Ozone Feed Rate Research Articles

Effect of ozone treatment on the chemical and mechanical properties of flax fibers

The surface of flax fiber is covered by noncellulosic substances, which results in many individual fibers that are bound into bundles. These noncellulosic materials must be removed to extract the usable fiber. In this study, ozone was used to remove the noncellulosic components from the surface of flax fiber. The changing regularity and mechanism of ozone treatment on the lignin content and degree of polymerization (DP) in flax fiber under different operational conditions (pH value, moisture content, ozone feed rate, and reaction time) were fully investigated. Then, the quality of untreated, ozone-treated (ozone 130 mg･L −1 ･min −1 , 20 min), ozone and acid treated (ozone 130 mg･L −1 ･min −1 , 20 min, pH 2.0, moisture content 70%) flax fiber were compared. The effect of ozone treatment on the change in strength, elongation, whiteness, copper number, and thermal stability of flax fiber was systematically tested. The results showed that the lignin content, DP, strength, elongation and thermal stability of flax fiber decreased after ozone treatment. The crystallinity, whiteness, copper number and roughness of flax fiber increased after ozone treatment. This phenomenon was more evident after ozone and acid treatment. Simultaneously, scanning electron microscopy (SEM) analysis showed that the noncellulosic components on the fiber surface were partially removed after ozone treatment and were thoroughly separated after ozone and acid treatment. This study could offer guidance into the removal of noncellulose materials on the surface of flax fiber using ozone treatment. • Ozone treatment was conducted in the gas phase under room temperature and pressure. • The noncellulosic components were removed after ozone treatment. • Lignin content and degree of polymerization was decreased after ozone treatment. • The effect of ozone treatment on flax fibers under acidic conditions were observed.

Mechanism and application of ozone fading: Oxidative decolorisation of disperse dyes and waste‐dyed polyester fabrics

AbstractAs the most common synthetic fibre, polyester has consistently been in high demand and usage, but its recycling has always been a problem for the textile industry. The decolorisation of dyed polyester is the key to expanding its recycling use, and there is no rapid, effective and simple decolorisation method. In this study, ozone was used to decolorise dispersed dyes developed for polyester. Ozone was effective in decolorising CI Disperse Orange 30 and CI Disperse Blue 60, and the process was extended to the decolorisation of dyed polyester fabric. Based on single factor analysis, the optimum decolorisation technological conditions were: an ozone feed rate of 130 mg L−1 min−1, treatment time of 2 hours, wet pick‐up of 100% and pH value of 3, with which the decolorisation rate and colour difference values could exceed 45% and 6%, respectively. The changes in dye structure during the process of ozone decolorisation were analysed using scanning electron microscopy, X‐ray diffraction and Fourier Transform–infrared spectroscopy, and the mechanism of ozone decolorisation was also investigated. The results showed that the crystallinity decreased from 41.18% to 36.30% with a strength retention rate of above 80%, and demonstrated that ozone can be used on polyester fabric and dye simultaneously. The aim of entering the fibre was achieved by etching the polyester and decolorisation was achieved by oxidising the chromaticity groups.

Degradation of Organics and Change Concentration in Per-Fluorinated Compounds (PFCs) during Ozonation and UV/H2O2 Advanced Treatment of Tertiary-Treated Sewage

This study aimed to investigate the effect of H2O2 addition, ozone feed rate, and UV addition on the change in the concentration of organics such as CODMn, CODCr, TOC, and PFCs in tertiary-treated effluent from a sewage treatment plant (STP) during the O3 and UV/H2O2 process. The degradation of organic pollutants from tertiary effluent is a significant challenge because biological treatment cannot degrade these recalcitrant pollutants. Therefore, the O3/UV/H2O2 process was an effective method for treating recalcitrant organics. Several batch tests were conducted to investigate the direct UV photolysis, UV/H2O2, and ozone-based advanced oxidation process to degrade CODMn, CODCr, TOC, and PFCs. The chemical oxygen demand (COD) and total organic carbon (TOC) with UV irradiation showed 95% and 50% removal efficiency percentages under optimal conditions (initial pH = 6.7, H2O2 dosage = 50 mg/L, ozone feed rate = 5.8 mg/L/min. Moreover, UV irradiation, with the addition of H2O2, and a sufficient dose of ozone, demonstrated the efficient removal of organic compounds by the indication of radical oxidation. (·OH) is the dominant mechanism. However, AOPs are not sufficient to fully treat the PFC compound; thus, additional procedures are required to degrade PFCs. In this study, the removal of organic recalcitrant contaminants and the change in added PFC concentration in tertiary-treated sewage were investigated by applying the ozone-based advanced oxidation process.

Degradation Treatment of Concentrated Landfill Leachate by Catalytic Ozonation in a Microbubble Reactor

ABSTRACT The catalytic ozonation, combining ozone with solid catalysts technology, was adopted to dispose of the reverse osmosis concentrate (ROC) produced from landfill leachate. To explore an effective and economically sustainable process, three different combined processes were investigated in a microbubble reactor. The considered catalytic oxidation processes were Ca(OH)2/O3+ AC/O3, Ca(OH)2+ AC/O3, and AC/O3. The results indicated the combined Ca(OH)2+ AC/O3 process was able to reduce obviously the economic requirements and have higher degrading efficiency. In particular, the final removal fraction of COD and CN reached 92.88%, 91.84%, respectively, and the value of BOD5/COD was 6.4 times higher than the original leachate. Meanwhile, the operational cost was 5.36 $/t through economic evaluation. The maximum removal fraction of COD reached 96.25% under the option condition of inlet ozone concentration of 65 mg/L, the ozone feed rate of 195 mg/min, reactor pressure of 0.2 MPa, the reaction time of 3 h, Ca(OH)2 dosage of 12 g/L, and AC dosage of 60 g/L. Furthermore, the mechanism of organic degradation in the ROC was explored through analysis of the macromolecular organics present by UV-vis, 3D-EEM, and GC-MS. The results demonstrated that the combination of Ca(OH)2 flocculation and AC-catalyzed ozonation can enhance the degradation efficiency of the organic pollutants. Results indicated that the new-proposed integrating process was an efficient and economically sustainable ozonation process for ROC treatment.

Investigation of Color Fading and Fabric-Touch Test for Jeans through Ozonation

ABSTRACT Color fading through ozonation has been previously studied by our and other labs. Although great progress has been achieved in this field, studies for the optimization of the operating process of the ozone water washing process and fabric-touch tests are important for the practical application in industry. An industrial-scale G2 ozone washing machine was used for the color fading of the samples. Since the color fading process factors are interrelated to each other, a specific experimental approach, i.e., orthogonal method, was used in this work. Three process factors used in the industrial scale color fading process, i.e. (i) ozone feed rate; (ii) moisture content in the fabric; and (iii) treatment time, were studied in this paper. Additionally, the color fading and tactility of fabric through ozonation were analyzed Our results show that the three investigated factors have a significant impact on the fading effect, in which the treatment time is the most significant. When using the G2 device for denim washing, the desired color-fading effect could be quickly obtained by adjusting the treatment time at 6.67 g/min of ozone feed rate and 50% of moisture content in the fabric. Finally, the tactile analysis by fabric-touch tester shows that there is no significant change in the total touch feel between the treated samples and the untreated sample.

Effects of ultraviolet-enhanced ozonation on the degradation of ammonia and urea in fertilizer plant wastewater

Ammonia and urea contained in fertilizer plant wastewater are pollutants to the environment. High concentration of ammonium and urea in wastewater can affects algae blooms in the ecosystem which will generate various diseases in aquatic biota. It is known that there are many methods for degradation of ammonium and urea contained in fertilizer plant wastewater. One of the potential method is ultraviolet-enhanced ozonation. Ozonation is oxidation with O3 that generates hydroxyl radicals which subsequently react with organic contaminants, while UV irradiation can break down O3 molecules and produce radical ions OH∗. The objectives of this study were to examine the effects of the utilization of the ultraviolet-enhanced ozonation method in degradation of various initial ammonium (100-300 ppm) and urea concentration (100-300 ppm) in inlet feed of ozonation-UV irradiation combination system. Some important variables such as contact time (0-120 minutes) and ozone feed rate of 0.2, 0.6, and 1.21 g/h were evaluated. Degradation process was carried out in two steps; ozonation and UV irradiation. Ozonation process was carried out in a contacting tank at a constant feed flow rate of 1.5 l/min and at room temperature, while UV irradiation process was conducted in pipeline equipped with a UV lamp at various contact time. The ultraviolet-enhanced ozonation could degrade ammonium and urea nitrogen up to 83.6% and 63.8%, respectively, at ozone feed rate 1,21 g/h, contacting time 60 and 120 min, initial feed concentration of ammonia (100 ppm) and urea (40 ppm).

Effects of Ultraviolet-Enhanced Ozonation on Degradation of Ammonia and Urea in Fertilizer Plant Wastewater

Ammonia and urea contained in fertilizer plant wastewater are pollutants to the environment. High concentration of ammonium and urea in wastewater can affects algae blooms in ecosystem which will generate various diseases in aquatic biota. It is known that there are many methods for degradation of ammonium and urea contained in fertilizer plant wastewater. One of potential method is ultraviolet-enhanced ozonation. Ozonation is oxidation with O3 that generates hydroxyl radicals which subsequently react with organic contaminants, while UV irradiation can break down O3 molecules and produce radical ions OH∗. The objectives of this study were to examine the effects of the utilization of the ultraviolet-enhanced ozonation method in degradation of various initial ammonium (100-300 ppm) and urea concentration (100-300 ppm) in inlet feed of ozonation-UV irradiation combination system. Some important variables such as contact time (0-120 minutes) and ozone feed rate of 0.2, 0.6, and 1.21 g/h were evaluated. Degradation process was carried out in two steps; ozonation and UV irradiation. Ozonation process was carried out in a contacting tank at constant feed flow rate of 1.5 l/min and at room temperature, while UV irradiation process was conducted in pipeline equipped with UV lamp at various contact time. The ultraviolet-enhanced ozonation could degraded ammonium and urea nitrogen up to 83.6% and 63.8%, respectively, at ozone feed rate 1,21 g/h, contacting time 60 and 120 min, initial feed concentration of ammonia (100 ppm) and urea (40 ppm).

Removal of Residual Pharmaceuticals in a Secondary Effluent from a Sewage Treatment Plant by Ozonation

This study evaluated the effect of ozonation on the removal of pharmaceuticals in a secondary effluent collected from a sewage treatment plant in Korea. 26 pharmaceuticals were detected in the range of 2.3~144.7 μg/L from a secondary effluent used as a tested water. Clarithromycin etc (macrolide antibiotics), Atenolol etc (antiarrythmics), N,N-diethyl-m-toluamide (repellents), Sulpiride (antipsychotics), Bezafibrate (antilipemics) etc showed a relatively high resistance to ozone compared to other pharmaceuticals at a low ozone feed rate of 0.036 mg/L/min. A high ozone feed rate of 0.36 mg/L/min removed by more than 90% of initial concentration for most of pharmaceuticals, indicating that ozonation is a promising treatment process for residual pharmaceuticals in sewage. The ratio of the number of pharmaceuticals with a removal efficiency of more than 70% to ozone consumption during ozonation showed that the supply of ozone gas by a low concentration could improve the performance of ozonation in removing pharmaceuticals at a same ozone gas flow rate condition. Key words: Pharmaceuticals, Micropollutants, Ozone, Antibiotics

Degradation of reactive blue 13 using hydrodynamic cavitation: Effect of geometrical parameters and different oxidizing additives

Decolorization of reactive blue 13 (RB13), a sulphonated azo dye, was investigated using hydrodynamic cavitation (HC). The aim of research article is to check the influence of geometrical parameters (total flow area, the ratio of throat perimeter to its cross-sectional area, throat shape and size, etc.) and configuration of the cavitating devices on decolorization of RB13 in aqueous solution. For this purpose, eight cavitating devices i.e. Circular and slit venturi, and six orifice plates having different flow area and perimeter were used in the present work. Initially, the effects of various operating parameters such as solution pH, initial dye concentration, operating inlet pressure and cavitation number on the decolorization of RB13 have been investigated, and the optimum operating conditions were found. Kinetic analysis revealed that the decolorization and mineralization of RB13 using HC followed first order reaction kinetics. Almost 47% decolorization of RB13 was achieved using only HC with slit venturi as a cavitating device at an optimum inlet pressure of 0.4MPa and pH of the solution as 2.0. It has been found that in case of orifice plates, higher decolorization rate of 4×10−3min−1 was achieved using orifice plate 2 (OP2) which is having higher flow area and perimeter (α=2.28). The effect of process intensifying agents (hydrogen peroxide and ferrous sulphate) and different gaseous additives (oxygen and ozone) on the extent of decolorization of RB13 were also examined. Almost 66% decolorization of RB13 was achieved using HC combined with 2Lmin−1 of oxygen and in combination with ferrous sulphate (1:3). Nearly 91% decolorization was achieved using HC combined with H2O2 at an optimum molar ratio (dye:H2O2) of 1:20 while almost complete decolorization was observed in 15min using a combination of HC and ozone at 3gh−1 ozone feed rate. Maximum 72% TOC was removed using HC coupled with 3gh−1 ozone feed rate.

Removal of dimethyl phthalate from water by ozone microbubbles

ABSTRACT This work investigates the removal of dimethyl phthalate (DMP) from water using ozone microbubbles in a pilot plant of 20 dm3 capacity. Experiments were performed under various reaction conditions to examine the effects of the initial concentration of DMP, pH of the medium, ozone generation rate, and the role of H2O2 on the removal of DMP. The DMP present in water was effectively removed by the ozone microbubbles. The removal was effective in neutral and alkaline media. Increase in the initial concentration of the target pollutant negatively affected its removal efficiency. The removal efficiency dramatically increased from 1% to 99% when the ozone generation rate was increased from 0.28 to 1.94 mg s−1 at pH 7. The total organic carbon measurements revealed that a complete mineralization of DMP was achieved within 1.8 ks at the high ozone feed rate. The use of t-butyl alcohol as the hydroxyl radical scavenger confirmed that the reaction between the target organic compound and ·OH radical dominated over its direct reaction with ozone. The reaction between DMP and ozone followed an overall second-order kinetics. The volumetric mass transfer coefficient of ozone in the reacting system and the enhancement factor increased with increasing initial concentration of DMP. Very low values of Hatta number were obtained at all initial concentrations of DMP and pH, which show that the mass transfer resistance was small.

Enhanced decomposition of 1,4-dioxane in water by ozonation under alkaline condition.

1,4-Dioxane is a probable human carcinogenic and refractory substance that is widely detected in aquatic environments. Traditional wastewater treatment processes, including activated sludge, cannot remove 1,4-dioxane. Removing 1,4-dioxane with a reaction kinetic constant of 0.32 L/(mol·s) by using ozone, a strong oxidant, is difficult. However, under alkaline environment, ozone generates a hydroxyl radical (•OH) that exhibits strong oxidative potential. Thus, the ozonation of 1,4-dioxane in water under different pH conditions was investigated in this study. In neutral solution, with an inlet ozone feed rate of 0.19 mmol/(L·min), the removal efficiency of 1,4-dioxane was 7.6% at 0.5 h, whereas that in alkaline solution was higher (16.3-94.5%) within a pH range of 9-12. However, the removal efficiency of dissolved organic carbon was considerably lower than that of 1,4-dioxane. This result indicates that several persistent intermediates were generated during 1,4-dioxane ozonation. The pseudo first-order reaction further depicted the reaction of 1,4-dioxane. The obvious kinetic constants (kobs) at pH 9, 10, 11 and 12 were 0.94, 2.41, 24.88 and 2610 L/(mol·s), respectively. Scavenger experiments on radical species indicated that •OH played a key role in removing 1,4-dioxane during ozonation under alkaline condition.

Ozonation of guaiacol solution in a rotating packed bed

As a building block of lignins, guaiacol represents a large number of mono- and dimethoxy phenols found in bio-oil derived from soft- or hardwood, respectively. During lignin degradation by ozone-based processes, the intermediate product guaiacol is also oxidized by ozone. Traditionally, ozonation of organic wastewater is carried out in a bubble column. This study employed a rotating packed bed that used high rotating speed to enhance ozone mass transfer rate for guaiacol degradation. The effects of guaiacol initial concentration, ozone feed rate, rotating speed, and solution pH on the residual guaiacol concentration, residual chemical oxygen demand (COD) and total organic carbon (TOC) were experimentally measured. The experimental results show that the guaiacol, COD, and TOC degradation rates increase with increasing initial concentration, ozone feed rate, rotating speed, or solution pH. A kinetic model has been developed to predict the residual guaiacol concentration, residual COD and TOC satisfactorily.

Decolorization and transformation of anthraquinone dye Reactive Blue 19 by ozonation

The decolorization and transformation of the anthraquinone dye, Reactive Blue 19 (RB‐19), by ozonation with a semi‐batch reactor were investigated. The effects of different operating parameters, such as the initial RB‐19 concentrations, ozone feed rates and initial pH, on the performance of color, dye and total organic carbon (TOC) removal were also evaluated based on their pseudo‐first‐order rate constants and removal efficiencies. The experimental results indicated that the removal of color and the dye itself was more rapid and complete than that of TOC in all the ozonation tests. However, increasing the initial RB‐19 concentration had a significant effect on decreasing the rate constant of RB‐19 reduction. In addition, increasing the ozone feed rate had positive effects on the color, dye and TOC removal, particularly on the TOC diminution. The rate constant and efficiency of color removal were highest at initial acidic pH conditions, but the dye and TOC removal were more effective at initial basic pH values, possibly due to the more powerful and non‐selective hydroxyl radical oxidation.

Degradation of pentachlorophenol in aqueous solution by audible-frequency sonolytic ozonation

The degradation of pentachlorophenol (PCP) in aqueous solution by audible-frequency sonolytic ozonation was studied. The sonolysis of H 2O and PCP/H 2O solutions and the dissolution and decomposition of ozone under audible-frequency sonication were evaluated as well. The results showed that the ozone dissolution rate and PCP degradation rate were significantly enhanced by sonication in comparison to using mechanical stirring and O 3 bubbling alone. This enhancement is most likely attributed to the strong turbulence induced by sonication. The first-order rate constant of PCP degradation by ozonation with sonication is more than 15 times faster than that with bubbling ozone alone, while the rate constant with mechanical stirring is only four times faster. The influence of the ozone feed rate on PCP degradation and the degradation byproducts were examined as well. In addition, results showed that no H 2O 2 was generated by sonolysis of water with audible-frequency sonication and no PCP was degraded by sonolysis alone.

Nitroaromatic Hydrocarbon Ozonation in Water. 2. Combined Ozonation with Hydrogen Peroxide or UV Radiation

The combined ozonation of nitrobenzene and 2,6-dinitrotoluene with hydrogen peroxide and UV radiation has been studied. Effects of variables such as pH, hydroxyl radical scavengers, ozone feed rate, or hydrogen peroxide to ozone feed molar ratios have been investigated. Results are also compared to those obtained from UV radiation and single ozonation (Beltrán et al., 1998). Quantum yields of nitrobenzene and 2,6-dinitrotoluene at 254 nm were found to be 7.0 × 10-3 and 2.2 × 10-2 mol einstein-1, respectively. Removal rates of nitrobenzene through single or combined ozonation with hydrogen peroxide at concentration lower than 10-2 M are similar, while under the same conditions combined ozonation of 2,6-dinitrotoluene leads to higher removal rates than single ozonation. Also, the latter compound is removed faster by UV radiation alone and UV/O3 oxidation than by single ozonation. Rate constants of the reaction between the hydroxyl radical and nitrobenzene and 2,6-dinitrotoluene were found to be 2.9 × 109 and 7.5 × 108 M-1 s-1, respectively. Nitrophenols and 2,6-dinitrobenzaldehyde appear to be some of the principal intermediates formed in the treatment of nitrobenzene and 2,6-dinitrotoluene, respectively, regardless of oxidation techniques applied. Apart from economic considerations UV/O3 oxidation is the technique among those studied leading to the highest removal rates.

Nitroaromatic Hydrocarbon Ozonation in Water. 1. Single Ozonation

Single ozonation of two nitroaromatic hydrocarbons (nitrobenzene and 2,6-dinitrotoluene) under different experimental conditions (ozone feed rate, pH, temperature, hydroxyl radical scavengers) has been studied. The absence of hydroxyl radical scavengers, pHs 7−9, and temperatures below 30 °C are optimum conditions for nitroaromatic removal. Due to the importance of hydroxyl radical reactions, removal rates in natural water are much lower than those observed in laboratory ultrapure water. Rate constants of the direct reaction between ozone and nitroaromatic hydrocarbons at 20 °C have been found to be lower than 6 M-1 s-1. More than 99% of nitroaromatic removal is due to hydroxyl radical oxidation. Single ozonation of nitroaromatics can then be classified as a real advanced oxidation technology. Nitrophenols, compounds very reactive toward ozone and hydroxyl radicals, and 2,6-dinitrobenzaldehyde, identified in the single ozonation of nitrobenzene and 2,6-dinitrotoluene, respectively, are some of the first i...

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.

Mass transfer and reaction kinetics in the ozone/tap water system

The mass transfer and the reaction kinetics of ozone in tap water were examined. The contacting system was a well-mixed reactor with perpendicular jets. The ozone residual range was the lowest detectable range. A simple mathematical model was proposed to describe the mechanism of the ozone in the reactor and was checked over the range of water flow rates from 2.170 to 3.080 l min −1, gas flow rates from 0.667 to 1.333 l min −1 and different temperature conditions. The proposed model describes quite accurately the mass-transfer behavior in the reactor and determines the operational parameters which control the reactor operation. There is a linear relationship between the ozone feed rate and ozone residual. Zero order kinetics best describe the autodecomposition of ozone in plain tap water. The mass transfer coefficient is about 1.14 min −1. Without use of agitation, there is a large decrease in the value of the mass transfer coefficient, to about 0.250 min −1. The magnitude of the reactor rate constant is between 0.05 and 0.13 mg min −1 l.

ChemInform Abstract: AUTOXIDATION OF ISOBUTYRALDEHYDE

Chemischer InformationsdienstVolume 5, Issue 43 Preparative Organic Chemistry ChemInform Abstract: AUTOXIDATION OF ISOBUTYRALDEHYDE SHINGO MIYAJIMA, SHINGO MIYAJIMASearch for more papers by this authorTAKASHI INUKAI, TAKASHI INUKAISearch for more papers by this authorHIROSHI HARADA, HIROSHI HARADASearch for more papers by this authorRYO YOSHIZAWA, RYO YOSHIZAWASearch for more papers by this authorTADAHIRO HIRAI, TADAHIRO HIRAISearch for more papers by this authorKAZUTOSHI MATSUNAGA, KAZUTOSHI MATSUNAGASearch for more papers by this authorMASATO HARADA, MASATO HARADASearch for more papers by this author SHINGO MIYAJIMA, SHINGO MIYAJIMASearch for more papers by this authorTAKASHI INUKAI, TAKASHI INUKAISearch for more papers by this authorHIROSHI HARADA, HIROSHI HARADASearch for more papers by this authorRYO YOSHIZAWA, RYO YOSHIZAWASearch for more papers by this authorTADAHIRO HIRAI, TADAHIRO HIRAISearch for more papers by this authorKAZUTOSHI MATSUNAGA, KAZUTOSHI MATSUNAGASearch for more papers by this authorMASATO HARADA, MASATO HARADASearch for more papers by this author First published: October 29, 1974 https://doi.org/10.1002/chin.197443133Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume5, Issue43October 29, 1974 RelatedInformation

Autoxidation of Isobutyraldehyde

Abstract The liquid phase autoxidation of isobutyraldehyde to peroxyisobutyric acid was investigated with ozone as an initiator. The selectivity of the peroxyacid increases with decrease in the amount of aldehyde converted per unit volume of reacting fluid, increase in the ozone feed rate, and decrease in temperature. A few percent of water in solvents increases the selectivity, although too much water brings about a reverse effect. Isopropyl alcohol, acetone, isopropyl formate, propane, propylene, carbon dioxide, and carbon monoxide are observed as by-products besides isobutyric acid. Purified peroxyisobutyric acid (97.2 wt%) was obtained by fractionally distilling the autoxidation product and some of its physical properties were determined. The utility of the peroxyacid as an epoxidizing agent is described.