Grain type and size of particulate matter from diesel vehicle exhausts analysed by transmission electron microscopy

Abstract

The aim of this research was to apply a simple and quick method of size and shape characterization by TEM to diesel exhaust particles from large-capacity, high-performance trucks. Particulate matter (PM) samples were collected while the engines were idling. Investigation of this type of emission is essential because vehicles are idling at stop lights, in traffic, or during slow movement, goods loading and unloading. In these conditions, PM emission cumulates in a small area. It was found that PM from vehicle exhaust emissions can be divided into three groups: soot, irregular-shaped particles and circular particles. Irregular-shaped particles and soot aggregates were present in the exhausts of the three types of vehicle tested. Circular particles were identified only in the samples collected from exhaust emissions from the MAN vehicle, and were present in small amounts. The average surface area was in the range of 0.06 microm2 to 0.24 microm2. Mean perimeter fluctuated from 2.09 microm to 4.14 microm, and Feret diameter from 0.21 microm to 0.31 microm. Circularity was in the range of 0.12 to 0.30. Aspect ratio was around 0.30 to 0.45. Feret diameter seems to be a good parameter to define the mean size of particles, but does not take into account the influence of the shape. Therefore, this measurement seems to be useful just in the case of spherical or very rounded particles, not for all diesel PM. Thus, it is necessary to consider circularity or aspect ratio for DPM characterization.

An experimental and modelling analysis of cloud droplet growth from vehicular emissions with non‐ideal microphysics over an Asian mega‐city

“…The presence of elemental Carbon in the collected deposits was estimated from an Energy‐dispersive X‐ray spectroscopy (EDAX) (see Figure S3). The samples contained 59% carbon (C) comparing favourably with earlier studies (Lai et al, 2016; Sielicki et al, 2012). Further details of the compositional inferences on the relative abundances of other metals resulting from break wear emissions are indicated in Data S1 which describes the use of a hand‐held X‐ray fluorescence spectrometer.…”

Environmental Risk Assessment of Vehicle Exhaust Particles on Aquatic Organisms of Different Trophic Levels

“…PAHs are indicated as one of the major contributors to the toxic effect of motor vehicle exhausts because of their mutagenic, carcinogenic, and teratogenic properties [14]. Moreover, the number and the characteristics of VEPs depend on many factors, such as the engine type, fuel type, mileage, and working conditions [15,16]. Many research groups have aimed to find technological solutions which reduce the emission of particulate matter (PM) by motor vehicles [17,18].…”

Conductometric Soot Sensors: Internally Caused Thermophoresis as an Important Undesired Side Effect

“…Soot is a highly complex matter. Characteristics like morphology, carbon content, adhered volatile organic components content or water, or its electrical charge will also influence the interaction with a measuring device [ 7 , 44 , 45 , 46 , 47 , 48 , 49 ]. For a further knowledge-based development of conductometric soot sensors, the influences of the applied voltage and of the sensor temperature on the soot deposition needs to be investigated.…”