Benzene quality standards

Table 4 summarises the air quality standards stipulated in the 2008 EC Directive. Additionally, benzene is regulated not to exceed 5 (ig/m3 as an annual average. 

An example of an evaluation undertaken according to this protocol is for the measurement of benzene in ambient air by tube type samplers subject to thermal desorption (EN, 2005b) and samplers subject to solvent desorption (EN, 2005a). These standards were developed specifically to provide measurement methods meeting requirements for checking compliance with the air quality standard for benzene set by the European Ambient Air Quality Directive (Directive 96/62/EC, 1996). Evaluation of published data concerning the samplers under the test conditions enabled an evaluation of the expanded relative uncertainty of measurement at a limit value (5 pgnT3) for benzene in air and for solvent and thermally desorbed samplers a value of 13.4% was obtained. 

EN (2005a) 14662-5. Ambient Air Quality-Standard Method for Measurement of Benzene Concentrations Diffusive Sampling Followed by Solvent Desorption and Gas Chromatography, The British Standards Institution, London, UK. 

The Environmental Protection Agency has promulgated a national ambient air quality standard for hydrocarbons 160 is the maximum 3-hr concentration not to be exceeded more than once a year. It was arrived at by considering the role of hydrocarbons in the formation of photochemical smog. Suppose that in an exhaust gas benzene vapor is mixed with air at 25°C such that the partial pressure of the benzene vapor is 2.20 mm Hg. The total pressure is 800 mm Hg. Calculate ... 

The CAA establishes national primary and secondary air quality standards for sulfur oxides, particulate matter, carbon monoxide, ozone, nitrogen dioxide, and lead. It also limits the emission of 189 listed hazardous waste pollutants such as vinyl chloride, arsenic, asbestos, and benzene (CAA, 1977). States are responsible for enforcement of the CAA. To assist in this effort. Air Quality Control Regions (AQCRs) were established. Allowable emission limits are determined by the AQCR or its subunit, the Air Quality Management District. These emission limits are based on whether or not the region is currently within attainment of National Air Quality Standards. 

Quality standards of benzene hydrocarbons are generally determined by their applications. 

A hazardous air pollutant is one for which no ambient air-quality standard is applicable, but which may cause or contribute to increased mortality or illness in the general population. Emission standards for such pollutants are required to be set at levels that protect the public health. These allowable pollutants emission levels are known as NESHAPS and include levels for radon-222, beryllium, mercury, vinyl chloride, radionuclides, benzene, asbestos, arsenic, and fugitive organic leaks from equipment. 

DIN EN 14662-2, Ambient air quality - standard method for measurement of benzene concentrations part 2 pumped sampling followed by solvent desorption and gas chromatography, 2005. 

Aspila et al. [338] reported the results of an interlaboratory quality control study in five laboratories on the electron capture gas chromatographic determination of ten chlorinated insecticides in standards and spiked and unspiked seawater samples (lindane, heptachlor, aldrin, 5-chlordane, a-chlordane, dield-rin, endrin, p, p -DDT, methoxychlor, and mirex). The methods of analyses used by these workers were not discussed, although it is mentioned that the methods were quite similar to those described in the water quality Branch Analytical Methods Manual [339]. Both hexane and benzene were used for the initial extraction of the water samples. 

EPA. 1980. Ambient water quality criteria for chlorinated benzenes. U.S. Environmental Protection Agency, Office of Water, Regulations and Standards, Washington, DC. EPA 440/5-80-028, NTIS No. PB81-117392. 

The P in KHP refers to phthalate. The phthalate ion is a benzene ring with two carboxyl groups on adjacent carbons. See Figure 5.8. Potassium hydrogen phthalate (KHP) is useful as a primary standard because it possesses all the qualities sought in a primary standard. See Section 4.5.2. 

Hydrogen produced, standard cu. ft./bbl. feed Quality, 100% C hydroformate Benzene, vol. %... 

Using standard anaerobic techniques, a 100-mL Schlenk flask equipped with a stir bar is charged with 50 mL dry benzene and 2 mL (1.96 g, 0.0172 mol) distilled free amine. If crude daco is used, the product will be less pure and of lower yields. The mixture is warmed to 50-60°C under N2. Three 1-mL (0.05 mol) portions of ethylene sulfide are added, allowing 20 min reaction time between additions. The mixture is then heated under N2 for 1 h. Complete reaction is indicated by the formation of a finely divided white precipitate after the final addition. The reaction mixture is filtered anaerobically through a bed of celite in a glass-fritted funnel. Solvent is removed under vacuum while continuing to heat at 50-60°C. The H2-bme-daco is obtained as a colorless to pale yellow oil. Irrespective of color, this material is of suitable quality to be converted to the nickel complex. If distilled daco is used, the product is quite pure. Attempts at vacuum distillation (bpo.immHg = 135°C) resulted in partial decomposition. Yield 3.21 g (80%). 

As noted before, the most significant refinery emissions were airborne. For those options that involved a change in emissions affecting air quality, impacts were modeled using standard air dispersion techniques. Exposure estimates were developed for three classes of chemicals (1) benzene, toluene, ethylbenzene and xylene (BTEX), (2) other chemicals reported in the refinery s TRI submissions, and (3) criteria pollutants (SO2, NO2, PMjo, and CO). Similar modeling techniques were used for all three classes. The project focused on the impact of benzene emissions, since benzene turned out to be the chemical species of greatest concern relative to other releases. 

Nicholson, developed processes for the successful bulk production of nitrobenzene and aniline in batteries of closed iron reactors fitted with power-driven stirrers (Figure 6). For aniline, Nicholson adopted the B6champ reduction process and introduced steam into the reaction mixture by employing a hollow stirrer tube. The product aniline was obtained by distilling with steam after the addition of lime. Within a few years the standard reduction mixture became iron filings and hydrochloric acid. Production improvements and better quality benzene enabled aniline to be obtained in 90-95% yield. 

International Standards Organisation (1997b) Water quality - determination of benzene and some derivatives - part 1 head-space gas cluomatographic method, ISO 11423-1 1997. 

The major important quality criteria for benzene, toluene and xylenes are summarized in Table 4.13.The specifications in various countries are covered by comparable national standards (ASTM, DIN, BSS etc.). 

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