Ozone Chamber Research Articles

A proposed optimized equivalent circuit and performance analysis of dielectric barrier discharge ozone generator

<span lang="EN-US">Traditionally, low-frequency power supplies are used in dielectric barrier discharge (DBD) ozone generators. These generators require a very high output voltage. This may limit ozone production due to limitations imposed by the dielectric strength of the insulating material. Low-frequency generators also present low efficiency, large volumes, and difficulty in controlling ozone production. On the other hand, the advantages of high frequency DBD ozone generators are the increased power density applied to the chamber electrodes, and the voltage applied to the ozone chamber decreases, allowing for higher ozone production efficiency. From this point of view, in order to enhance and control the DBD ozone generator operating at high frequency, it is necessary to determine all parameter values and optimize the equivalent model for this type of generator. This work presents and proposes the practical methodologies used to extract all parameters of the high voltage high frequency (HVHF) transformer which can be used in these systems. Resonant frequency control techniques are presented in this paper. Elimination of the stray capacitance effect will also be implemented in this paper.</span>

Microbial Inactivation: Gaseous or Aqueous Ozonation?

For decades, ozone has been known to have antimicrobial properties when dissolved or generated in water and when utilized in its gaseous form on different substrates. This property (the ability to be used in air and water) makes it versatile and applicable to different industries. Although the medium of ozonation depends on the specific process requirements, some industries have the inherent flexibility of medium selection. Thus, it is important to evaluate the antimicrobial efficacy in both media at similar concentrations, an endeavor hardly reported in the literature. This study provides insights into ozone’s efficacy in air and water using two Gram-negative bacteria (Escherichia coli NTCC1290 and Pseudomonas aeruginosa NCTC10332), two Gram-positive bacteria (Staphylococcus aureus ATCC25923 and Streptococcus mutans), and two fungi (Candida albicans and Aspergillus fumigatus). For gaseous ozonation, we utilized a custom-made ozone chamber (equipped with ultraviolet lamps), whereas an electrolysis oxygen radical generator was applied for ozone generation in water. During gaseous ozonation, the contaminated substrates (fabric swatches inoculated with bacterial and fungal suspensions) were suspended in the chamber, whereas the swatches were immersed in ozonated water for aqueous ozone treatment. The stability of ozone nanobubbles and their resulting impact on the aqueous disinfection efficiency were studied via dynamic light scattering measurements. It was observed that ozone is more effective in air than in water on all tested organisms except Staphylococcus aureus. The presented findings allow for the adjustment of the treatment conditions (exposure time and concentration) for optimal decontamination, particularly when a certain medium is preferred for ozonation.

Bacterial and fungal disinfection via ozonation in air

Ozone treatment is an eco-friendly and cost-effective approach to achieve material disinfection, and this disinfection method is of utmost importance in the present global pandemic. The efficacy of ozone's oxidative potential on common microorganisms has been extensively studied, particularly in the food and water treatment industries. However, little is still understood regarding its antimicrobial capabilities for the treatment of textile substrates in air. In this study, fabric swatches inoculated with bacterial and fungal suspensions are exposed to ozone for different durations and at different ozone concentrations. Pathogenic bacteria (Escherichia coli, Staphylococcus aureus), and fungi (Aspergillus fumigatus, and Candida albicans), are the microbes utilised in this study. The efficacy of ozone is demonstrated by the complete removal of microbiota on the tested swatches when a concentration and exposure duration of 20 ppm and 4 mins are respectively maintained in a test ozone chamber. We expect the insights from this work to guide the development of new ozonation techniques capable of rapid sterilisation in industrial & public settings.

Evaluation of an Ozone Chamber as a Routine Method to Decontaminate Firefighters' PPE.

Ozone chambers have emerged as an alternative method to decontaminate firefighters’ Personal Protective Equipment (PPE) from toxic fire residues. This work evaluated the efficiency of using an ozone chamber to clean firefighters’ PPE. This was achieved by studying the degradation of pyrene and 9-methylanthracene polycyclic aromatic hydrocarbons (PAHs). The following experiments were performed: (i) insufflating ozone into PAH solutions (homogeneous setup), and (ii) exposing pieces of PPE impregnated with the PAHs to an ozone atmosphere for up to one hour (heterogeneous setup). The ozonolysis products were assessed by Fourier Transform Infrared Spectroscopy (FTIR), Thin-Layer Chromatography (TLC), and Mass Spectrometry (MS) analysis. In the homogeneous experiments, compounds of a higher molecular weight were produced due to the incorporation of oxygen into the PAH structures. Some of these new compounds included 4-oxapyren-5-one (m/z 220) and phenanthrene-4,5-dicarboxaldehyde (m/z 234) from pyrene; or 9-anthracenecarboxaldehyde (m/z 207) and hydroxy-9,10-anthracenedione (m/z 225) from 9-methylanthracene. In the heterogeneous experiments, a lower oxidation was revealed, since no byproducts were detected using FTIR and TLC, but only using MS. However, in both experiments, significant amounts of the original PAHs were still present even after one hour of ozone treatment. Thus, although some partial chemical degradation was observed, the remaining PAH and the new oxygenated-PAH compounds (equally or more toxic than the initial molecules) alerted us of the risks to firefighters’ health when using an ozone chamber as a unique decontamination method. These results do not prove the ozone-advertised efficiency of the ozone chambers for decontaminating (degrading the toxic combustion residues into innocuous compounds) firefighters’ PPE.

Engineering Aspects and Parameter Evaluation of Ozone Generator

This paper introduces the Ozone generator parameters analysis and its engineering design aspects. Practically, Ozone is successfully used in water treatment applications; furthermore, it can be used to treat the secondary system cooling water in nuclear research reactors. The main element in this process is the Ozone generator; it has many parameters that need to be set at its design. These parameters can be divided into those related to the electrical equivalent circuit of corona dielectric barrier discharge (DBD), those associated with injected gas flow between the two electrodes, and those belonging to temperature of the electrodes. This paper is intended to those parameters that are related to the electrical equivalent circuit which has two standard models: linear and nonlinear. In this regard, the determination of the component values of nonlinear model can be achieved very hardly. To handle such determination, the nonlinear model can be approximately treated as a linear model in an approaching fashion. Based on this approximation, Lissajous plot and differential evolution (DE) methodologies are used for the computation of DBD ozone chamber parameters. Additionally, a new theoretical technique will be presented

Optimization of ozone chamber using pulse width modulation for sterilization and preservation on fruits and vegetables

Ozonizer is a method used for sterilization and food preservation by utilizing ozone produced from plasma discharge. The effective way of obtaining ozone is to use dielectric barrier discharge (DBD) plasma. The manufacture of a controlled ozonizer chamber system is important to result in effective and efficient performance. The aim of this study is to design and optimize the ozone chamber parameter using pulse width modulation (PWM). The system design is added with the Arduino Mega 2560 microcontroller and the L296N motor driver as an ozone generator radiation controller by changing the pulse width modulation to determine the ozone levels produced. The experimental results show that the ozone concentration increases by 50 % on average with increasing variations of the 10 % duty cycle (PWM) and the ignition time length. The optimum value is achieved on a 70 % duty cycle for 60 - 300 seconds, where the ozone level of 3 ppm is obtained and sustained for fruits/vegetables sterilization and preservation application.

The effect of protecting waxes on staining antidegradant performance in tyre sidewall formulation

Certain materials such as wax, when incorporated into rubber formulations, bloom and form a surface barrier layer against ozone attack. The ozone resisting film results in an unpleasant appearance on the rubber surface. In tyres, sidewalls are more susceptible to ozone attack leading to degradation both in dynamic and static conditions. Also, tyre appearance is an important factor in quality control visual inspections and the acceptance of the final product in the market. In this paper, the effect of oil contents in different waxes on the physico-mechanical properties of rubber vulcanisates was investigated. It was found that in UV–Vis spectra, at different ageing times, the absorbance of extracted cured tyre sidewall compound samples at 472 nm showed the concentration of the antidegradants in the rubber vulcanisates. The migration, based on protecting function leading to degrading the antidegradants after the ageing time of 72 h. With 72 h of ageing time in the ozone chamber, the waxes with higher oil content showed a faster migration of antidegradants to the surface of the rubber vulcanisates and degraded faster than the waxes with lower oil content.

Evaluation of Stabilizing Additives Content in the Mechanical Properties of Elastomeric Compositions Subject to Environmental and Accelerated Aging

This research aimed to evaluate the ideal proportion of two stabilizers in elastomeric compositions indicated for tire sidewall. The stabilizers applied in different proportions were N-1,3-dimethyl-butyl-N'-phenyl-p-phenylenediamine (6PPD) and oligomerized 2,2,4-trimethyl-quinoline (TMQ). Nine compositions were prepared with 0.5, 1.5 and 2.5 phr of 6PPD combined with 0.5, 1.0 and 1.5 phr of TMQ. The compounds were exposed to accelerated aging processes, including thermo-oxidative, photochemical and ozone chamber. Also, the samples were aged in the environment for 440 days. At regular intervals, the samples were evaluated. Gas chromatography was used to quantify the content of 6PPD. Overall, the samples exposed to thermo-oxidative aging showed the greatest loss of mechanical properties (tear and tensile strength) as well as the 6PPD content. From the mechanical strength results, it was possible to conclude that the best combination of stabilizers was 2.5 phr of 6PPD and 1.0 of TMQ.

Development of a Maximum Frequency and Voltage Regulated Power Supply for Ozone Generation System

This paper is proposed full-bridge inverter-based power supply with dynamic PFC converter for an ozone generator. The ozone chamber is required high-voltage range 5KV to 6KV. It derived from AC primary supply 230V with the help of a step-up transformer. The mains supply has variations as a consequence; the output voltage also gets changes. It affects ozone production and also affects the ozone chamber. To avoid the above problem, the regulation of voltage is required. The active boost converter is utilized to direct the dc-connect voltage to improve the input power factor. The voltage control method is utilized to manage the enhanced converter. Thus the projected power supply produces stable voltage and has high performance.

Comparison of Sulfur Curing Systems (Insoluble-Rhombic) on Physical and Thermal Properties of the Matrix Polymeric of Styrene-Butadiene Rubber and Natural Rubber

Vulcanization, by creating a three-dimensional cross-linked network, improves the physicalmechanical and thermal properties of elastomers. Sulfur is one of the most common vulcanization agents used in the rubber industry. Curing agents used in this research are polymeric sulfur (insoluble sulfur, IS) and rhombic sulfur (RS). These two allotropes of sulfur are compared with regard to their ability to vulcanize styrene- butadiene rubber (SBR) and natural rubber (NR). According to the results obtained on that about curing characterization, was seen, the optimal time for the cure of both intended rubbers gotten with RS, and about the compression set test, obtained similarly result. This while that is about tensile strength, Mooney viscometer and aging tests seen for both rubbers, insoluble sulfur was the best option for curing and about hardness and tear tests were observed, results for SBR were similar and for NR were founded, insoluble sulfur was the best option. About ozone chamber test, all results of the samples were similar. With all these interpretations due to lack of blooming in sulfur polymer, this option is preferred for industrial rubber.

Selected Aspects of Cbrn Protection in Military Peace Support Operations

Abstract This paper presents the results of studies based on the analysis of field exercises organized for the purpose of disinfection of preventive sub-units regrouping from the areas threatened with endemic infectious diseases. The research also concerns the analysis of the possibility of conducting the liquidation of contamination in the conditions of access to the local infrastructure with the use of chemical weapons equipment and cooperation with the non-military system: police, fire brigade, emergency medical services and municipal guards. The method of preparation of the ozone chamber in field conditions is also presented

The influence of modifiers on the conservation of rubber products of agricultural machinery

The purpose of the research is to determine the efficiency of various modifiers for increasing the re-sistance of rubber products to the effects of ozone contained in the air, under a long-term storage of agri-cultural machinery in open areas during the off-season. The task of the research is to determine the pro-tective properties of rubber modifiers under the conditions of the destructive effect of ozone. Experimental investigations were carried out in the ozone chamber OMS-1 using standard techniques. Ozone aging was carried out consistently in three stages respectively with stretching samples at 20, 30, 50 %, the duration of each stage of the experiment - 6 hours. After each stage of the tests, visual inspection of the samples was carried out. The ability of a deformed sample to resist the destructive effect of ozone was determined by the time of appearance of the first cracks visible to the naked eye on the surface of the sample. The results of the data obtained during the experiment showed that the introduction of the modifiers «Stillage bottoms of telomeric alcohols» and «Fluorine paraffins» into the rubber of the brand NO-68-1B-1 (from BNKS-18A rubber) already at the first stage of testing leads to the appearance of a continuous mesh small cracks on the samples surface. On samples from this rubber, subjected to surface fluoridation at the last stage of the test, a number of edge cracks up to 11 mm in length and up to 1 mm deep are appeared. On samples from the rubber of grade 26-82-4 (from SKEPT-50 rubber), the pointed cracks appear on rubber samples, and the modification of this rubber with the composition «Stillage bottoms of telomeric alcohols» accelerates this process. The experimental samples of rubber IR-5-1, as modified and as subjected to surface fluorination, have withstood the ozone aging test without traces of destruction. The results of the conducted studies allow us to conclude that it is necessary to develop new protective compositions that exclude the destruction of rubber technical products of agricultural machinery during long-term storage in open areas.

Biofilms in Full-Scale Drinking Water Ozone Contactors Contribute Viable Bacteria to Ozonated Water.

Concentrations of viable microbial cells were monitored using culture-based and culture-independent methods across multichamber ozone contactors in a full-scale drinking water treatment plant. Membrane-intact and culturable cell concentrations in ozone contactor effluents ranged from 1200 to 3750 cells/mL and from 200 to 3850 colony forming units/mL, respectively. Viable cell concentrations decreased significantly in the first ozone contact chamber, but rose, even as ozone exposure increased, in subsequent chambers. Our results implicate microbial detachment from biofilms on contactor surfaces, and from biomass present within lime softening sediments in a hydraulic dead zone, as a possible reason for increasing cell concentrations in water samples from sequential ozone chambers. Biofilm community structures on baffle walls upstream and downstream from the dead zone were significantly different from each other ( p = 0.017). The biofilms downstream of the dead zone contained a significantly ( p = 0.036) higher relative abundance of bacteria of the genera Mycobacterium and Legionella than the upstream biofilms. These results have important implications as the effluent from ozone contactors is often treated further in biologically active filters and bacteria in ozonated water continuously seed filter microbial communities.

Effect of Ozone Treatment on Properties of Screw Pressed and Non-Screw Pressed Empty Fruit Bunch Medium Density Particleboard

This study was done to investigate the effects of ozone treatment as a method to improve the properties of empty fruit bunch (EFB) medium density particleboard. Two types of EFB were used in this study i.e. screw pressed and non-screw pressed empty fruit bunch. These EFB were treated in an ozone chamber for 8 hours prior to particleboard manufacturing. The mechanical properties, Modulus of Elasticity (MOE), Modulus of Rupture (MOR) and Internal Bonding (IB) and physical properties, water Absorption (WA) and Thickness Swelling (TS) of EFB particleboard were determined. The results showed that the ozone treatment could increase the MOR and IB values of EFB particleboard, but had no significant effect on MOE values. For physical properties, the values showed no improvement for TS and WA. The panels manufactured using ozone treatment was found suitable for applications for furniture products.

A Model Parameter Extraction Method for Dielectric Barrier Discharge Ozone Chamber using Differential Evolution

Abstract In order to design an efficient resonant power supply for ozone gas generator, it is necessary to accurately determine the parameters of the ozone chamber. In the conventional method, the information from Lissajous plot is used to estimate the values of these parameters. However, the experimental setup for this purpose can only predict the parameters at one operating frequency and there is no guarantee that it results in the highest ozone gas yield. This paper proposes a new approach to determine the parameters using a search and optimization technique known as Differential Evolution (DE). The desired objective function of DE is set at the resonance condition and the chamber parameter values can be searched regardless of experimental constraints. The chamber parameters obtained from the DE technique are validated by experiment.

Analysis, Design, and Implementation of Multiple Parallel Ozone Chambers for High Flow Rate

It is well known that ozone concentration depends on air/oxygen input flow rate and power consumed by the ozone chamber. For every chamber, there exists a unique optimum flow rate that results in maximum ozone concentration. If the flow rate is increased (beyond) or decreased (below) from this optimum value, the ozone concentration drops. This paper proposes a technique whereby the concentration can be maintained even if the flow rate increases. The idea is to connect n number of ozone chambers in parallel, with each chamber designed to operate at its optimum point. Aside from delivering high ozone concentration at high flow rate, the proposed system requires only one power supply to drive all these (multiple) chambers simultaneously. In addition, due to its modularity, the system is very flexible, i.e., the number of chambers can be added or removed as demanded by the (output) ozone requirements. This paper outlines the chamber design using mica as dielectric and the determination of its parameters. To verify the concept, three chambers are connected in parallel and driven by a single transformer-less LCL resonant power supply. Moreover, a closed-loop feedback controller is implemented to ensure that the voltage gain remains at the designated value even if the number of chambers is changed or there is a variation in the components. It is shown that the flow rate can be increased linearly with the number of chambers while maintaining a constant ozone concentration.

실내식물과 소나무의 오존에 대한 광합성 능력, 항산화 효소의 활성, 해부학적 반응

The purpose of this study was to identify the effects of ozone pollution on the one woody species and two indoor plants in controlled environment. Pinus densiflora, Spathiphyllum patinii and Epipremnum aureum seedlings were exposed in both control and ozone chambers to investigate photosynthetic rate, water use efficiency, antioxidative enzyme activities such as GR(Glutathione reductase) and APX(Ascorbate peroxidase) activity and leaf anatomical response. Ozone was fumigated 8 hours for a day with 30 ppb concentration for 50 days. Pinus densiflora seedlings showed no significant difference on photosynthetic rate, water use efficiency, antioxidant enzyme activity during ozone exposure. Ozone concentration (30 ppb in this study) is not high enough to generate ozone damage on Pinus densiflora species. In contrast, ozone generally altered photosynthetic rate, antioxidant enzyme (especially GR) activity and leaf anatomy in two indoor species (Spathiphyllum patinii and Epipremnum aureum) exposed in ozone chamber were significantly differ from those of control in every measurement. These data suggest that two indoor species(Spathiphyllum patinii and Epipremnum aureum) are more sensitive to ozone than Pinus densiflora.

Inactivation of Norovirus Surrogates after Exposure to Atmospheric Ozone

Human norovirus is the leading cause of epidemic gastroenteritis, especially in semiclosed settings such as daycares, nursing homes, hospitals, schools and on cruise ships. Outbreaks are often accompanied by contamination of environmental surfaces and commonly handled items. Surface disinfection of norovirus surrogates, feline calicivirus and murine norovirus, by 20 parts per million atmospheric ozone in a chamber maintaining 80% relative humidity was investigated. After treatment, neither virus could be detected on glass surfaces, but >5 log infectious virus was recovered from untreated controls. Ozone chambers used to decontaminate small, hand-contact items could be an important tool for controlling norovirus outbreaks.

A Simple and Effective Method to Estimate the Model Parameters of Dielectric Barrier Discharge Ozone Chamber

This paper presents a simple yet effective method to determine the electrical model parameters of the dielectric barrier discharge (DBD) ozone chamber at frequencies above 20 kHz. The method is an alternative to the conventional Lissajous plot estimation method which appears to yield unsatisfactory results in this frequency range. Furthermore, the proposed technique allows for the chamber parameters to be determined at different frequencies-a flexibility which is not easily achievable using the typical Lissajous method. The measurement setup consists of a full-bridge inverter and a high-frequency variable inductor connected to the DBD chamber. The inductor can be adjusted to allow for parameter determination at different frequencies. The chamber parameters obtained from experimental results are validated by applying them in a high-voltage power supply for ozone generator.

Analysis and Implementation of Transformerless LCL Resonant Power Supply for Ozone Generation

This paper describes the analysis and design of an LCL resonant power supply for ozone generation. The main advantage of the proposed topology is the absence of high-voltage transformer; the high voltage gain is achievable by means of double-resonance phenomena. Furthermore, the bandwidth is wider than the ordinary LC and its phase difference is constant over specific frequency range; as a result, an open-loop operation can be implemented. The complete analysis and design procedure of the power supply is presented. The design procedure is verified by implementing the power supply to drive a dielectric barrier discharge prototype ozone chamber. The hardware results are found to be in close agreement with simulation and thus justify the validity of the design procedures. The proposed circuit is suitable for portable ozone power supply fed by low-voltage source such as battery or photovoltaic module.