Ammonium particulate

The gaseous ammonia is passed through electrostatic precipitators for particulate removal and mixed with the cooled gas stream. The combined stream flows to the ammonia absorber where the ammonia is recovered by reaction with a dilute solution of sulfuric acid to form ammonium sulfate. Ammonium sulfate precipitates as small crystals after the solution becomes saturated and is withdrawn as a slurry. The slurry is further processed in centrifuge faciHties for recovery. Crystal size can be increased by employing one of two processes (99), either low differential controUed crystallization or mechanical size enlargement by continuous compacting and granulation. 

Carbonates. Basic zirconium carbonate [37356-18-6] is produced in a two-step process in which zirconium is precipitated as a basic sulfate from an oxychloride solution. The carbonate is formed by an exchange reaction between a water slurry of basic zirconium sulfate and sodium carbonate or ammonium carbonate at 80°C (203). The particulate product is easily filtered. Freshly precipitated zirconium hydroxide, dispersed in water under carbon dioxide in a pressure vessel at ca 200—300 kPa (2—3 atm), absorbs carbon dioxide to form the basic zirconium carbonate (204). Washed free of other anions, it can be dissolved in organic acids such as lactic, acetic, citric, oxaUc, and tartaric to form zirconium oxy salts of these acids. 

Solid particulates are captured as readily as hquids in fiber beds but can rapidly plug the bed if they are insoluble. Fiber beds have frequently been used for mixtures of liqmds and soluble sohds and with soluble solids in condensing situations. Sufficient solvent (usually water) is atomized into the gas stream entering the collector to irrigate the fiber elements and dissolve the collected particulate. Such nber beds have been used to collect fine fumes such as ammonium nitrate and ammonium chloride smokes, and oil mists from compressed air. 

ITie major component of atmospheric haze is sulfate particulate matter (particularly ammonium sulfate), along with varying amounts of nitrate particulate matter, which in some areas can equal the sulfate. Other components include graphitic material, fine fly ash, and organic aerosols. 

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. 

Particulate matter is the principal air pollutant emitted from ammonium sulfate plants. Most of the particulates are found in the gaseous exhaust of the dryers. Uncontrolled discharges of particulates may be of the order of 23 kg/t from rotary dryers and 109 kg/t from fluidized bed dryers. Ammonia storage tanks can release ammonia, and there may be fugitive losses of ammonia from process equipment. 

Ammonium Sulfate Plants - In ammonium sulfate plants, use of fabrie filters, with injeetion of absorbent as neeessary, is the preferred means of eontrol. Discharges of not more than 0.1 kg/t of produet should be attainable for particulate matter. 

Ammonium Nitrate Plants - In ammonium nitrate plants, wet scrubbers can be considered for prill towers and the granulation plant. Particulate emissions of 0.5 kg/t of product for the prill tower and 0.25 kg/t of product for granulation should be the target. Similar loads for ammonia are appropriate. Other effluents that originate in a nitrogenous fertilizer complex include boiler blowdown, water treatment plant backwash, and cooling tower blowdown from the ammonia and nitric acid plants. 

These compounds should be dissolvable in a clean-up solution containing a quaternary organic ammonium salt, or simply ammonium chloride [1749]. The solubilities of some selected particulate bridging agents are shown in Table 9-1. A chelating agent such as citric acid or its salts is also included in the clean-up solution. 

Particulate bridging agent Aqueous ammonium salt clean-up solution Solubility [g/lOOml]... 

Normal-phase HPLC has also found application in the analysis of pigments in marine sediments and water-column particulate matter. Sediments were extracted twice with methanol and twice with dichloromethane. The combined extracts were washed with water, concentrated under vacuum and redissolved in acetone. Nomal-phase separation was performed with gradient elution solvents A and B being hexane-N,N-disopropylethylamine (99.5 0.5, v/v) and hexane-2-propanol (60 40, v/v), respectively. Gradient conditions were 100 per cent A, in 0 min 50 per cent A, in 10 min 0 per cent A in 15 min isocratic, 20 min. Preparative RP-HPLC was carried out in an ODS column (100 X 4.6 mm i.d. particle size 3 jum). Solvent A was methanol-aqueous 0.5 N ammonium acetate (75 25, v/v), solvent B methanol-acetone (20 80, v/v). The gradient was as follows 0 min, 60 per cent A 40 per cent A over 2 min 0 per cent A over 28 min isocratic, 30 min. The same column and mobile phase components were applied for the analytical separation of solutes. The chemical structure and retention time of the major pigments are compiled in Table 2.96. 

In simple experiments, particulate silica-supported CSPs having various cin-chonan carbamate selectors immobilized to the surface were employed in an enantioselective liquid-solid batch extraction process for the enantioselective enrichment of the weak binding enantiomer of amino acid derivatives in the liquid phase (methanol-0.1M ammonium acetate buffer pH 6) and the stronger binding enantiomer in the solid phase [64]. For example, when a CSP with the 6>-9-(tcrt-butylcarbamoyl)-6 -neopentoxy-cinchonidine selector was employed at an about 10-fold molar excess as related to the DNB-Leu selectand which was dissolved as a racemate in the liquid phase specified earlier, an enantiomeric excess of 89% could be measured in the supernatant after a single extraction step (i.e., a single equilibration step). This corresponds to an enantioselectivity factor of 17.7 (a-value in HPLC amounted to 31.7). Such a batch extraction method could serve as enrichment technique in hybrid processes such as in combination with, for example, crystallization. In the presented study, it was however used for screening of the enantiomer separation power of a series of CSPs. 

Vertical profiles of O2 and particulate and dissolved trace metal concentrations at 32.5°E and 44.5°N in the Black Sea. (a) Temperature, salinity, fluorescence, and O2 (b) ammonium, silica, nitrate+nitrite, and phosphate (c) Fe (d) Mn (e) Co (f) Pb (g) Cu (h) Zn (I) Cd and Ni. In the trace metal profiles, the dissolved concentrations are represented as solid circles, the total particulate concentrations by open circles, the acid-leachable particulate concentrations by open squares, and the suspended particulate matter concentrations by the solid triangles. Source-. After Tankere, S. P. C., et al. (2001). Continental Shelf Research, 21, 1501-1532. 

Several investigators have utilized thermal techniques for the separation of sulfate species collected on filter media with subsequent analysis by electron impact mass spectrometry, wet chemical analysis or sulfur flame photometry. In most instances the separation between sulfuric acid and its ammonium salts was incomplete or problems were encountered in recovering the species of interest from filters heavily laden with particulate (29-34). 

Substances that can potentially be taken up across the skin include gases and vapors, liquids and particulates. Liquids and substances in solution are taken up more readily than dry particulates. Dry particulates will have to dissolve into the surface moisture of the skin before uptake can begin. Absorption of volatile liquids across the skin may be limited by the rate at which the liquid evaporates off the skin surface. As a result of binding to skin components, the uptake of chemicals with the following groups can be slowed certain metal ions, acrylates, quaternary ammonium ions, heterocyclic ammonium ions, and sulfonium salts. 

A potential drawback of this technology is the potential formation of ammonium sulfate salts and their resulting fouling. This can be mitigated through either use of high pressure soot blowers or on-line water washing in the economizer. These salts will exist as small particulates that will increase opacity. 

Stelson, A.W. Friedlander, S.K. Seinfeld, J.H., A Note on the Equilibrium Relationship between Ammonia and Nitric Acid and Particulate Ammonium Nitrate, Atmospheric Environment,... 

Rapsomanikis, S., M. Wake, A.-M. N. Kitto, and R. M. Harrison, Analysis of Atmospheric Ammonia and Particulate Ammonium by a Sensitive Fluorescence Method, Environ. Sci. Technol., 22, 948-952 (1988). 

However, as expected from the chemistry discussed in Chapter 7.E, simultaneous control of NH3 has a significant effect on particle nitrate formation, since the formation of ammonium nitrate is a major mechanism for conversion of gaseous HN03 to particulate nitrate. Thus, Meng et al. (1997) predict that a 50% reduction in both NO. and NH3 would give about the same reduction in particulate nitrate. 

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