ABSTRACTThe utilization of gaseous ozone (a powerful oxidant) in air, for disinfection and sterilization purposes, has been extensively studied for diverse applications; however, the optimal deployment of this technology for textile disinfection is deserving of further research attention and is this the focus of this work. In this study, the penetration efficiency of ozone gas into hard-to-reach regions of different garment types is critically examined. The impacts of garment packing density, hanging orientation and ozonation duration are also considered, and the resultant disinfection efficiencies are comparatively analyzed. An ozonation chamber fitted with remote ozone detection is utilized for the ozonation of fabric swatches inoculated with Escherichia coli bacteria. The number of colony-forming units per cm2 and the bacterial lawn area fraction are evaluated pre- and post-ozonation to quantify the level of disinfection. This study shows that the attainment of sufficient ozone concentrations in hard-to-reach regions of different garment types coupled with the inter-garment spacing utilized are vital for effective decontamination. This study also demonstrates the effectiveness of ozonation as a necessary technology for decontamination, particularly in this era, where the sterilization of textiles and other materials is paramount for public health and safety.

ABSTRACTThe key objective of this review is to summarize the available information on the effects of medical ozone therapy in COVID-19 and its therapeutic potentials. An electronic literature search was performed using the PubMed, Cochrane, Web of Science, Science Direct, Scopus, Google Scholar, Ovid Medline, J Stage and China Knowledge Resource Integrated (CNKI) databases to September 2021. In total, 1833 articles were identified. Twenty-six articles were selected out of 667 articles. The most preferred and effective administration method for COVID-19 is major autohemotherapy (MAHT), followed by rectal insufflation and minor autohemotherapy (MiAHT). However, other methods, including ozonized oils and ozonated saline, are also used for COVID-19 due to ease of application, prophylactic and therapeutic effects. In studies, 850 patients were treated with ozone therapy as a complementary treatment. The effectiveness of ozone concentrations below 20 μg/mL or above 45 μg/mL for MAHT are yet to be proven in the COVID-19 patient population, and may be less effective. Complementary ozone therapy combined with antivirals increase the activity of antivirals against COVID-19. Large-scale, multicenter randomized clinical trials are needed to be able to isolate the effect of ozone therapy where the clinical variables are distributed more homogeneously. Also, an extended period of follow-up of COVID-19 patients may give more accurate indications about the effectiveness of the treatment in the long term.

Published in Ozone: Science & Engineering: The Journal of the International Ozone Association (Vol. 45, No. 1, 2023)

ABSTRACTThe applications of ozonized oils in human medicine, veterinary, and dentistry have been experiencing a significant increase in the last years. An important chemical property of ozonized oils is their oxidizing capacity, which is directly related to the therapeutical effects. This work aimed to study the light emission caused by the oxidation of luminol by ozonized sesame oil. Sesame oil was ozonized at different time intervals and characterized by peroxide index, Fourier-transform infrared spectroscopy, and thermal analysis. The light emission efficiency was correlated with the pH of the medium, the concentration of horseradish peroxidase (HRP), used as a catalyst, and solvents. A linear correlation was obtained between the concentration of ozonized oil and the integrated light emission. In a second approach, taurine chloramine (Tau-NHCl) was used instead of HRP. The light emission was dependent on both ozonized oil and Tau-NHCl, showing the involvement of intermediate oxidative species in the reaction. Considering the growing therapeutic applications of ozonized oils and Tau-NHCl, these findings instigate further biological investigations to characterize additive or synergic microbicidal properties.

ABSTRACTCopper modified sepiolite (Cu-SEP) with high catalytic activity was successfully prepared and used in ozonation to remove oxalic acid from water. The influence of Cu-SEP dosage, initial pH, ozone dosage and initial oxalic acid concentration on the removal of oxalic acid in heterogeneous catalytic ozonation was investigated, and XRD, FTIR, SEM, TEM and XPS were employed to characterize the Cu-SEP to clarify its working mechanism in ozonation. The experimental results showed that under the optimal condition, the removal of oxalic acid could reach 95.8%. Cu element successfully replaced Mg in the sepiolite lattice to form the Cu-SEP, it existed mainly in the form of Cu2+. Cu-SEP contained abundant surface hydroxyl groups, which played an important role in the catalytic ozonation process. With the combination of free radical quenching experiment, the possible mechanism of Cu-SEP catalyzed ozonation to degrade oxalic acid was proposed. After ozonation, Cu-SEP retained the original structure, and exhibited excellent stability and reusability.

ABSTRACTThe aim of this study was to investigate microbubble ozonation for the removal of toxic cyanobacteria, Microcystis aeruginosa. The microbubble ozonation (30 min) at 3.47 mg O3 L−1 decreased the M. aeruginosa concentration from 1.5 × 107 to 0.8 × 107 cell mL−1. However, the acute toxicity (48 h) to Daphnia magna (<24 h old) was considerably increased after the microbubble ozonation, possibly owing to the release of intracellular microcystins (MCs). Considering the release of toxic MCs, the microbubble ozonation was optimized at an environmentally relevant concentration (1.74 × 106 cell mL−1) of M. aeruginosa. Microbubble ozonation at 0.26–1.92 mg O3 L−1 for 30 min removed M. aeruginosa by 26 to 83% without any acute toxicity on D. magna. Moreover, D. magna feeding enhanced the removal rate from 85 to 100% for 48 h. These findings suggest that microbubble ozonation, possibly combined with D. magna biomanipulation, can be a promising tool to control toxic cyanobacteria in ambient water.

ABSTRACTCatalytic ozonation including homogeneous and heterogeneous ozonation has been extensively used in water and wastewater treatment in recent years. The liquid homogeneous catalysts cause secondary pollution and have limited development prospects. The heterogeneous catalyst exists in solid form, which is easy to separate solid from liquid, convenient to operate, and has high catalytic ozone decomposition efficiency. It can effectively mineralize organic pollutants and has great development potential. The catalyst is the core part of the whole method. In this study, the mechanism of heterogeneous catalytic ozone oxidation is briefly introduced. Several common preparation methods of ozone catalysts are reviewed. Various catalytic ozonation catalysts such as metal oxides, metals/metal oxides on supports, and carbon-based materials are summarized in detail. The application of heterogeneous catalytic ozonation in the degradation of phenols, pesticides, dyes, drugs, and other toxic organic pollutants is reviewed. At present, the structure of the catalyst is unstable, the active components of the catalyst are easily lost, and the catalytic effect is lost. Therefore, the development of supported catalysts with good stability has become the main direction of current research. The preparation and application of heterogeneous catalytic oxidation are also reviewed, which will be beneficial to further research.

ABSTRACTDue to the high recurrence of microbial infections, developing new technologies for preventing the dissemination of pathogens is essential, especially to prevent infection in humans. Thus, devices for the decontamination of surfaces reduce not only the spread of pathogens in the environment, but provide greater security and protection for communities. Ozone (O3) is a substance capable of reducing or eliminating several types of microorganisms owing to its biocidal capacity, including when it is dissolved in water. The objective of this study was to develop an instant decontamination device using ozonated water. To confirm its biocidal action and verify the device’s efficacy, the reduction of the microbial load of important pathogens on personal protective equipment (PPE) was assessed. In addition, in order to confirm the biocidal action of ozonated water against SARS-CoV-2, in vitro tests on a viral model of Gammacoronavirus were performed. The results showed the efficacy of ozonated water in the disinfection device at concentration ranges of 0.3–0.6 mg/L and 0.7–0.9 mg/L of ozonated water, with growth reductions above 2 log10 for both concentration ranges tested and inactivation fractions above 60% (0.3–0.6 mg/L) and 80% (0.7–0.9 mg/L), with a high proportion of the tested PPE showing 100% microbial reduction. In vitro results for the evaluation of ozonated water in a viral model showed a 99.9% reduction percentage in the concentration range of 0.3 to 0.5 mg/L and a 99% reduction in the concentration range of 0.6 to 0.8 mg/L, with a 5.10 log EDI50/mL and 6.95 log EDI50/mL reduction, respectively. The instant decontamination system developed in this study proved effective for microbial reduction, and we confirmed the potential of ozonated water as a biocidal agent. Therefore, the proposed decontamination device could be considered as a tool for reducing contamination on surfaces using ozonated water.

ABSTRACTAn experiment was conducted at Woodhouse farm, Horticultural Research Station, Ooty, during October 2017 to March 2018 to quantify the impact of elevated ozone and ozone protectant spray on plant growth, nutrients, biochemical and yield properties of turnip crop. The experiment was laid out in a factorial completely randomized block design and was replicated thrice. Elevated ozone exposure on turnip significantly reduced the plant height, tuber size, tuber weight, chlorophyll ‘a,’ chlorophyll ‘b’ and total chlorophyll content as well as the nutrient content of plant, viz., total nitrogen, total potassium, total manganese, iron, zinc and copper, also affected. Elevated ozone exposure significantly increased the antioxidant enzyme activity like catalase and peroxidase activity in addition to increment in total phosphorus content in leaf tissues. However, ozone protectants played a major role in nullifying the tropospheric ozone effect on growth and development, physiological traits and yield of turnip while tested with panchagavya performed better followed by neem oil and ascorbic acid.

Published in Ozone: Science & Engineering: The Journal of the International Ozone Association (Vol. 45, No. 1, 2023)

ABSTRACTWastewater generated from agricultural activities and food production is a source of environmental pollution, and its treatment is a challenging technological issue. Ozone gas (O3), and the possibility of associating it with hydrogen peroxide (H2O2), has the potential to remove persistent organic compounds in effluents. In the present work, wastewater from industrial potato processing was characterized, and its treatment with ozone combined with hydrogen peroxide was assessed. The inlet ozone concentration and the flow rate were 84.5 mg L−1 and 62.5 mL min−1, respectively. The promising conditions of temperature, pH, and H2O2/O3 proportion were determined to reduce the chemical oxygen demand, turbidity, and color, according to a central composite rotatable design. The H2O2/O3 proportions were 0.1, 0.3, 0.5, and 0.6. Additionally, the response variables were evaluated as a function of the ozone and hydrogen peroxide treatment time for up to 24 h. The conditions obtained for treating wastewater from industrial potato processing were the following: temperature = 25°C; pH = 3.0, and H2O2/O3 proportion = 0.1. For the water quality parameters adopted, the combination of ozone and hydrogen peroxide was effective at removing color and turbidity. The chemical oxygen demand, color, and turbidity reduction stabilized after 1.16 h, with cumulative applied dosages of ozone and hydrogen peroxide equal to 380 mg L−1 and 35 mg L−1, respectively.

ABSTRACTAs a set of persistent organic pollutants (POPs) that cause serious harm to human and animal health, polycyclic aromatic hydrocarbons (PAHs) degradation has attracted attentions of many scholars. Ozonation is one of the promising techniques for removing PAHs from various aqueous solutions because of its molecular structures, rapid reaction with ozone (O3), and oxidation by-products of PAHs produced during ozonation are more biodegradable than initial PAHs. However, its application is constrained by the high cost of ozone production, and organic matter in water is only partially oxidized. In recent years, to improve the efficiency of the ozonation process and optimize economic efficiency, several methods of O3-based advanced oxidation processes (AOPs) (i.e. O3/UV, O3/H2O2, O3/H2O2/UV, O3/Fenton, O3/Catalyst) have been studied. These AOPs generate more HO• than molecular ozone. This review summarized recent developments relating to the degradation of PAHs via O3-based AOPs and their exciting mechanisms. Compared different processes characteristics in terms, such as radical species, operational conditions, by-products and their toxicity, and cost. We considered that O3/photocatalyst seems to be a better choice for PAHs degradation. Finally, the challenges and future trends of PAH degradation have prospected.

ABSTRACTThis is an experimental study on the decolorization efficiency and the degradation of organic compounds from textile wastewater by the ozonation process in a batch system. The effects of different sample volumes of textile wastewater over time were investigated. The experiments were performed in a 1 L glass reactor with a magnetic stirrer and a bubble diffuser at the bottom to feed the ozone. The applied cumulative ozone dosage varied at 120 gO3 L−1, 60 gO3 L−1, and 30 gO3 L−1, and the total interaction time for each test was 1 h. To investigate the physicochemical properties of the textile wastewater (solid and liquid phases) before and after the treatment, multiple analytical characterization methods were used: Thermal Gravimetric Analysis, Scanning Electron Microscopy coupled with Energy-Dispersive X-ray Spectroscopy, X-ray diffraction, Fourier Transform Infrared spectroscopy, and Spectrophotometer. The most perceptive change was observed in the color of the liquid medium, which turned from black to transparent, and a visual color number indicator known as DurchsichtFarbZahl (DFZ) was used for the evaluation of this process. Absorbance values decreased about 3.5 times after 5 min of treatment with a 0.15 L sample volume, and these values differed for tests with larger sample volumes. FTIR spectroscopy demonstrated that the bands’ intensities associated with the C − H, C − N, and C − O decrease during treatment. On the other hand, it was possible to conclude that combining treatment methods to improve the degradation of persistent compounds after the ozonation process is necessary. Finally, the ozonation of the textile wastewater proved to be effective at removing color due to its high reaction capacity.

ABSTRACTOzone is a powerful oxidizing agent, so its effect on quality parameters must be considered prior to any potential food application. The effect of gaseous ozone on the quality-related attributes of onion bulbs was examined. Onions were exposed to different ozone concentrations (100, 200, 300 ppm) at pulse mode (i.e., frequency of exposures 1, 2, 3). The pungency imparting pyruvic acid and ascorbic acid contents decreased with an increase in the concentration of ozone and the number of exposures, while total phenol and flavonoid content increased to an effective concentration of 400 ppm of ozone. Higher concentrations inadvertently decreased the antioxidant properties. Ozone treatment resulted in a non-significant decrease in firmness, anthocyanin content, and color of onion. Scanning electron microscopic analysis exhibited structural breakdown in the tunic (outer surface) of ozone-treated onion. At higher concentrations, structural changes were observed up to the first bulb scale.

ABSTRACTThe objectives were to evaluate the ozonation effects on germination and disinfection of sashi inchi seeds. Seeds groups were treated applying concentrations of gaseous ozone of 5 and 20 mg/L for 20 min. Others were immersed in water with dissolved ozone (0.5 and 1.0 mg/L) during 15 min. Ozone did not register negative effects on germination or on the quality of the seeds. Treatments with lower ozone concentrations recorded the best results in germination percentage and vigor indicator (86%, 94% and 84%). The gaseous phase was the most suitable one for treating the seeds (5 mg/L for 20 min). Only a treated group reached greater seedlings survival (53%), resisting the fungal attack. Applied disinfection allowed reducing the microbial load.

ABSTRACTThe use of ozone in food processing has become an eco-friendly, cost-effective way to manage insect pests and improve grain quality. The present study examined the efficacy of different ozone concentrations (500–1000 ppm), exposure time (2–6 h), and grain moisture content (11–15%, wb) on mortality of different developing stages (egg, larvae, and pupae) and adult of Callosobruchus maculatus. Treated Mung bean was also analyzed for in-vitro protein digestibility (IVPD), grain hardness, and germination rate. A comparison between untreated (control) and treated mung bean samples at optimized conditions was conducted to determine the influence of ozone on proximate and mineral analysis, thermal and pasting properties. C. maculatus pupae and adults were least susceptible to ozonation, with mortality rates of 11.11 and 13.04–100%, respectively. In the optimal condition of 11.17% grain moisture content, 1000 ppm ozone concentration, and 2 h exposure time, mortality of different life stages (egg, larvae, pupae, and adults) of C. maculatus was calculated as 104.07%, 90.15%, 86.82%, and 83.55%, respectively. The corresponding values of IVPD, hardness, and grain germination were 67.85%, 57.43 N, and 87.74%, respectively. There was a noticeable decrease in protein, fat, and mineral content in ozone-treated mung bean compared to the control. Furthermore, enhancement in thermal and pasting properties of ozonated mung beans suggest that ozone can be utilized to develop high quality grain products’ while ensuring their safety.

ABSTRACTOzone treatment of corn seeds with respect to determination on changes in germination ability, germination under salt stress, seedling growth, seedling root length, conductivity and inactivation of endogenous microflora was studied. Corn seeds immersed in water treated by fixed ozone dose of 12.5 g/m3 for 1 (1O3), 3 (2O3) and 5 min (3O3) at room temperature. Ozone treatment provided full germination (100%) of the corn seeds on the 2nd day; whereas 66.6% of the control seeds germinated on the 8th days after planting. Ozone treated seedling were significantly taller and stronger than the control samples with significantly longer seedling root. Germination under 100 mM salt stress for ozone treated seeds was significantly higher than that of the control samples. Electrical conductivity of the seeds was significantly affected by the measurement time rather than ozone treatments. Ozone treatments provided significant inactivation on total aerobic mesophilic bacteria and total mold and yeast of the endogenous bacteria revealing maximum of 5.31 and 6.15 log reductions, respectively. It was concluded that ozone treatment at 12.5 g/m3 for 5 min can be utilized to treat corn seeds as these treatment parameters provided maximum inactivation on endogenous microflora with improvement of vigor and stronger seedling formation.

ABSTRACTThe aim of this study is to examine the effects of ozone treatment applied at two different times, followed by the in vitro application of a reductant solution, on the shear bond strength of four different restorative materials to enamel and dentin. A total of 400 caries-free human molar teeth were randomly divided into enamel and dentin groups, and each was divided into five subgroups. The O20 group received 20-s ozone, O20 + R received 20-s ozone+reductant solution, O80 received 80-s ozone, O80 + R received 80-s ozone+reductant solution, and C was the control group. Each subgroup was then divided into four more subgroups based on restorative material (i.e., nanohybrid resin composite, silorane-based microhybrid resin composite, compomer, or conventional capsulated glass ionomer cement). After water storage for seven days, shear bond-strength data (MPa) were measured using a universal testing machine at a crosshead speed of 0.5 mm/min until fracture, and failure types were examined. The effects of ozone and ozone+reductant applications on enamel and dentin were examined via scanning electron microscopy (SEM). Bond strength data were statistically evaluated using a three-way analysis of variance and Tukey’s honestly significant difference test (a= 0.05). The bond strength of the control group was like that of the O20 group (p > 0.05), but it was higher than all other groups regardless of the type of restorative material or tooth structure (p < 0.05). Adhesive-type failures were found in most groups. Via SEM examinations, it was observed that ozone applications did not change the enamel morphology, but they did cause narrowing of the dentinal tubule openings in O80 + R.

ABSTRACTAflatoxins are one of the highly toxic secondary metabolites with high decomposition temperatures, ranging from 237 °C to 306 °C. Therefore, non-thermal treatments are preferred to ensure safe food while preserving food quality. High voltage atmospheric cold plasma (HVACP) is a novel non-thermal technology with the potential to reduce contaminants (e.g. mycotoxins) owing to reactive species such as ozone. Therefore, the aim of this study was to investigate the efficacy of HVACP to degrade Aflatoxin M1 (AFM1) in pure water. A dielectric barrier discharge HVACP was performed at 90 kV using modified air (MA65: 65% O2, 30% CO2, 5% N2) fill gas for 1, 3, and 5 min in a direct and indirect mode with no post-treatment or 4.0 h post-storage at room temperature. The chemical properties of water were evaluated. Ozone concentration in both gas and liquid phases was also measured. A 77% reduction of AFM1 was observed after 1 min of direct treatment with no post-treatment storage. The nitrate and peroxide contents after 1 min of direct treatment were 4.50 ± 0.70 and 9.5 ± 0.70 mg/L, respectively. Longer treatment time and direct mode of exposure resulted in a higher ozone concentration in either the gas or liquid phase. These results demonstrate the potential of HVACP as a non-thermal treatment for reducing AFM1 concentration. HVACP was capable of significantly degrading AFM1 using a very short treatment time and 4.0-h post-treatment storage.

ABSTRACTSince phosphorus (P) is a nonrenewable element essential for life, it is extremely important to understand its potential supply sources. This paper describes the behavior of P during the ozonation of waste activated sludge (WAS) as it is an important pool of P. Also, we investigated whether ozonation of WAS could be an effective method for both P recovery in solution and its bio- and plant-availability in solid residues based on the analysis by the Standards, Measurements, and Testing Program. The results showed that P was enriched in WAS at concentrations above 23 mg/g. Phosphorus transferred from the solid phase to the liquid phase, and the total P content in the liquid phase increased from 1.67 to 40.68 mg/L as the ozone dosage increased from 0 to 0.20 g O3/g MLSS. PO43–P was the main form of P in the liquid phase after ozonation, which is beneficial for P recovery. The P fraction analysis revealed that the released P mainly came from apatite P (AP) during ozonation. Additionally, P was more available in solid residues as the proportion of bio-available P (non-apatite inorganic P (NAIP) + organic P (OP)) improved from 73.6% in the raw WAS to 91.7% at an ozone dosage of 0.20 O3/g MLSS. In addition, the solid residues were suitable for plant availability at a moderate Fe/P ratio (0.91) after ozonation. Thus, ozonation is recommended as the preferable solution to achieve an advanced P supply in both the liquid phase and solid residues.