Determination of Rate Constants for Ozonation of Ofloxacin in Aqueous Solution

The ozonation of the quinolone antibiotic ofloxacin in water has been investigated with focus on kinetic parameters determination. The apparent stoichiometric factor and the second-order rate constants of the reactions of ozone and hydroxyl radical with ofloxacin were determined at 20 °C in the pH range of 4–9. The apparent stoichiometric factor was found to be about 2.5 mol O₃/mol ofloxacin regardless of the pH. The rate constant of the reaction between ozone and ofloxacin was determined by a competitive method (pH = 6–9) and a direct ozonation method (pH = 4). It was found that this rate constant increases with pH due to the dissociation of ofloxacin in water. The direct rate constants of ofloxacin species were determined to be 1.0?×?10², 4.3?×?10⁴ and 3.7?×?10⁷ for cationic, neutral-zwitterion and anionic species, respectively. Accordingly, the attack of ozone to ofloxacin mainly takes place at the tertiary amine group of the piperazine ring, though some reactivity is also due to the quinolone structure and oxazine substituent. The rate constant of the reaction between ofloxacin and hydroxyl radical was obtained from UV/H₂O₂ photodegradation experiments. It was found that this rate constant varies with pH from 3.2?×?10⁹ at pH 4 to 5.1?×?10⁹ at pH 9.     

Ozonation of unstretched natural rubber film from Hevea brasiliensis studied by ozone consumption and 13C NMR

Unstretched films of natural rubber (NR) from Hevea brasiliensis were exposed to ozone flow of 15 ml min^?1 from 4 to 300 min. The efficiency of reaction was determined by ozone consumption of NR films. Plots of reacted ozone mass versus film thickness show that the ozone penetration and the ozone reaction progressed into deeper layers (170 µm) than described in the literature (～0.5 µm). The previous proposed model based on viscometry measurements was corroborated by ozone consumption results. The effect of thickness on the O₃/NR stoichiometric ratio indicated that the diffusion process that controls the ozonation in unstretched film does not consist of the boundary progression behind which all reactive sites have been saturated. Ozonation in unstretched rubber film, while being less efficient than ozonolysis in solution, does have a reaction efficiency of the same order of magnitude. NMR spectroscopy was used to characterise the products formed by ozonation. Copyright © 2004 Society of Chemical Industry     

UV-induced Decomposition of Ozone and Hydrogen Peroxide in the Aqueous Phase at pH 2–7

The photolysis of ozone and formation of hydrogen peroxide were investigated in solution of pH 2–7, in a 200 cm³ photoreactor in the incident photon flow range 9.6 x 10^?8 - 4.2 x 10^?7 einstein s^?1. The quantum yield of the primary photochemical reactions was measured in a direct way by suppressing the secondary radical reactions. The determined quantum yields of the photo-decompositions of ozone and hydrogen peroxide were 0.42 ± 0.042 ± 0.04 and 0.49 ± 0.04, respectively.

A correct mathematical treatment is given for calculation of the light absorption of the individual components of a multi-absorbent reaction mixture.

On the basis of the literature data and die present results, a probable chemical and reaction kinetic model was proposed to characterize the investigated reaction systems. Reaction kinetic simulations demonstrated that the model predicts a good fit to the measured data with the preferred literature rate constants, except that for the HO₃ radical decomposition reaction. A reasonable reduction of this rate coefficient value is in accordance with the latest published results.     

Process Control For Ozonation Systems: A Novel Real-Time Approach

For real-time control of ozonation processes in water works, a sequencing batch reactor was constructed to measure the ozone decay rate constant (k_O3) in short time intervals of about 15 min. The batch reactor is filled during the production process, immediately after dissolving ozone in water by a static mixer. On the basis of k_O3 and the initial ozone concentration ([O₃]₀), and the experimentally determined ratio of the concentrations of ^?OH radicals to ozone (R_ct), the degradation of micropollutants in ozone reactors (modeled as Continuously Stirred Tank Reactors - CSTRs) were calculated for compounds with known reaction rate constants with ozone and ^?OH radicals. Calculated degradation of atrazine, iopromide, benzotriazole and acesulfame are in good agreement with measured data. For acesulfame the following rate constants were determined in this study at 20 ^oC: reaction rate constant with ozone = 88 M^?1s^?1, reaction rate constant with ^?OH radical = 4.55?×?10⁹ M^?1s^?1. For the ozone reaction an activation energy of 35 kJ/mol was determined. Similarly to micropollutants, the relative inactivation of microorganisms (N/N₀) can be calculated based on the inactivation rate constant for ozone and if applicable the lag phase. The pI-value (=??logN/N₀) was introduced and implemented in the process management system to calculate online the log inactivation of reference microorganisms such as B. subtilis spores. The system was tested for variation of pH (6.5–8.5), DOC (1.2–4.2 mg/L) flowrate 3.2–12 m³/h and temperature (5.7–9 ^oC). Furthermore, a given pI-value, e.g. 1 for a 1-log inactivation of B. subtilis spores, can be set as control parameter in the process management system. The ozone gas flow is then adjusted until the set pI-value is reached. The process control concept was validated with B. subtilis spores. Generally, a good agreement was found between calculated and measured inactivation data. It was also demonstrated, that a constant ozone residual may lead to insufficient disinfection or overdosing of ozone. The new process control concept for ozonations based on onsite measurement of the ozone decay rate constant and the pI-value allows to assess disinfection and degradation processes quantitatively in real-time.     

Chemical Oxidation of Thiocyanate Ion by Ozone

Thiocyanate ion and weak ammonia liquor from a coking operation were ozonated in a semi-batch reactor. In a typical case, 500 mg/L thiocyanate ion disappeared in 8 minutes using an ozone dose of 82 mg/min at pH 7. The cyanide ion concentration was maximized immediately after the thiocyanate ion disappeared. The ozone-to-thiocyanate ion stoichiometric molar ratio was found to be 2.0 ± 0.2. The rate constants for the reaction of thiocyanate ion and cyanide ion with ozone under the typical conditions listed above were 5.4 × 10⁴ L²/(mmole²-min) and 1.5 L/(mmole-min), respectively.     

Production of Structured Phosphatidylcholine with High Content of DHA/EPA by Immobilized Phospholipase A1-Catalyzed Transesterification

This paper presents the synthesis of structured phosphatidylcholine (PC) enriched with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) by transesterification of DHA/EPA-rich ethyl esters with PC using immobilized phospholipsase A₁ (PLA₁) in solvent-free medium. Firstly, liquid PLA₁ was immobilized on resin D380, and it was found that a pH of 5 and a support/PLA₁ ratio (w/v) of 1:3 were the best conditions for the adsorption. Secondly, the immobilized PLA₁ was used to catalyze transesterification of PC and DHA/EPA-rich ethyl esters. The maximal incorporation of DHA and EPA achieved was 30.7% for 24 h of reaction at 55 °C using a substrate mass ratio (PC/ethyl esters) of 1:6, an immobilized PLA₁ loading of 15% and water dosage of 1.25%. Then the reaction mixture was analyzed by ³¹P nuclear magnetic resonance (NMR). The composition of reaction product included 16.5% PC, 26.3% 2-diacyl-sn-glycero-3-lysophosphatidylcholine (1-LPC), 31.4% 1-diacyl-sn-glycero-3-lysophosphatidylcholine (2-LPC), and 25.8% sn-glycerol-3-phosphatidylcholine (GPC).     

Energy Conversion and Temperature Dependence in Ozone Generator Using Pulsed Discharge in Oxygen

A detailed reaction kinetic model consisting of 10 species and 63 reactions is developed to investigate the energy conversion and temperature dependence in an ozone generator using oxygen pulsed discharge. The energy conversion ratios of total electric energy converted into reaction heat, heat carried by gas and heat loss to ambient, namely η_reaction, η_gas and η_loss, are obtained for the first time. The ratio of reaction heat η_reaction decreases substantially with increasing specific energy and inlet gas temperature, which represents how much energy is utilized effectively to synthesize ozone. Correspondingly, η_loss and η_gas increase gradually. η_reaction declines from 55.4% to 27.7% at inlet gas temperature of 298 K when specific energy changes from 0.06 J/cm³ to 0.78 J/cm³. The detailed reaction pathway including the degree of transformation among species for ozone formation is also obtained via kinetics simulation. Meanwhile, sensitivity analysis and rate-of-production analysis for the four most important species O₃, O, O(1D) and O₂(b¹∑) obtained from the reaction pathway are executed to understand quantitatively the temperature dependence of sensitivity coefficient and production rate for each individual reaction. The production rate of ozone via the most important ozone generation reaction O+O₂+O₂ = > O₃+O₂ increases linearly with the increase of gas temperature, as well as the destruction rates of ozone via the most important ozone decomposition reactions O₃+O₃ = > O₂+O₂+O₂ and O₃ + O = > O₂(b¹∑)+O₂.     

Modified Indigo Method For Gaseous And Aqueous Ozone Analyses

The indigo method developed by Bader and Hoigné for aqueous ozone analysis was modified to allow for both gaseous and aqueous ozone determination. Gas or water samples were extracted with a gas-tight syringe containing a known volume of indigo reagent. The modified procedure provided a more consistent basis for gaseous and aqueous ozone determination allowing for more accurate ozone mass balance calculations. Direct gaseous ozone UV absorbance with molar absorptivity of 3,000 M^?1cm^?1 at 258 nm was used as primary standard to determine the molar absorptivity of the indigo reagent. The molar absorptivity of indigo reagent, assuming a 1:1 stoichiometric ratio for the reaction between indigo and ozone, was determined to be 23,150 ± 80 M^?1cm^?1, or approximately 16 percent higher than that of 20,000 M^?1cm^?1 suggested by Bader and Hoigné. An independently calibrated membrane-electrode ozone monitor showed good correlation with indigo method results using the molar absorptivity value determined in this study. The apparent molar absorptivity of aqueous ozone at the wavelength of 258 nm measured by the modified indigo method increased from 2,400 to 3,600 M^?1cm^?1 in the investigated ozone concentration range of 0.4 to 11.0 mg/L. This variation might have been caused by the inherent interference of unidentified ozone byproducts, which presence was supported with scanning spectra in the wavelength range of 200 to 300 nm.     

Performance evaluation of ozonation and an ozone/hydrogen peroxide process toward development of a new sewage treatment process—Focusing on organic compounds and emerging contaminants

Performance of ozonation and an ozone/hydrogen peroxide process under a new concept centering on ozonation and/or ozone/hydrogen peroxide processes in sewage treatment processes comprising only physical and chemical processes are discussed, with focus on the removal of matrix organic compounds and emerging contaminants. Matrix organic compounds of filtrated primary sewage effluents were removed to as low as 3.2 mgC/L in the ozone/hydrogen peroxide process at an ozone consumption of around 400 mg/L. Linear relationships between ozone consumption and removal amounts of organic compounds were observed, in which the amounts of ozone required to remove 1 mg of organic carbon were 9.5 and 8.3 mg (2.4 and 2.1 mol-O₃/mol-C) in ozonation and the ozone/hydrogen peroxide process, respectively. Ratios of hydroxyl radical exposure to ozone exposure were in the order of 10^–9 to 10^–8 for ozonation and 10^–7 to 10^–6 for the ozone/hydrogen peroxide process. Experiments and a kinetic evaluation showed that ozonation and/or the ozone/hydrogen peroxide process have high elimination capability for emerging contaminants, even in primary sewage effluent with the thorough removal of matrix organic compounds. Newly found reaction phenomena, the temporal increase and decrease of dissolved ozone and accumulation of hydrogen peroxide in the early stage of oxidation with the continuous feeding of hydrogen peroxide, were presented. Possible reaction mechanisms are also discussed.     

Ultraviolet-Enhanced Ozonation of Organic Compounds: 1,2-Dichloroethane and Trichloroethylene as Model Substrates

1,2–Dichloroethane (DCE) and trichloroethylene (TCE) were used as model compounds to study the oxidation of organic chemicals by ozone/ultraviolet radiation, ozone, and hydrogen peroxide/ultraviolet radiation. It was found that ozone/ultraviolet radiation oxidized both 1,2–dichloroethane and trichloroethylene in batch systems, at pH = 2 (phosphate buffer). At ozone concentrations in the 1 to 5 mg/L range, the reaction was first order in both ozone and substrate. At pH = 2 and initial ozone concentration 2.2–2.6 mg/L, rate constants (k)Q = 25 and 130 M^-1sec^-1 were observed for the ozone/ultraviolet radiation oxidation of DCE and TCE, respectively. The rat e constants for ozone oxidation of DCE and TCE without ultraviolet radiation were 4.3 and 47 M^-1sec^-1, respectively.

The higher rate of TCE oxidation implies that direct reaction occurs with the double bond. Finite reaction rate of DCE with ozone, and substantial increases in rate at higher pH imply the participatation of hydroxyl radicals in the oxidation of both compounds. For example, at pH = 7, initial ozone concentration of 2.3 mg/L, the k_o for TCE oxidation by ozone/ultraviolet radiation is approximately 500 M^?1 sec^?1 almost too fast to measure in a batch system.The rate also is increased by increased ultraviolet radiation intensity, and by the presence of hydrogen peroxide, which acts as a catalyst.     

Influence of presence of tannic acid on removal of sodium dodecylbenzenesulphonate by O3 and advanced oxidation processes

BACKGROUND: The objective of the present investigation was to determine the role of the tannic acid (TAN) component of organic matter dissolved in water, in the removal of sodium dodecylbenzenesulphonate (SDBS) by ozone and by O₃/H₂O₂, O₃/granular activated carbon (GAC) and O₃/powdered activated carbon (PAC) advanced oxidation processes. RESULTS: Low doses of TAN (1 mg L^?1) during SDBS ozonation cause (i) an increased ozone decomposition rate and (ii) an increased SDBS removal rate. The SDBS removal rate with ozone in the presence of TAN was reduced when HCO₃^? ions were added. A rise in TAN concentration increased the SDBS removal rate, with a linear relationship between added TAN and the removal rate. SDBS was removed more effectively by O₃/GAC, O₃/PAC and O₃/H₂O₂ systems in the presence of TAN. CONCLUSIONS: Results obtained indicated two mechanisms involved in the generation of HO^· radicals by the O₃/TAN interaction: (i) direct generation of HO^· radicals from the reaction between ozone and TAN, and (ii) increased generation of O₂^?· radicals in the medium, enhancing the transformation of ozone into HO^· radicals by different radical reactions. In O₃/GAC and O₃/PAC systems, HO^· radicals are mainly generated in the O₃/TAN interaction, which is a homogeneous reaction with fast kinetics, whereas the O₃/GAC and O₃/PAC interactions are in a heterogeneous phase with much slower kinetics, and are therefore not competitive in the generation of HO^· radicals. Copyright © 2008 Society of Chemical Industry     

Kinetics of Estrone Ozone/Hydrogen Peroxide Advanced Oxidation Treatment

Ozone/hydrogen peroxide batch treatment was utilized to study the degradation of the steroidal hormone estrone (E1). The competition kinetics method was used to determine the rate constants of reaction for direct ozone and E1, and for hydroxyl radicals and E1 at three pH levels (4, 7, and 8.5), three different molar O₃/H₂O₂ ratios (1:2, 2:1, and 4:1) and a temperature about 20°C. The average second-order rate constants for direct ozone-E1 reaction were determined as 6.2?×?10³?±?3.2?×?10³ M^?1s^?1, 9.4?×?10⁵?±?2.7?×?10⁵ M^?1s^?1, and 2.1?×?10⁷?±?3.1?×?10⁶ M^?1s^?1 at pH 4, 7, and 8.5, respectively. It was found that pH had the greatest influence on the reaction rate, whereas O₃/H₂O₂ ratio was found to be slightly statistically significant. For the hydroxyl radical-E1 reaction, apparent rate constants ranged from 1.1?×?10¹⁰ M^?1s^?1 to 7.0?×?10¹⁰ M^?1s^?1 with an average value of 2.6?×?10¹⁰ M^?1s^?1. Overall, O₃/H₂O₂ is shown to be an effective treatment for E1.     

The Reaction of Ozone with Bisulfide (HS−) in Aqueous Solution – Mechanistic Aspects

The ozone demand to oxidize HS^?/H₂S [pK_a(H₂S) = 6.9, k(HS^? + O₃) = 3 × 10⁹ M^?1 s^?1, k(H₂S + O₃) = 3 × 10⁴ M^?1 s^?1] to SO₄ ^2? is only 2.4 mol ozone per mol SO₄ ^2? formed, much lower than stoichiometric 4.0 mol/mol if a series of O-transfer reactions would occur. As primary step, the formation of an ozone adduct to HS^?, HSOOO^–, is suggested that decomposes into HSO^– and singlet oxygen (16%) or rearranges into peroxysulfinate ion, HS(O)OO^– (84%). Potential reactions of the above intermediates are discussed. Some of these can account for the low ozone demand.     

Removal of diazinon by various advanced oxidation processes

Diazinon is a widely used organophosphorus insecticide that is an important pollutant in aquatic environments. The chemical removal of diazinon has been studied using UV radiation, ozone, Fenton's reagent, UV radiation plus hydrogen peroxide, ozone plus hydrogen peroxide and photo‐Fenton as oxidation processes. In the photodegradation process the observed quantum yields had values ranging between 2.42 × 10^?2 and 6.36 × 10^?2 mol E^?1. Similarly, the ozonation reaction gave values for the rate constant ranging between 0.100 and 0.193 min^?1. In the combined systems UV/H₂O₂ and O₃/H₂O₂ the partial contributions to the global oxidation reaction of the direct and radical pathways were deduced. In the Fenton's reagent and photo‐Fenton systems, the mechanism of reaction has been partially discussed, and the predominant role of the radical pathway pointed out. Additionally, the rate constant for the reaction between diazinon and the hydroxyl radicals was determined, with the value 8.4 × 10⁹ L mol^?1 s^?1 obtained. A comparison of the different oxidation systems tested under the same operating conditions revealed that UV radiation alone had a moderate oxidation efficiency, which is enhanced in the case of ozone, while the most efficient oxidant is the photo‐Fenton system. Copyright © 2007 Society of Chemical Industry     

Acceleration of Ozone Decomposition and ·OH Generation by Hydroxylamine

Most of protonated amines show very low reactivity with ozone in the process of generating hydroxyl radical (·OH). This study proved that protonated hydroxylamine (HA) can accelerate the decomposition of ozone and promote the yield of ·OH. Benzoic acid (BA) was used as ·OH probe, the stimulation of ozone decomposition and ·OH generation by HA in the condition of pHs ranging from 3.0 to 8.0 were studied. The results revealed the effect of HA, especially the protonated form of HA, on the ozone decomposition. Moreover, two reaction pathways of the reactive oxidant formation in O₃/HA process were proposed: (1) protonated HA reacted with ozone by the way of direct electron transfer to produce O₃^·-; (2) unprotonated HA reacted directly with ozone to form O₂^·- and O₂^·- later reacted with O₃ to form O₃^·- .     

Ozonolysis Post-Treatment of Anaerobically Digested Distillery Wastewater Effluent

ABSTRACT

In this study, the ozonolysis of real anaerobically digested distillery wastewater (DWW) was carried out. The effect of operating parameters, such as pH, initial concentration, and ozone dosage, on the efficiency of ozone utilization, color removal, and sludge solubilization was studied. The highest ozone utilization of 99% was observed at the highest initial concentration (COD of 3000 mg/L) and lowest ozone flowrate (22.5 mg O₃/L/min), but with a very low color reduction of 20%, after 60 minutes of ozonolysis. To achieve a higher color reduction >80% and at ozone utilization >95%, the DWW had to be diluted twice (COD 1500 mg/L), and the flowrate doubled to 45 mg O₃/L/min. The reduction in color signified the oxidation of the color causing biorecalcitrant aromatic melanoidin compounds. This was confirmed by the 47% reduction in ultraviolet absorbance at 254 nm indicating the breakdown of the complex aromatic compounds into low molecular weight organics. Moreover, increases in average oxidation state from ?0.6 to ?0.2 suggested a decline in aromaticity and formation of easily biodegradable aliphatic compounds. The ozonolysis process was found to follow the first-order reaction kinetic model with the highest rate constant of 0.0326 min^?1 obtained. A reduction in suspended COD by 88% indicated solubilization of the sludge contained in the effluent.     

Oxidation of Esculetin,a Model Pollutant Present in Cork Processing Wastewaters,by Chemical Methods

The ozonation of esculetin (6,7-dihydroxycoumarin), a major pollutant present in the wastewater generated in the cork industry, was accelerated at high pH, with apparent second-order rate constants in the range from 3.3 × 10⁴ L/(mol·s) at pH=2 to 8.4 × 10⁷ L/(mol·s) at pH=9. The acid-base equilibrium of esculetin was studied, resulting in a pK_a value of 7.37. Taking into account this pK_a, the rate constants for the reaction between ozone and the un dissociated and dissociated forms of esculetin were 3.0 × 10⁴ and L/(mol·s) 6.67 × 10⁸ L/(mol·s), respectively. Apparent first-order rate constants for the photolysis by UV irradiation were also evaluated, with values between 0.12 × 10^?2 min^?1 at pH=2 and 1.15 × 10^?2 min^?1 at pH=9, while the quantum yields for this photo-degradation reaction varied from 0.99 × 10^?2 mol/Eins to 11.1 × 10^?2 mol/Eins at these pHs. The Fenton's reagent system was used for the generation of hydroxyl radicals, and the rate constant for the reaction between esculetin and these radicals was determined to be 1.06 × 10¹⁰ L/(mol·s). Finally, several chemical oxidation systems were used in the degradation of this pollutant: single oxidants (ozone, UV irradiation) and advanced oxidation processes (Fenton's reagent, UV/H₂O₂, O₃/H₂O₂, O₃/UV, O₃/H₂O₂ /UV, and photo-Fenton system). The results revealed that the most efficient methods in terms of esculetin removal were ozonation among the single oxidants, and the photo-Fenton system among the combined processes.     

Oxidation of Methyl tert-Butyl Ether (MTBE) and Ethyl tert-Butyl Ether (ETBE) by Ozone and Combined Ozone/Hydrogen Peroxide

The aim of this work was to study the reaction of ozone and combined ozone/hydrogen peroxide on oxygenated additives such as methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) in dilute aqueous solution using controlled experimental conditions. Experiments conducted in a semi-continuous reactor with MTBE and ETBE in combination (initial concentration: 2 mmol/L of each) showed that ETBE was better eliminated than MTBE with both ozone and combined O₃/H₂O₂. Batch experiments led to the determination of the ratio of the kinetic constants for the reaction of OH°-radical with MTBE and ETBE [k_OH°/ETBE/k_OH°/MTBE = 1.7). Tert-butyl formate and tert-butyl acetate were identified as the ozonation byproducts of MTBE and ETBE, respectively, while tert-butyl alcohol was found to be produced during the ozonation of both compounds.     

Model of simultaneous denitrification and methanogenesis in an Upflow Packed‐Bed Biofilm Reactor: Nitrogen compounds' inhibition and pseudo two‐dimensional biofilm model

BACKGROUND: The modelling of simultaneous denitrification and methanogenesis (DM) in upflow packed‐bed biofilm reactors (UPBR) and the effect of inhibition by nitrogen compounds on methanogenesis has received little attention. This study evaluated the effect using a model that incorporates a pseudo‐two‐dimensional biofilm model. RESULTS: The model was validated through comparison with experimental data, and achieved deviations below 5% for the liquid and gas phases. The model indicated that biomass stratification exists throughout the reactor and within the biofilm interior. At C/N ratios close to the stoichiometric C/N ratio, the process achieves efficiencies greater than 70% for nitrogen load rate (NLR) < 270 mg NO₃^?‐N dm^?3 h^?1. At high C/N ratios (50 mg total organic carbon (TOC) mg^?1 NO₃^?‐N), the process achieves efficiencies greater than 70% for organic load rate (OLR) < 83 mg TOC dm^?3 h^?1. CONCLUSION: The inclusion of the inhibition of methanogenesis by nitrogen compounds did not improve the predictions. Indeed, mass transfer in the biofilm was the phenomenon that most influenced the process. At C/N ratios close to the stoichiometric C/N ratio, process efficiency depends on the NLR; while at high C/N ratios, process efficiency depends on the OLR. Copyright © 2008 Society of Chemical Industry     

The Benefits of Small Quantities of Nitrogen in the Oxygen Feed to Ozone Generators

This paper reports the ozone generation in pulsed multichannel dielectric barrier discharge. The influence of nitrogen addition (0.1%–10%) on ozone concentration and ozone generation efficiency in nitrogen–oxygen gas mixtures is studied. Results show that adding 0.1% N₂ would not seriously increase the ozone production. Meanwhile, 1% N₂ content exhibits the highest ozone production efficiency in low SIE (J/L, defined as the ratio of power to gas flow rate) region (0–200 J/L) while adding 0.3% N₂ would lead to the highest ozone generation efficiency in high SIE region (300–800 J/L). The increase of ozone production induced by N₂ addition is more significant in low SIE region compared with that in high SIE region. At 100 J/L, ozone production efficiency increases 26.9% to 201.6 g/kWh with 1% N₂ addition when compared with that in oxygen. At 18 J/L, the observed maximum ozone generation efficiency reaches 252 g/kWh at 1.3 g/Nm³ with 1% N₂ addition. An increase of ozone production can be obtained with 0.3%–2% N₂ addition in all explored SIE ranges.