The effective density and fractal dimension of soot particles from premixed flames and motor vehicle exhaust

Abstract. The single particle soot photometer (SP2) uses laser-induced incandescence (LII) for the measurement of atmospheric black carbon (BC) particles. The BC mass concentration is obtained by combining quantitative detection of BC mass in single particles with a counting efficiency of 100% above its lower detection limit (LDL). It is commonly accepted that a particle must contain at least several tenths of femtograms BC in order to be detected by the SP2. Here we show the unexpected result that BC particles from a PALAS spark discharge soot generator remain undetected by the SP2, even if their BC mass, as independently determined with an aerosol particle mass analyser (APM), is clearly above the typical LDL of the SP2. Comparison of counting efficiency and effective density data of PALAS soot with flame generated soot (combustion aerosol standard burner, CAST), fullerene soot and carbon black particles (Cabot Regal 400R) reveals that particle morphology can affect the SP2's LDL. PALAS soot particles are fractal-like agglomerates of very small primary particles with a low fractal dimension, resulting in a very low effective density. Such loosely-packed particles behave like "the sum of individual primary particles" in the SP2's laser. Accordingly, the PALAS soot particles remain undetected as the SP2's laser intensity is insufficient to heat the primary particles to vaporisation because of their small size (primary particle diameter ~5–10 nm). It is not surprising that particle morphology can have an effect on the SP2's LDL, however, such a dramatic effect as reported here for PALAS soot was not expected. In conclusion, the SP2's LDL at a certain laser power depends on total BC mass per particle for compact particles with sufficiently high effective density. However, for fractal-like agglomerates of very small primary particles and low fractal dimension, the BC mass per primary particle determines the limit of detection, independent of the total particle mass. Consequently, care has to be taken when using the SP2 in applications dealing with loosely-packed particles that have very small primary particles as building blocks.

Download Full-text

Assessing Population Exposures to Motor Vehicle Exhaust

Reviews on Environmental Health ◽

10.1515/reveh.2005.20.3.195 ◽

2005 ◽

Vol 20 (3) ◽

Cited By ~ 2

Author(s):

C. Van Atten ◽

M. Brauer ◽

Τ. Funk ◽

N.L. Gilbert ◽

L. Graham ◽

...

Keyword(s):

Motor Vehicle ◽

Vehicle Exhaust

Download Full-text

Composition of Light-Duty Motor Vehicle Exhaust Particulate Matter in the Denver, Colorado Area

Environmental Science & Technology ◽

10.1021/es9810843 ◽

1999 ◽

Vol 33 (14) ◽

pp. 2328-2339 ◽

Cited By ~ 126

Author(s):

Steven H. Cadle ◽

Patricia A. Mulawa ◽

Eric C. Hunsanger ◽

Ken Nelson ◽

Ronald A. Ragazzi ◽

...

Keyword(s):

Particulate Matter ◽

Motor Vehicle ◽

Vehicle Exhaust ◽

Light Duty ◽

Exhaust Particulate

Download Full-text

The Effects of Lead (Pb) Exposure to Blood Pb Concentration and Hemoglobin Levels in Book Sellers and Street Vendors of Surakarta

Jurnal Kesehatan Masyarakat ◽

10.15294/kemas.v13i2.5743 ◽

2017 ◽

Vol 13 (2) ◽

Author(s):

Khotijah Khotijah ◽

Ipop Sjarifah ◽

Putu Gede Oka Mahendra ◽

Vitri Widyaningsih ◽

Haris Setyawan

Keyword(s):

Motor Vehicle ◽

Public Health Problem ◽

Vehicle Exhaust ◽

Cross Sectional ◽

Street Vendors ◽

Pb Exposure ◽

Cross Sectional Design ◽

Susceptible Populations ◽

Data Analysis Result ◽

Pb Concentration

Anemia is still a public health problem in the world and in Indonesia. WHO (2008) reported more than 75% of anemia in Asia is iron deficiency and 63.5% anemia in Indonesia is caused by lack of nutrition. Previous studies described that lead (Plumbum /Pb) can decrease hemoglobin levels. Sriwedari markets book sellers and Solo Wholesale Centers street vendors are susceptible populations exposed to Pb as a result of motor vehicle exhaust. Approximately 70% of Pb in vehicle exhausts emissions are emitted into the air. This study aimed to analyze the effects of Pb exposure on blood Pb concentration and hemoglobin levels. This study was a quantitative observational analytic study with cross sectional design conducted in 2015-2016 at Sriwedari Market. Samples were 97 respondents obtained through random sampling and Spearman correlation was used for data analysis. Result showed that there were association between Pb exposure in the air and blood Pb levels (p=0,000; r=0,606) and blood Pb levels and hemoglobin levels (p=0,000; r=-0,623)

Download Full-text

Research on Motor Vehicle Exhaust Pollution Monitoring Technology

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.620.244 ◽

2014 ◽

Vol 620 ◽

pp. 244-247 ◽

Cited By ~ 4

Author(s):

Xiu Li Gao ◽

Tian Jun Hu ◽

Ke Wang

Keyword(s):

Remote Sensing ◽

Motor Vehicle ◽

Pollution Monitoring ◽

Vehicle Exhaust ◽

Monitoring Method ◽

Monitoring Technology ◽

Advantages And Disadvantages ◽

Remote Sensing Technology ◽

Sensing Technology

This paper starts from the influence of vehicle exhaust, first introduces a major vehicle exhaust monitoring technology--Remote Sensing Technology, gives its monitoring principles and then analyzes the advantages and disadvantages of this method. Then,it takes the most abundant types of substances in vehicle exhaust (NOx) as example,illustrates the principles and methods for monitoring. Finally,it introduces a new vehicle exhaust monitoring method and makes a full summary.

Download Full-text

Performance of Visible-Light-Driven Photocatalytic Pavement in Reduction of Motor Vehicles’ Exhaust Gas

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198120947084 ◽

2020 ◽

Vol 2674 (11) ◽

pp. 512-519

Author(s):

Zhuoying Jiang ◽

Xiong (Bill) Yu

Keyword(s):

Absorption Spectrum ◽

Visible Light ◽

Motor Vehicle ◽

Computational Simulation ◽

Motor Vehicles ◽

Traffic Density ◽

Ultraviolet Region ◽

Exhaust Gas ◽

Vehicle Exhaust ◽

Three Dimensional Model

Titanium dioxide (TiO2) is a widely used photocatalyst that can oxidize motor vehicle exhaust, for example, carbon monoxide (CO), nitrogen oxides (NOx), hydrocarbons, and sulfur dioxide, under the irradiation of sunlight. It has been reported that nano-scale TiO2 particles can be effectively used to modify the concrete-asphalt pavement, and make it as a photocatalytic pavement. However, the pure TiO2 additive limits its absorption spectrum to the ultraviolet region, which only occupies a small portion of sunlight irradiance. To increase the utilization of the full spectrum of sunlight, it has been demonstrated that doping TiO2 with substances such as Carbon (C), Nitrogen (N), or metal can reduce the band-gap and extend the threshold of the absorption spectrum to the visible light region. Therefore, doped-TiO2 has a better photocatalytic performance under sunlight irradiation. This paper conducted computational simulation of the kinetics of photocatalytic pavement to quantify the efficiency of doped-TiO2 embedded pavement in reducing exhaust gas from motor vehicles. A three-dimensional model is developed on a section of local road with doped-TiO2 embedded pavement. The effects of doped-TiO2 concentration, daylight conditions, and traffic flow conditions on the removal of NOx and CO were studied. The results indicate that the pavement with doped-TiO2 coating is effective to remove CO and NOx under different traffic density and daylight intensity conditions. Compared with UV activated TiO2, visible-light-activated doped-TiO2 features significantly higher removal efficiency of poisonous exhaustive gas including NOx and CO.

Download Full-text