Precipitation, Applications

Precipitator application Average value3 Typical range... 

To examine the suitability of AAH precipitates applications to the removal of selective contaminants from wastewater comparative experiments were conducted. 

Atmosphere Evaporation Precipitation Application Drift Photodecomposition Condensation... 

This chapter provides a review of the synthesis, growth, structural properties, and practical applications of carbon nanofibers. The mechanism of growth always involves dissociation of the gas at the metal surfaces, followed by dissolution of carbon into the bulk, followed by diffusion to the surface of the particle where graphite is precipitated. Applications of... 

Oximes (compare Section III,74,B). The following procedure has wide application. Dissolve 0-5 g. of hydroxylamine hydrochloride in 2 ml. of water, add 2 ml. of 10 per cent, sodium hydroxide solution and 0-2 g. of the aldehyde (or ketone). If the latter is insoluble, add just sufficient alcohol to the mixture to give a clear solution. Heat the mixture under reflux for 10-15 minutes, and then cool in ice. If crystals separate, filter these off, and recrystallise from alcohol, dilute alcohol, benzene or light petroleum (b.p. 60-80°). If no solid separates on cooling, dilute with 2-3 volumes of water, filter the precipitated sohd, and recrystallise. 

Other types of reactions can be used to chemically separate an analyte and interferent, including precipitation, electrodeposition, and ion exchange. Two important examples of the application of precipitation are the... 

Quantitative Calculations In precipitation gravimetry the relationship between the analyte and the precipitate is determined by the stoichiometry of the relevant reactions. As discussed in Section 2C, gravimetric calculations can be simplified by applying the principle of conservation of mass. The following example demonstrates the application of this approach to the direct analysis of a single analyte. 

Gravimetric methods based on precipitation or volatilization reactions require that the analyte, or some other species in the sample, participate in a chemical reaction producing a change in physical state. For example, in direct precipitation gravimetry, a soluble analyte is converted to an insoluble form that precipitates from solution. In some situations, however, the analyte is already present in a form that may be readily separated from its liquid, gas, or solid matrix. When such a separation is possible, the analyte s mass can be directly determined with an appropriate balance. In this section the application of particulate gravimetry is briefly considered. 

The following experiments may he used to illustrate the application of titrimetry to quantitative, qtmlitative, or characterization problems. Experiments are grouped into four categories based on the type of reaction (acid-base, complexation, redox, and precipitation). A brief description is included with each experiment providing details such as the type of sample analyzed, the method for locating end points, or the analysis of data. Additional experiments emphasizing potentiometric electrodes are found in Chapter 11. 

Applications. Both industrial emissions reduction and indoor air-poUution abatement uses will grow. For example, the development of adsorbents with higher capacity for removal of radon from humid air could allow the development of a one-bed, delay-for-decay system in which radon adsorbs, decays to lead, and is precipitated onto the adsorbent. 

Applications. In 1994, approximately 675,000 metric tons of amorphous precipitated sihca were manufactured for sale (38,62). Degussa, J. M. Huber, and PPG in the United States and in Europe, and Akzo (Germany), Aluflour (Sweden), Crosfield (United Kingdom), Nippon Sihca (Japan), Rhc ne-Poulenc (France), Shionogi (Japan), Tokuyama Soda (Japan), and Vitro PQ (Mexico) are the primary producers. 

Other Applications. Among other industrial uses of lime are causticizing agent in kraft (sulfate) paper (qv) plants recovery of ammonia (qv) from NH4CI (Solvay process) recovery of magnesium (qv) from seawater and brines via precipitation of Mg(OH)2 production of pesticides such as... 

Typical applications in the chemical field (Beaver, op. cit.) include detarring of manufactured gas, removal of acid mist and impurities in contact sulfuric acid plants, recovery of phosphoric acid mists, removal of dusts in gases from roasters, sintering machines, calciners, cement and lime Idlns, blast furnaces, carbon-black furnaces, regenerators on fluid-catalyst units, chemical-recoveiy furnaces in soda and sulfate pulp mills, and gypsum kettles. Figure 17-74 shows a vertical-flow steel-plate-type precipitator similar to a type used for catalyst-dust collection in certain fluid-catalyst plants. 

A development of interest to the chemical industiy is the tubular precipitator of reinforced-plastic construction (Wanner, Gas Cleaning Plant after T1O2 Rotary Kilns, technical bulletin, Lurgi Corp., Frankfurt, Germany, 1971). Tubes made of polyvinyl chloride plastic are reinforced on the outside with polyester-fiber glass. The use of modern economical materials of construction to replace high-maintenance materials such as lead has been long awaited for corrosive applications. 

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