Soot characteristics

Improvement of the atmosphere continues to be of great concern. The continual search for fossil fuel resources can lead to the exploitation of coal, shale, and secondary and tertiary oil recovery schemes. For instance, the industrialization of China, with its substantial resource of sulfur coals, requires consideration of the effect of sulfur oxide emissions. Indeed, the sulfur problem may be the key in the more rapid development of coal usage worldwide. Furthermore, the fraction of aromatic compounds in liquid fuels derived from such natural sources or synthetically developed is found to be large, so that, in general, such fuels have serious sooting characteristics. 

In a study conducted at the Lovelace Inhalation Toxicology Research Institute (ITR1), rats were exposed for up to 30 months, 7 h/day, 5 days/wk, to diesel exhaust containing 0, 0.35, 3.5, or 7.1 mg soot/m3 of air. The diesel engine exhaust was generated as indicated in the section of this paperon "Physical/Chemical Characteristics of Diesel Soot." The lowest exposure concentration, 0.35 mg soot/m3, is directly relevant to some occupational exposures and is 10 to 100 times higher than any current or anticipated environmental exposures. Observations of the animals were made at 6-mo intervals and included measures of dosimetry (mg soot/g lung),... 

The characteristics of soot are well described in the article by Palmer and Cullis [49], who provide detailed references on the topic. Aspects of their review are worth summarizing directly. They report the detailed physical characteristics of soot as follows ... 

As additives to reduce soot output in flames, metal and organometallic compounds, such as ferrocene, have attracted the attention of many investigators (see Ref. [113]). The effect in premixed flames is best described by Bonczyk [114], who reported that the efficiency with which a given metal affects soot production characteristics depends almost exclusively on temperature and the... 

Evidence also exists for a terrestrial source of the iridium enrichment as volcanic ejecta is enriched in this rare element. Thus, the enriched sediment layer could also have been caused by an abrupt and large increase in volcanic activity. Evidence for this is suggested by high levels of volcanic ash, soot, and shocked minerals in the iridium-enriched layer. Other geochemical characteristics of this sediment layer appear to have been caused by acid rain and tsunamis, both of which are by-products of volcanic activity. 

O Dowd, C. D and M. H. Smith, Submicron Particle, Radon, and Soot Carbon Characteristics over the Northeast Atlantic, J. Geophys. Res., 98, 1123-1135 (1993a). 

To prepare the standardized dispersion electrode, a mixture of 100 mg soot, 100 g 97% sulfuric acid and 100 mg pigment was stirred direct into the dilute sulfuric acid of the measuring vessel, so that the concentration of sulfuric acid in the electrolyte after stirring in was about 4.5 N. The current collector electrode was a gold-platinum mesh (90/10) of about 4.5 cm2 area. The current/voltage characteristics shown in Fig. 12 make it possible to compare CoTAA with various phthalocyanines. 

Scientists are interested in the physical characteristics ol flame, such a size and shape, and the role of soot formation in combustion. Investigations also study air flows and the transfer nf heat and mass in fuel vapors, liquid pools, paper and metal solids. 

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