Ppm Ozone Research Articles

Pesticide Residue Reduction on Curly Chili (Capsicum annum L.) Using Ozone Fine Bubble Technology.

Pesticide residues in curly chilies may cause health problems in consumers. Washing curly chilies using ozone fine-bubble water is a promising method for reducing pesticide residues. The aim of this study was to determine the optimal dose and duration to degrade pesticide residues, especially for profenofos, and to determine their effect on the shelf life and physical quality of curly chilies. After washing, the curly chilies were stored at room temperature and observed every two days. The results showed that washing with 1 ppm ozone fine bubble water for 10 min was effective in reducing profenofos residue on curly chili by up to 89.8% without reducing its quality. The shelf life of curly chilies was observed, and they started losing their commercial value after 6-8 days.

Effect of ozone, hydrogen peroxide, and chlorine solution in reduction of chlorpyrifos and cypermethrin residues from cauliflower

The extensive utilization of chlorpyrifos and cypermethrin in agriculture raises concerns regarding the accumulation of pesticide residues in human food, posing a threat to human health. This study aimed to investigate the effect of ozonation on cauliflower to decrease the level of pesticides. Cypermethrin and organophosphate chlorpyrifos were applied to cauliflower at specific doses. High-performance liquid chromatographic techniques were employed to detect pesticide residues in cauliflower. The effects of common oxidizers (hydrogen peroxide, chlorine, and ozone) on the reduction of pesticide residues were investigated. Solutions of hydrogen peroxide (10 and 100 ppm), chlorine (10 and 100 ppm), and ozone (10 and 100 ppm) were prepared, and the cauliflower sample was immersed for 20 min. The immersion in 10 ppm hydrogen peroxide solution reduced chlorpyrifos and cypermethrin by 68 and 65%, respectively. Meanwhile, at 100 ppm hydrogen peroxide solution, the reduction rates of chlorpyrifos and cypermethrin residues were 72 and 75%, respectively. Immersion in ozone solution at 10 ppm concentration reduced chlorpyrifos and cypermethrin by 58 and 57%, respectively. At 100 ppm ozone, chlorpyrifos was reduced up to 64%, and cypermethrin reduction was 74%. Chlorine immersion at 10 ppm reduced chlorpyrifos residues by 68% and cypermethrin residues by 81%, while a 100 ppm chlorine solution reduced chlorpyrifos residues by 100% and cypermethrin residues by 84%. From these results, it was concluded that chlorine was the most effective of all the cleaning solutions to remove pesticides from vegetables.

A-site doped LaFeO3 perovskite for highly active O3 catalytic decomposition

Nowadays, the treatment of ozone has become critically important due to the health risks caused by even minimal amount of ozone in the ambient air. In this work, LaFeO3 doped with Mg, Ca, Sr and Ce on A-site are synthesized by sol-gel method and adopted as a highly active ozone decomposition catalyst. The results show that the Ce doped LaFeO3 exhibits the highest catalytic activity with the optimal doping concentration marked as La0.5Ce0.5FeO3. It reaches high conversion efficiency of 97 % and 90 % to 1000 ppm ozone at high weight hourly space velocity of 720,000 and 1440,000 mL g−1 h−1, which is one of the highest in the literature. The distortion of [FeO6] octahedra reached the maximum when the doping amount of Ce was 0.5 as revealed by X-ray diffraction and Rietveld fitting. The high ozone catalytic activity could be assigned to the easy electron loss from eg orbit caused by high crystal field splitting energy, abundant oxygen vacancies resulting from the biggest distortion of [FeO6] octahedra and quick transfer between Fe2+ and Fe3+.

Advanced oxidation of Arsenic(III) to Arsenic(V) using ozone nanobubbles under high salinity

Arsenic, a highly toxic element, is present in various water resources as As(III) and/or As(V). The removal of As(V) using adsorption is considered to be easier than the removal of As(III). In this work, we report the oxidation of As(III) to As(V) using ozone nanobubbles. Ozone has been widely used in the advanced oxidation process (AOP) to remove organics and inorganics in wastewater. The major advantage of ozone nanobubbles is their enhanced half-life, which leads to higher ozone solubility in water. In addition, the rate of mass transfer by using nanobubbles can be enhanced drastically. The effect of ozone flow rates, initial As(III) concentrations, pH levels, and the presence of salt is systematically studied in this work. The present results revealed that ozone nanobubbles positively impacted the oxidation of As(III) to As(V). AOP process based on O3 NBs (nanobubbles) was most efficient with 99 % oxidation rates of 1 ppm of As(III) within 20 minutes at 6.5 ppm ozone concentrations. An acidic pH of 3–7 promoted quick oxidation due to the high mass transfer coefficient of ozone nanobubbles. About ∼70 % degradation of As(III) to As(V) was achieved with 0.10854 min-1 rate constant at acidic (pH = 3) compared to ∼39 % degradation with 0.046 min-1 rate constant at pH =11. The presence of salt (∼50 mM) in the solution not only hindered the ozone mass transfer coefficient but also reduced the stability of nanobubbles. The detection of reactive oxygen species, particularly hydroxyl radical was unravelled by utilizing 2-propanol as a scavenger.

P‐95: Exploration of Microbial Control Methods in Wet Cleaning Equipment during LCD Production Process

During the cleaning process of LCD production, the internal environment of wet cleaning equipment is conducive to microbial growth and can easily form biofilms. The shedding of these biofilms can result in product defects. This study employed 0.25 ppm ozone water to pass through the tank inside the wet washing equipment, which increased the number of days that the tank remained clean from 20 days to more than 130 days. And the lifespan of the filter has been extended from 10 days to over 60 days.

Altered metabolome and microbiome associated with compromised intestinal barrier induced hepatic lipid metabolic disorder in mice after subacute and subchronic ozone exposure

Exposure to ozone has been associated with metabolic disorders in humans, but the underlying mechanism remains unclear. In this study, the role of the gut-liver axis and the potential mechanism behind the metabolic disorder were investigated by histological examination, microbiome and metabolome approaches in mice during the subacute (4-week) and subchronic (12-week) exposure to 0.5 ppm and 2.5 ppm ozone. Ozone exposure resulted in slowed weight gain and reduced hepatic lipid contents in a dose-dependent manner. After exposure to ozone, the number of intestinal goblet cells decreased, while the number of tuft cells increased. Tight junction protein zonula occludens-1 (ZO-1) was significantly downregulated, and the apoptosis of epithelial cells increased with compensatory proliferation, indicating a compromised chemical and physical layer of the intestinal barrier. The hepatic and cecal metabolic profiles were altered, primarily related to lipid metabolism and oxidative stress. The abundance of Muribaculaceae increased dose-dependently in both colon and cecum, and was associated with the decrease of metabolites such as bile acids, betaine, and L-carnitine, which subsequently disrupted the intestinal barrier and lipid metabolism. Overall, this study found that subacute and subchronic exposure to ozone induced metabolic disorder via disturbing the gut-liver axis, especially the intestinal barrier. These findings provide new mechanistic understanding of the health risks associated with environmental ozone exposure and other oxidative stressors.

Exposure to Ozone Downregulates Bcl-2 and Increases Executing Caspases-3 and -8 in the Hippocampus, Frontal Cortex, and Cerebellum of Rats.

Introduction Ozone (O3) is one of the most prevalent atmospheric pollutants, arising from a photochemical reaction between volatile organic compounds (VOC), nitrogen oxides (NOx), and sunlight.O3 triggers oxidative stress, resulting in lipid oxidation, inflammation, alterations in metabolic and cellular signaling, and potentially initiating cell death in vulnerable brain regions.Inflammation and oxidative stress are recognized for their ability to induce cell death, primarily through the apoptosis pathway, involving various proteins that participate in this process via two pathways: intrinsic and extrinsic. Objective This study aims to identify the expression of pro-apoptotic proteins and Bcl-2 in the frontal cortex, cerebellum, and hippocampus of rats exposed to O3 acutely. Methods Two groups of 20 Wistar rodents (250-300 g) were established. The control group (n=10) was exposed to unrestricted polluted air for 12 hours, while the experimental group (n=10) was exposed to 1 ppm of O3. After exposure, the animals were sacrificed for immunofluorescence and Western blot analysis. Using a t-test, the arbitrary units of pro-apoptotic proteins and Bcl-2 were compared between the two groups. Results Significant increases in caspase-8 and caspase-3 activation were found in the O3-exposedgroup compared to the control group, specifically in the frontal cortex, cerebellum, and hippocampus. Additionally, notable changes in Bcl-2 expression were observed in these brain regions. The TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay further indicated significant differences in immunopositivity between the groups in the same areas. However, intrinsic apoptotic proteins such as Bax, VDAC1, and cytochrome-c did not show significant differences between the groups within these structures. Western blotanalyses aligned with the immunofluorescence results, showing statistically significant concentrations of caspase-8 in the cerebellum, caspase-3 in the hippocampus, and Bcl-2 in the frontal cortex in the O3exposed group. Conversely, proteins like Bax, cytochrome-c, and VDAC1 did not exhibit significant differences in all analyzed structures. Conclusions This study demonstrates that acute exposure to 1 ppm of ozone can trigger neuronal apoptosis in the frontal cortex, hippocampus, and cerebellum of rats, primarily through the activation of the extrinsic apoptosis pathway via caspase-8 and caspase-3. Additionally, it causes a reduction in Bcl-2 expression, an essential antiapoptotic protein. Despite not observing the activation of intrinsic pathway proteins like BAX, VDAC, or cytochrome-c, the study suggests that chronic O3 exposure might promote cell death by activating this pathway, requiring further long-term research.

Templated Synthesis of Cu2S Hollow Structures for Highly Active Ozone Decomposition

Nowadays, it is highly desired to develop highly active and humidity-resistive ozone decomposition catalysts to eliminate the ozone contaminant, one of the primary pollutants in the air. In this work, a series of Cu2S hollow structured materials were rapidly synthesized using different structured Cu2O templates. The Cu2S from porous Cu2O showed the highest ozone catalytic decomposition efficiency of >95% to 400 ppm ozone with a weight hourly space velocity of 480,000 cm3·g−1·h−1 in dry air. Importantly, the conversion remained >85% in a high relative humidity of 90%. The mechanism was explored by diffusive reflectance infrared spectroscopy which showed the decomposition intermediate of O22−, and X-ray photoelectron spectroscopy revealed the dual active site of both Cu and S. The EPR and UPS characterization results also explained the superiority of porous Cu2S catalysts from the material itself. All these results show the effective decomposition of ozone by Cu2S, especially in harsh environments, promising for active ozone elimination.

Reduced graphene oxide-cuprous oxide composites for low concentration ozone detection

In this research, cuprous oxide (pristine Cu2O) and rGO (reduced graphene oxide)-doped Cu2O were prepared using a simple synthetic route and adopted as sensitive materials for ozone detection. The microstructural, morphological and compositional properties of as-prepared samples have been analyzed by several characterization techniques including X-ray diffraction (XRD), High resolution transmission electron microscopy (HRTEM), Energy dispersive spectrometer (EDS), UV-Visible spectrophotometer (UV–vis), Multi-functional field emission scanning electron microscope (FESEM), X-ray Photoelectron Spectroscopy (XPS) and Brunauer-Emmett-Teller (BET). Meanwhile, the sensing features of as-prepared samples have been investigated carefully and the as-prepared 0.5 wt% rGO-Cu2O exhibited best ozone sensing properties, such as high stability, sensitivity and selectivity. It can be found that the response value of 0.5 wt% rGO-Cu2O-based sensor towards 20 ppb ozone and 1 ppm ozone were 9.2/1734, respectively, and the corresponding response and recovery times were 11/64 s and 11/411 s, respectively. More importantly, the detection limit of the 0.5 wt% rGO-Cu2O sensor was as low as 0.1 ppb. Furthermore, the possible mechanism for the enhanced sensing performance of the as-prepared rGO-Cu2O has been discussed.

Engineering the Crystal Facet of Monoclinic NiO for Efficient Catalytic Ozonation of Toluene.

Modulating oxygen vacancies of catalysts through crystal facet engineering is an innovative strategy for boosting the activity for ozonation of catalytic volatile organic compounds (VOCs). In this work, three kinds of facet-engineered monoclinic NiO catalysts were successfully prepared and utilized for catalytic toluene ozonation (CTO). Density functional theory calculations revealed that Ni vacancies were more likely to form preferentially than O vacancies on the (110), (100), and (111) facets of monoclinic NiO due to the stronger Ni-vacancy formation ability, further affecting O-vacancy formation. Extensive characterizations demonstrated that Ni vacancies significantly promoted the formation of O vacancies and thus reactive oxygen species in the (111) facet of monoclinic NiO, among the three facets. The performance evaluation showed that the monoclinic NiO catalyst with a dominant (111) facet exhibits excellent performance for CTO, achieving a toluene conversion of ∼100% at 30 °C after reaction for 120 min under 30 ppm toluene, 210 ppm ozone, 45% relative humidity, and a space velocity of 120 000 h-1. This outperformed the previously reported noble/non-noble metal oxide catalysts used for CTO at room temperature. This study provided novel insight into the development of highly efficient facet-engineered catalysts for the elimination of catalytic VOCs.

Aqueous Ozone Efficacy for Inactivation of Foodborne Pathogens on Vegetables Used in Raw Meat-Based Diets for Companion Animals

The present study evaluates the efficacy of a batch wash ozone sanitation system (BWOSS) and spray wash ozone sanitation system (SWOSS) against Listeria monocytogenes (two strains) and Salmonella enterica subsp. enterica (three serovars) inoculated on the surface of carrots, sweet potatoes, and butternut squash, commonly used in raw meat-based diets (RMBDs) marketed for companion animals such as dogs and cats. Produce either remained at room temperature for 2 h or were frozen at −20°C and then tempered overnight at 4°C to mimic the preprocessing steps of a raw pet food processing operation (‘freeze-temper’) prior to ozone treatment. Two ozone concentrations (0 and 5 ppm) were applied for either 20 s or 60 s for BWOSS and 20 s for SWOSS. Based on an ANOVA, BWOSS data showed no significant difference (P > 0.05) in microbial reduction between 0 and 5 ppm ozone concentration across all treatment durations for each produce type. BWOSS resulted in mean microbial reductions of up to 1.56 log CFU/mL depending on the treatment time and produce type. SWOSS data were analyzed using a generalized linear model with Quasipoisson errors. Freeze-tempered produce treated with SWOSS had a higher bacterial log reduction at 5 ppm ozone compared to 0 ppm ozone (P = 0.0013) whereas room temperature produce treated with SWOSS did not show any significant difference in microbial reduction between ozone concentrations. The potential to mitigate microbial cross-contamination was also investigated during SWOSS treatment. The results indicate that 5 ppm ozone decreased pathogens in the rinsate and proximal surfaces by 0.63–1.66 log CFU/mL greater than no ozone depending on the pathogen and sample. Overall, data from this study indicate that SWOSS would be more effective compared to BWOSS in reducing the microbial load present on the surface of root tubers and squash subjected to freezing and thawing and has the potential to mitigate cross-contamination within RMDB manufacturing environments.

Biological effects of air pollution on the function of human skin equivalents.

The World Health Organization reports that 99% of the global population are exposed to pollution levels higher than the recommended air quality guidelines. Pollution-induced changes in the skin have begun to surface; however, the effects require further investigation so that effective protective strategies can be developed. This study aimed to investigate some of the aging-associated effects caused by ozone and particulate matter (PM) on human skin equivalents. Full-thickness skin equivalents were exposed to 0.01 μg/μL PM, 0.05 μg/μL PM, 0.3 ppm ozone, or a combination of 0.01 μg/μL PM and 0.3 ppm ozone, before skin equivalents and culture medium were harvested for histological/immunohistochemical staining, gene and protein expression analysis using qPCR, Western blotting, and ELISA. Markers include MMP-1, MMP-3, COL1A1, collagen-I, 4-HNE, HMGCR, and PGE2. PM was observed to induce a decrease in epidermal thickness and an enhanced matrix building phenotype, with increases in COL1A1 and an increase in collagen-I protein expression. By contrast, ozone induced an increase in epidermal thickness and was found to induce a matrix-degrading phenotype, with decreases in collagen-I gene/protein expression and increases in MMP-1 and MMP-3 gene/protein expression. Ozone was also found to induce changes in lipid homeostasis and inflammation induction. Some synergistic damage was also observed when combining ozone and 0.01 μg/μL PM. The results presented in this study identify distinct pollutant-induced effects and show how pollutants may act synergistically to augment damage; given individuals are rarely only exposed to one pollutant type, exposure to multiple pollutant types should be considered to develop effective protective interventions.

Removal of binary and ternary synergistic mixtures of ozone and VOCs by activated carbon filter: Mathematical modelling

Evaluating the activated carbon filter's performance in removing gaseous pollutants is essential to determining the filter maintenance schedule for indoor environments. This paper describes the development of a mathematical model to predict an activated carbon filter's performance for removing mixtures of ozone and volatile organic compounds (toluene and limonene) at their low-level concentrations in typical indoor environments. Mass transfer equations were employed to estimate the filter's dynamic behaviour by including the reaction rates of ozone with carbon surfaces and the reactive volatile organic compound, as well as the adsorption isotherm for a single volatile organic compound or binary mixtures of volatile organic compounds. The reaction rate constant for the ozone-limonene reaction was calculated by fitting the model to the experiment results of their binary mixture at 9 ppm of limonene and 0.1 ppm of ozone. Additionally, the ozone-exposed filters at 0.1 ppm were used to perform adsorption tests to determine the parameters of the Dubinin-Radushkevich isotherm using experimental results at 9, 30, 50, 70, and 90 ppm of volatile organic compounds. The Dubinin-Radushkevich isotherm was extended using the volume exclusion theory to consider the effect of by-products on the removal modelling of the binary mixture of ozone and limonene and the ternary mixture of ozone, limonene, and toluene.The model was able to show the reduced accessibility of the surface of activated carbon for reaction with ozone because of the adsorption of volatile organic compounds and generated by-products (keto-limonene and carvone). The initial influence is of minor magnitude; however, as the surface load intensifies, its significance can progressively amplify over time. Pre-exposing the filter to ozone prior to conducting adsorption tests was able to capture the average change in the adsorption properties of the filter. These considerations in the modelling result in a remarkable predictive capability in determining the breakthrough behaviour of the filter in removing the binary or ternary mixture of ozone and volatile organic compounds at various concentrations. The insignificant effect of the homogeneous reaction between ozone and limonene for the investigated experimental setup was confirmed by comparing the predictions made by the proposed model with those made by another model that considers the homogeneous reaction. Finally, the sensitivity analysis revealed that the model is more sensitive to adsorption isotherm parameters compared to the reaction kinetic parameter between ozone and limonene.

Effects of low concentrations of ozone gas exposure on percutaneous oxygen saturation and inflammatory responses in a mouse model of Dermatophagoides farinae-induced asthma.

Ozone gas is widely used in hospitals as well as homes to control COVID-19 infection owing to its cost-effectiveness. Safety standard value and the tolerable value of ozone gas are set at 0.05ppm and 0.1ppm, respectively, in developed countries; however, this value was principally determined for healthy individuals, and the risks associated with ozone gas inhalation in patients with pulmonary diseases remains unknown. Recently, we demonstrated that 0.1ppm ozone gas exposure significantly aggravates the symptoms of acute lung injury in mice. In the present study, we further examined the influence of ≤ 0.1ppm ozone gas exposure on percutaneous oxygen saturation (SpO2) and pro-inflammatory responses in a mouse model of asthma. Female BALB/c mice were subjected to repetitive intranasal sensitization of Dermatophagoides farinae to generate a mouse model of asthma. Inhalation exposure of ozone gas (0.1, 0.03, 0.01ppm), generated using an ultraviolet lamp, was performed for five consecutive days immediately before the final sacrifice. There were no abnormal findings in control mice exposed to 0.1ppm ozone; however, 0.1ppm ozone exposure significantly reduced the SpO2 level in asthmatic mice. Histological evaluation and gene expression analysis revealed that pro-inflammatory cytokine levels were significantly increased in mice exposed to 0.1ppm ozone, indicating that 0.1ppm ozone exposure affects the development of asthma symptoms. Notably, 0.03 and 0.01ppm ozone exposure did not have any effects even in asthmatic mice. Our findings indicate that the tolerable level of ozone gas should be adjusted for individuals based on a history of respiratory disorders.

Multi-tissue transcriptomic and serum metabolomic assessment reveals systemic implications of acute ozone-induced stress response in male Wistar Kyoto rats.

Air pollutant exposures have been linked to systemic disease; however, the underlying mechanisms between responses of the target tissue and systemic effects are poorly understood. A prototypic inducer of stress, ozone causes respiratory and systemic multiorgan effects through activation of a neuroendocrine stress response. The goal of this study was to assess transcriptomic signatures of multiple tissues and serum metabolomics to understand how neuroendocrine and adrenal-derived stress hormones contribute to multiorgan health outcomes. Male Wistar Kyoto rats (12-13 weeks old) were exposed to filtered air or 0.8 ppm ozone for 4-hours, and blood/tissues were collected immediately post-exposure. Each tissue had distinct expression profiles at baseline. Ozone changed 1,640 genes in lung, 274 in hypothalamus, 2,516 in adrenals, 1,333 in liver, 1,242 in adipose, and 5,102 in muscle (adjusted p-value < 0.1, absolute fold-change > 50%). Serum metabolomic analysis identified 863 metabolites, of which 447 were significantly altered in ozone-exposed rats (adjusted p-value < 0.1, absolute fold change > 20%). A total of 6 genes were differentially expressed in all 6 tissues. Glucocorticoid signaling, hypoxia, and GPCR signaling were commonly changed, but ozone induced tissue-specific changes in oxidative stress, immune processes, and metabolic pathways. Genes upregulated by TNF-mediated NFkB signaling were differentially expressed in all ozone-exposed tissues, but those defining inflammatory response were tissue-specific. Upstream predictor analysis identified common mediators of effects including glucocorticoids, although the specific genes responsible for these predictors varied by tissue. Metabolomic analysis showed major changes in lipids, amino acids, and metabolites linked to the gut microbiome, concordant with transcriptional changes identified through pathway analysis within liver, muscle, and adipose tissues. The distribution of receptors and transcriptional mechanisms underlying the ozone-induced stress response are tissue-specific and involve induction of unique gene networks and metabolic phenotypes, but the shared initiating triggers converge into shared pathway-level responses. This multi-tissue transcriptomic analysis, combined with circulating metabolomic assessment, allows characterization of the systemic inhaled pollutant-induced stress response.

Investigation of Different Ozone Gas Doses Treatments on Broccoli (Brassica oleracea var. italica) Postharvest Quality During Cold Storage

At postharvest, the main factor for the fruit and vegetable quality protection is to apply low storage temperature. Also, by the developing technology, alterative protection techniques start to come into prominence in addition cold storage. In a summary, the purpose of these technologies is to preserve food quality for longer time and to provide increasing of shelf-life of foods. One of the alternatives preserving technologies that has taken importance at recent years is ozone technology. In this study, different dozes of ozone gas effect on the broccoli quality were investigated. 0.05 ppm and 0.3 ppm ozone treatments were applied to samples that were kept in the vegetable compartment at refrigerator. Broccoli samples were evaluated with regards to vitamin C, chlorophyll, weight loss, total viable and mold-yeast count and visual quality parameters. As a result, it was indicated that ozone treatment has positive effects on vitamin C, chlorophyll, weight loss and visual quality during cold storage whereas hardness, total viable and mold-yeast count values do not be affected by ozone application.

A cobalt-vacant Co3O4 as a stable catalyst for room-temperature decomposition of ozone in humid air

Conventionally ozone-decomposition catalysts such as MnO2 face the gradual deactivation due to occupation of reactive site, i.e., oxygen vacancy by intermediates like O22- or ubiquitous water vapor in air. Herein, we synthesized a Co2+-vacant Co3O4 (Co3−xO4) with dominant exposure of (110) facets, it maintained superior efficiency of 98% in decomposing 100 ppm ozone over 180 h under the space velocity of 1200 L/g·h at 25 ℃ and relative humidity (RH) of 50%, well beyond the performance of any reported metal oxides catalysts. Especially, it kept stable efficiency even under RH 90% and ultrahigh space velocity of 6000 L/g·h. A new ozone decomposition mechanism under humid conditions is revealed, i.e., the Co2+ vacancy significantly promotes O3 adsorption and the hydroxylation of coordination-unsaturated oxygen (CUO), and Co3+ work together with surface OH group to decompose ozone avoiding the deactivation. This study demonstrates a new way, i.e., creating metal vacancy rather than oxygen vacancy to design stable and efficient catalysts for ozone decomposition under humid conditions.

Microbiological and physicochemical quality of tilapia fillets treated with ozone and chlorine solution and stored under refrigeration

Fish are foods of high nutritional value for the human diet. However, they deteriorate easily due to microbial activity. The combined action of sanitizing solutions on fillets, the antimicrobial and physicochemical effects of aqueous ozone and chlorine used to wash fillets were investigated immediately after application and during storage. The fillets were treated with demineralized water (control), 5 ppm chlorine solution (Cl), 5 ppm ozone solution (Oz) or 5 ppm chlorine solution with 5 ppm ozone (Cl+Oz). The proximate composition and pH of the fillets were not altered immediately after treatment. The mesophilic count decreased by 0.49 log CFU/g at Cl and 0.56 log CFU/g at Cl+Oz. The Cl treatment showed lower values of lipid oxidation, and the control and Cl treatments showed lower values for total volatile base nitrogen (TVB-N). The treatments did not differ from each other during storage; increases in lipids, TVB-N, lipid oxidation and mesophilic and psychrotrophic counts, as well as a reduction in proteins, were observed. These results were expected due to microbial degradation during storage. The results indicated that the combined action of the sanitizers regulated microbial activity better than the control but was not able to promote the shelf life of the product.

Catalysts for highly water-resistant catalytic decomposition of ozone: Hausmannite Mn3O4 on exposed (101) crystal surface

Recently, ozone pollution has gradually replaced PM2.5 as the main pollutant affecting air pollution. In this study, we synthesized a series of Mn3O4 catalysts by hydrothermal method changing the precursors and tested their activities at different relative humidity, gas volume space velocity of 150,000 h−1 and 5 ppm ozone. Remarkably, Mn3O4-SO4 prepared with MnSO4 as precursor showed excellent catalytic ozone decomposition activity, almost completely converting 5 ppm of ozone at different relative humidity ranges. Finally, the most active Mn3O4-SO4 catalyst was tested for its usability limit at RH= 90%, after 28 h of testing under high humidity conditions, it had retained successfully the complete decomposition of low concentrations of ozone. The catalysts were characterized by XRD, Raman, HRTEM, XPS, BET, H2O-TPD and in situ IR NH3 adsorption. The characterization analysis revealed that the Mn3O4-SO4 surface could exposed a highly active (101) crystalline surface with high specific surface area, excellent hydrophobicity as well as ozone adsorption capacity, which were highly favorable for ozone decomposition under high humidity conditions. In this work, Mn3O4 exhibits good catalytic activity, which provides an additional option for future studies of manganese oxides.

Coordination-Controlled Catalytic Activity of Cobalt Oxides for Ozone Decomposition.

Nowadays, it is still elusive and challenging to discover the active sites of cobalt (Co) cations in different coordination structures, though Co-based oxides show their great potency in catalytic ozone elimination for air cleaning. Herein, different Co-based oxides are controllably synthesized including hexagonal wurtzite CoO-W with Co2+ in tetrahedral coordination (CoTd2+) and CoAl spinel with dominant CoTd2+, cubic rock salt CoO-R with Co2+ in octahedral coordination (CoOh2+), MgCo spinel with dominant Co3+ in octahedral coordination (CoOh3+), and Co3O4 with mixed CoTd2+ and CoOh3+. The valences are proved by X-ray photoelectron spectroscopy, and the coordinations are verified by X-ray absorption fine structure analysis. The ozone decomposition performances are CoOh3+ ∼ CoOh2+ ≫ CoTd2+, and CoOh3+ and CoOh2+ show a lower apparent activation energy of ∼42-44 kJ/mol than CoTd2+ (∼55 kJ/mol). In specific, MgCo shows the highest decomposition efficiency of 95% toward 100 ppm ozone at a high space velocity of 1,200,000 mL/gh, which still retains at 80% after a long-term running of 36 h at room temperature. The high activity is explained by the d-orbital splitting in the octahedral coordination, favoring the electron transfer in ozone decomposition reactions, which is also verified by the simulation. These results show the promising prospect of the coordination tuning of Co-based oxides for highly active ozone decomposition catalysts.