Sulfur dioxide in air

Analytical Methods. The official NIOSH recommended method for determining sulfur dioxide in air consists of drawing a known prefiltered volume of air through a bubbler containing hydrogen peroxide, thus oxidising the sulfur dioxide to sulfuric acid. Isopropyl alcohol is then added to the contents in the bubbler and the pH of the sample is adjusted with dilute perchloric acid. The resultant solution is then titrated for sulfate with 0.005 M. barium perchlorate, and Thorin is used as the indicator. 

Concentration of sulfur dioxide in air (ppm) Exposure time Human symptoms and effects on vegetation... 

The oxidizing power of the catalytic sulfite ion/02 systems was utilized in oxidative cleavage of DNA (118-121), in an analytical application for the determination of sulfur dioxide in air (122) and in developing a luminescent probe for measuring oxygen uptake (123). 

It is well known that ozone is quite soluble in water. Therefore, one expects that ozone absorption wi sulfur dioxide would contribute to significant oxidation of sulfur dioxide. Experiments of Penkett have shown that oxidation of sulfur dioxide in air at 7 ppb when absorbed in water droplets with ozone, which is present in surrounding air at 0.05 ppm, can be as large as 13%/h. Thus, foggy or cloudy air mixed with... 

Schwarz, F. P H. Okabe, and J. K. Whittaker, Fluorescence Detection of Sulfur Dioxide in Air at the Parts Per Billion Level, Anal. Chem., 46, 1024-1028 (1974). 

Concentrations of trace gases and particles in the atmosphere can be expressed as mass per unit volume, typically pg m . The difficulty with this unit is that it is not independent of temperature and pressure. Thus, as an airmass becomes warmer or colder, or changes in pressure, so its volume will change, but the mass of the trace gas will not. Therefore, air containing 1 pg m of sulfur dioxide in air at 0°C will contain less than 1 pg m of sulfur dioxide in air if heated to 25°C. For gases (but not particles), this difficulty is overcome by expressing the concentration of... 

Friend J.P., Barnes R.A. and Vasta RM., Nucleation by free radicals from the photooxidation of sulfur dioxide in air. J. Phys. Chem., 84, 2423-2436 (1980). 

Reporting of concentrations of one gas in another on a volume for volume basis is normally corrected to 25°C and 1 atm (760 mm Hg) pressure [22, 23]. Under this system, relatively high concentrations are specified in percent so that 3% sulfur dioxide in air would correspond to 3 mL of sulfur dioxide mixed with 97 mL of air, both specified at 25°C and 1 atm. This also corresponds to 3 parts by volume of sulfur dioxide in 100 parts by volume of the sulfur dioxide/air mixture, both specified in the same volume units. Lower concentrations are specified in smaller units, ppm (or ppmv, v for volume) for parts per million (1 in 10 ), ppb for parts per billion (1 in 10 ), and even ppt for parts per trillion (1 in 10 ), now that adequate sensitivity has been developed for the analysis of some air pollutants at these low concentrations. 

Gerhard, E. R. and Johnstone, H. F 1955 Photochemical oxidation of sulfur dioxide in air. Indust. Engineer. Chem. 47, 972-976. 

Sulfur trioxide, which is used to make sulfuric acid, is produced by catalytic oxidation of sulfur dioxide in air with vanadium pentoxide catalyst particles at 1.2 atm and a temperature... 

Typical examples of analytical applications of conventional MECA include the determination of saccharin (sulfur-containing sweetener) in soft drinks, total sulfur and sulfate in detergents, phosphate in detergents and rocks, sulfur dioxide in air, inorganic sulfate in urine, and halides in pesticides. 

Thomas, M. D., Ivie, J. O., Abersold, J. N., and Hendricks, R. H. 1943. Automatic apparatus for determination of small concentrations of sulfur dioxide in air. Application to hydrogen sulfide, mercaptan and other sulfur and chlorine compounds. Ind. Eng. Chem., Anal. Ed. 15, 287-290. 

Schematic diagram of an FIA-CL system for the determination of sulfur dioxide in air. IV injection valve sample gaseous sulfur dioxide absorbed from air samples into 1 mM NaOH solution.

A CL flow system with luminol immobilized on an anion-exchange column was developed for the indirect determination of sulfur dioxide in air (see Figure 7.11). Sulfite is detected by the CL reaction with the luminol bleeding from the column by hydrolysis [20]. 

Huge numbers of analyses must often be performed to get meaningful results and for reasons of economics. This has resulted in the development of a number of automated procedures in which traditional wet chemical methods of analysis have been adopted to automate procedures. With such procedures, the samples are introduced through a sampler and the analyses performed and results posted without manual manipulation of reagents and apparatus. Such procedures have been developed and instruments marketed for the determination of a number of analytes. In water, automated analyses have been developed from wet chemical procedures for alkalinity, sulfate, ammonia, nitrate/nitrite, and metals. The somewhat cumbersome West-Gaeke determination of sulfur dioxide in air has been adapted to automated analyzers. Colorimetric (absorption spectrophotometric) procedures are popular for such automated analytical instruments, using simple, rugged colorimeters for absorbance measurements. 

Sulfur dioxide in air is absorbed by pure water at 1 atm and 20°C. The gas feed stream is 5000 kg/h containing 8 mol% SOj in air. A 95% recovery of the sulfur dioxide is required. The inlet solvent is pure water with inlet mass flow rate of 29.5 kg/s. The solubility of SOj in water is shown in Table 7.3. For packing material, 1 1/2 in. ceramic Intalox Saddles is used. Design an absorber column for this purpose [9]. 

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