Wet chemical systems

Since 1970, new analytical techniques, eg, ion chromatography, have been developed, and others, eg, atomic absorption and emission, have been improved (1—5). Detection limits for many chemicals have been dramatically lowered. Many wet chemical methods have been automated and are controlled by microprocessors which allow greater data output in a shorter time. Perhaps the best known continuous-flow analy2er for water analysis is the Autoanaly2er system manufactured by Technicon Instmments Corp. (Tarrytown, N.Y.) (6). Isolation of samples is maintained by pumping air bubbles into the flow line. Recently, flow-injection analysis has also become popular, and a theoretical comparison of it with the segmented flow analy2er has been made (7—9). 

NFPA 17A Standard for Wet Chemical Extinguishing Systems, 1998 edition. National Fire Protection Association, Quincy, MA. 

Wet chemical decomposition in a closed system, with nitric acid or mixed acids consisting of nitric acid, hydrochloric acid, perchloric acid, hydrogen peroxide and hydrofluoric acid. The following devices are available ... 

In previous studies we found that improved emission-control devices (such as hot-side electrostatic precipitaters and wet-scrubber systems) now being installed on modern pulverized-coal-fired power plants modify the quantity, chemical composition, and distribution characteristics of fine aerosol emissions (12,13). Such modifications must be understood to adequately assess human health and environmental hazards, and to apportion the contributions of sources to urban pollutant inventories. 

We have further applied these techniques to investigate the chemical modification of aerosols by a modern flue-gas desulfurization system. This study confirms our earlier work with a high-energy Venturi wet scrubber system, in which we observed high chemical enrichment of aerosols from evaporative processes. 

CEI produced the Sulphlex-233/ in 7.5 ton (6.8 tonne) batches the reaction vessel has a nominal 9 ton (8.2 tonne) capacity, is steam heated, and is equipped with a wet scrubber system to control potential hydrogen sulfide emissions. Since no cooling capability was available, the reaction exotherm was controlled by the rate at which the preblended chemical modifiers were added to the reaction mass. 

Carbon-, nitrogen-, and sulfur-containing species account for most of the mass of aerosol particles. In spite of years of effort by many investigators, the exact chemical forms of carbon, sulfur, and nitrogen in these particles are not known nor are the formation mechanisms of these species known with certainty. There are many reasons for this situation, including the complexity of the system and the dependence of the apparent chemical composition on the analytical methods used. For example, wet chemical analyses of sulfur and nitrogen species report only ions in solution. These ions, however, may be originally water soluble (e.g., sulfate and ammonium from ammonium sulfate), or they may be ionic products of hydrolyzable species such as amides (1). Of course, insoluble species will not be detected by wet chemical techniques. 

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