Characteristics of Atmospheric Elemental Carbon (Char and Soot) in Ultrafine and Fine Particles in a Roadside Environment, Japan

An intensive campaign for atmospheric pollution was carried out from October to November 2004 in Pearl River Delta Region (PRDR) of China in order to better understand the dominative factors for controlling air quality and impacts of pollutants on the regional environment. The object of this study aimed to investigate the characters and sources of particulates through the study of chemical compositions in different wind pattern in Guangzhou city. The ambient concentrations of mass, soluble species, and carbonaceous matter in PM 2.5 particulates with time resolutions of 15 minutes, 15 minutes, and 12 hours were measured by TEOM, in-situ IC system, and carbon analyzer, respectively. During the sampling time, high concentrations of PM 2.5 mass and its chemical compositions were found, which was comparable or higher than other measurements in mainland China. The average SO 4 2-, NH 4 + , and NO 3 -concentrations were 38.6, 13.6, and 8.8 μg/m 3 , which accounted for 26.5%, 13.6%, and 5.7% of the total particulate mass, respectively. In the frontal system, biomass burning was the significant emission source and the great amount of SO 4 2-and NH 4 + particulates were observed in the aged secondary particulates, together with the dry prevailing northerly wind. In the local system, low value of sulfur oxidation ratio and high correlation coefficient between sulfate and elemental carbon were also observed under the prevailing southeasterly wind. It could be explained that the heterogeneous reaction of sulfate on soot particles causes high levels of NO x in Guangzhou. Great amount of SO 2 would further convert to secondary sulfate particles through photochemical reactions during transport to the inner areas, which will cause more serious air pollutions in the southern China.

Section: Introductionmentioning

confidence: 99%

The Characteristics of PM2.5 and Its Chemical Compositions between Different Prevailing Wind Patterns in Guangzhou

Chang

Chou

Liu

et al. 2013

“…PAHs were formed possibly via the consecutive addition and cyclization of hydrocarbon free radicals (Wang et al, 1999a). Moreover, such soot formation in the RF plasma reactor is different from the particle depositions from others combustion process in atmospheric environment (Chiu et al, 2011;Kim et al, 2011;Ruttanachot et al, 2011) In the 1970s, MTBE represented the great hope for replacing tetraethyllead as the main antiknock additive in gasoline. However, people are now trying to work MTBE out of the motor fuel systems.…”

Section: Soot Formation In the Rf Plasma Reactormentioning

confidence: 99%

Decomposition of Methyl Tert-Butyl Ether by Adding Hydrogen in a Cold Plasma Reactor

Hsieh

Tsai

Chang

et al. 2011

Methyl tert-butyl ether (MTBE) is extensively used as an oxygenate and octane enhancer in gasoline. Its release to the environment has generated great public and governmental concern. In this study, we give a brief review of the decomposition of air toxics by the application of radio frequency (RF) plasma reactors and then present our study on decomposition of methyl tert-butyl ether by adding hydrogen in a cold plasma reactor. Based on our references, there are four types of the application in the RF plasma reactors are discussed, including: (i) Application I.: Converting methane, decomposing carbon dioxide, ethoxyethane, and ethylene oxide; (ii) Application II.: Decomposing methyl chloride, 1,1-C 2 H 2 Cl 2 , and CH 2 Cl 2 ; (iii) Application III.: Decomposing dichlorodifluoromethane, CHF 3 , CH 2 F 2 , CCl 2 F 2 , and BF 3 ; (iv) Application IV.: Decomposing dichlorodifluoromethane, CH 3 SH, CS 2 , SF 6 , and SF 6 + H 2 S mixture. Moreover, this study demonstrates the feasibility of applying a radio frequency (RF) plasma reactor for decomposing and converting MTBE. Experimental results indicate that the decomposition efficiency (η MTBE ) and the fraction of total input carbon converted into CH 4 , C 2 H 2 and C 2 H 4 (F CH4+C2H2+ C2H4 ) increased with the input power and decreased as both the H 2 /MTBE ratio and the MTBE influent concentration in the MTBE/H 2 /Ar plasma environment increased. Interestingly, applying radio frequency plasma to the decomposition of MTBE while adding hydrogen constitutes alternative method of decomposing and converting MTBE into CH 4 , C 2 H 4 , C 2 H 2, iso-butane and iso-butene.

“…Furthermore, the deposition of soot can accelerate the melting of snow and ice due to additional surface absorption, and decrease the reflectivity of snow and ice, which also enhances global warming (Hansen and Nazarenko, 2004). The absorption of soot is a million times stronger than that of CO 2 , but the residence time in the Earth's atmosphere of soot is much shorter than that of CO 2 (Kim et al, 2011). Thus, reducing soot emissions into the atmosphere is regarded as a near-term climate change mitigation approach (Shindell et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Particle Size Distribution of Soot from a Laminar/Diffusion Flame

Chen

Zhou

et al. 2017

A practical method is proposed to determine the inflame soot particle size distribution via an explicit solution derived from time-resolved laser-induced incandescence (TiRe-LII). Three appropriate time intervals are selected from the TiRe-LII decay signal. The equivalent mean sizes as well as relative ratios of number densities for three classes of monodisperse particles are determined with the mono-exponential fit to each interval, which allows an explicit solution for the particle size distribution. Simulations show that inversed log-normal distributions from the explicit solution are coincident with the input parameters in terms of trend, and there exist critical time intervals where inversed results are most insensitive to the variation of interval length. The error of inversion is critically dependent on the geometric standard deviation but weakly dependent on the count median particle diameter. Influences of experimental conditions on the inversed error are additionally evaluated. The results show that flame temperature has a significant impact on the error of inversion. Thus, a database of the error as a function of flame temperature at a fixed aggregate size is established. The error database allowed the inversed results from experimental TiRe-LII signals to be readily corrected at various flame locations by interpolation. The corrected inversed log-normal distributions were consistent in trend with those determined from the established nonlinear regression method, and the modeling LII signals reproduced agree with the experimental data. The small deviation of the results potentially stemmed from the statistical noise contained in recorded LII signals.