Emission, aqueous

There is also a standard test method for determination of major and minor elements in coal ash by inductively coupled plasma (ICP)-atomic emission spectrometry (ASTM D-6349). In the test method, the sample to be analyzed is ashed under standard conditions and ignited to constant weight. The ash is fused with a fluxing agent followed by dissolution of the melt in dilute acid solution. Alternatively, the ash is digested in a mixture of hydrofluoric, nitric, and hydrochloric acids. The solution is analyzed by (ICP)-atomic emission spectrometry for the elements. The basis of the method is the measurement of atomic emissions. Aqueous solutions of the samples are nebulized, and a portion of the aerosol that is produced is transported to the plasma torch, where excitation and emission occurs. Characteristic line emission spectra are produced by a radio-frequency inductively coupled plasma. A grating monochromator system is used to separate the emission lines, and the intensities of the lines are monitored by photomultiplier tube or photodiode array detection. The photocurrents from the detector... 

EXPOSURE ROUTES air emissions aqueous effluent and solid waste products from manufacturing and processing plants incineration of DEP containing plastics ingestion of food inhalation and dermal exposure occupational exposure... 

The life cycle inventory analysis involves data collection and calculation procedures to quantify the total system s inputs and outputs that are relevant from an environmental point of view, i.e., mainly resource use, atmospheric emissions, aqueous emissions, solid waste and land use. 

The life cycle inventory analysis (ii) involves data collection and calculation procedures to quantify the total system s inputs and outputs that are relevant from an environmental point of view, that is, mainly resource use, atmospheric emissions, aqueous emissions, solid waste, and land use. The LCIA (iii) aims at evaluating the significance of potential environmental impacts using the results of the life cycle inventory analysis. The life cycle interpretation (iv) is the final step of the LCA where conclusions are drawn from both the life cycle inventory analysis and the LCIA or, in the case of life cycle inventory studies, from the inventory analysis only. The important LCA requirements are given in Figure 15.5 [150]. 

Once the life-cycle inventory has been quantified, we can attempt to characterize and assess the eflfects of the environmental emissions in a life-cycle impact analysis. While the life-cycle inventory can, in principle at least, be readily assessed, the resulting impact is far from straightforward to assess. Environmental impacts are usually not directly comparable. For example, how do we compare the production of a kilogram of heavy metal sludge waste with the production of a ton of contaminated aqueous waste A comparision of two life cycles is required to pick the preferred life cycle. 

The density of heavy fuels is greater than 0.920 kg/1 at 15°C. The marine diesel consumers focus close attention on the fuel density because of having to centrifuge water out of the fuel. Beyond 0.991 kg/1, the density difference between the two phases —aqueous and hydrocarbon— becomes too small for correct operation of conventional centrifuges technical improvements are possible but costly. In extreme cases of fuels being too heavy, it is possible to rely on water-fuel emulsions, which can have some advantages of better atomization in the injection nozzle and a reduction of pollutant emissions such as smoke and nitrogen oxides. 

All the cations of Group I produce a characteristic colour in a flame (lithium, red sodium, yellow potassium, violet rubidium, dark red caesium, blue). The test may be applied quantitatively by atomising an aqueous solution containing Group I cations into a flame and determining the intensities of emission over the visible spectrum with a spectrophotometer Jlame photometry). 

Multiple-Bubble Sonoluminescence. The sonoluminescence of aqueous solutions has been often examined over the past thirty years. The spectmm of MBSL in water consists of a peak at 310 nm and a broad continuum throughout the visible region. An intensive study of aqueous MBSL was conducted by VerraH and Sehgal (35). The emission at 310 nm is from excited-state OH, but the continuum is difficult to interpret. MBSL from aqueous and alcohol solutions of many metal salts have been reported and are characterized by emission from metal atom excited states (36). 

Single-Bubble Sonoluminescence. The spectra of MBSL and SBSL are dramatically different. MBSL is generally dominated by atomic and molecular emission lines, but SBSL is an essentially featureless emission that iacreases with decreasiag wavelength. For example, an aqueous solution of NaCl shows evidence of excited states of both OH- and Na ia the MBSL spectmm however, the SBSL spectmm of an identical solution shows no evidence of either of these peaks (30). Similady, the MBSL spectmm falls off at low wavelengths, while the SBSL spectmm continues to rise, at least for bubbles containing most noble gases (38). 

The iaterpretation of the spectroscopy of SBSL is much less clear. At this writing, SBSL has been observed primarily ia aqueous fluids, and the spectra obtained are surprisiagly featureless. Some very interesting effects are observed when the gas contents of the bubble are changed (39,42). Furthermore, the spectra show practically no evidence of OH emissions, and when He and Ar bubbles are considered, continue to iacrease ia iatensity even iato the deep ultraviolet. These spectra are reminiscent of blackbody emission with temperatures considerably ia excess of 5000 K and lend some support to the concept of an imploding shock wave (41). Several other alternative explanations for SBSL have been presented, and there exists considerable theoretical activity ia this particular aspect of SBSL. 

Reaction takes place ia aqueous solution with hydrogen peroxide and catalysts such as Cu(II), Cr(III), Co(II), ferricyanide, hernia, or peroxidase. Chemiluminescent reaction also takes place with oxygen and a strong base ia a dipolar aprotic solvent such as dimethyl sulfoxide. Under both conditions Qcis about 1% (light emission, 375—500 am) (105,107). 

When the mercury present in the atmosphere is primarily in the form of an organic mercury compound, it may be preferable to utilise an aqueous scmbber. This method is particularly useful for control of emissions from reactors and from dryers. For efficient and economical operation, an aqueous solution of caustic soda, sodium hypochlorite, or sodium sulfide is reckculated through the scmbber until the solution is saturated with the mercury compound. 

Fig. 1. Absorption spectra of (-----) H2O2, and (—) O in aqueous media together with the (-----------) terrestrial air mass one (AMI) solar emission spectmm...

With the ever increasing awareness of the need of environment protection, the emission of solvent vapors and organic fumes into the atmosphere should be prevented by treating the exhaust through a proper scmbber. The solvent used for cleaning the reactor is usually consumed as part of the thinning solvent. Aqueous effluent should be properly treated before discharge. 

The classical wet-chemical quaUtative identification of chromium is accompHshed by the intense red-violet color that develops when aqueous Cr(VI) reacts with (5)-diphenylcarba2ide under acidic conditions (95). This test is sensitive to 0.003 ppm Cr, and the reagent is also useful for quantitative analysis of trace quantities of Cr (96). Instmmental quaUtative identification is possible using inductively coupled argon plasma—atomic emission spectroscopy... 

One important consideration in any catalyst oxidation process for a complex mixture in the exhaust stream is the possible formation of hazardous incomplete oxidation products. Whereas the concentration in the effluent may be reduced to acceptable levels by mild basic aqueous scmbbing or additional vent gas treatment, studying the kinetics of the mixture and optimizing the destmction cycle can drastically reduce the potential for such emissions. 

Particulate emissions from zinc processing are collected in baghouses or ESPs. SO2 in high concentrations is passed directly to an acid plant for production of sulfuric acid by the contact process. Low-concentration SO2 streams are scrubbed with an aqueous ammonia solution. The resulting ammonium sulfate is processed to the crystalline form and marketed as fertilizer. 

Adsorption, which utilizes the ability of a solid adsorbent to adsorb specific components from a gaseous or a liquid solution onto its surface. Examples of adsorption include the use of granular activated carbon for the removal of ben-zene/toluene/xylene mixtures from underground water, the separation of ketones from aqueous wastes of an oil refinery, aad the recovery of organic solvents from the exhaust gases of polymer manufacturing facilities. Other examples include the use of activated alumina to adsorb fluorides and arsenic from metal-finishing emissions. 

The plant disposes of two waste streams gaseous and aqueous. The gaseous emission results from the ammonia and the artunonium nitrate plants. It is fed to an incinerator prior to atmospheric disposal. In the incinerator, ammonia is converted into NOj,. Ehie to more stringent NO regulations, the conqmsition of ammonia in the feed to the incinerator has to be reduced from 0.57 wt% to 0.07 wt%. The lean streams presented in Table 9.5 may be employed to remove ammonia. The main aqueous waste of the process results from the nitric acid plant. Due to its acidic content of nitric acid, it is neutralized with an aqueous ammonia solution before biotreatment. 

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