Aerosol ammonium chloride

Gas-phase reactions can also be used to produce products of low volatility that condense to give an aerosol. The reaction of gaseous NH3 with HC1 to form particles of solid ammonium chloride and the reaction of gaseous S03 with water vapor to form H2S04 are typical examples. Such methods tend to give submicron particles. 

Allen AG, Harrison RM, Erisman J-W. 1989. Field measurements of the dissociation of ammonium nitrate and ammonium chloride aerosols. Atmos Environ 23(7) 1591-1599. 

Harrison RM, Sturges WT, Kitto A-MN, et al. 1990. Kinetics of evaporation of ammonium chloride and ammonium nitrate aerosols. Atmos Environ 24(7) 1883-1888. 

FIGURE 8.23 Measured size distributions of aerosol sulfate, nitrate, ammonium, chloride, sodium, and hydrogen ion in Claremont, CA (Wall et al. 1988). 

Aerosol Na+ and Cl are present in substantial concentrations in regions close to seawater. Sodium and chloride interact with several aerosol components (Table 10.7). A variety of solids can be formed during these reactions including ammonium chloride, sodium nitrate, sodium sulfate, and sodium bisulfate, while HCl(g) may be released to the gas phase. 

Octadecyidimethyl [3-(trimethoxysilyl) propyl] ammonium chloride coupling agent, household aerosols Sorbitan sesquioleate coupling agent, household cleaners Methoxydiglycol Methoxyisopropanol Octoxynol-1 Octoxynol-3 Octoxynol-10 Octoxynol-30 Octoxynol-40 PEG-5 laurate Phenoxyethanol Propylene glycol n-propyl ether... 

Some examples of amphiphilic molecules a) dodecyl trimethyl ammonium chloride (DTACl), b) aerosol OT,c) dipalmitoyl phosphatidylcholine (DPPC), d) sodium decyl sulfate (SdS), e) deoanol, f) cetyl pyridinium chloride (CPCl). 

Chemical radicals—such as hydroxyl, peroxyhydroxyl, and various alkyl and aryl species—have either been observed in laboratory studies or have been postulated as photochemical reaction intermediates. Atmospheric photochemical reactions also result in the formation of finely divided suspended particles (secondary aerosols), which create atmospheric haze. Their chemical content is enriched with sulfates (from sulfur dioxide), nitrates (from nitrogen dioxide, nitric oxide, and peroxyacylnitrates), ammonium (from ammonia), chloride (from sea salt), water, and oxygenated, sulfiirated, and nitrated organic compounds (from chemical combination of ozone and oxygen with hydrocarbon, sulfur oxide, and nitrogen oxide fragments). ... 

Atmospheric aerosols are hygroscopic, taking up and releasing water as the RH changes (see also Section C.l) because some of the chemical components are themselves deliquescent in pure form. For example, sodium chloride, the major component of sea salt, deliquesces at 298 K at an RH of 75%, whereas ammonium sulfate, (NH4)2S04, and ammonium nitrate, NH4N03, deliquesce at 80 and 62% RH, respectively. (See Table 9.16 for the deliquescence points of some common constituents of atmospheric particles.) De-... 

Toon, O. B., J. B. Pollack, and B. N. Khare, 1976. The optical constants of several atmospheric aerosol species ammonium sulfate, aluminum oxide and sodium chloride, J. Geophys. Res.. 81, 5733-5748. 

Organic carbon (OC) and elemental carbon (EC) concentrations in smoke aerosol can be measured by using a semicontinuous thermal-optical OC/EC instruments [18]. Water-soluble organic carbon (WSOC) and water-soluble ions can be detected in smoke plumes with a PILS combined with a total organic carbon analyzer [30] and IC [19]. Besides smoke-specific tracers, the HR-ToF-AMS enables to study the concentrations of organic matter (OM), nitrate, ammonium, sulfate, and chloride in smoke particles [30]. Black carbon (BC) can be measured in real-time with several instruments, e.g., with aethalometer [19], multi-angle absorption photometer [29], and particle soot absorption photometer [25]. 

In continental air sulfate tends to be associated with finer particles, and as ammonia is more likely to be present in the air this can neutralize the sulfuric acid with the formation of ammonium sulfate- or bisulfate-containing particles over land. Sulfuric acid can displace chloride from seasalt aerosols and represent a source of hydrogen chloride ... 

The first section of this chapter is a review of fundamental chemical thermodynamic principles focusing on the chemical potential of species in the gas, aqueous, and solid phases. Further discussion of fundamentals of chemical thermodynamics can be found in Denbigh (1981). Chemical potentials form the basis for the development of a rigorous mathematical framework for the derivation of the equilibrium conditions between different phases. This framework is then applied to the partitioning of inorganic aerosol components (sulfate, nitrate, chloride, ammonium, and water) between the gas and particulate phases. The behavior of organic aerosol components will be discussed in Chapter 14. 

Atmospheric aerosols at high relative humidities are aqueous solutions of species such as ammonium, nitrate, sulfate, chloride, and sodium. Cloud droplets, rain, and so on are also aqueous solutions of a variety of chemical compounds. 

Aerosol particles in the atmosphere contain a variety of volatile compounds (ammonium, nitrate, chloride, volatile organic compounds) that can exist either in the particulate or in the gas phase. We estimate in this section the timescales for achieving thermodynamic equilibrium between these two phases and apply them to typical atmospheric conditions. The problem is rather different compared to the equilibration between the gas and aqueous phases in a cloud discussed in the previous section. Aerosol particles are solid or concentrated aqueous solutions (cloud droplets are dilute aqueous solutions), they are relatively small, and aqueous-phase reactions in the aerosol phase can be neglected to a first approximation because of the small liquid water content. 

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