Ozone ratio

Plants respond in different ways to pollutant mixtures less than additive, additive, and greater than additive effects have been reported. Mixtures of ozone with sulfur dioxide and of nitrogen dioxide with sulfur dioxide can cause oxidantlike symptoms in some sensitive plants. Mixtures can cause effects below the threshold for either gas, although there is some disagreement here in r ard to ozone. Ratios of mixtures, intermittent exposures, sequential exposures to pollutants, and predisposition by one pollutant to the effects of a second pollutant may all be important in nature, but little research has been done. 

In a study on the oxidation of lower al hatic alcohols by ozone on alumina and ca from 293 and 363 K [4], it was found that the converted ethanol to ozone ratio was about unity. However, in that study the main oxidation products were acetaldehyde and ketones, while the only products observed on the supported manganese catalysts of this study were carbon dioxide and water. 

Six selected Aromatic Dyes with various chromophores were reacted with ozone by adjusting the pH and dye/ozone ratio of the reaction mixture. The concentrations of the dyes were determined by HPLC. The kinetics of the ozonation and the ratio of direct/indirect oxidation were studied quantitatively from the results. 

Figure 17 Pseudo first-order decay of A1 at different initial dye concentrations (mmoI/L) (Left) Ozonation of three different dyes at various dye/ozone ratios (Right). Three purified dye concentrations (14.4, 7.2, and 3.6 x 10 2 mmol/L) under saturated ozone concentrations (in excess) were applied to investigate the reaction kinetics of dye ozonation.

On the first part of this research, Advanced Chemical Oxidation, a quantitative estimation of direct ozonation and indirect free radical oxidation of dyes with assorted chromophores was studied through the examination of reaction kinetics in the ozonation process. The reaction kinetics of dye ozonation under different conditions was determined by adjusting the ozone doses, dye concentration, and reaction pH. The ozonation of dyes was found dominant by pseudo first-order reaction, and the rate constants decreased as the dye/ozone ratio increased. For all selected azo dyes, the dye decay rates increased as the initial pH of the solution increased, yet the decay rates of anthraquinone dyes would decrease in the same situation because of their insensible structure for ozone oxidation, formation of leuco-form, and higher solubility at a lower pH. The ozonation of dyes at a high pH contributed by hydroxyl free radicals was qualitatively verified by the use of a free radical scavenger. A proposed model, in another way, quantitatively determines the fraction of contribution for dye decomposition between free radical oxidation and direct ozonation. 

Aim effect of initial pH different dye/ozone ratio in the reaction system Solution preparation ... 

Ozonation of three different dyes at various dye/ozone ratios 83... 

Dutkiewicz, V. A., and L. Husain (1979). Determination of stratospheric ozone at ground level using beryllium 7/ozone ratios. Geophys. Res. Lett. 6, 171-174. 

In this sequence the Cl also acts as a catalyst and two molecules are destroyed. It is estimated that before the Cl is finally removed from the atmosphere in 1—2 yr by precipitation, each Cl atom will have destroyed approximately 100,000 molecules (60). The estimated O -depletion potential of some common CFCs, hydrofluorocarbons, HFCs, and hydrochlorofluorocarbons, HCFCs, are presented in Table 10. The O -depletion potential is defined as the ratio of the emission rate of a compound required to produce a steady-state depletion of 1% to the amount of CFC-11 required to produce the 1% depletion. The halons, bromochlorofluorocarbons or bromofluorocarbons that are widely used in fire extinguishers, are also ozone-depleting compounds. Although halon emissions, and thus the atmospheric concentrations, are much lower than the most common CFCs, halons are of concern because they are from three to ten times more destmctive to O, than the CFCs. 

Experimental studies show that the ozone concentration iacreases with specific energy (eV/O2) before reaching a steady state. The steady-state ozone concentration varies iaversely with temperature but directiy with pressure, reaching a maximum at about 101.3 kPa (1 atm). Above atmospheric pressure the steady-state ozone concentration decreases with pressure, apparentiy due to the pressure dependence of the rate constant ratio for the... 

The process yields a random, completely soluble polymer that shows no evidence of crystallinity of the polyethylene type down to —60°C. The polymer backbone is fully saturated, making it highly resistant to ozone attack even in the absence of antiozonant additives. The fluid resistance and low temperature properties of ethylene—acryUc elastomers are largely a function of the methyl acrylate to ethylene ratio. At higher methyl acrylate levels, the increased polarity augments resistance to hydrocarbon oils. However, the decreased chain mobiUty associated with this change results in less fiexibihty at low temperatures. 

Nonattainment area classification One-hour ozone concentration design value, ppm Attainment date Major source threshold level, tons VOGs/yr Offset ratio for new/modified sources... 

Equation (12-17) is called the photostationary state expression for ozone. Upon examination, one sees that the concentration of ozone is dependent on the ratio NO2/NO for any value of k. The maximum value of k is dependent on the latitude, time of year, and time of day. In the United States, the range of k is from 0 to 0.55 min T Table 12-5 illustrates the importance of the NO2/NO ratio with respect to how much ozone is required for the photostationary state to exist. The conclusion to be drawn from this table is that most of the NO must be converted to NO2 before O3 will build up in the atmosphere. This is also seen in the diurnal ambient air patterns shown in Fig. 12-2 and the smog chamber simulations shown in Fig. 12-3. It is apparent that without hydrocarbons, the NO is not converted to NO2 efficiently enough to permit the buildup of O3 to levels observed in urban areas. 

Pre- or post-treatment with ozone of wastewater may also be applied. Pretreatment with ozone takes place in the presence of biorefractory compounds, as ozone increases the BOD/COD ratio. 

A 0.10-mol sample of pure ozone, 03, is placed in a sealed 1.0-E container and the reaction 2 03(g) 3 0,(g) is allowed to reach equilibrium. A 0.50-mol sample of pure ozone is placed in a second 1.0-L container at the same temperature and allowed to reach equilibrium. Without doing any calculations, predict which of the following will be different in the two containers at equilibrium. Which will be the same (a) Amount of 02 (b) concentration of 02 (c) the ratio [0, / 0.] (d) the ratio [02 3/[03 2 (e) the ratio [03 2/[02 Explain each of your answers. 

Mole fractions, parts per million, and parts per billion all are ratios of moles of a particular substance to total moles of sample. Mole fraction is moles per mole, ppm is moles per million moles, and ppb Is moles per billion moles. These measures are related by scale factors ppm = 10 JT, and ppb = lO X - In other words, a concentration of 1 ppm is a mole fraction of 10 , and a concentration of 1 ppb is a mole fraction of 10. When the ozone concentration in the atmosphere reaches 0.5 ppm, the mole fraction of ozone is 0.5 X 10 , or 5 X 10. Example shows how to work with parts per million. 

Akiyama, T. Sugimoto, T. Matsumoto, Y. Meshitsuka, G. Erythrolthreo ratio of [i-O-4 structures as an important structural characteristic of lignin. I improvement of ozonation method for the quantitative analysis of lignin side-chain structure. J. Wood Sci. 2002, 48, 210-215. 

Fig. 14. Plot of the quantum efficiency for the formation of C>2(v < 26) as a function of wavelength. The value at 193 nm is taken from Stranges et aJ.44 A 10% branching ratio into the triplet channel is assumed. The absorption cross-section for ozone is plotted as the dashed curve on the right-hand axis.

Treatment of isoprene, 2,3-dimethylbutadiene or cyclopentadiene in pentane at —78°C with a high ratio ozone/oxygen stream led to immediate ignition and flames in both liquid and gas phases. 

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