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Vapor-phase mercury

Keeler et al. (1995) reported that particulate mercury may contribute a significant portion of the deposition of mercury to natural waters. Mercury can be associated with large particles (>2.5 m) at concentrations similar to vapor phase mercury. Particulate phase mercury levels in rural areas of the Great Lakes and Vermont ranged from 1 to 86 pg/m3, whereas particulate mercury levels in urban and industrial areas were in the range of 15-1,200 pg/m3. Sweet and Vermette (1993) sampled airborne inhalable particulate matter in urban areas (southeast Chicago and East St. Louis) and at a rural site. [Pg.450]

Principles of EPA Method 30B Determination of Total Vapor Phase Mercury Emissions From Coal Fired Combustion Sources Using Carbon Sorbent Traps... [Pg.261]

The total amount of mercury release to the atmosphere from anthropogenic and natural sources each year is estimated to be 5,500 tons [2]. Coal-fired power plants (CFPPs) are one the largest (about 60 tons per year in the U.S.) anthropogenic sources of vapor phase mercury emissions. The concentration of mercury in flue gases generated by CFPPs typically is 1 to 10 pg/m. ... [Pg.459]

A carbon development program was initiated at the Illinois State Geological Survey (ISGS) and the University of Illinois at Urbana-Champaign (UIUC) to investigate the effects of different carbon types, carbon structures, and carbon surface functional groups on the rate and extent of adsorption of vapor-phase mercury. The results from a study to prepare Illinois coal-based activated carbons are presented. Carbon products were made both in bench- and pilot-scale reactors. [Pg.469]

The specific surface area of Darco FGD carbon, manufactured by American Norit, was 502 m /g. FGD is a gas-phase carbon and has heen used for removal of vapor-phase mercury from combustion flue gases. It had a mass median particle size of 15 pm. Compared with ICDACs, commercial Darco FGD carbon had a higher ash content (32.1 wt.%) and lower total sulfur content (0.98 wt.%). FGD carbon contained less microporosity, about 17 % of the total porosity than those of the ICDACs (44 to 74 %). [Pg.476]

Liquid- and vapor-phase processes have been described the latter appear to be advantageous. Supported cadmium, zinc, or mercury salts are used as catalysts. In 1963 it was estimated that 85% of U.S. vinyl acetate capacity was based on acetylene, but it has been completely replaced since about 1982 by newer technology using oxidative addition of acetic acid to ethylene (2) (see Vinyl polymers). In western Europe production of vinyl acetate from acetylene stiU remains a significant commercial route. [Pg.102]

Vinyl acetate (ethenyl acetate) is produced in the vapor-phase reaction at 180—200°C of acetylene and acetic acid over a cadmium, 2inc, or mercury acetate catalyst. However, the palladium-cataly2ed reaction of ethylene and acetic acid has displaced most of the commercial acetylene-based units (see Acetylene-DERIVED chemicals Vinyl polymers). Current production is dependent on the use of low cost by-product acetylene from ethylene plants or from low cost hydrocarbon feeds. [Pg.393]

Manufacture and Processing. Until World War II, phthaUc acid and, later, phthaUc anhydride, were manufactured primarily by Hquid-phase oxidation of suitable feedstocks. The favored method was BASF s oxidation of naphthalene [91-20-3] by sulfuric acid ia the presence of mercury salts to form the anhydride. This process was patented ia 1896. During World War I, a process to make phthaUc anhydride by the oxidation of naphthalene ia the vapor phase over a vanadium and molybdenum oxide catalyst was developed ia the United States (5). Essentially the same process was developed iadependendy ia Germany, with U.S. patents being granted ia 1930 and 1934 (6,7). [Pg.482]

In the vapor phase experiments, the photograftings are carried out in specially designed photoreactor constructed and built in our laboratory (Figure 1). The reactor is equipped with a 1 kW high pressure mercury UV lamp (HPM-15 from Philips) which can be moved to vary the distance to the substrate. The grafting takes place in an atmosphere of nitrogen in a thermostated chamber closed with a clear quartz window. Sensitizer and monomer evaporates from a solution of a volatile solvent in an open bucket which is shielded from the UV-irradiation with aluminium foil. [Pg.169]

Photolytic. A n-hexane solution containing /n-xylene and spread as a thin film (4 mm) on cold water (10 °C) was irradiated by a mercury medium pressure lamp. In 3 h, 18.5% of the p-xylene photooxidized into p-methylbenzaldehyde, p-benzyl alcohol, p-benzoic acid, and p-methylacetophenone (Moza and Feicht, 1989). Glyoxal and methylglyoxal were produced from the photooxidation of p-xylene by OH radicals in air at 25 °C (Tuazon et al., 1986a). The rate constant for the reaction of p-xylene and OH radicals at room temperature was 1.22 x lO " cmVmolecule-sec (Hansen et al., 1975). A rate constant of 7.45 x 10 L/molecule-sec was reported for the reaction of p-xylene with OH radicals in the gas phase (Darnall et al, 1976). Similarly, a room temperature rate constant of 1.41 x 10 " cm /molecule-sec was reported for the vapor-phase reaction of p-xylene with OH radicals (Atkinson, 1985). At 25 °C, a rate constant of 1.29 x lO " cmVmolecule-sec was reported for the same reaction (Ohta and Ohyama, 1985). [Pg.1163]

Mullin JB, Irvine SJC (1994) Metalorganic Vapor-Phase Epitaxy of Mercury Cadmium Telluride. Progress in Crystal Growth and Characterization of Materials 29(1-4), 217-252... [Pg.227]

Another variation of the stoichiometric method involves loading known amounts of gas and IL into the cell and then increasing the pressure (at constant temperature) until all the gas dissolves in the liquid and, consequently, the vapor phase disappears. Using different loadings of the gas, one can determine the solubility at various different pressures and temperatures. Mercury was used as the pressurization fluid by Peters and coworkers to determine gas solubilities in ILs [4]. Maurer and coworkers used a similar method, but they introduced and withdrew additional known amounts of the IL to pressurize or depressurize the mixture and observe the phase change [5]. [Pg.231]

One other method of recovering mercury from the vapor phase is to extract mercury using a suitable solvent (e.g. toluene or chloroform) in a scrubber, e.g. a packed tower. The mercury in the solvent can be reprocessed commercially. But, the poor solubility of mercury in such solvents warrants consumption of huge quantities of solvent thus limiting the use of a packed tower process for mercury recovery. It is therefore apparent that a preconcentration step must be used to facilitate the removal and recovery of mercury from the air phase. [Pg.377]

A biological process for detoxification of mercury in polluted water and sludges has been developed. Recovery of elemental mercury from the vapor phase for reuse is being studied and preliminary results show promise for the process. A full-scale process is under investigation for field/commercial application. [Pg.380]

Nanosized metal sulfide powders of Ag2S, CuS, FeS, Ga2S3. In2S3, MnS, NiS, and ZnS were synthesized for use as gas- and liquid-phase mercury sorbents. An aqueous-based synthesis method using the surfactant cetyltrimethylammonium bromide (CTAB) is described. The vapor- and aqueous-phase mercury-sorption characteristics of the nanocrystalline powders synthesized and of commercially produced Ag2S, AU2S. and AU2S3 are presented. [Pg.765]

Detection. Nearly all of the vapor-phase organic compounds will respond when added to a flame ionization detector, Consequently, this detector is most commonly used. Other special-purpose detectors include photoionization, mass spectrometry, atomic emission, ion mobility, mercury oxide reduction, and chemiluminescence detectors. [Pg.293]

Pyridine, treated with iodine in the vapor phase, gave only poor yields of 3,5-di- and penta-iodopyridines (57JCS387). Decarboxylative iodination of the mercury(II) salt of nicotinic acid gave a 44% yield of 3-iodopyridine (83JOC3297). [Pg.291]

Ames, M., Gullu, G. and Olmez, I. (1998) Atmospheric mercury in the vapor phase, and in fine and coarse particulate matter at Perch River, New York. Atmos. Environ., 32,865-872. [Pg.179]

Methods of manufacturing mercury cadmium telluride material have evolved from bulk melt growth to liquid phase epitaxy (LPE) technology, vapor phase epitaxy (VPE) and metal-organic chemical vapor deposition (MOCVD) [5-7], These new methods have made it possible to manufacture large two-dimensional focal plane arrays [8-11],... [Pg.452]

The general principles of Hg photosensitization are fully discussed in Calvert and Pitts text [1], and the early history of the subject is covered in a 1963 article by Gunning and Strauss [2]. Briefly, a low-pressure mercury-vapor lamp produces 254 nm radiation that is absorbed by trace mercury in the vapor phase of a quartz photoreactor. A drop of mercury can be added to the reactor to ensure enough Hg vapor is present. The mercury atom in the reactor is excited to the relatively long-lived (ca 10 7 s) 3P2 state, denoted Hg this is the reactive species that attacks the organic substrate. [Pg.554]

The critical property of the Mercat process [3-8] that gives it its selectivity is that only Hg atoms in the vapor phase undergo reaction, because their absorption line is narrow and matched with the sharp emission line of the lamp. Mercury dissolved in the liquid phase has a broadened and shifted absorption band and Hg in solution has a short excited-state lifetime, so the liquid phase undergoes no significant reaction. In the vapor, Eqs. (2)—(5) produce the dehydro dimer, which condenses. [Pg.555]

Dehydrodimerization. On excitation with a mercury vapor lamp, mercury is converted to an excited state, Hg, which can convert a C—H bond into a carbon radical and a hydrogen atom. This process can result in dehydrodimerization, which has been known for some time, but which has not been synthetically useful because of low yields when carried out in solution. Brown and Crabtree1 have shown that this reaction can be synthetically useful when carried out in the vapor phase, in which the reaction is much faster than in a liquid phase, and in which very high selectivities are attainable. Secondary C—H bonds are cleaved more readily than primary ones, and tertiary C—H bonds are cleaved the most readily. Isobutane is dimerized exclusively to 2,2,3,3-tetramethylbutane. This dehydrodimerization is also applicable to alcohols, ethers, and silanes. Cross-dehydrodimerization is also possible, and is a useful synthetic reaction. [Pg.198]

Although these liquid-phase and vapor-phase alkylations serve well to attach aliphatic groups to silicon, they are not so satisfactory for the substitution of aromatic groups. Very early in the history of organosilicon chemistry, Ladenburg found that the aryl compounds of mercury were more effective reagents than those of zinc. For example, mercury diphenyl reacted with silicon tetrachloride in a sealed tube at 300° to form phenyltrichlorosilane ... [Pg.22]


See other pages where Vapor-phase mercury is mentioned: [Pg.926]    [Pg.713]    [Pg.977]    [Pg.436]    [Pg.451]    [Pg.477]    [Pg.478]    [Pg.637]    [Pg.401]    [Pg.926]    [Pg.713]    [Pg.977]    [Pg.436]    [Pg.451]    [Pg.477]    [Pg.478]    [Pg.637]    [Pg.401]    [Pg.773]    [Pg.431]    [Pg.232]    [Pg.310]    [Pg.147]    [Pg.118]    [Pg.353]    [Pg.173]    [Pg.175]    [Pg.353]    [Pg.302]    [Pg.38]    [Pg.194]    [Pg.765]    [Pg.433]    [Pg.99]    [Pg.199]    [Pg.83]   


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Mercury phase

Mercury vapor

Vapor-phase mercury photosensitization

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