Automobiles particles from

FIGURE 9.11 Surface distribution of particles from the combustion of several organics and from automobiles and a candle (adapted from National Research Council, 1979). 

Transportation sources, particularly automobiles, are a major source of air pollution and include smoke, lead particles from tetraethyl lead additives, CO, nitrogen oxides, and hydrocarbons. Since the mid-1960s there has been significant progress in reducing exhaust emissions, particularly with the use of low-lead or no-lead gasoline as well as... 

The chemical and thermal characteristics of PGE make them highly useful as catalysts in a wide variety of industrial, chemical, electrical and pharmaceutical processes (Johnson Matthey 2007). Their use as catalysts in automotive catalytic converters to reduce noxious emissions from the burning of fossil fuels has undoubtedly been one of the most far-reaching and important applications. Automobiles have been equipped with catalytic converters since 1975 and 1986 in the US and Europe, respectively. Initially, Pt and Pd were used to reduce hydrocarbon and carbon monoxide emissions. Since the early 1990s, Rh has also been used in various combinations and ratios with Pt and Pd in three-way catalytic converters to reduce emissions. PGE appear to be emitted together with alumina particles from the washcoat as a result of various chemical, physical and... 

Most automobiles, trucks, industrial vehicles, and other equipment depend on lead-acid batteries. These batteries can explode during charging operations, causing battery acid and particles from the case to injure the eyes or skin. Two types of explosions are possible one related to... 

Automobile mechanics and other transportation-related workers can be at risk from inhalation hazards, such as metal fume fever, from inhalation exposures to manganese, which is released in automobile exhaust from combustion of manganese antiknock additives in nonleaded gasoline. According to the EPA (185), 30% of the manganese in gasoline is released from the automobile exhaust pipe. The size of manganese particles emitted to the atmosphere varies from 0.25 to... 

Macroscopic properties often influence tlie perfoniiance of solid catalysts, which are used in reactors tliat may simply be tubes packed witli catalyst in tlie fonii of particles—chosen because gases or liquids flow tlirough a bed of tliem (usually continuously) witli little resistance (little pressure drop). Catalysts in tlie fonii of honeycombs (monolitlis) are used in automobile exliaust systems so tliat a stream of reactant gases flows witli little resistance tlirough tlie channels and heat from tlie exotlieniiic reactions (e.g., CO oxidation to CO,) is rapidly removed. 

Almost all the materials which are being considered as components in automobile exhaust catalyst are somewhat toxic (74)- Most of the compounds considered are low vapor pressure solids which can only escape from the exhaust system as very fine airbone dust particles formed by catalyst attrition. A few compounds, such as the highly toxic metal carbonyls and ruthenium tetroxides, are liquid under ambient conditions and have boiling points less than 100 °C. These compounds are not present in... 

Recently, it is reported that Xi02 particles with metal deposition on the surface is more active than pure Ti02 for photocatalytic reactions in aqueous solution because the deposited metal provides reduction sites which in turn increase the efficiency of the transport of photogenerated electrons (e ) in the conduction band to the external sjistem, and decrease the recombination with positive hole (h ) in the balance band of Xi02, i.e., less defects acting as the recombination center[l,2,3]. Xhe catalytic converter contains precious metals, mainly platinum less than 1 wt%, partially, Pd, Re, Rh, etc. on cordierite supporter. Xhus, in this study, solutions leached out from wasted catalytic converter of automobile were used for precious metallization source of the catalyst. Xhe XiOa were prepared with two different methods i.e., hydrothermal method and a sol-gel method. Xhe prepared titanium oxide and commercial P-25 catalyst (Deagussa) were metallized with leached solution from wasted catalytic converter or pure H2PtCl6 solution for modification of photocatalysts. Xhey were characterized by UV-DRS, BEX surface area analyzer, and XRD[4]. 

A catalyst used for cleaning exhaust gases from automobiles consist, among other things, of Rh particles on an AI2O3 support material. The Rh particles expose primarily Rh(lll) and secondarily Rh(lOO) surface structures. Rh is a FCC metal with a lattice distance of a = 0.381 nm. 

Patterson thought he could identify the culprit If the high concentrations of lead observed in a few surface waters of the Pacific were representative of the sea surface of the entire northern hemisphere, the bulk of this lead could be readily be accounted for as originating from leaded gasolines. The hypothesis was unproven, but Patterson immediately understood its social implications. Automobile exhaust emitted lead as soluble lead-halide particles, which humans and other mammals easily absorb. When Patterson reported his ocean sediment research in an encyclopedic, 45-page article in 1962, he handed a copy to a colleague saying, Read it. It s important. ... 

Information available regarding the chemistry of lead in air is limited. Before the ban on sales of leaded gasoline, lead particles were emitted to the atmosphere from automobiles as lead halides (mostly PbBrCl) and as double salts with ammonium halides (e.g., 2PbBrCl NH4Cl. Pb3[P04]2, and PbS04 [Biggins and Harrison 1979 Ter Haar and Bayard 1971]). After 18 hours, approximately 75% of the bromine and 30-40% of the chlorine disappeared, and lead carbonates, oxycarbonates and oxides were produced. 

Note that the chemical dimensions do not yield such robust "markers", or tracers, as the isotopic dimensions. For a given combustion source, for example, one is apt to find chemical--but not isotopic—fractionation varying significantly with time, particle size, particle history (differential volatilization or reaction), etc. The ratio K/Fe, for example, was quite different in the fine and coarse fractions from a slash burn (1.5 vs. 0.3) [33] and Pb/Br, which has been popular as an automobile exhaust tracer, varies with the "age" of urban particles [22]. 

Particle-phase tailpipe emission rate from a noncatalyst-equipped gasoline-powered automobile was 37.3 pg/km (Schauer et al, 2002). 

Particle-phase tailpipe emission rates from gasoline-powered automobiles with and without cataiytic converters were 0.021 and 41.0 pg/km, respectively (Schauer et al., 2002). 

Lead aerosol in the air is poisonous to breathe, especially for young children. Many people called for the abolition of lead in gasoline. In the 1970s, the photochemical smog in California was attributed to unburned hydrocarbons and carbon monoxide from automobile tailpipes, and the best solution was the catalytic converter which works with finely divided platinum particles deposited on alumina monoliths. When leaded gasoline is used, these platinum atoms would be quickly covered by a barrage of lead aerosols. This finally led to the abolishment of TEL as a gasoline additive. 

Automobile tires are the largest-volume mbber material manufactured, and they are formed from natural or synthetic monomers with sulfur compounds added to crosslink the polymer within the tire mold. Tires also contain large amounts (typically 35%) of carbon black particles, which are made by hydrocarbon combustion in excess fuel, as we have considered previously in Chapters 9 and 10. 

In both component and factor analysis, the properties of the system being observed are assumed to be linearly additive functions of the contribution from each of the m causalities that actually govern the system. For example, for airborne particles, the amount of particulate lead in the air could be considered to be a sum of contributions from several sources including automobiles, incinerators and coal-fired power plants, etc. 

The most appropriate models for CYC is probably equation (14) as this is the simplest and is most closely related to the results of the factor analysis which indicated that the variances in CYC were most closely related to those in V and PB. The inclusion of coarse particle manganese as a soil tracer diminished the significance of the coefficient of PB and the contribution of automotive sources. Ideally, MN would be used as a tracer for resuspended soil but Interferences from the use of MMT as a fuel additive during part of the period in which this data were collected make this a mixed source tracer for the contributions of automobiles and soil resuspension. 

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