Ozone Reaction Rate Research Articles

A kinetic model for multicomponent wastewater substrate removal by partial ozonation and subsequent biodegradation

A kinetic model for multicomponent substrate removal by the partial ozonation process is presented. The model consists of a component describing the co-evolution of COD and BOD as a function of ozone dosage and a mass transfer based component describing ozone dosage as a function of time. A multiple zero order reaction concept is used to describe the multicomponent kinetic behaviour. The model has been verified experimentally by comparing stoichiometric ratio and ozone reaction rate of conventional partial ozonation processes and partial ozonation processes with intermittent biodegradation. The model is found to effectively describe the change in stoichiometry and reaction rate that typically occurs during ozonation processes. Intermittent biodegradation is found to have no effect on the instantaneous stoichiometric ratio or the instantaneous ozone reaction rate. This implicates that intermittent BOD removal results in an additional decrease in required ozonation time and ozone demand compared to the conventional partial ozonation process and in addition to the expected decrease resulting from BOD removal.

The importance of atmospheric ozone and hydrogen peroxide in oxidising sulphur dioxide in cloud and rainwater

The process by which sulphur dioxide is oxidised in atmospheric droplets has been studied in laboratory experiments designed to collect a large amount of chemical data pertinent to the atmospheric situation. Thus the oxidation of sodium sulphite solutions by oxygen, ozone and hydrogen peroxide has been studied at different pH's and temperatures. In all cases the reaction is first order with respect to sulphite ion but the order with respect to oxidant differs. For oxygen the order is zero whereas the order for ozone and hydrogen peroxide is one. Varying the hydrogen ion concentration has little effect on the oxygen reaction rate between pH 6 and 9; the ozone reaction rate is inversely proportional to the square root of the hydrogen ion concentration and the hydrogen peroxide rate is almost directly proportional to the hydrogen ion concentration. These last two observations are very important since in the case of ozone it indicates that the reaction proceeds via a free radical mechanism involving hydroxyl radicals and in the case of hydrogen peroxide it is the only oxidation process of sodium sulphite so far investigated that shows a positive response to the presence of hydrogen ions. The experimental data was used to calculate the rate of sulphate formation in water droplets under atmospheric conditions for each of the three oxidants. If it is assumed that the ozone and hydrogen peroxide gas phase concentrations are initially 50 parts in 10 9 and 1 part in 10 9 by volume respectively, then the rates of sulphate formation are equal in cloud water at pH 5.8. Above this pH the ozone reaction is faster and below it the hydrogen peroxide reaction is faster due to the positive catalysis by hydrogen ions; the oxygen rate is unimportant by comparison at all pH's below 7. The rate of hydrogen peroxide reaction is such that substantial amounts of sulphate can still be formed rapidly in water droplets at pH values from 3 to 5, and thus this process will be very important in creating acidity in rainwater.

On the reactive uptake of gaseous PAH molecules by micron-sized atmospheric water droplets

A falling droplet reactor was used to study the heterogeneous oxidation of gaseous PAH molecules adsorbed on a 92 μm diameter water droplet by ozone. The dynamic partition constant for the PAH between the droplet and air and the first-order surface rate constant was measured. The increase in uptake with ozone concentration was due to increased mass transfer via surface reaction of co-adsorbed ozone and PAH. The surface rate constant was rationalized through the Langmuir–Hinshelwood mechanism. The rate constant was smaller for phenanthrene than naphthalene. The main reaction products identified in the aqueous phase indicated the peroxidic route for surface reaction of ozone with PAH. The heterogeneous reaction rate of ozone with adsorbed phenanthrene at the air–water interface of a 92-μm droplet was estimated to be 9300 times larger than the homogeneous reaction of ozone with phenanthrene in the gas phase and it was 76 times larger than the homogeneous oxidation by hydroxyl radical in the gas phase. For naphthalene that is more volatile, however, the homogeneous reaction with hydroxyl was more important. Increased organic carbon added to the droplet increased both the partition constant for phenanthrene and surface reaction with ozone. The partition constant for a droplet formed from actual fog water was much larger than for pure distilled water.

Heterogeneous ozonation kinetics of polycyclic aromatic hydrocarbons on organic films

The room temperature heterogeneous reaction rates of gas-phase ozone with naphthalene, anthracene, fluoranthene, phenanthrene, pyrene, and benzo[ a]pyrene were measured over a range of ozone concentrations from 3.5×10 14 to 2.3×10 16 molec. cm −3. The polycyclic aromatic hydrocarbons (PAHs) were dissolved in organic mixtures composed of octanol or decanol along with proxies for compounds known to be present in “urban grime” films. In all cases, the reaction kinetics were well-described by the Langmuir–Hinshelwood mechanism, which suggests a surface reaction. The adsorption of PAHs to the air–organic interface was confirmed by an adsorption isotherm of anthracene. The presence of the additional organic compounds generally did not affect the reaction rates; however, unsaturated species such as oleic acid and squalene reduced the observed rates significantly.

Analysis of Atmospheric Sesquiterpenes: Sampling Losses and Mitigation of Ozone Interferences

Atmospheric standards containing parts-per-billion levels of 14 semivolatile hydrocarbon compounds, including eight sesquiterpenes (SQTs) (longipinene, alpha-copaene, isolongifolene, alpha-cedrene, trans-caryophyllene, aromadendrene, alpha-humulene, delta-cadinene), two oxidized sesquiterpenoids (cisnerolidol, trans-nerolidol), one biogenic ketone (geranylacetone) and three aromatic compounds (1,3,5-triisopropylbenzene, diphenylmethane, nonylbenzene), were collected onto four solid adsorbent materials at increasing ozone mixing ratios (0-100 ppbv 03) for analysis by thermodesorption-gas chromatography. Substantial sampling losses of up to >90% were found for the most reactive SQT, even at the lowest ozone level investigated of 20 ppbv. Loss rates from the ozone-SQT reaction were used to derive estimates of gas-phase ozone reaction rate constants for longipinene, alpha-copaene, isolongifolene, geranylacetone, aromadendrene, delta-cadinene, cis-nerolidol, and transnerolidol. Three different ozone mitigation techniques were investigated to prevent these sampling losses. These strategies included (a) placing glass fiber filters impregnated with sodium thiosulfate (Na2S2O3) into the sampling line, (b) titration of ozone in the sampling stream with nitric oxide (NO), and (c) catalytically removing ozone with a commercially available manganese dioxide (MnO2) catalyst. All three techniques reduced ozone-mixing ratios from 100 ppbv to <0.6 ppbv at sampling flow rates of 1 L min(-1). When the Na2S2O3 filters and the NO-titration techniques were applied, SQT loss rates decreased from 25-60% to 0-5% for most SQT compounds and from >90% to approximately 10-50% for the two most reactive compounds at ozone mixing ratios of up to 100 ppbv. The commercial manganese dioxide scrubber, however, caused complete analyte losses (>98%) even at 0 ppbv ozone. These results underline the need and present applicable techniques for removal of ozone in air samples for SQT analysis by solid adsorption techniques.

Ligninsulfonate Ozonation in the Presence of Transition Metal Ions

The kinetics of ozone reactions with aqueous solutions of ligninsulfonate (LS) in the presence of transition metal ions Fe2+, Mn2+, Co2+ has been investigated. Metal ions are found to influence the rate and pathways of ozone reaction with LS. The acceleration of the reaction in the presence of Fe2+ is the most significant. The mechanism of these processes is discussed. The formation of Me2+ complex with LS functional groups is shown. Me2+ oxidation in [LS…Me2+] complex is indicated to be the limit stage of the reaction. Metal ions addition to LS solutions is proved to cause slowing down of LS aromatic rings destruction by ozone.

Kinetics of Ketone Oxidation by Ozone in Water Solutions

The spectrophotometric monitoring of ozone consumption in a liquid phase is used to study the kinetics of cyclopentanone and methyl butyl ketone oxidation. The rate of ozone reaction with ketones (RH) at 303–344 K in acidic (HClO4) aqueous solutions is described by the equation w = k1[RH][O3] + kEn[RH][HClO4], where k1 is the rate constant for the reaction of ozone with RH and kEn is the rate constant for the enolization of RH. The kinetic parameters of the process are found.

45] Reactive absorption of ozone: An assay for reaction rates of ozone with sulfhydryl compounds and with other biological molecules

Publisher Summary Ozone is toxic to both plants and animals. Because the reactions of ozone with many types of biological molecules are extremely fast, ozone reacts very close to the surface of tissues that are in direct contact with the atmosphere. In animals, ozone reacts with biomolecules present in the fluid lining the air passages of lungs. In plants, ozone reacts with biomolecules within the cell walls lining the air passages of leaves. As ozone is consumed within tissues through reactions with biological molecules, more ozone is drawn into the tissues in a process called reactive absorption. Mathematical models of reactive absorption are well established and provide a means of calculating reaction rate constants for gases that react with nonvolatile solutes in liquids. While most of the development of these mathematical models has occurred within the chemical engineering literature, the measurement of reactive absorption can provide some unique insights about ozone reactions with biological molecules close to the surface of a solution. Using a very simple apparatus, it is possible to obtain values for even very large reaction rate constants.

Reactive Absorption of Ozone by Aqueous Biomolecule Solutions: Implications for the Role of Sulfhydryl Compounds as Targets for Ozone

The rates of reactive absorption of ozone by various biomolecule solutions were measured. At pH 7, the ability of various biomolecules to reactively absorb ozone was in the following sequence: thiosulfate > ascorbate > cysteine ≍ methionine > glutathione. The rates of reactive absorption under a variety of conditions were then analyzed using a mathematical model in order to estimate the reaction rate constants for the various ozone-biomolecule reactions. Compared to the ozone-methionine rate constant, the relative rate constants for thiosulfate, ascorbate, cysteine, and glutathione reactions were 18 ± 2, 12 ± 1, 1.1 ± 0.1, and 0.62 ± 0.03, respectively. Using an ozone-methionine reaction rate constant of 4 × 106 M−1 s−1, the rate constants for thiosulfate, ascorbate, cysteine, and glutathione were 7.2 × 107, 4.8 × 107, 4.4 × 106, and 2.5 × 106 M−1 s−1, respectively. Competitive studies using tryptophan as a standard ozone target were consistent with these rate constants. Compared to tryptophan, the relative ozone reaction rate constants for methionine, cysteine, and glutathione were 0.77 ± 0.08, 0.88 ± 0.19, and 0.42 ± 0.01, respectively. These relative rate constants refer to ozone consumption rather than biomolecule consumption, so they may be compared with the relative rate constants obtained from reactive absorption. In addition, various inconsistencies in the literature regarding the rates of the ozone-cysteine and the ozone-glutathione reactions were reviewed.

Modeling of an ozone-wastewater system's kinetics

The mass transfer of ozone into aqueous solution is important in both disinfection and reduction of organic matter, i.e. the more ozone transferred into the solution the better the disinfection and the less the amount of organic matter left in the effluent. The mathematical model proposed by Sheffer and Esterson (Wat. Res. 16, 383, 1982) for an ozone-tap water system is modified to predict the amount of ozone input required for a given ozone residual, and COD in an actual ozone-wastewater system. Knowing the amount of ozone needed as input to obtain a specific ozone residual in a given wastewater can prevent wastage of ozone and conserve energy for a required degree of treatment. The values of ozone mass transfer rate k L a (1.243 min −1), ozone decomposition rate k 1 (0.087 min −1) and ozone reaction rate k 2 [0.091 (l/mg) 1 2 min −1] obtained by using the proposed model are similar to the values reported in the literature.

Photochemical Damping of Inertio–Gravity Waves

A simple model is developed for the coupling effect of radiative heating and ozone photochemistry on inertio-gravity waves in the region 16-70 km. It is found that the photochemical damping rate is the weighted sum of the rates caused by two individual processes. One, suggested by Craig and Ohring, involves the temperature dependence of ozone reaction rate coefficients; the other, suggested by Leovy, involves the vertical gradient of the ozone mixing ratio. The relative importance of these two processes depends on the ratio of dynamical and chemical relaxation times. Calculations show that the most important region for coupling is near 48 km where the total relaxation time is 8 days for equinox and 6 days for summer midlatitude.

Kinetics and mechanism of ozonation of free cyanide species in water

The reaction rates of ozone with free cyanide species were determined by a stopped-flow spectrophotometer in the pH range 2.5-12.0. The direct reaction of molecular ozone and the free radical reactions which contribute to the overall reaction were identified. A reaction mechanism consistent with the observations was proposed. The rate constant for the direct reaction of molecular ozone with cyanide ion was calculated to be 2600 +/- 700 M/sup -1/ s/sup -1/. Batch and bubble-column experiments indicated stoichiometric conversion of cyanide to cyanate and an ozone consumption of 1.2 +/- 0.2 mol/mol of oxidized cyanide.

Modelling of water-ozone reaction system

Mass transfer and reaction kinetics of raw Nile water ozonation are examined. The contact system is a perfectly mixed reactor, and ozone is bubbled through a glass diffuser at different supply rates. The ozone residual is detected for different reaction time intervals. A simple mathematical model is proposed to describe the mechanism of the ozone reactions in the reactor. The proposed model quite accurately describes the mass transfer behaviour in the reactor and determines the ozone dissociation rate constant, together with the effect of the chemical reaction on the ozone transfer. A linear relationship is observed between the ozone feed rate and the ozone residual. First order reaction kinetics describes fairly well the autodecomposition and the global reaction rates of ozone in raw water. The mass transfer coefficient is about 0.18 min −1. The dissociation and the reaction rate constants are evaluated to be 0.33 mg L −1 and 0.19 mg L −1 min −1.

Effect of solvent polarity on the rate of ozone reaction with unsaturated compounds

AbstractThe effect of the polarity of seven solvents (ϵ ≈ 2–60) on the rate of ozone reactions with stilbene and allyl chloride has been studied. The data show that the rate of the reaction is insensitive to the medium polarity. The results of earlier publications are revised and are shown to be in agreement with the present data.

Ozonation of water containing chlorine or chloramines. Reaction products and kinetics

Ozone reacts with free aqueous chlorine when present as hypochlorite ion (OCl −) with a second order rate constant of 120 ± 15 M −1 s −1 at 20°C. About 77% of the chlorine reacts to produce Cl − and 23% is oxidized to ClO − 3. No ClO − 4 is formed. Conversion of chlorine to monochloramine reduces the ozone reaction rate to 26 ± 4 M −1 s −1, independent of pH, NH 2Cl is transformed quantitatively to NO − 3 and Cl − by O 3. Rate data for other chloramines are also presented. The direct reaction of ozone with chlorine accounts for a significant amount of the chlorine and ozone demand found when the two oxidants are used in combination under water works conditions.

An in vitro system for studying the effects of ozone on mammalian cell cultures and viruses

A unique in vitro system was developed for exposing mammalian cell cultures, viruses, or both to ozone under conditions mimicking those of the respiratory tract. The system used borosilicate glass roller culture bottles equipped with specially designed caps to permit the flow of humidified gas (ozone or filtered air) through the rotating vessels. The system was designed to allow two test cultures and one control culture to be simultaneously exposed to different precisely defined concentrations of ozone. The input and exhaust concentrations of ozone were sequentially monitored with an ultraviolet photometric ozone analyzer. The system was used to determine the reactivity of ozone with several tissue culture media at different flow rates. The reaction rate of ozone with media was shown to be a function of the input concentration and increased as the gas flow rate was increased. Input ozone concentrations measured during 48-hr test exposures remained stable, yielding standard deviations of less than 4%. Exposure of Madin-Darby bovine kidney cells to ozone concentrations of 0.16 and 0.64 ppm for 24 hr resulted in a slight but significant decrease in the synthesis of RNA as measured by the incorporation of [ 3H]uridine into TCA-precipitable material. The synthesis of protein and DNA was not significantly affected by identical treatments. Vesicular stomatitis virus exposed to ozone at concentrations of 0.16 and 0.64 ppm for 12 hr showed marked loss of biological function when compared to identical controls exposed to filtered air. The feasibility of using enveloped viruses as a model for investigation of ozone-induced damage to cellular membranes and membrane proteins is discussed.

Temperature dependence of the nitric oxide + ozone reaction rate from 195 to 369 K

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTemperature dependence of the nitric oxide + ozone reaction rate from 195 to 369 KJ. V. Michael, J. E. Allen Jr., and W. D. BrobstCite this: J. Phys. Chem. 1981, 85, 26, 4109–4117Publication Date (Print):December 1, 1981Publication History Published online1 May 2002Published inissue 1 December 1981https://doi.org/10.1021/j150626a032RIGHTS & PERMISSIONSArticle Views270Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (855 KB) Get e-Alerts

The importance of atmospheric ozone and hydrogen peroxide in oxidising sulphur dioxide in cloud and rainwater

The process by which sulphur dioxide is oxidised in atmospheric droplets has been studied in laboratory experiments designed to collect a large amount of chemical data pertinent to the atmospheric situation. Thus the oxidation of sodium sulphite solutions by oxygen, ozone and hydrogen peroxide has been studied at different pH's and temperatures. In all cases the reaction is first order with respect to sulphite ion but the order with respect to oxidant differs. For oxygen the order is zero whereas the order for ozone and hydrogen peroxide is one. Varying the hydrogen ion concentration has little effect on the oxygen reaction rate between pH 6 and 9; the ozone reaction rate is inversely proportional to the square root of the hydrogen ion concentration and the hydrogen peroxide rate is almost directly proportional to the hydrogen ion concentration. These last two observations are very important since in the case of ozone it indicates that the reaction proceeds via a free radical mechanism involving hydroxyl radicals and in the case of hydrogen peroxide it is the only oxidation process of sodium sulphite so far investigated that shows a positive response to the presence of hydrogen ions. The experimental data was used to calculate the rate of sulphate formation in water droplets under atmospheric conditions for each of the three oxidants. If it is assumed that the ozone and hydrogen peroxide gas phase concentrations are initially 50 parts in 10 9 and 1 part in 10 9 by volume respectively, then the rates of sulphate formation are equal in cloud water at pH 5.8. Above this pH the ozone reaction is faster and below it the hydrogen peroxide reaction is faster due to the positive catalysis by hydrogen ions; the oxygen rate is unimportant by comparison at all pH's below 7. The rate of hydrogen peroxide reaction is such that substantial amounts of sulphate can still be formed rapidly in water droplets at pH values from 3 to 5, and thus this process will be very important in creating acidity in rainwater.

Study of effect of nature of solvent on reaction rate of ozone with an olefin

1. The rate with which ozone reacts with a double bond is independent of the polarity of the solvent. 2. The experimental data testify in support of the activated complex having a nonpolar nature.

Kinetics of ozone decomposition and reaction with organics in water

AbstractThe decomposition of ozone in water is found to be second order at pH 2 and 4 with the rate insensitive to pH. At pH 6 the reaction order is 3/2 to 2 and at pH 8 it is first order. Above pH 6 the rate increases rapidly with pH. Ozonation can greatly reduce the organic matter in waste water. The reaction rate of ozone with organics in flocculated secondary sewage effluent is found to depend on the rate of ozone decomposition, which is independent of the subsequent reaction with the organics.