Ozone Bubbling Research Articles

Mineralization of Poly(vinyl alcohol) by Ozone Microbubbles under a Wide Range of pH Conditions.

Poly(vinyl alcohol) (PVA) is a well-known recalcitrant pollutant that threatens ecological systems and human health. In this study, ozone-microbubble treatment was evaluated as a physicochemical method to mineralize PVA in solution for wastewater treatment. Microbubbles are very small bubbles (<50 μm in diameter) and shrink in water because of the rapid dissolution of the interior gas. Ozone microbubbles were generated by a hybrid microbubble generator in PVA solutions with pH conditions of 2, 7, and 10. Ordinary ozone bubbling was also performed as control tests. The change in the total-organic-carbon content was measured to evaluate the efficiency of the system for wastewater treatment. Ordinary ozone bubbling was not able to mineralize aqueous PVA solutions under nonalkaline conditions, and approximately 30% of the total organic carbon remained at pH 2 and 7. Conversely, ozone microbubbles effectively mineralized PVA in aqueous solution to almost 0% in total organic carbon regardless of the pH condition. Effective mineralization of PVA, a recalcitrant organic chemical, demonstrates the potential of ozone-microbubble systems for physicochemical wastewater treatment.

Surfactant-Assisted Ozonolysis of Alkenes in Water: Mitigation of Frothing Using Coolade as a Low-Foaming Surfactant.

Aqueous-phase ozonolysis in the atmosphere is an important process during cloud and fog formation. Water in the atmosphere acts as both a reaction medium and a reductant during the ozonolysis. Inspired by the atmospheric aqueous-phase ozonolysis, we herein report the ozonolysis of alkenes in water assisted by surfactants. Several types of surfactants, including anionic, cationic, and nonionic surfactants, were investigated. Although most surfactants enhanced the solubility of alkenes in water, they also generated excessive foaming during the ozone bubbling, which led to the loss of products. Mitigation of the frothing was accomplished by using Coolade as a nonionic and low-foaming surfactant. Coolade-assisted ozonolysis of alkenes in water provided the desired carbonyl products in good yields and comparable to those achieved in organic solvents. During the ozonolysis reaction, water molecules trapped within the polyethylene glycol region of Coolade were proposed to intercept the Criegee intermediate to provide a hydroxy hydroperoxide intermediate. Decomposition of the hydroxy hydroperoxide led to formation of the carbonyl product without the need for a reductant typically required for the conventional ozonolysis using organic solvents. This study presents Coolade as an effective surfactant to improve the solubility of alkenes while mitigating frothing during the ozonolysis in water.

Direct detection of diphenylamino radical formed by oxidation of diphenylamine using atmospheric pressure chemical ionization mass spectrometry.

Diphenylamine (DPAH) and its derivatives have been widely used as antioxidants. Its antioxidation behaviors are started with the formation of diphenylamino radical (DPA• ) by loss of hydrogen atom through reaction with oxygen or ozone. DPAH was oxidized by ozonation to produce DPA• and DPA• was directly detected using atmospheric pressure chemical ionization mass spectrometry (APCI-MS). The influence of oxidation time on generation of DPA• and consumption of DPAH was also investigated. Experiments were performed using a home-made ozone bubbling apparatus for oxidation of DPAH. DPAH solution (1000 ppm) in acetone was stirred during the ozonation. The oxidized sample was diluted 100-fold and analyzed using APCI-MS. Structures and energies of DPAH, DPA• and detected ions were obtained using electronic structure calculations with Spartan 10 and Gaussian 09. DPA• was detected in positive APCI-MS in the form of DPAH•+ by proton transfer reaction with protonated acetone. Formation of DPAH•+ from DPA• was more favorable than that of [DPAH + H]+ from DPAH and it was also much more favorable than that of DPA+ from DPA• . By increasing the oxidation time, the relative abundance of DPAH•+ was increased whereas that of [DPAH + H]+ was notably decreased. Existence of DPA• was directly analyzed using APCI-MS. DPAH and DPA• were differently detected as [DPAH + H]+ and DPAH•+ , respectively. Direct APCI-MS analysis is a suitable technique for identification and quantitation of DPA• .

A Simple Electrostatic Precipitator for Trapping Virus Particles Spread via Droplet Transmission.

The purpose of this study was to develop a simple electrostatic apparatus to precipitate virus particles spread via droplet transmission, which is especially significant in the context of the recent coronavirus disease 2019 (COVID-19) pandemic. The bacteriophage φ6 of Pseudomonas syringae was used as a model of the COVID-19 virus because of its similar structure and safety in experiments. The apparatus consisted of a spiked, perforated stainless plate (S-PSP) linked to a direct-current voltage generator to supply negative charge to the spike tips and a vessel with water (G-water) linked to a ground line. The S-PSP and G-water surface were paralleled at a definite interval. Negative charge supplied to the spike tips positively polarised the G-water by electrostatic induction to form an electric field between them in which ionic wind and negative ions were generated. Bacteriophage-containing water was atomised with a nebuliser and introduced into the electric field. The mist particles were ionised by the negative ions and attracted to the opposite pole (G-water). This apparatus demonstrated a prominent ability to capture phage-containing mist particles of the same sizes as respiratory droplets and aerosols regardless of the phage concentration of the mist particles. The trapped phages were successfully sterilised using ozone bubbling. Thus, the present study provides an effective system for eliminating droplet transmission of viral pathogens from public spaces.

PFAS removal from wastewater by in-situ formed ferric nanoparticles: Solid phase loading and removal efficiency

PFAS removal by in-situ formed ferric nanoparticles via ozonation was evaluated in this study. The tests were conducted with synthetic contaminated water prepared from the firefighting foam concentrate at PFAS concentrations of 8.33–133 µg/L, pHs of 3–7.5, and ozone bubbling times of 15–45 s. It was found the particle sizes of the in-situ formed ferric nanoparticles were affected by ferrous dose, pH value, and ozone bubbling time. The highest PFAS removal achieved was 44%, when the PFAS feed concentration was 8.33 µg/L, ferrous dose was 40 µg/L, feed pH value was 6.2 and ozone bubbling time was 45 s. The PFAS solid phase loading of the ferric nanoparticles was significantly higher than conventionally used adsorbents. The highest PFAS solid phase loading achieved was 80% when the PFAS concentration was 8.33 µg/L, pH was 3, and mass ratio of ferrous sulphate to PFAS was 1:1.7 ± 0.3. It was found that the specific area of the nanoparticles was directly related to PFAS removal and solid phase loading. It was also found that the highest PFAS and highest PFAS solid phase loading of ferric nanoparticles could not be achieved simultaneously under the tested experimental conditions.

Lignin's ability to nucleate ice via immersion freezing and its stability towards physicochemical treatments and atmospheric processing

Abstract. Aerosol–cloud interactions dominate the uncertainties in current predictions of the atmosphere's radiative balance. Specifically, the ice phase remains difficult to predict in mixed-phase clouds, where liquid water and ice co-exist. The formation of ice in these clouds originates from heterogeneous ice nucleation processes, of which immersion freezing is a dominant pathway. Among atmospheric surfaces capable of forming a template for ice, mineral dust, biological material and more recently organic matter are known to initiate freezing. To further our understanding of the role of organic matter in ice nucleation, we chose to investigate the ice nucleation (IN) ability of a specific subcomponent of atmospheric organic matter, the biopolymer lignin. Ice nucleation experiments were conducted in our custom-built freezing ice nuclei counter (FINC) to measure freezing temperatures in the immersion freezing mode. We find that lignin acts as an ice-active macromolecule at temperatures relevant for mixed-phase cloud processes (e.g. 50 % activated fraction up to −18.8 ∘C at 200 mg C L−1). Within a dilution series of lignin solutions, we observed a non-linear effect in freezing temperatures; the number of IN sites per milligram of carbon increased with decreasing lignin concentration. We attribute this change to a concentration-dependant aggregation of lignin in solution. We further investigated the effect of physicochemical treatments on lignin's IN activity, including experiments with sonication, heating and reaction with hydrogen peroxide. Only harsh conditions such as heating to 260 ∘C and addition of a mixture with a ratio of 1 : 750 of grams of lignin to millilitres of hydrogen peroxide were able to decrease lignin's IN activity to the instrument's background level. Next, photochemical and ozone bubbling experiments were conducted to test the effect of atmospheric processing on lignin's IN activity. We showed that this activity was not susceptible to changes under atmospherically relevant conditions, despite chemical changes observed by UV–Vis absorbance. Our results present lignin as a recalcitrant IN-active subcomponent of organic matter within, for example, biomass burning aerosols and brown carbon. They further contribute to the understanding of how soluble organic material in the atmosphere can nucleate ice.

A simple ozone bubbling procedure for the preparation of graphene oxide

As the demand for graphene oxide (GO) increases, the need for a simple and practical GO preparation method that does not involve a chemical agent and time-consuming procedures increases. Herein, we propose an approach to the direct oxidation of multilayer graphene and natural graphite via the simple ozone bubbling method using atmospheric pressure barrier discharge. Although this method does not require chemical agents or long and complex procedures, it enabled users to achieve the successful oxidation of multilayer graphene and natural graphite. X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, atomic force microscopy, UV–vis spectroscopy and Raman spectroscopy results indicate that the products obtained from the ozone-based oxidation comprised oxygenated functional groups, mainly the carboxyl group, located at the edges of few-layer graphene structures characterised by low defect density. This simple preparation method can widen and accelerate the practical use of GO.

Normal boundary intersection applied as multivariate and multiobjective optimization in the treatment of amoxicillin synthetic solution

Amoxicillin is a useful antibiotic to combat bacterial infections. However, this drug can cause serious problems when discarded in waterways due to its great bioaccumulation potential. This compound can be treated via advanced oxidation processes (AOPs), which are capable of converting amoxicillin into carbon dioxide and water. In this context, the use of ozone as an oxidizer has excelled in amoxicillin degradation. This paper aims at treating a synthetic solution of amoxicillin (0.1gL-1) in a reactor with ozone bubbling. A Design of Experiment (DoE) with a response surface known as Central Composite Design (CCD) was used to optimize the treatment process. In addition, a Normal Boundary Intersection (NBI) method was used in the construction of a Pareto boundary chart. Results after 1-h treatment showed a reduction of 53% of the initial organic matter from a designed model using factors, such as pH, ozone generator power, and O3 flow. A model was built from the CCD with score of 0.9929. Thus, the model was able to represent the real scenario with confidence.

Photocatalytic ozonation of metronidazole by synthesized zinc oxide nanoparticles immobilized on montmorillonite

Abstract Released antibiotics in the aquatic environment have undesirable biological and ecotoxicological effects. In this work, photocatalytic ozonation process was used for removal of metronidazole (MET) as commonly used antibiotic from aqueous media. ZnO nanoparticles as an effective photocatalyst were immobilized on the surface of montmorillonite (MMT). The ZnO/MMT catalyst was characterized by X-ray diffraction (XRD), N2 adsorption/desorption, Fourier transform infrared (FT-IR), scanning electron microscope (SEM), and high resolution transmission electron microscope (HR-TEM). The ZnO/MMT activity was examined in the degradation of metronidazole under ozone bubbling and UV-A irradiation through photocatalytic ozonation process. The main influence factors on the photocatalytic ozonation activity such as ZnO/MMT dosage, pH, metronidazole initial concentration and ozone flow rate were studied. The results indicated that the MET removal efficiency was increased with increasing all the investigated factors except initial MMT concentration. The effect of organic and inorganic radical scavengers on the photocatalytic ozonation of MET was studied. Finally, several by products were identified by GC–MS analysis, which allowed to depict a possible mechanism for the MET degradation.

オゾンを援用したSnO&lt;sub&gt;2&lt;/sub&gt;量子ドットの合成

SnO2 quantum dot was successfully synthesized at ambient temperature via ozone bubbling to suspension including Sn6O4(OH)4 under pH of 12. It was clarified that use of SnF2 as starting material enables to obtain clear and stable SnO2 quantum dot suspension. Possible formation mechanism of quantum dot was proposed and shift of fluorescence was predicted with use of varied basic solution for neutralization and pH adjustment based on the hypothesis that shift of fluorescence is attributed to change in size. And this prediction was confirmed by experiment. Finally addition of Zn as dopant gave improved luminescence intensity without shift of fluorescence.

Effect of Microbubbles on Ozonized Water for Photoresist Removal

In this paper, we describe the use of ozone microbubbles in photoresist removal from silicon wafers. Ozonized water has attracted much attention as an environmental friendly cleaning method in semiconductor manufacturing. However, it would be desirable to enhance the oxidative ability of ozonized water for practical application. The existence of microbubbles in ozonized water has been shown to significantly enhance the photoresist removal rate due to an elevated dissolved ozone concentration (approximately 2.5 times that of ordinary ozone bubbling) and a direct effect of the microbubbles (removal rate is approximately 1.3 times faster than water with the same concentration of dissolved ozone without microbubbles). Additionally, the ozone microbubble solution was able to effectively remove a high-dose ion-implanted photoresist, which is extremely resistant to removal by ozonized water and other wet chemicals because of its amorphous carbon-like layer, or “crust”. Electron spin resonance experiments were al...

A spectrophotometric study of the reduction of Pu(VIII) and Pu(VII) in alkaline solutions

The reduction of Pu(VIII) with water in ozonized 15 and 6 MNaOH solutions after termination of the ozone bubbling was studied by spectrophotometry. Kinetic curves reflecting the whole set of processes that occur in NaOH solutions of different concentrations were obtained. Calculations performed with the experimental curves made it possible to construct the kinetic curves describing the behavior of plutonium in higher oxidation states in solution and to obtain the individual absorption spectra of Pu(VII) and Pu(VIII). The processes occurring in ozonized solutions of Pu(VI) in 6 and 15 M NaOH after termination of the ozone bubbling were found to occur by different mechanisms, yielding in 4 days Pu(VI) and Pu(V), respectively.

Free fatty acids degradation in grease trap purification using ozone bubbling and sonication

The oil and fat were treated at first by only ozone bubbling and it was confirmed that the collection efficiency of them became 98.4% when the aeration was used. It showed that the aeration method in a grease trap cleared the standard value of 90% and there was no worry on the oil and fat outflow from a grease trap. The characteristics of sonication process were studied for free fatty acids degradation. The free saturated fatty acids are the most hard-degradable compounds of the fats, oils and greases (FOGs) in the grease trap. The influence of various parameters such as immersion level of an ultrasound probe in the liquid and bubbling of various gases (Ar, O2, air, O3) on the sonochemical and energy efficiency of the sonication process was investigated. The most effective degradation treatment method for saturated free fatty acids was the combination of sonication and low flow rate argon bubbling.

Decolorization of Humate Solution by Ozone Bubbling and Ultraviolet Irradiation

Previously, we presented the results of experiment on the decolorization of the humate solution, which is one of the persistent substances utilizing the pulsed discharge in bubbles. In this paper, we describe experimental results and discussions on the decolorization of humate solution by ozone bubbling and ultraviolet (UV) irradiation.A silent discharge type ozone generator and low pressure mercury lamps are provided in this study. Ozone concentration is varied with applied voltage across the both electrodes in the ozone generator which has a concentric cylinder electrode. Two kinds of low pressure mercury lamps of which the shortest wave length of light emission are limited at 180nm, and 200nm are prepared as UV source. The absorbance, pH and total carbon concentration in the humate solution are measured by a spectrophotometer, a pH meter and a total organic carbon analyzer. From the results, the temporal variations of absorbance and total carbon concentration in humate solution are observed after the ozone bubbling and ultraviolet irradiation. It is clarified that the variation of absorbance in humate solution by ozone bubbling is effective and UV in shorter than 200nm wavelength is remarkable to decolorize the humate solution.

Multiphase reacting flow studies of bubble column ozonation reactor for water remediation

AbstractA multiphase Volume‐of‐fluid (VOF) model was developed to gain further insights into the reactive flow parameters and electrical capacitance tomography (ECT) measurements on the remediation of hazardous organic pollutants. Low ozone bubble frequencies were obtained for high surface tension fluids, and the liquid viscosity affected the ozone bubbling frequency. The VOF model indicated that the increase of inlet gas velocity enriched the ozone bubble detachment and concomitantly generated larger ozone bubbles, decreasing the detoxification rates. VOF mappings and ECT visualizations of gas‐liquid unveiled preferential routes and highlighted the attenuation of the axisymmetric behavior of the ozonation bubble column under high‐interaction regimes.

Reuse of Organic Matter from Coagulated Sludge Using a Membrane-Coupled Anaerobic Organic Acid Fermentor in Advanced Municipal Wastewater Treatment

Abstract This study focused on the development of an advanced municipal wastewater treatment process using a membrane-coupled anaerobic organic acid fermentor (MAOF) to remove dissolved organic matter from coagulated sludge. Intermittent ozone bubbling was effective in preventing increases in permeation resistance that were caused by particle accumulation on the membrane surface and in maintaining a high permeation flux. With regard to taxonomy, approximately 20 isolates were identified in the MAOF and are believed to represent the principal cell types in the fermentor. MAOF, coupled with intermittent ozone bubbling, is an effective system that can be implemented to recover organic matter that is used in biological denitrification or other basic materials.

Effect of Microbubbles on Ozonized Water for Photoresist Removal

In this paper, we describe the use of ozone microbubbles in photoresist removal from silicon wafers. Ozonized water has attracted much attention as an environmental friendly cleaning method in semiconductor manufacturing. However, it would be desirable to enhance the oxidative ability of ozonized water for practical application. The existence of microbubbles in ozonized water has been shown to significantly enhance the photoresist removal rate due to an elevated dissolved ozone concentration (approximately 2.5 times that of ordinary ozone bubbling) and a direct effect of the microbubbles (removal rate is approximately 1.3 times faster than water with the same concentration of dissolved ozone without microbubbles). Additionally, the ozone microbubble solution was able to effectively remove a high-dose ion-implanted photoresist, which is extremely resistant to removal by ozonized water and other wet chemicals because of its amorphous carbon-like layer, or crust. Electron spin resonance experiments were also performed without the influence of serious metal contamination and indicated the presence of hydroxyl radicals, which are thought to be formed by interaction of ozone with hydroxide ions adsorbed at the gas-water interface upon collapse of the microbubbles. The hydroxyl radicals play an important role in photoresist removal by the ozone microbubble treatment.

Ozonation of oxalic acid catalyzed by ion-exchanged montmorillonite in moderately acidic media

Ion-exchanged montmorillonite-rich materials (ca. 96% purity) like NaMt, Fe(II)Mt, Co(II)Mt, Ni(II)Mt and Cu(II)Mt showed catalytic activity in the ozonation of oxalic acid in water at room temperature, in the pH range 3.4-6.0. The conversion of oxalic acid exceeds 95% after 180 min of ozone bubbling in the presence of Fe(II)Mt. The oxalic acid removal efficiency was found to increase swiftly with the acid character of the clay surface up to a certain level, but decreases gently with excessive surface acidity. The pH exerts a strong influence on the catalyst efficiency, because it induces changes in the composition of both the liquid media and catalyst. The synergic action of ozone and clay catalysts at acidic pH seems to involve ozone adsorption and interaction between cation and adsorbed oxalate. The negative effect of increasing pH between 3.44 and 6.0 is discussed in terms of a decrease in the amount and mobility of the cation in the vicinity of the clay surface, and of a decay in the clay surface area available to ozonation.

Treatment and degradability of direct dyes in textile wastewater by ozonation: A laboratory investigation

In this study the factors affecting the rate of chemical oxygen demand of a synthetic waste solution containing water soluble direct dyes (Sirius Red F3B and Sirius Blue SBRR) by ozone gas were investigated. The research was conducted using a batch bubble column to take the advantage of the intensive back-mixing that prevails in bubble columns. In result of our experimental study, we have shown that the COD of direct dyestuff wastewater was reduced 58.89% for Sirius Red F3B and 60.95% for Sirius Blue SBRR after ozone bubbling treatment for 2 h. In addition the results indicate that during the ozonation, even though complete Sirius Red F3B and Sirius Blue SBRR degradation occurs in 10 min, ozone consumption goes on for a further 20 min after which time most degradation reactions are completed. Results of kinetic study showed that ozonation of the aqueous direct dyes were a pseudo-first-order reaction with respect to the dye. The apparent rate constant increased with both applied ozone dose and temperature, but declined logarithmically with the initial dye concentration. The main ozonation by-products, identified by HPLC, IC and GC-MS are formaldehyde, acetaldehyde, glyoxal, acetone, acetic acid, formic acid, oxalic acid and carbonic acid, plus nine Sirius Red F3B and twelve Sirius Blue SBRR derivatives are scarcely degradable.

Simultaneous Treatment of Washing, Disinfection and Sterilization Using Ultrasonic Levitation, Silver Electrolysis and Ozone Oxidation

A new type of ultrasonic washer-disinfector-sterilizer, able to clean, disinfect and sterilize most kinds of reusable medical devices, has been developed by using the ultrasonic levitation function with umbrella-shape oscillators and ozone bubbling together with sterilization carried out by silver electrolysis. We have examined the biomedical and physicochemical performance of this instrument. Prokariotic and gram-negative Escherichia coli and eukariotic Saccharomyces cerevisiae were killed by silver electrolysis in 18 min and 1 min, respectively. Prokariotic and gram-positive Geobacillus stearothermophilus and Bacillus atrophaeus, which are most resistant to autoclave and gas sterilization, respectively, were killed by silver electrolysis within 20 min. Prokariotic and gram-negative Pseudomonas aeruginosa was also killed by silver electrolysis in 10 min. The intensity distribution of the ultrasonic levitation waves was homogeneous throughout the tank. The concentration of ozone gas was 2.57 mg/ kg. The concentration of dissolved silver ions was around 0.17 mg/L. The disulfide bond in proteins was confirmed to be destroyed by silver electrolysis.