Aerosols solid

An aerosol is a suspension of either a solid or a liquid in a gas. Fog, for example, is a suspension of small liquid water droplets in air, and smoke is a suspension of small solid particulates in combustion gases. In both cases the liquid or solid particulates must be small enough to remain suspended in the gas for an extended time. Solid aerosol particulates, which are the focus of this problem, usually have micrometer or submicrometer diameters. Over time, solid particulates settle out from the gas, falling to the Earth s surface as dry deposition. 

Typical examples of gaseous samples include automobile exhaust, emissions from industrial smokestacks, atmospheric gases, and compressed gases. Also included with gaseous samples are solid aerosol particulates. 

Atmospheric aerosols have a direct impact on earth s radiation balance, fog formation and cloud physics, and visibility degradation as well as human health effect[l]. Both natural and anthropogenic sources contribute to the formation of ambient aerosol, which are composed mostly of sulfates, nitrates and ammoniums in either pure or mixed forms[2]. These inorganic salt aerosols are hygroscopic by nature and exhibit the properties of deliquescence and efflorescence in humid air. That is, relative humidity(RH) history and chemical composition determine whether atmospheric aerosols are liquid or solid. Aerosol physical state affects climate and environmental phenomena such as radiative transfer, visibility, and heterogeneous chemistry. Here we present a mathematical model that considers the relative humidity history and chemical composition dependence of deliquescence and efflorescence for describing the dynamic and transport behavior of ambient aerosols[3]. 

The predicted solids based on thermodynamic measurements and models derived from them depend strongly on chemical composition. However, small aqueous aerosols remain meta-stable with decreasing RH until reaching a crystallization relative humidity(CRH). In contrast, solid aerosols t e up water at the thermodynamically favored deliquescence relative humidity(DRH). This hysteresis causes a dependence of aerosol phase on RH history. 

Solid Solid suspension Suspension Solid aerosol... 

PR Byron, AJ Hickey. Spinning-disk generation and drying of monodisperse solid aerosols with output concentrations sufficient for single-breath inhalation studies. J Pharm Sci 76 60-64, 1987. 

There are other aerosol methods which can yield uniform powders, such as by dispersing aqueous dispersions of particles (e.g. of latex) and evaporating the water (12). In this case each droplet should contain only one particle, a task not easily accomplished. Alternatively, it is possible to nebulize solutions of electrolytes or other substances, which on removal of the liquid result in solid particles, dispersed in the carrier gas (13,14). This process has been expanded to include sintering of resulting solid aerosols in a continuous process to produce powders for various applications (15-18). 

Herein, / is the single particle collection efficiency. According to literature [9] for liquids or very soft substances the adhesion coefficient has a value near to one. Another study indicates that for solid aerosols having a diameter in the range of 0.7 pm the adhesion coefficient may vary from 0.001 to 0.01 [4]. 

Nanoparticles are frequently used as a suspension in some kind of solvent. This is a two phase mixture of suspended solid and liquid solvent and is thus an example of a colloid. The solid doesn t separate out as a precipitate partially because the nanoparticles are so small and partially because they are stabilised by coating groups that prevent their aggregation into a precipitate and enhance their solubility. Colloidal gold, which has a typical red colour for particles of less than 100 nm, has been known since ancient times as a means of staining glass. Colloid science is a mature discipline that is much wider than the relatively recent field of nanoparticle research. Strictly a colloid can be defined as a stable system of small particles dispersed in a different medium. It represents a multi-phase system in which one dimension of a dispersed phase is of colloidal size. Thus, for example, a foam is a gas dispersed in a liquid or solid. A liquid aerosol is a liquid dispersed in gas, whereas a solid aerosol (or smoke) is a solid dispersed in a gas. An emulsion is a liquid dispersed in a liquid, a gel is liquid dispersed in a solid and a soils a solid dispersed in a liquid or solid. We saw in Section 14.7 the distinction between sol and gel in the sol gel process. 

Solid-gas Adsorption Solid aerosol, adsorption, catalysis, corrosion, diffusion, surface energy, thin films, permeation, osmosis, filtration, oxidation, charge transfer, condensation and nucleation... 

Sorption by sediment and suspended solids Sedimentation and resuspension of solids Aerosol formation at the air-water interface Uptake and release by biota Transport within water bodies Turbulent dispersion and convection Diffusion between upper mixed layer and bottom layer Transformation Biodegradation Photochemical degradation... 

None (all gases are infinitely Liquid aerosol (fog, mist, Solid aerosol (smoke,... 

Only one study was located regarding death in animals after inhalation exposure to DNOC aerosols (Burkatskaya 1965a). In this study, I of 3 and 2 of 6 cats died after being exposed to 40 and 100 mg/m of an aerosol of DNOC solution for 4 hours, respectively. Two of six cats died after being exposed to 100 mg/m DNOC solid aerosols (dusts). The data suggest that the DNOC solution aerosol was no more toxic than the dust. In addition, 2 of 3 cats died after being exposed to an aerosol of 2.0 mg/m DNOC in solution 4 hours/day for 1 month. 

As part of the NAFTA Technical Working Group on Pesticides, priority areas for development of biocide applicator data have been agreed upon. These include, in order of priority, high-pressure spray, low-pressure spray, painting (roller/brush), wipe/mop, place solids, aerosol spray, painting (airless), pour solid, pour liquid and pump liquid. 

Some diverse VOCs (halocarbons, isoprene (CH2C(CH3) CH2CH2), monoterpenes, ethanol, and methyl tert-butyl ether, (CHslsCOCHs)) were found to be photooxidized efficiently on solid aerosols. Solid photocatalyst particles, such as Ti02, ZnO, and Fe20s, were here of special importance, but the VOC oxidation was photoassisted also by dessert sand, volcanic ash, or even by chalk particles (23-25). Similarly, sulfur dioxide was found to... 

When NH3 is added to O3 in the reaction vessel, the O3 is consumed, and a white solid aerosol is produced which settles on the cell walls. The O3 consumption is monitored by its intense absorption at 2537 A. For a freshly cleaned cell some decay of the O3 occurs even in the absence of NH3. However the reaction with NH3 is much more rapid but is not reproducible. As the solid deposit accumulates from several runs, the background reaction becomes negligible, and the reaction with NH3 becomes slower and reproducible. All reported results here are for the cell (packed and unpacked) conditioned this way. 

CN (chloroacetophenone, a tear gas) is generally used as a solid aerosol or smoke solutions (Mace) are used at close quarters. 

In humid air, solid aerosols formed in the reactions 17-21 are converted into liquid droplets (deliquescence) for example above 75% humidity (5°C). The liquid aerosols are very concentrated salt solutions (up to 26 M). 

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