Tetraethyl lead in gasoline

Worldwide pollutant of the at- mosphere. concentrated in urban areas from the combustion of tetraethyl lead in gasoline local pollutant "j from mines some poisoning from lead-based paint pigments. 

Use Oxidation inhibitor and stabilizer in gasoline (satisfies ASTM D910-64T as antioxidant in aviation gasoline), prevents decomposition of tetraethyl lead in gasoline. 

MMT. MMT is a fuel additive developed in the 1950s to increase the octane level of gasoline and thus improve the antiknock properties of the fuel (Davis 1998 EPA 1984a HSDB 1993 Lynam et al. 1990 NAS 1973). It can also be used as a fuel oil additive and a smoke inhibitor (HSDB 1999). MMT was introduced into Canada in 1976 and its use has increased so substantially that it completely replaced tetraethyl lead in gasoline in that country in 1990 (Zayed et al. 1999). Ethyl Corporation, the manufacturer of MMT, has been marketing its product to U.S. refineries since late 1995 (Davis 1998). There are no data concerning the extent of its use in the U.S. 

What was the advantage of using tetraethyl lead in gasoline What were two disadvantages ... 

Using the web, find information about the amount of lead in the environment during the past 40 years. Correlate what you observe with the presence or absence of tetraethyl lead in gasoline. 

Even more important, his decision to remain an untenured senior research fellow meant that he could be fired at any time. After the Ethyl Corporation s representatives visited Patterson s office, the petroleum industry upped the pressure a notch. A member of Caltech s board of trustees was a vice president of a petroleum company that used tetraethyl lead in its gasoline. The trustee telephoned Caltech s president, Lee DuBridge, about Patterson. DuBridge in turn phoned Patterson s boss Robert P. Sharp, chair of Caltech s geological and planetary sciences division. 

Catalysts that decrease reaction rates are usually referred to as inhibitors. They usually act by interfering with the free radical processes involved in chain reactions, and the mechanism differs from that involved in accelerating a reaction. The most familiar example of the use of inhibitors is the addition of tetraethyl lead to gasoline to improve its antiknock properties. 

The reduction in tetraethyl lead for gasoline production is expected to increase the demand for petroleum alkylate both in the U.S. and abroad. Alkylate producers have a choice of either a hydrofluoric acid or sulfuric acid process. Both processes are widely used. However, concerns over the safety or potential regulation of hydrofluoric acid seem likely to convince more refiners to use the sulfuric acid process for future alkylate capacity. 

The total lead in gasoline may be determined gravimetrically (ASTM D-52, IP 96), polarographically (ASTM D-1269), by atomic absorption spectrometry (ASTM D-3237, IP 428), by the iodine chloride method (ASTM D-3341, IP 270), by inductively coupled plasma atomic emission spectrometry (ASTM D-5185), and by X-ray fluorescence (ASTM D-5059). When it is desired to estimate tetraethyl lead a method is available (IP 116X whereas for the separate determination of tetramethyl lead and tetraethyl lead recourse can be made to separate methods (ASTM D-1949, IP 188). 

Through natural occurrence and its industrial use, lead is ubiquitous in the environment. The removal of tetraethyl lead from gasoline has resulted in a decline in blood levels from 13 pg/dL in the 1980s to <5 pg/dL in the general U.S. population. However, many children living in central portions of large cities still have blood lead concentrations >10 pg/dL. The primary sources of environmental exposure to lead are leaded paint and drinking water most of the overt toxicity from lead results from environmental and industrial exposures. 

Although crude petroleum contains substantial quantities of metals, the largest sources of metals entering the environment from petroleum products are tetraethyl lead added to gasoline, metal compounds added to lubricants, and wear metals that accumulate in used lubricants. The fate of lead in gasoline has been studied extensively and will not be discussed here. 

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