with the lowest ignition temperature (207.8 °C).…”

Oxidation Kinetic Analysis of Diesel Particulate Matter using Single- and Multistage Methods

“…This statistical approach used for the primary diameter distributions was completely different from the professional methods, such as electrical low-pressure impactor (ELPI) and engine exhaust particle sizer (EEPS), scanning mobility particle sizer (SMPS) and condensation particle counter (CPC) [47][48][49][50] . In this paper, the diameter was the geometry value, nevertheless, it was aerodynamic diameter for those tested using professional instruments 13,51,52 .…”

“…Based on the oxidation profiles, different methods were used to calculate kinetic parameters (activation energy, pre-exponential factors, and reaction rate constant) [7][8][9] . Activation energy of diesel PM sampled at different conditions (engine operation conditions, engine types, fuel types, aftertreatment technologies) was in the range of 80 kJ/mol ~230 kJ/mol [10][11][12][13][14][15][16][17] . The values, calculated using multiple ramp rate oxidation profiles (Kissinger, Akahira and Sunose method), increased generally with mass drop in the oxidation process.…”