Ozone solubility

Solubility data for mucus are not available, but Table 7-1 indicates that the Henry s law constant for ozone in water under the conditions of the lung is 9,700. Solubility data for pure ozone and other physical properties are available from various sources. Air Quality Criteria for Photochemical Oxidants reports an ozone solubility of 0.494 ml/ 100 ml of water at 0 C for ozone at 760 mm Hg extrapolation of data from Thorp indicates 1.09 g/liter of water at 0 C and approximately 0.31 g/liter of water at 37 C for 100% ozone. The value for 37 C agrees closely with the solubility calculated from the Henry s law constant for pure ozone at 760 mm Hg. 

Rischbieter, E., Stein, H., and Schumpe, A. Ozone solubilities in water and aqueous salt solutions, J. Chem. Eng. Data, 45(2) 338-340, 2000a. 

Figure 3-4 Ozone solubility s as a function of the fluid temperature (T = 5-35 °C).

A more comprehensive analysis of the influences on the ozone solubility was made by Sotelo et al., (1989). The Henry s Law constant H was measured in the presence of several salts, i. e. buffer solutions frequently used in ozonation experiments. Based on an ozone mass balance in a stirred tank reactor and employing the two film theory of gas absorption followed by an irreversible chemical reaction (Charpentier, 1981), equations for the Henry s Law constant as a function of temperature, pH and ionic strength, which agreed with the experimental values within 15 % were developed (Table 3-2). In this study, much care was taken to correctly analyse the ozone decomposition due to changes in the pH as well as to achieve the steady state experimental concentration at every temperature in the range considered (0°C [Pg.86]

The selectivity of the ozone reaction in pure solvent or water-solvent systems is known from early studies conducted by chemists under analytical and preparative aspects (Bailey, 1958). Inert solvents (e. g. pentane, carbon tetrachloride) provide an opportunity to produce and study oxidation products of the ozonolysis, such as ozonides at low temperatures (Criegee, 1975). Only in the last two decades have ozonation techniques been developed and studied that utilize the higher ozone solubility, enhanced mass transfer rates, higher reaction rates etc. to be found in water-solvent systems. 

In Eq. (10) z is the stoichiometric coefficient of the ozone-compound reaction [reaction (8)], Z)M is the diffusivity of compound M in water (which can be calculated from the Wilke and Chang equation), and C o3 is the ozone solubility (or properly defined, the ozone concentration at the gas-water interface). If the parameters of Eqs. (9) and (10) are known, the kinetic regime can be established, and hence the kinetics of ozonation can be determined. Table 3 gives the kinetic equations corresponding to different kinetic regimes found in ozonation processes. As can be deduced from the equations in Table 3, the rate constant, mass transfer coefficients, and ozone solubility must be previously known to establish the actual ozonation kinetics. The literature reports extensive information on research studies dealing with kinetic parameter determination as quoted below. 

Ozone Solubility, Rate Constants, and Mass Transfer Coefficients... 

Similar to ozone decomposition, ozone solubility has been the subject of multiple studies. These studies usually propose an empirical equation for the Henry s law constant as a function of pH, ionic strength, and temperature [59,60]. For example, Sotelo et al. [60] found the following equation valid for phosphate buffer aqueous solutions at temperatures between 0 and 20°C, pH range of 2 to 8.5, and ionic strength varying from 10-3 to KT1 M ... 

C o3 Concentration of dissolved ozone at the gas-water interface or ozone solubility, M... 

Andreozzi R, Caprio V, Ermellino I, Insola A, Tufano V. Ozone solubility in phosphate buffer aqueous solutions effect of temperature, tert-butyl alcohol and pH. Ind Eng Chem Res 1996 35 1467-1471. 

Results are compared in Figure 5 for the ozonation of cyanide at 13 , 20°, 25°, and 30° C. Although the value of K increases slightly with increase in temperature, it can only be concluded that the temperature coefficient of the reaction rate constant is small. Thus, the rate of ozonation of cyanide does not depend, for practical purposes, on the temperature in the range of 13° to 30° C. It would be highly interesting to study the temperature effect of this reaction in the light of the rate of ozone decomposition and ozone solubility in solution. 

This reaction results in a lifetime of 03(aq) of the order of 1 s, but because of the small ozone solubility, this rate corresponds to a consumption of... 

We turn our attention first to ozone (Figure 12.10). Since ozone solubility does not depend on pH, all points (k, o3, //o3) at a given temperature for different pH values fall on a horizontal line shown on the lower part of the graph. The increase with pH of both the S(IV) solubility and the effective reaction constant k0l leads to an increase of k, q3 with increasing pH. The points (/ci,o3, //o3) lie well below the bounds of gas-phase mass... 

Although the rate of this reaction is estimated to be around 0.1 % 03(g) h, because of the low ozone solubility this rate results in a lifetime of 03(aq) on the order of 1 second. 

Determination of ozone solubility in polymeric materials, Chem. Eng. J., 138, 172, 2008. 

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