Aerosols materials

SC Johnson Wax—Pledge—Wax, Spray, Refinish, Aerosol, Material Safety Data Sheet. http //www.biosci.ohio-state.edu/ jsmith/MSDS/PLEDGE.htm... 

C. Symptoms that occur during the work day and clear up after work are often due to inhalation exposure of volatile or aerosol materials. The solvents used in printing inks cause light-headedness and sedation. The symptoms are not those of herbicide exposure and insecticide exposure. 

Figure 2. Compositional diagram for the preparation of bismuth molybdate catalysts using the HI AD process configuration shown in Figure 1 at 900°C using air as make up gas. Plot is of concentrations of bismuth used in the reacting solution vs arc plasma analyzed concentrations of the finished catalysts directly fi-om HTAD reactor Circles Co-precipitation prepared materials. Triangles Up flow prepared aerosol materials. Squares. Down flow prepared aerosol materials.

Values of Y. vary for different aerosol components, the large values corresponding to the components with the highest extinction coefficients per unit mass of aerosol material. When Y. is constant, the extinction coefficient is linearly related through the coefficients Y. to the mass contributions of the various sources this considerably simplifies analyses relating visibility degradation to source contributions. 

Please be advised that all chemicals should be considered hazardous and should be handled in a hood and with proper personal protective equipment (lab coat, proper gloves, approved safety glasses, and/or goggles). Avoid inhaling vapors and/or aerosolized materials. Avoid skin/eye contact with all chemicals at all times. Wash hands frequently. See the instructor if you have any questions or concerns. 

Many aerosol materials have been used, and the aerosol material can be specifically chosen to minimize interference with the chemical separation being conducted. Widely used were KC1 aerosols which can easily be generated by sublimation of KC1 from a porcelain boat within a tube furnace. By choosing a temperature between 650°C and 670°C, specially tailored aerosols with a mean mobility diameter of about 100 nm and number concentrations of few times 106 particles/cm3 could be generated. The same technique could be applied to produce MoOj aerosols. Carbon aerosol particles of similar dimensions were generated by spark discharge between two carbon electrodes. 

Gas-particle interactions Accommodation processes on surfaces growth of particles by condensation atmospheric chemistry chemical processing of aerosolized materials aerosol catalysis chemical vapor deposition surface and cluster chemistry. 

Most aerosol materials will vary in their refractive index depending on the wavelength of light used, their chemical composition, and, in some cases, their orientation with respect to the light source and receptor. Since complex indices of refraction are not well established for most materials (Deirmendjian, 1969), optical models of aerosols may contain errors because of the uncertainty of these values. 

Aerosols in the atmosphere change the contrast of the atmosphere. This is evident to anyone who has viewed objects at a distance. Visibility decreases as the atmospheric load of aerosol material increases. 

Photochemical aerosols, only about 10% of the total pollutant aerosol material, can contribute to long distance, downwind effects from pollutant sources, and as part of the total pollutant aerosols probably have contributed to changes in the aerosol background concentration over the North Atlantic. 

The ID50 of aerosolized EA 3580 was calculated to be 8.4 ug/kg, with 95Z confidence limits of 5.8 and 12.2 ug/kg. The time to onset of Incapacitation was about 2 h, and spontaneous recovery from severe effects required about 9 h from their Inception. The effects Induced Inhalation of aerosolized EA 3580 were the same as chose induced by Intramuscular injection of this agent. To judge by comparison of the retained IC50 for the aerosolized material and the ZD50 estimated by Crowell (267) for the Intramuscularly Injected compound, the Inhaled compound seems to have only 46.4Z of the activity of the Injected compound. 

Several types of filter material are used for collecting aerosol materials (glass, PVC or Microsorban filters). All commercial filter media, when used properly, have adequate efficiencies. The filters are usually compressed to provide a standard counting geometry and are measured by gamma spectrometry, after which they may be dry- or wet-ashed for radiochemical analysis. 

Figure 5. Light scattering per unit volume of aerosol material (G) as a function of particle diameter (dp), integrated over the wavelengths 360-680 nm for a refractive index of 1.5. The curve is independent of the particle size distribution. From Friedlander (2000) by Oxford University Press, Inc. Used by permission.

The size of the particles is determined by the particular material selected and the vapor concentration used. In practice, limited variation in particle size can be achieved for a particular aerosol material because conditions for stable aerosol formation require a particular set of thermal and vapor concentration conditions. The monodispersity of the aerosol can be improved by revaporization and recondensation. In systems in which the condensation occurs in a container with a high ratio of volume to surface areas, relatively monodisperse particles can be obtained (frg 1.1). Otherwise, the particle size varies with the proximity to the wall. In cylindrical or tubular systems, such as in the condensation aerosol generator developed by Liu et al. [10] or the falling-film generator, the particle size that is produced varies radially (see Ref. [3]). A more monodisperse aerosol can be produced by extracting the central portion of the flow, which is less subject to wall effects. Liu et al. [10] found that the monodispersity improved from a ug value of 1.35 to 1.15 by using only the central 5% of the aerosol flow. A commercial version of a modified Sinclair-LaMer generator is available with particle size control suited for inhalation studies [11]. 

Examples of size distribution functions are shown ill Figs. 1.4 and 1.5. Figure 1.4 shows number distributions of commercially produced silica particles in terms of the fraction of particles in the,size range around dp, dN/N d dp) = na(,dp)fNxs where is the total particle concentration. The total particle surface area corresponding to each size distribution is shown. Commercial silica manufactured by the oxidation of SiCU is used as a filler (additive) in rubber. Both coordinate axes in Fig. 1.4 are linear, and the area under each curve should be normalized to unity. A bimodal volume distribution with a minimum near a particle size of 1 is shown in Fig. 1.5. Distributions of this type are often observed for atmospheric aerosols (Chapter 13) the volume of aerosol material per unit volume of gas above and below a micron is about the same as shown by the area under the curve. Bimodal distributions are also often observed in aerosols from industrial sources as discus.sed below. 

Figure 5.8 Light scaltering per unii volume of aerosol material us a function of parlidc size, integrated over all wavelengths for a relVaetive index, in = 1.5. The incident radiation is as.sumcd to have the standiird distribution of soiar radiation at. sea level (Bolz and Tuve 1970). The limits of integration on wavelength were 0.36 to 0.680 w. The limits of visible light are approximately 0.350 to 0.700 m. The curve is independent of the particle size distribution.

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