Bases precipitation collectors

S. Zaromb, D. Martell, N. Schattke, and G. Hankins, Electrostatic-Precipitation-Based Aerosol Collector, 2006 Scientific Conference on Obscuration and Aerosol Research (Battelle Eastern Science Technology Center, Aberdeen, Maryland, 2006). 

Platt ). Monitoring for wet deposition currently is based on collectors such as those shown in Figure 2. The device in Figure 2A consists of two buckets, one of which is open for dry fallout and the other is opened automatically with onset of precipitation. A precipitation sample is collected in a chemically inert vessel which is sealed by the cover after an event. A rain gauge is often used with this device to record the quantity of precipitation. Samples are removed either at regular intervals (which should not exceed 24 hours), or on an... 

Yebra et al. [83] used a continuous-flow procedure for the indirect determination of sodium cyclamate by flame atomic absorption spectrometry (FAAS). This method is based on oxidation of the sulfamic group derived from cyclamate to sulfate in acidic conditions and in the presence of sodium nitrite. The procedure is adapted to a flow system with precipitate dissolution (Figure 24.11), where sulfate formed is continuously precipitated with lead ion. The lead sulfate formed is retained on a filter, washed with diluted ethanol, and dissolved in ammonium acetate (because of the formation of soluble lead acetate) for online FAAS determination of lead, the amount of which in the precipitate is proportional to that of cyclamate in the sample. In this work a home-made filtration device was used made of a Teflon tubing packed with a cotton pulp and the ends of the filter column were plugged with filter paper (chamber inner volume 141 J,L). This precipitate collector was effective in retaining the precipitate and did not produce excessive back-pressure if the precipitate was dissolved following each precipitation cycle. 

Inputs and outputs to the lake have been measured to calculate net retention for the pre-acidified lake. Precipitation inputs of sulfate were based on data from wet collectors (1980-1983) compiled by the National Atmospheric Deposition Program (NADP). SO2 inputs were calculated from regional ambient air concentrations (22) usinga deposition velocity of 0.5 cm/sec. Aerosol sulfate was estimated from NADP dry bucket measurements and from dry bucket and snow core measurements made in this study (22). Groundwater inputs occur largely at the southeast corner of the lake and were calculated from modeled inseepage (21) and measured sulfate concentrations in a well located in the major inseepage area. Sulfate output was estimated from mean lakewater sulfate concentration and modeled outflows. 

National Dust Collector, developed a process based on dry limestone injection in the boiler. By 1972, the Combustion Engineering process had been installed on five boilers, but these installations proved inadequate owing mainly to boiler plugging, low sulfur dioxide absorption, and reduced particulate collection efficiency in the electrostatic precipitator. 

The present Section provides a discussion of the following separation and preconcentration methods solvent extraction, precipitation and co-precipitation with collectors, volatilization, and methods based on the use of ion-exchangers and other sorbents. These methods are used not only with spectrophotometry, but also in conjunction with other methods of determination. 

The liquid (sulfur-based compounds) and sohd sulfur cathodes (items 6 and 7) do not develop surface chemistry that can be separated from their main electrochemical redox reactions. Hence, when the reduction of sulfur SO2 or SOCI2 produces insoluble species such as LiCl, LijS, and LijO, they precipitate on the current collector [9]. When formed, LijS can be reoxidized, up to elemental sulfur, via various LLS intermediate compounds [10]. Hence, the current collector, which may be aluminum (Al) plus carbon in the case of sulfur cathodes or carbon in the case of SOCI2 cathodes, does not develop intrinsic surface chemistry beyond the precipitation of the reduction products of the active mass. 

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