Lead antiknocks

Whitcomb, R.M. (1975), Non-lead antiknock agents for motor fuels . Chemical Technology Review No. 49, Noyes Data Corporation, Park Ridge, NJ. 

Heavy-walled drums once used for lead antiknock chemicals have been used for water storage or as barbecue pits, with subsequent risk to the user from residual toxic material. Equipment from the industry cited has for many years been cleaned, cut up, and sent under supervision to steel mills for recycle to eliminate the possible misuse of scrapped containers. 

During the 1960s, Americans lived in a lead-drenched society. They fueled their cars with leaded, antiknock gasoline. They ate food and their babies drank milk from lead-soldered cans. They stored drinking water in lead-lined tanks and transported it through lead or lead-soldered pipes. They squeezed toothpaste from lead-lined tubes and poured wine from bottles sealed with lead-covered corks. They picked fruit sprayed with lead arsenate pesticide and served it on lead-glazed dishes in houses painted and puttied with lead-based compounds. 

Robinson TR. 1974. Delta-aminolevulinic acid and lead in urine of lead antiknock workers. Arch Environ Health 28 133-138. 

Diminishes the Effectiveness of Alkyl Lead Antiknock Compounds... 

Leaded gasoline gasoline containing tetraethyl lead or other organometallic lead antiknock compounds. 

Soulages, N. L. The analysis of lead antiknock additives by gas chromatography. 

The extensive use of lead antiknock additives in gasoline has made lead perhaps the most widely distributed toxic heavy metal in the urban environment and has greatly increased its availability for solution in natural waters. It is important for this reason to know whether its introduction into surface and ground waters by rainfall and runoff will make it available for solution or whether chemical processes will place a safe upper limit on its solubility. 

In addition to the tetraethyl or tetramethyl lead, both types of antiknock fluids also contained 1,2-dichloroethane and 1,2-dibromoethane (ca. 35% by weight) to react with the lead released on combustion to form lead bromide and lead chloride. These lead halides are volatile at the cylinder combustion temperatures of 800-900°C, and leave the combustion chamber with the exhaust, which prevented the buildup of lead deposits. This was also the final step in the chain of events occurring with the alkylated lead antiknock compounds, which contributed to the widespread dispersal of lead compounds to the air and soil wherever gasoline powered vehicles operated. For this reason, and the toxic exposures during refueling, the alkylated lead addition rate was reduced to not more than 0.5 g of contained lead per U.S. gallon by 1980, even for leaded gasolines [29], and was phased out in the U.S. and Canada by 1985. 

EFFECT OF LEAD ANTIKNOCK REGULATIONS ON GASOLINE AROMATICS AND AROMATIC EXHAUST EMISSIONS... 

Certainly, aromatics are a significant replacement for lead antiknocks. This will have an impact on the availability and cost of aromatics now going to the petrochemical industry. The amount of additional aromatics required will depend on the volume and octane levels of the various grades of gasoline, the use of high-octane blending stocks from alkylation and isomerization processing units, and the use of alcohols and ethers. 

To evaluate the effect of lead antiknock restrictions, we have developed a general relationship of aromatic content to Research octane number for both unleaded gasolines and the clear base stocks of leaded regular gasolines, as shown in Figure 1. These curves are the same as in our earlier paper (1). The lower unleaded-fuel curve was developed from data on commercial gasolines. Although the relationship is expressed by a line, in actuality it is a rather broad band. There are, of... 

To determine the extent to which refiners in Europe have replaced lead antiknocks with aromatic octanes, we analyzed the aromatic content vs lead content for premium and regular-grade gasolines. The data used were from surveys conducted by Ethyl S.A. of service station samples collected in selected European cities during three sampling periods from April 1979 to September 1980. 

This large effect of lead antiknock concentration on aromatic content of European gasolines is explained in a CONCAWE report (3), which stated ... 

Du Pont and other major lead antiknock manufacturers have been developing automotive exhaust lead traps since the middle 1960s (3). Other road tests have shown these traps to be effective under benign climate conditions, but none have considered the wide range found in Canada. 

Standardization, no special topic was estimated an emergency in the fields surveyed. We need more data before answering questions on the dangers related to a possible increase in POM (as an unavoidable consequence of decreased lead antiknock additives) and on the use of diesel fuel. Presently, no standard exists for PAH in ambient air in any country. There is a TLV for the benzene soluble fraction of coke oven smoke in factories, and a standard exists for PAH in drinking water, but these conditions are not relevant to the case of automobile exhaust. 

Decreasing lead antiknock additives could possibly create increases in the emission of polycyclic aromatic hydrocarbons. Conversion to diesel motors for automobile transportation could also create in our environment a new hazard due to the possible mutagenic/carcinogenic properties of the aromatic combustion products from this type of engine, e.g., nitroaromatics. 

A very large market for such chemical as tertiary butyl alcohol may open if lead antiknock additives are reduced in gasoline blends. Alcohols (methanol, ethanol, tertiary butyl-alcohol) and ethers (methyltertbutylether) are among these components which can be used to boost octane number. Their synthesis will involve addition of water or alcohols to olefins. This can be realized in three phase systems. 

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