Ozone degradation of tetracycline hydrochloride enhanced by magnetic nanofluid composed of Fe3O4 nanoparticles

Magnetic Fe3O4 nanoparticles were added into the aqueous phase to form nanofluid systems, in which ozone was used for the oxidation of tetracycline hydrochloride (TC) in the solution. The nanomaterials were characterized using SEM, XRD, EDS, and FT-IR. The effects of nanoparticles size, addition ratio, and number of cycles on the process of ozone oxidation of TC were investigated. The results indicated that the addition ratio of nanoparticles have a certain impact on the performance of ozone oxidation. When the addition ratio increased from 0.02% to 0.4%, the removal rate of TC in the solution was improved significantly. Besides, the particle size of nanoparticles showed a greater impact on ozone oxidation. At the nanoscale, Fe3O4 nanoparticles exhibited significant strengthening properties, which is attributed to the construction of nanofluid systems. The removal rate of TC in solution decreased obviously with the increase of nanoparticles size. The Fe3O4 nanoparticles with particle size of 20 nm showed the most significant effect on TC degradation. The recycling experiment showed that magnetic Fe3O4 nanoparticles had stable regeneration performance. For three times of recycling treatment, with a Fe3O4 addition ratio of 0.4%, the removal rate of TC reached 98.7%, 97.21%, and 96%, respectively. Based on the characterization results, the strengthening mechanism was analyzed. The experimental results indicated that construction of nanofluids systems could improve the utilization rate of ozone, and Fe3O4 nanoparticles were reusable and easily recyclable.

Effect of ozone gas on cultures of Candida albicans and Aspergillus fumigatus: evaluation of two ozonation devices

INTRODUCTION

Candida albicans and Aspergillus fumigatus are two important agents of Healthcare-associated infections. This study aimed to evaluate the antifungal activity of ozone (O3) gas produced by two commercial devices against cultures of these two species.

METHODOLOGY

Sterile plastic plates were inoculated with C. albicans and A. fumigatus and placed on a countertop at three distances (30 cm, 1 m, and 2 m) and three positions in relation to the wall (near, middle, and away), considering the source of O3. Plates were exposed to O3 for one hour and incubated. After incubation, the counting of colony-forming units was performed. As a control, an inoculated plate was incubated, without being exposed to O3. Tests were carried out with two different devices (namely, Mod.I and Mod.II), with the air conditioner on and off, in triplicate.

RESULTS

Both devices showed antifungal activity. Mod. I presented better results, due to a higher flow rate. The best activity was on plates at 30 cm, middle position. Contrarily, on plates at 2m, near the wall, the inhibition activity was lower. The best results were obtained with the air conditioner off. Candida albicans was more sensitive to O3 than A. fumigatus.

CONCLUSIONS

This method of decontamination by O3 gas shows potential due to its fast and easy execution. The establishment of new protocols for hygiene and hospital disinfection using this approach should be considered, which may reduce environmental contamination by fungi and, consequently, the burden of fungal infections.

Toxicity of commercial and pure forms of three nonsteroidal anti-inflammatory drugs in Xenopus laevis embryos before and after ozonation

In this study, the toxic and teratogenic effects of three commercial drugs and their active ingredients on Xenopus laevis embryos before and after ozonation were evaluated using the Frog Embryos Teratogenesis Assay-Xenopus (FETAX). First, the median lethal concentration (LC50) and, if data were available, the median effective concentration, teratogenic index and minimum growth inhibitory concentration were determined for each drug substance without ozonation. Then, the active substance amounts of three selected nominal concentrations (LC50/2, LC50, and LC50×2) of each test substance before ozonation were measured by HPLC analysis and the toxicity of these substances was evaluated after 2, 3, 4, and 5 h of ozonation. In addition, degradation products that may occur during ozonation were evaluated by LC-MS analysis. The 96-h LC50s of Dolphin-diflunisal, Dichloron-diclofenac sodium, and Apranax-naproxen drug-active substance pairs were determined to be 22.3 and 11.1, 25.7 and 18.7, and 47.8 mg active substance/L and 45.3 mg/L, respectively. According to the FETAX test results, the Dolphin-diflunisal drug-active ingredient pair did not cause growth retardation in exposed embryos. Dichloron-diclofenac sodium and Apranax-naproxen drug-active ingredient pairs were both teratogenic and growth inhibitory. In the second stage of the study, in which the effectiveness of ozonation in eliminating the toxic effects of drugs is evaluated, it is seen that ozonation is partially successful in eliminating the toxic effects of Dolphin-diflunisal and Dichloron-diclofenac sodium pairs, but insufficient for eliminating the effects of the Apranax-naproxen pair.

Immobilizing Bimetallic RuCo Nanoalloys on Few-Layered MXene as a Robust Bifunctional Electrocatalyst for Overall Water Splitting

Doping Co atoms into Ru lattices can tune the electronic structure of active sites, and the conductive MXene can adjust the electrical conductivity of catalysts, which are both favorable for improving the electrocatalytic activity of the catalyst for water splitting. Here, ruthenium-cobalt bimetallic nanoalloys coupled with exfoliated Ti3 C2 Tx MXene (RuCo-Ti3 C2 Tx ) have been constructed by ice-templated and thermal activation. Due to the strong interaction between the RuCo nanoalloys and conductive MXene, RuCo-Ti3 C2 Tx not only exhibits an excellent hydrogen evolution reaction (HER) performance with a low overpotential and Tafel slope (60 mV, 34.8 mV dec-1 in 0.5 M H2 SO4 and 52 mV, 38.7 mV dec-1 in 1 M KOH), but also good oxygen evolution reaction (OER) performance in an alkaline electrolyte (266 mV, 111.1 mV dec-1 in 1 M KOH). The assembled RuCo-Ti3 C2 Tx ||RuCo-Ti3 C2 Tx electrolyzer requires a lower potential (1.56 V) than does the Pt/C||RuO2 electrolyzer at 10 mA cm-2 . A boosted catalytic HER activity from immobilizing the RuCo nanoalloys on MXene was unveiled by density functional theory calculations. This study provides a feasible and efficient strategy for developing MXene-based catalysts for overall water splitting.

Phototransformation of Brominated Disinfection Byproducts and Toxicity Elimination in Sunlit-Ozonated Reclaimed Water

Ozonation is universally used during water treatment but can form hazardous brominated disinfection byproducts (Br-DBPs). While sunlight exposure is advised to reduce the risk of Br-DBPs, their phototransformation pathways remain insufficiently understood. Here, sunlight irradiation was found to reduce adsorbable organic bromine by 63%. Applying high-resolution mass spectrometry, the study investigated transformations of dissolved organic matter in sunlit-ozonated reclaimed water, revealing the number and abundance of assigned formulas decreased after irradiation. The Br-DBPs with O/C < 0.6 and MW > 400 Da were decreased or removed after irradiation, with the majority being CHOBr compounds. The peak intensity reduction ratio of CHOBr compounds correlated positively with double bound equivalent minus oxygen ratios but negatively with O/C, suggesting that photo-susceptible CHOBr compounds were highly unsaturated. Mass difference analysis revealed that the photodegradation pathways were mainly oxidation aligned with debromination. Three typical CHOBr molecular structures were resolved, and their photoproducts were proposed. Toxicity estimates indicated decreased toxicity in these photoproducts compared to their parent compounds, in line with experimentally determined values. Our proposed phototransformation pathways for Br-DBPs enhance our comprehension of their degradation and irradiation-induced toxicity reduction in reclaimed water, further illuminating their transformation under sunlight in widespread environmental scenarios.

Integrated Ozonation Ni-NiO/Carbon/g-C3N4 Nanocomposite-Mediated Catalytic Decomposition of Organic Contaminants in Wastewater under Visible Light

Developing a hybrid process for wastewater purification is of utmost importance to make conventional methods more efficient and faster. Herein, an effective visible light-active nickel-nickel oxide/carbon/graphitic carbon nitride (Ni-NiO/C/g-C3N4)-based nanocatalyst was developed. A hybrid process based on ozonation and Ni-NiO/C/g-C3N4 visible light photocatalysis was applied to decolourize the Congo red (CR), Alizarin Red S (ARS), and real dairy industry wastewater. The synthesized catalyst was characterized using scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), Χ-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and UV-Vis diffuse reflectance spectrophotometry (UV-Vis DRS). The factors affecting the catalytic process were evaluated, including contact time, solution pH, initial dye concentration, etc. The degradation rate of CR and ARS was compared between the photocatalysis, ozonation, and integrated photocatalytic ozonation (PC/O3) methods. The results showed 100% degradation of CR and ARS within 5 min and 40 min, respectively, by integrated PC/O3. The reusability of the modified catalyst was evaluated, and four successive regenerations were achieved. The modified Ni-NiO/C/g-C3N4 composite could be considered an effective, fast, and reusable catalyst in an integrated PC/O3 process for the complete decolourization of wastewater.

Hydrogen Peroxide Formation during Ozonation of Olefins and Phenol: Mechanistic Insights from Oxygen Isotope Signatures

Mitigation of undesired byproducts from ozonation of dissolved organic matter (DOM) such as aldehydes and ketones is currently hampered by limited knowledge of their precursors and formation pathways. Here, the stable oxygen isotope composition of H2O2 formed simultaneously with these byproducts was studied to determine if it can reveal this missing information. A newly developed procedure, which quantitatively transforms H2O2 to O2 for subsequent 18O/16O ratio analysis, was used to determine the δ18O of H2O2 generated from ozonated model compounds (olefins and phenol, pH 3-8). A constant enrichment of 18O in H2O2 with a δ18O value of ∼59‰ implies that 16O-16O bonds are cleaved preferentially in the intermediate Criegee ozonide, which is commonly formed from olefins. H2O2 from the ozonation of acrylic acid and phenol at pH 7 resulted in lower 18O enrichment (δ18O = 47-49‰). For acrylic acid, enhancement of one of the two pathways followed by a carbonyl-H2O2 equilibrium was responsible for the smaller δ18O of H2O2. During phenol ozonation at pH 7, various competing reactions leading to H2O2 via an intermediate ozone adduct are hypothesized to cause lower δ18O in H2O2. These insights provide a first step toward supporting pH-dependent H2O2 precursor elucidation in DOM.

Critical Review on Bromate Formation during Ozonation and Control Options for Its Minimization

Ozone is a commonly applied disinfectant and oxidant in drinking water and has more recently been implemented for enhanced municipal wastewater treatment for potable reuse and ecosystem protection. One drawback is the potential formation of bromate, a possible human carcinogen with a strict drinking water standard of 10 μg/L. The formation of bromate from bromide during ozonation is complex and involves reactions with both ozone and secondary oxidants formed from ozone decomposition, i.e., hydroxyl radical. The underlying mechanism has been elucidated over the past several decades, and the extent of many parallel reactions occurring with either ozone or hydroxyl radicals depends strongly on the concentration, type of dissolved organic matter (DOM), and carbonate. On the basis of mechanistic considerations, several approaches minimizing bromate formation during ozonation can be applied. Removal of bromate after ozonation is less feasible. We recommend that bromate control strategies be prioritized in the following order: (1) control bromide discharge at the source and ensure optimal ozone mass-transfer design to minimize bromate formation, (2) minimize bromate formation during ozonation by chemical control strategies, such as ammonium with or without chlorine addition or hydrogen peroxide addition, which interfere with specific bromate formation steps and/or mask bromide, (3) implement a pretreatment strategy to reduce bromide and/or DOM prior to ozonation, and (4) assess the suitability of ozonation altogether or utilize a downstream treatment process that may already be in place, such as reverse osmosis, for post-ozone bromate abatement. A one-size-fits-all approach to bromate control does not exist, and treatment objectives, such as disinfection and micropollutant abatement, must also be considered.

Optimization of stabilized anaerobic landfill leachate treatment using ozonation with metallic compound using response surface methodology

Malaysia encounters a consistent rise in the generation of solid waste and leachate on a daily basis. It should also be noted that leachate has a low degree of biodegradability (BOD5 /chemical oxygen demand [COD]), as shown by its BOD5 /COD ratio. Its high toxicity levels significantly threaten the environment, water bodies, and human well-being. High concentrations of COD, color, and ammoniacal nitrogen (NH3 -N) in leachate prevent this wastewater from being allowed to be discharged directly into the water body. Therefore, an effective process to remove the pollutant is desired. The aims of this study are to investigate the performance of ozonation with two metallic compounds, ZrCl4 and SnCl4 , and optimize their performance using response surface methodology (RSM). In this study, the performance of ozonation with ZrCl4 (O3 /ZrCl4 ) recorded better pollutant removals compared with the ozonation with tin tetrachloride (O3 /SnCl4 ), as seen in the removals of 99.8%, 93.5%, and 46.3% for color, COD, and NH3 -N, respectively. These removals were achieved by following the experimental model (optimum experiment condition) generated by RSM at O3 dosage of 31 g/m3 , COD and ZrCl4 dosage ratio (COD, mg/L/ZrCl4 , mg/L) of 1:1.35, with the pH solution of 8.78 and reaction time of 89 min. The R2 of each parameter for this model was recorded as 0.999 (COD), 0.999 (color), and 0.998 (NH3 -N), respectively. These data indicated that the model is well fitted as the predicted data by statistical calculation and in good agreement with the actual data. PRACTITIONER POINTS: The performance of O3 /ZrCl4 and O3 /SnCl4 was examined for remediate stabilized landfill leachate. The performance of O3 /ZrCl4 and O3 /SnCl4 was optimized using RSM, and a set of experimental models was generated and tested. O3 /ZrCl4 recorded the higher removal of COD, color, and NH3 -N compared with O3 /SnCl4 . At best condition, both methods recorded removal as 89% to 99.8% of pollutants in leachate and product clear effluent. This finding gives a new approach to treat landfill leachate effectively and efficiently.

Predicting ciprofloxacin and levofloxacin decomposition utilizing ozone micro-nano bubbles through the central composite design method

Antibiotics have several negative effects on aquatic ecosystems and are difficult to degrade using traditional water/wastewater treatment methods. As a result, new treatment techniques must be employed to eliminate these contaminants from aquatic environments. Research on the relationship between the decomposing process of antibiotics and different factors by new technologies is scarce. This research focuses on the capability of ozone micro-nano bubbles (OzMNBs) to eliminate the antibiotics ciprofloxacin (CIPR) and levofloxacin (LEVO) in aqueous solutions. We studied the CIPR and LEVO decomposition to different variables through the central composite design method. The main variables included pH, ozonation time, and initial antibiotic concentration. The correlation coefficients of the quadratic model obtained by using the software, Design Expert version 13.0.1. Analysis of variances proved the significance of models and main factors. Verification tests also confirmed that the final optimum conditions of the antibiotics decomposition were: pH 9, ozonation for 40 min and, initial antibiotic concentration of 5 mg/L. In optimum conditions, removal rate of about 97% and 100% was obtained for CIPR and LEVO, respectively. The order of influence of various factors on CIPR and LEVO decomposition were obtained and the interactions between the main factors were also investigated. At the last stage of the research, the efficiency of OzMNBs in the removal of total organic carbon and mineralization of the solutions containing CIPR and LEVO under optimum conditions was examined.

Experimental study of the removal NOx and SO2 from flue gas using the O3/H2O2, and O3/UV processes

The study investigates the effect of different parameters for the removal of SO2 and NOx through a wet process concurrently. Two separate processes have been compared for the removal of flue gases, that is, Ozone/UV and H2O2/UV. The research aims to develop a comparative study for the removal of SO2 and NOx simultaneously using Ozone/H2O2 and UV light and find the energy consumption (also known as EEO) for each process. Combining UV with O3 and H2O2 play a crucial role in generating hydroxyl radicals. Different combinations of Ozone/H2O2, flue gas, and UV intensity were studied at different pH and temperatures of the solution to achieve maximum removal of the flue gases. For, the ozonation process it was observed that the removal% of flue gases increases with increasing UV intensity, and at higher UV intensity (250 W), the removal% for NOx is 92% and SO2 is 95% simultaneously at optimum temperature 308 K. For H2O2/UV process (250 W UV intensity), removal% for NOx is 95% and SO2 is 100% at 313 K, 0.3 LPM flow rate of flue gases. The EEO values obtained for both processes were less than 1 for 95% NOx/SO2 removal efficiency.

Ecotoxicity of Diazinon and Atrazine Mixtures after Ozonation Catalyzed by Na+ and Fe2+ Exchanged Montmorillonites on Lemna minor

The toxicity of two pesticides, diazinon (DAZ) and atrazine (ATR), before and after montmorillonite-catalyzed ozonation was comparatively investigated on the duckweed Lemna minor. The results allowed demonstrating the role of clay-containing media in the evolution in time of pesticide negative impact on L. minor plants. Pesticides conversion exceeded 94% after 30 min of ozonation in the presence of both Na+ and Fe2+ exchanged montmorillonites. Toxicity testing using L. minor permitted us to evaluate the change in pesticide ecotoxicity. The plant growth inhibition involved excessive oxidative stress depending on the pesticide concentration, molecular structure, and degradation degree. Pesticide adsorption and/or conversion by ozonation on clay surfaces significantly reduced the toxicity towards L. minor plants, more particularly in the presence of Fe(II)-exchanged montmorillonite. The results showed a strong correlation between the pesticide toxicity towards L. minor and the level of reactive oxygen species, which was found to depend on the catalytic activity of the clay minerals, pesticide exposure time to ozone, and formation of harmful derivatives. These findings open promising prospects for developing a method to monitor pesticide ecotoxicity according to clay-containing host-media and exposure time to ambient factors.

Relationship between the Change in E/T Ratio and the Cooking Performance of Eucalyptus and Acacia Woods during Kraft Pulping Process

Lignin structure is an important factor affecting the cooking part of the pulping process. In this study, the effect of lignin side chain spatial configuration on cooking performance was analyzed, and the structural characteristics of eucalyptus and acacia during cooking were compared and studied by combining ozonation, GC-MS, NBO, and 2D NMR (¹H-¹³C HSQC). In addition, the changes in the lignin content of four different raw materials during the cooking process were studied via ball milling and UV spectrum analysis. The results showed that the content of lignin in the raw material decreased continuously during the cooking process. Only in the late cooking stage, when the lignin removal reached its limit, did the lignin content tend to be stable due to the polycondensation reaction of lignin. At the same time, the E/T ratio and S/G ratio of the reaction residual lignin also followed a similar rule. At the beginning of cooking, the values of E/T and S/G decreased rapidly and then gradually rose when they reached a low point. The different initial E/T and S/G values of different raw materials lead to the disunity of cooking efficiency and the different transformation rules of different raw materials in the cooking process. Therefore, the pulping efficiency of different raw materials can be improved using different technological means.

Use of ozonation technology to combat viruses and bacteria in aquatic environments: problems and application perspectives for SARS-CoV-2

COVID-19 is a global health threat with a large number of confirmed cases and deaths worldwide. Person-to-person transmission through respiratory droplets and contact with aerosol-infected surfaces are the main ways in which the virus spreads. However, according to the updated literature, the new coronavirus (SARS-CoV-2) has also been detected in aqueous matrices, with the main route of transmission being feces and masks from patients diagnosed with the disease. Given the emergence of public health and environmental protection from the presence of lethal viruses and bacteria, this review article aims to report the major challenges associated with the application of ozonation in water contaminated with viruses and bacteria, in order to clarify whether these communities can survive or infect after the disinfection process and if it is efficient. Available data suggest that ozonation is able to increase the inactivation effect of microorganisms by about 50% in the logarithmic range, reducing infectivity. In addition, the evidence-based knowledge reported in this article is useful to support water and sanitation safety planning and to protect human health from exposure to cited contaminants through water.

Role of Silica on Clay-Catalyzed Ozonation for Total Mineralization of Bisphenol-A

Catalytic ozonation for the total mineralization of bisphenol-A (BPA) from aqueous solution was investigated in the presence of various silica-based catalysts such as mesoporous silica, acid-activated bentonite (HMt) and montmorillonite-rich materials (Mt) ion-exchanged with Na⁺ and Fe²⁺ cations (NaMt and Fe(II)Mt). The effects of the catalyst surface were studied by correlating the hydrophilic character and catalyst dispersion in the aqueous media to the silica content and BPA conversion. To the best of our knowledge, this approach has barely been tackled so far. Acid-activated and iron-free clay catalysts produced complete BPA degradation in short ozonation times. The catalytic activity was found to strongly depend on the hydrophilic character, which, in turn, depends on the Si content. Catalyst interactions with water and BPA appear to promote hydrophobic adsorption in high Si catalysts. These findings are of great importance because they allow tailoring silica-containing catalyst properties for specific features of the waters to be treated.

Enhancing the Antimicrobial Effect of Ozone with Mentha piperita Essential Oil

This study aimed to obtain and analyse Mentha piperita essential oil (MpEO) for the prospect of being used as an enhancement agent for the antimicrobial potential of ozone against gram-positive and gram-negative bacteria and fungi. The research was done for different exposure times, and it gained time-dose relationships and time-effect correlations. Mentha piperita (Mp) essential oil (MpEO) was obtained via hydrodistillation and further analysed by using GC-MS. The broth microdilution assay was used to determine the strain inhibition/strain mass growth by using spectrophotometric optical density reading (OD). The bacterial/mycelium growth rates (BGR/MGR) and the bacterial/mycelium inhibition rates (BIR/MIR) after ozone treatment in the presence and absence of MpEO on the ATTC strains were calculated; the minimum inhibition concentration (MIC) and statistical interpretations of the time-dose relationship and specific t-test correlations were determined. The effect of ozone on the following tested strains at maximum efficiency was observed after 55 s of single ozone exposure, in order of effect strength: S. aureus > P. aeruginosa > E. coli > C. albicans > S. mutans. For ozone with the addition of 2% MpEO (MIC), maximum efficacy was recorded at 5 s for these strains, in order of effect strength: C. albicans > E. coli > P. aeruginosa > S. aureus > S. mutans. The results suggest a new development and affinity regarding the cell membrane of the different microorganisms tested. In conclusion, the use of ozone, combined with MpEO, is sustained as an alternative therapy in plaque biofilm and suggested as helpful in controlling oral disease-causing microorganisms in medicine.

Study on the Use of Ozone Water as a Chemical Decontamination Agent for Antineoplastic Drugs in Clinical Settings

The exposure of healthcare workers to antineoplastic drugs in hospitals has been recognized to be harmful. To minimize the risk of exposure, the removal of these drugs from work environments, such as compounding facilities, has been recommended. In our previous paper, the degradation and inactivation efficacy of ozone water, which is being introduced into Japanese hospitals as a chemical decontamination agent, was reported for its effects on typical antineoplastic drugs (gemcitabine, irinotecan, paclitaxel). This article aims to further investigate the efficacy of ozone water for eight antineoplastic drugs to clarify its application limitations. A small amount (medicinal ingredient: typically ca. 1.5 μmol) of formulation containing 5-fluorouracil, pemetrexed, cisplatin, oxaliplatin, cyclophosphamide, ifosfamide, doxorubicin, or docetaxel was mixed with 50 mL of ozone water (~8 mg/L), and the resulting solutions were analyzed by high-performance liquid chromatography over time to observe the degradation. Consequently, the ozonation was overall effective for the degradation of the drugs, however this varied depending on the chemical structures of the drugs and additives in their formulations. In addition, after the parent drugs were completely degraded by the ozonation, the degradation mixtures were subjected to 1H nuclear magnetic resonance spectroscopy and evaluated for mutagenicity against Salmonella typhimurium strains and cytotoxicity against human cancer cells. The degradation mixtures of cisplatin and ifosfamide were mutagenic while those of the other drugs were non-mutagenic. Further, the ozonation resulted in clear decreases of cytotoxicity for 5-fluorouracil, oxaliplatin, and doxorubicin, but increases of cytotoxicity for pemetrexed, cisplatin, cyclophosphamide, and ifosfamide. These results suggest that the ozone water should be restrictedly used according to the situation of contamination in clinical settings because the ozonation enhances toxicity depending on the drug even if degradation is achieved.

[Efficiency and Mechanism of O3-SBBR Combined Process for Advanced Treatment of Biochemical Effluent from Printing and Dyeing Industrial Park]

With the aim of addressing the difficult problem of biodegradable organic nitrogen in biochemical effluent of a printing and dyeing industrial park, the combined ozonation-sequencing batch biofilm reactor (O₃-SBBR) process was used for advanced treatment. The influencing factors and degradation kinetics were analyzed; quenching experiments were carried out; and the types of free radicals, succinate dehydrogenase activity, and denitrification function genes were determined. The results showed that the suitable ozonation condition was pH 8.0-8.5, O₃ concentration was approximately 35.0 mg·L^-1, O₃ dosage was approximately 100.0 mg·L^-1, and reaction time was 90.0-120.0 min. Organic nitrogen in the biochemical effluent by ozonation conformed to the pseudo first-order kinetic model, and the maximum rate constant k was 0.01035 min^-1 (experimental conditions:pH 8.0, ozone dosage 150.0 mg·L^-1, and ozone concentration 35.0 mg·L^-1). Ozonation significantly improved the denitrification performance of the sequencing biofilm batch reactor (SBBR), and the denitrification efficiency increased from 19.8% (SBBR) to 32.9% (O₃-SBBR). Ozonation could convert organic nitrogen and organic substances with strong toxicity and difficult biological utilization into small molecular substances with low toxicity and biodegradability. The abundance of functional genes (nirS, nirK, and nor) in the O₃-SBBR combined process was significantly higher than that in the single SBBR, which further confirmed that ozonation could improve the nitrogen removal performance of SBBR. The operation cost of the combined process was 0.74-1.07 yuan·m^-3, with good technical economy. This study provided a basis for the application of the O₃-SBBR combined process in the advanced treatment of biochemical effluent in printing and dyeing industrial parks.

Low-pressure ozone injection system: relationship between reaction kinetics and physical properties of grains

BACKGROUND

The ozonation of grains in a closed system at low pressure is a strategy with the potential for treating packaged products. Research is necessary to characterize the reaction kinetics of ozone in this type of injection system so that it is possible to design chambers and determine the ozone concentrations suitable for commercial-scale applications. The objective of this study was therefore to characterize the low-pressure ozone injection system in relation to the physical properties of the grains and determine possible changes in their quality. Samples (5 kg each) of common beans, cowpea beans, corn, popcorn kernels, paddy rice, and polished rice were exposed to ozone in a 70 L hypobaric chamber. Initially, the internal pressure of the chamber was reduced to 500 hPa. Then, ozone was injected at a concentration of 32.10 g m^-3 at a volumetric flow rate of 1 L min^-1 until reaching a pressure of 1000 hPa. To relate the decomposition of ozone to the grains that were being evaluated, different physical properties were determined, and quality analysis was conducted.

RESULTS

Ozone gas half-life outside and inside the package depended on the grain type. Ozone decomposition was quickest in polished rice and slowest in common beans. The half-life of the different grains ranged from 17.8 to 52.9 and 16.4 to 52.9 min, outside and inside the package, respectively. Considering the physical properties, specific surface (Ss), surface area (SA), and sphericity (φ) exhibited a significant correlation with the decomposition rate constant (k) of ozone. However, the variables volume (V), permeability (K), porosity (ε), and specific mass (ρ) showed no correlation with k.

CONCLUSION

The physical properties of grain influenced the reaction kinetics of ozone gas during the low-pressure injection process. Ozone gas injection at low pressures did not alter the quality attributes of the grains under study. © 2022 Society of Chemical Industry.

Ozone Diffusion through a Hollow Fiber Membrane Contactor for Pharmaceuticals Removal and Bromate Minimization

Recently, ozonation has been advocated as a solution to tackle emerging contaminants. Hollow fiber membrane contactors (HFMC) have a lower residual ozone concentration than bubble reactors that could limit the formation of potential ozonation by-products, especially bromates that are regulated in drinking water. The aim of this study was to evaluate ozonation with HFMC for pharmaceutical abatement and bromate minimization compared to bubble columns in wastewater. A HFMC, composed of 65 polytetrafluoroethylene hollow fibers with a 0.45 mm/0.87 mm inner/external diameter and a 0.107 m² exchange surface, was used for the ozonation of real-treated wastewater spiked with 2 µM of p-chlorobenzoic acid (p-CBA) and 3 mg.L^-1 of bromide. p-CBA was tracked to monitor the production of strongly-oxidant hydroxyl radicals from the decomposition of the molecular ozone. At 100% p-CBA abatement, 1600 µg.L^-1 of bromate was formed with the HFMC, whereas 3486 µg.L^-1 was formed with the bubble column. These results demonstrate that HFMC can produce a significant amount of hydroxyl radicals while limiting bromate formation in real-treated wastewater. The test water was also spiked with carbamazepine and sulfamethoxazole to evaluate the abatement efficiency of the process. Short contact times (approximately 2s) achieved high rates of pharmaceuticals removal without bromate formation.

Pharmaceutical Transformation Products Formed by Ozonation-Does Degradation Occur?

The efficiency of an advanced oxidation process (AOP) using direct and indirect ozonation for the removal of pharmaceutical residues from deliberately spiked deionized water was examined. Both direct and indirect ozonation demonstrated 34% to 100% removal of the parent compounds. However, based on the products' chemical structure and toxicity, we suggest that despite using accepted and affordable ozone and radical concentrations, the six parent compounds were not fully degraded, but merely transformed into 25 new intermediate products. The transformation products (TPs) differed slightly in structure but were mostly similar to their parent compounds in their persistence, stability and toxicity; a few of the TPs were found to be even more toxic than their parent compounds. Therefore, an additional treatment is required to improve and upgrade the traditional AOP toward degradation and removal of both parent compounds and their TPs for safer release into the environment.

Degradation of malathion and carbosulfan by ozone water and analysis of their by-products

BACKGROUND

Treatment by ozone water is an emerging technology for the degradation of pesticide residues in vegetables. The ozone dissolved in water generates hydroxyl radicals (^· OH), which are highly effective in decomposing organic substances, such as malathion and carbosulfan.

RESULTS

We found that washing pak choi with 2.0 mg L^-1 ozone water for 30 min resulted in 58.3% and 38.2% degradation of the malathion and carbosulfan contents respectively, and the degradation rates of these pure pesticides were 83.0% and 66.3% respectively. In addition, the 'first + first'-order reaction kinetic model was found to predict the trend in the pesticide content during ozone water treatment. Based on investigations by gas chromatography-mass spectrometry combined with the structures of the pesticides, the by-products generated were identified. More specifically, the ozonation-based degradation of carbosulfan generated carbofuran and benzofuranol, whereas malathion produced succinic acid and phosphoric acid. Although some new harmful compounds were formed during degradation of the parent pesticides, these were only present in trace quantities and were transient intermediates that eventually disappeared during the reaction.

CONCLUSION

Our results, therefore, indicate that ozone water treatment technology for pesticide residue degradation is worthy of popularization and application. © 2022 Society of Chemical Industry.

Effect of Ozonation on the Mechanical, Chemical, and Microbiological Properties of Organically Grown Red Currant (Ribes rubrum L.) Fruit

Red currant fruits are a valuable source of micro- and macronutrients, vitamins, and chemical compounds with health-promoting properties, the properties of which change depending on the harvest date and the time and method of storage. This study analysed the effect of applying 10 ppm ozone gas for 15 and 30 min on the mechanical properties, chemical properties and microbiological stability of three organic-grown red currant fruit cultivars. Fruits harvested at the time of harvest maturity had significantly larger diameters and weights and lower water contents compared with fruits harvested seven days earlier, and the ozonation process, regardless of its harvesting date, reduced the physical parameters in question (diameter, weight, and water content). The ascorbic acid content of the ozonated fruit varied, with the highest decreases observed for fruit harvested 7 days before the optimal harvest date and stored for 15 days under refrigeration (an average decrease of 13.31% compared with the control fruit without ozonation). In general, the ozonation process had a positive effect on the variation of fruit antioxidant activity, with the highest average values obtained for fruit harvested 7 days before the optimum harvest date and stored for 15 days under refrigeration conditions; in addition, it also had an effect on reducing the development of microorganisms, including mesophilic aerobic bacteria, yeasts, and moulds, mainly for the cultivar 'Losan'.

Characterization of Various Titanium-Dioxide-Based Catalysts Regarding Photocatalytic Mineralization of Carbamazepine also Combined with Ozonation

Titanium-dioxide-based semiconductors proved to be appropriate for photocatalytic application to efficiently degrade emerging organic pollutants such as various herbicides, pesticides, and pharmaceuticals in waters of environmental importance. The characterization of various TiO2 catalysts, both bare and modified (Ag- and/or N-doped), by mechanochemical treatment was carried out in this work, regarding their structure, morphology, and photocatalytic activity. For the latter investigations, carbamazepine, an antidepressant, proved to be applicable and versatile. The photocatalytic behavior of the catalysts was studied under both UV and visible light. Besides the decomposition efficiency, monitoring the intermediates provided information on the degradation mechanisms. Mechanochemical treatment significantly increased the particle size (from 30 nm to 10 μm), causing a considerable (0.14 eV) decrease in the band gap. Depending on the irradiation wavelength and the catalyst, the activity orders differed, indicating that, in the mineralization processes of carbamazepine, the importance of the different oxidizing radicals considerably deviated, e.g., Ag-TiO2 < DP25-TiO2 < ground-DP25-TiO2 < N-TiO2 ≈ N-Ag-TiO2 for O2•− and N-TiO2 ≈ Ag-TiO2 < N-Ag-TiO2 < ground-DP25-TiO2 ≈ DP25-TiO2 for HO• generation under UV irradiation. Toxicity studies have shown that the resulting intermediates are more toxic than the starting drug molecule, so full mineralization is required. This could be realized by a synergistic combination of heterogeneous photocatalysis and ozonation.

Influence of ozonation and roasting on functional, microstructural, textural characteristics, and aflatoxin content of groundnut kernels

The present study was conducted to evaluate the influence of ozonation, roasting and their combination on the moisture content, color, functional, structural, textural components, and aflatoxins in groundnut kernels. Samples were subjected to three treatments namely, dry roasting (R): 166°C for 7 min; gaseous ozone treatment (O): 6 mg/L for 30 min; combined ozonation-roasting (OR): gaseous ozonation at 6 mg/L for 30 min followed by dry roasting at 166°C for 7 min. The ozonated-roasted samples had the lowest moisture content (3.45%), the highest total phenolic content (4.18 mg gallic acid equivalents/100 g), and antioxidants capacity (69.59%). The treatments did not induce significant changes in color of kernels (p < .05). Scanning electron microscopy indicated cracking of granules in roasted and swelling in ozonated kernels whereas more uniform orientation of granules was observed in ozonated-roasted kernels. Roasted and ozonated kernels indicated a significant reduction of fracturability force to 54.60 and 14.11%, respectively, whereas ozonated-roasted samples demonstrated a nonsignificant increase (4.37%). An increase in wave number of ozonated samples to 3,289.37 cm^-1 in Fourier transform infrared (FTIR) spectrum (FTIR) indicated stretching in OH groups. FTIR spectrum of ozonated-roasted kernels suggested the formation of a new compound with CC and CC groups. The major aflatoxin B1 was reduced to maximum, that is, 100% in ozonated-roasted kernels followed by ozonated (80.95%) and roasted (57.14%) samples. The findings indicate that the ozonation-roasting treatment had a prominent role in the enhancement of functional compounds, structural and textural attributes along with the considerable reduction in aflatoxin content.

Clay-Catalyzed Ozonation of Hydrotalcite-Extracted Lactic Acid Potential Application for Preventing Milk Fermentation Inhibition

An unprecedented route for mitigating the inhibitory effect of lactic acid (LA) on milk fermentation was achieved through lactate adsorption on hydrotalcite (Ht) from simulated lactate extracts. During its regeneration by ozonation, Ht displayed catalytic activity that appeared to increase by addition of montmorillonite (Mt). Changes in the pH, Zeta potential and catalyst particle size during LA ozonation were found to strongly influence LA–LA, LA–catalyst and catalyst–catalyst interactions. The latter determine lactate protonation–deprotonation and clay dispersion in aqueous media. The activity of Mt appears to involve hydrophobic adsorption of non-dissociated LA molecules on silica-rich areas at low pH, and Lewis acid–base and electrostatic interactions at higher pH than the pKa. Hydrotalcite promotes both hydrophobic interaction and anion exchange. Hydrotalcite–smectite mixture was found to enhance clay dispersion and catalytic activity. This research allowed demonstrating that natural clay minerals can act both as adsorbents for LA extract from fermentation broths and as catalysts for adsorbent regeneration. The results obtained herein provide valuable and useful findings for envisaging seed-free milk clotting in dairy technologies.

[Removal Performance of Suspended Solid (SS) and Organic Compounds in the Pre-treatment of Actual Pharmaceutical Wastewater by Microbubble Ozonation]

Actual pharmaceutical wastewater was pretreated with ozone microbubbles and compared with the treatment processes of nitrogen microbubbles, ozone common bubbles, and nitrogen common bubbles. The removal process and performance of suspended solids (SS) and organic compounds were investigated. The results showed that ozone microbubble treatment with strong adsorption-flotation-oxidation effects could enhance SS removal significantly, and the corresponding SS removal efficiency reached 81.67% at 60 min. The SS particle size was reduced, and the negative charge on the SS surface was simultaneously changed into a positive charge. Microbubble ozonation with a strong·OH oxidation effect also significantly enhanced the degradation and removal of organic compounds. The removal efficiency of soluble COD (SCOD) reached 36.60% at 60 min, and the SCOD removal was accelerated after the SS removal. The removal efficiency of UV₂₅₄ also reached 36.91%. The biodegradability was improved, and the biological toxicity was obviously eliminated. The analysis of three-dimensional fluorescence and GC-MS showed that the macromolecular organic compounds with complex structure could be oxidized and decomposed efficiently with microbubble ozonation, resulting in the aromatic reduction in organic compounds in wastewater. Therefore, microbubble ozonation could be considered as an efficient and feasible pretreatment method for high concentration and refractory pharmaceutical wastewater.

on Eggshells

Three Salmonella enterica strains were used in the study (serovars: S. enteritidis, S. typhimurim and S. virchow). This study evaluated the efficacy of radiant catalytic ionization (RCI) and ozonation against Salmonella spp. on eggshell (expressed as log CFU/egg). The egg surface was contaminated three different bacterial suspension (10³ CFU/mL, 10⁵ CFU/mL and 10⁸ CFU/mL) with or without poultry manure. Experiments were conducted at 4 °C and 20 °C in three different time period: 30 min, 60 min and 120 min. Treatment with RCI reduced Salmonella numbers from 0.26 log CFU/egg in bacterial suspension 10⁸ CFU/mL, 4 °C and 20 °C, with manure for 30 min to level decrease in bacteria number below the detection limit (BDL) in bacterial suspension 10⁵ CFU/mL, 20 °C, with or without manure for 120 min. The populations of Salmonella spp. on eggs treated by ozonizer ranged from 0.20 log CFU/egg in bacteria suspension 10⁸ CFU/mL, 20 °C, with manure for 30 min to 2.73 log CFU/egg in bacterial suspension 10⁵ CFU/mL, 20 °C, with manure for 120 min. In all treatment conditions contamination with poultry manure decrease effectiveness the RCI and ozonation. In summary, RCI technology shows similar effectiveness to the ozonation, but it is safer for poultry plant workers and consumers.

Hydrophilization of Hydrophobic Mesoporous High-Density Polyethylene Membranes via Ozonation

This work addresses hydrophilization of hydrophobic mesoporous membranes based on high-density polyethylene (HDPE) via ozonation. Mesoporous HDPE membranes were prepared by intercrystallite environmental crazing. Porosity was 50%, and pore dimensions were below 10 nm. Contact angle of mesoporous membranes increases from 96° (pristine HDPE) to 120° due to the formation of nano/microscale surface relief and enhanced surface roughness. The membranes are impermeable to water (water entry threshold is 250 bar). The prepared membranes were exposed to ozonation and showed a high ozone uptake. After ozonation, the membranes were studied by different physicochemical methods, including DSC, AFM, FTIR spectroscopy, etc. Due to ozonation, wettability of the membranes was improved: their contact angle decreased from 120° down to 60°, and they became permeable to water. AFM micrographs revealed a marked smoothening of the surface relief, and the FTIR spectra indicated the development of new functionalities due to ozonolysis. Both factors contribute to hydrophilization and water permeability of the ozonated HDPE membranes. Hence, ozonation was proved to be a facile and efficient instrument for surface modification of hydrophobic mesoporous HDPE membranes and can also provide their efficient sterilization for biomedical purposes and water treatment.

The Effect of the Addition of Ozonated and Non-Ozonated Fruits of the Saskatoon Berry (Amelanchier alnifolia Nutt.) on the Quality and Pro-Healthy Profile of Craft Wheat Beers

Research into the suitability of domestic raw materials, including, for example, new wheat cultivars and fruit additives for the production of flavoured beers, is increasingly being undertaken by minibreweries and craft breweries. The fruits of the Saskatoon berry are an important source of bioactive compounds, mainly polyphenols, but also macro- and microelements. The fruits of two Canadian cultivars of this species, 'Honeywood' and 'Thiessen', were used in this study. Physicochemical analysis showed that wheat beers with the addition of non-ozonated fruit were characterised by a higher ethanol content by 7.73% on average. On the other hand, enrichment of the beer product with fruit pulp obtained from the cv. 'Thiessen' had a positive effect on the degree of real attenuation and the polyphenol profile. Sensory evaluation of the beer product showed that wheat beers with the addition of 'Honeywood' fruit were characterised by the most balanced taste and aroma. On the basis of the conducted research, it can be concluded that fruits of both cvs. 'Honeywood' and 'Thiessen' can be used in the production of wheat beers, but the fermentation process has to be modified in order to obtain a higher yield of the fruit beer product.

Comparison performance of coagulation flocculation process and combination with ozonation process of stabilized landfill leachate treatment

Landfill leachate is well known as a hazardous byproduct from dumpling sites that has a negative impact on the environment and human life. Therefore, an effective treatment is imperative to overcome this issue. This research study investigates the effectiveness of zirconium tetrachloride (ZrCl4 ) and tin tetrachloride (SnCl4 ) as a coagulant in leachate treatment. Two parameters selected as a performance indicator in this study are color and chemical oxygen demand (COD). The data obtained showed that SnCl4 performed well as a coagulant with removal percentages of color and COD, which are 97% and 77%, respectively. Furthermore, the potential of integrated treatment using ozonation (O3 ) and the coagulation-flocculation process was also investigated. Four sequences of integrated treatment setup for this study were ozonation followed by jar test (ZrCl4 as a coagulant), ozonation followed by jar test (SnCl4 as a coagulant), jar test (ZrCl4 as a coagulant) followed by the ozonation process, and jar test (SnCl4 as a coagulant) followed by the ozonation process. The experimental data showed that the combination treatment of SnCl4 as a coagulant (jar test) followed by the ozonation process had recorded the highest removal of color (97.1%) and COD (88%) compared to other sequences. Moreover, the biodegradability ratio of this sequence also improved from 0.03 to 0.28, compared with other methods. Comparatively, integrated treatment is more effective in treating stabilized landfill leachate compared to the coagulation flocculation process alone. PRACTITIONER POINTS: Stabilized landfill leachate is difficult to be treated by natural coagulants or biological process. SnCl4 performed well as a coagulant in removing COD and colour from landfill leachate compared to ZrCl4 . However, too much usage of SnCl4 potentially generate secondary pollutant. Therefore, combination with O3 as pre-treatment is investigated. Combination treatment of SnCl4 ( as coagulant) with O3 had recorded the highest removal of colour (97.1%) and COD (88%). The biodegradability ratio of this sequence also improved from 0.03 to 0.28.

Simultaneous study of the interaction effect of chemical and hydrothermal pretreatment on the yield of methane produced from municipal waste

Municipal waste has the potential to be a significant source of energy production. This study investigated pretreatment methods such as NaOH, hydrothermal, and ozonation to increase biomethane production from municipal waste. In addition, these pretreatments were further evaluated using ultrasonic pretreatment after achieving optimal conditions by RSM CCD methods. The optimum pretreatment conditions were observed to be 8% NaOH concentration, 132 °C hydrothermal temperature, and O₃ equal to 0.19 g/g TS. The maximum biomethane produced and achieved during the tests was 394 mL/kg TS, which increased to 410 mL/kg TS after ultrasonic pretreatment. The best sCOD reduction in the optimal pretreatment conditions and after the ultrasonic pretreatment was 87% and 91%, respectively. Also, in the absence of ozone pretreatment, the highest yields of biomethane and biogas occurred at a 6.4% concentration of NaOH and a temperature of 135 °C; however, in the presence of ozone, the yield of biomethane and biogas produced was greater and the inhibitory effect of sodium hydroxide also occurs in higher amounts. Experiments have shown that ozonation increases biomethane production rather than increasing biogas production (hence the ratio of methane to biogas).

Improvement of biotreatability of environmentally persistent antibiotic Tiamulin by O3 and O3/H2O2 oxidation processes

The aim of the work was to assess the efficiency of ozonation and ozonation in combination with H₂O₂ in jet loop reactor to increase biotreatability of persistent veterinary antibiotic Tiamulin. The efficiency of oxidative processes was monitored by combined approach based on determination of efficiency of wastewater treatment and impact to waste sludge stabilization. Degradation of Tiamulin in model wastewater (100 mg L^-1) during oxidation was followed by COD and DOC measurements while changes in biodegradability were determined by respirometric measurements. Biogas production potential was also determined to identify problems related to anaerobic digestion of waste sludge resulted in treatment of Tiamulin-contaminated wastewater. At ozone dose of 69 g_ozone g_COD^-1 and 220 g_ozone g_DOC^-1removal for COD and DOC was 26% and 17%, respectively. Better biotreatability was confirmed by respirometric testing. H₂O₂ addition did not improve removal efficiency (11-13%). The second stage of nitrification was suppressed by the addition of Tiamulin and ozonation again recovered N-NO3- formation. O₃/H₂O₂ treated sample reduced the nitrification, especially formation of N-NO2- in the first phase of the process. Simultaneously, quadratic model was developed to describe the relationship between oxygen uptake rate and changes in ammonium nitrogen concentration due to the oxidative treatment. The positive impact of ozone was also confirmed by ozonation of Tiamulin-contaminated (400 mg L^-1) waste sludge where biogas production potential was increased for 6-times. Combination of approaches confirmed, that O₃ effectively increase the treatability of Tiamulin in wastewater and sludge while addition of the hydrogen peroxide generally did not improve the performance of the processes.

Enrichment of hydrogen production from fruit waste biomass using ozonation assisted with citric acid

In this study, the impact of ozonation abetted with the citric acid pretreatment (OZCAP) method on fruit waste was investigated for ameliorating hydrogen production. Initially, the ozonation pretreatment (OZP) method was performed by varying ozone (O₃) dosage and disintegration time. At optimized conditions (O₃ dosage (0.04 g/g suspended solid; SS) and disintegration time (40 minutes)), 17.6% of liquefied organics emancipate rate (LER) and 13.5% of SS reduction were perceived. Further augmenting LER of fruit waste, OZCAP method was proceeded by varying citric acid dosage and disintegration time at an optimized OZP dosage (0.04 g/g SS). A higher LER (24.4%) and SS reduction (19%) were described at an optimal citric acid dosage (0.03 g/g SS) and disintegration time (20 minutes). Then, the hydrogen production potential of OZCAP, OZP and raw fruit waste were evaluated in which OZCAP method exhibited a higher cumulative hydrogen production (30 mL/g volatile solids). Energy valuation reveals that OZCAP method exhibited a net energy of 3.7 kWh/kg of fruit waste.

Ozone Treatment Improves the Texture of Strawberry Fruit during Storage

The major aim of this study was to check whether a cyclic ozonation process will affect the preservation of the texture of strawberries stored at room temperature. Strawberry fruit was stored for 3 days at room temperature and ozonated with gaseous ozone at a concentration of 10 and 100 ppm for 30 min, every 12 h of storage. Research showed that the ozonation process inhibited the texture deterioration of the fruit during storage. The positive effect of ozone was directly related to the inhibition of the activity of enzymes involved in the degradation of the fruit cell walls, as well as indirectly from the improved energy metabolism of the fruit. The higher level of energy charge corresponded to the higher resistance of ozonated fruit to abiotic stress, leading to the maintenance of the integrity of cell membranes and, consequently, to maintaining good hardness of the fruit throughout the storage period.

Analysis of Ozonation Processes Using Coupled Modeling of Fluid Dynamics, Mass Transfer, and Chemical Reaction Kinetics

The efficacy of oxidation of recalcitrant organic contaminants in municipal and industrial wastewaters by ozonation is influenced by chemical reaction kinetics and hydrodynamics within a reactor. A 3D computational fluid dynamics (CFD) model incorporating both multiphase flow and reaction kinetics describing ozone decay, hydroxyl radical (^•OH) generation, and organic oxidation was developed to simulate the performance of continuous flow ozonation reactors. Formate was selected as the target organic in this study due to its well-understood oxidation pathway. Simulation results revealed that the dissolved ozone concentration in the reactor is controlled by rates of O₃(g) interphase transfer and ozone self-decay. Simulations of the effect of various operating conditions showed that the reaction stoichiometric constraints between formate and ozone were reached; however, complete utilization of gas phase ozone was hard to achieve due to the low ozone interphase mass transfer rate. Increasing the O₃(g) concentration leads to an increase in the formate removal rate by ∼5% due to an enhancement in the rate of O₃(g) interphase mass transfer. The CFD model adequately describes the mass transfer occurring in the two-phase flow system and confirms that O₃(g) interphase mass transfer is the rate-limiting step in contaminant degradation. The model can be used to optimize the ozone reactor design for improved contaminant degradation and ozonation efficiency.

Combined Analytical Study on Chemical Transformations and Detoxification of Model Phenolic Pollutants during Various Advanced Oxidation Treatment Processes

Advanced oxidation processes (AOPs) have been introduced to deal with different types of water pollution. They cause effective chemical destruction of pollutants, yet leading to a mixture of transformation by-products, rather than complete mineralization. Therefore, the aim of our study was to understand complex degradation processes induced by different AOPs from chemical and ecotoxicological point of view. Phenol, 2,4-dichlorophenol, and pentachlorophenol were used as model pollutants since they are still common industrial chemicals and thus encountered in the aquatic environment. A comprehensive study of efficiency of several AOPs was undertaken by using instrumental analyses along with ecotoxicological assessment. Four approaches were compared: ozonation, photocatalytic oxidation with immobilized nitrogen-doped TiO₂ thin films, the sequence of both, as well as electrooxidation on boron-doped diamond (BDD) and mixed metal oxide (MMO) anodes. The monitored parameters were: removal of target phenols, dechlorination, transformation products, and ecotoxicological impact. Therefore, HPLC–DAD, GC–MS, UHPLC–MS/MS, ion chromatography, and 48 h inhibition tests on Daphnia magna were applied. In addition, pH and total organic carbon (TOC) were measured. Results show that ozonation provides by far the most suitable pattern of degradation accompanied by rapid detoxification. In contrast, photocatalysis was found to be slow and mild, marked by the accumulation of aromatic products. Preozonation reinforces the photocatalytic process. Regarding the electrooxidations, BDD is more effective than MMO, while the degradation pattern and transformation products formed depend on supporting electrolyte.

Discovery of Polar Ozonation Byproducts via Direct Injection of Effluent Organic Matter with Online LC-FT-ICR-MS

Effluent organic matter (EfOM), a major ozone consumer during wastewater ozonation, is a complex mixture of natural and anthropogenic organic molecules. Ozonation of EfOM adds to molecular complexity by introducing polar and potentially mobile ozonation byproducts (OBPs). Currently, nontargeted direct infusion (DI) ultrahigh resolution mass spectrometry (e.g. FT-ICR-MS) is used to study OBPs but requires sample extraction, limiting the accessible polarity range of OBPs. To better understand the impact of ozonation on EfOM and the formation of polar OBPs, nonextracted effluent was analyzed by direct injection onto a reversed-phase liquid chromatography system (RP-LC) online hyphenated with an FT-ICR-MS. Over four times more OBPs were detected in nonextracted EfOM compared to effluent extracted with solid phase extraction and measured with DI-FT-ICR-MS (13817 vs 3075). Over 1500 highly oxygenated OBPs were detected exclusively in early eluting fractions of nonextracted EfOM, indicating polar OBPs. Oxygenation of these newly discovered OBPs is higher than previously found, with an average molecular DBE-O value of -3.3 and O/C ratio of 0.84 in the earliest eluting OBP fractions. These polar OBPs are consistently lost during extraction but may play an important role in understanding the environmental impact of ozonated EfOM. Moreover, 316 molecular formulas classified as nonreactive to ozone in DI-FT-ICR-MS can be identified with LC-FT-ICR-MS as isomers with varying degrees of reactivity, providing for the first time experimental evidence of differential reactivity of complex organic matter isomers with ozone.

Changes in the activity of flavanone 3β-hydroxylase in blueberry fruit during storage in ozone-enriched atmosphere

BACKGROUND

The present study aimed to determine whether the ozonation process affects the flavonoid biosynthesis in highbush blueberry (Vaccinum corymbosum L.) fruit. Flavanone 3β-hydroxylase (F3H) was used as a marker of the flavonoid biosynthesis pathway. The activity of F3H, the expression of gene encoding F3H and the antioxidant status in blueberries treated with ozone at a concentration of 15 ppm for 30 min, every 12 h of storage, and maintained at 4 °C for 4 weeks were investigated.

RESULTS

The results showed that ozonation process increases the expression of the F3H gene after 1 week of storage, which translates into a higher catalytic capacity of protein, as well as a higher content of flavonoids and total antioxidant potential of ozonated blueberries compared to non-ozonated fruits.

CONCLUSION

The present study provides experimental evidence indicating that ozone treatment in proposed process conditions positively affects flavonoid metabolism in highbush blueberry fruit leading to the maintainance of the high quality of the fruit during storage. © 2021 Society of Chemical Industry.

Approaches to Inactivating Aflatoxins-A Review and Challenges

According to the World Health Organization, the contamination of crops with aflatoxins poses a significant economic burden, estimated to affect 25% of global food crops. In the event that the contaminated food is processed, aflatoxins enter the general food supply and can cause serious diseases. Aflatoxins are distributed unevenly in food or feedstock, making eradicating them both a scientific and a technological challenge. Cooking, freezing, or pressurizing have little effect on aflatoxins. While chemical methods degrade toxins on the surface of contaminated food, the destruction inside entails a slow process. Physical techniques, such as irradiation with ultraviolet photons, pulses of extensive white radiation, and gaseous plasma, are promising; yet, the exact mechanisms concerning how these techniques degrade aflatoxins require further study. Correlations between the efficiency of such degradation and the processing parameters used by various authors are presented in this review. The lack of appropriate guidance while interpreting the observed results is a huge scientific challenge.

Optimization of ozonation process for organic matter and ecotoxicity removal from landfill leachate by applying rotatable central composite design (RCCD)

Ozonation process was used for leachate treatment from a landfill located in Rio de Janeiro, Brazil. The influence of pH and ozone concentration on COD (Chemical Oxygen Demand), TOC (Total Organic Carbon), Absorbance at 254 nm (ABS254nm), and True color was evaluated through RCCD (Rotatable Central Composite Design) experimental design, resulting in mathematical models that were statistically analyzed in Statistica and Design Expert software. The removals obtained was up to 26.1%, 29.9%, 56.9%, and 97.9% for COD ([COD]₀=3,323 mg/L), TOC ([TOC]₀=1,275 mg/L), ABS254nm (ABS₀=32.2), and True color ([True color]₀=3,467 mgPt-Co/L), respectively. Statistical and variance analysis of the experimental data revealed that one quadratic model obtained in Statistica was valid, ABS254nm reduction. However, by applying the Design Expert software, modified models were generated to predict the behavior of all dependent variables. Thus, the optimum point for the best response after ozonation of the landfill leachate was at the highest pH and the lowest ozone dose (9 and 2.2 mgO₃/m³, respectively). Toxicity toward Allivibrio fischeri bacteria was abated at the same time that it decreased the impact of the effluent to Danio rerio fish (from 125 UT to 62 UT) on the treated leachate.

Recovery of Biologically Treated Textile Wastewater by Ozonation and Subsequent Bipolar Membrane Electrodialysis Process

The Bipolar Membrane Electrodialysis process (BPMED) can produce valuable chemicals such as acid (HCl, H₂SO₄, etc.) and base (NaOH) from saline and brackish waters under the influence of an electrical field. In this study, BPMED was used to recover wastewater and salt in biologically treated textile wastewater (BTTWW). BPMED process, with and without pre-treatment (softening and ozonation), was evaluated under different operational conditions. Water quality parameters (color, remaining total organic carbon, hardness, etc.) in the acid, base and filtrated effluents of the BPMED process were evaluated for acid, base, and wastewater reuse purposes. Ozone oxidation decreased 90% of color and 37% of chemical oxygen demand (COD) in BTTWW. As a result, dye fouling on the anion exchange membrane of the BPMED process was reduced. Subsequently, over 90% desalination efficiency was achieved in a shorter period. Generated acid, base, and effluent wastewater of the BPMED process were found to be reusable in wet textile processes. Results indicated that pre-ozonation and subsequent BPMED membrane systems might be a promising solution in converging to a zero discharge approach in the textile industry.

Can ozone be used as antimicrobial in the dairy industry? A systematic review

Milk and dairy products are abundantly consumed in all cultures, but unprocessed products can harbor pathogenic microorganisms that can cause serious health risks for its consumers. To avoid this, it is necessary to process the products. Ozonation is a clean technique that has antimicrobial power due to its oxidation potential, reducing the microorganisms and limiting the production of enzymes, but the effectiveness of ozone treatment can be affected by the temperature, pH, additives, humidity, and the amount of organic matter around the cells. The goal of this systematic review was to analyze whether the use of ozone could improve the microbiological quality of dairy products and whether it could be used as an antimicrobial technique. Six databases (PubMed, Scielo, CAPES, Science Direct, Science Core Collection, and PLOS) were used in this research, with 2 independent reviewers selecting articles up to November 21, 2020, with experiments that used ozone as an antimicrobial in dairy products. A total of 731 articles were found, but only 9 were selected. The remainder were excluded according to the following criteria: was not related to the main theme; was a review; did not contain microbiological analysis; did not mention the concentration of gas and time of the ozone treatment; and was not an experiment. Important points were noted in quality criteria, which resulted in the need to standardize the methodology applied in research to improve the quality of the experiments. Studies were carried out with many different samples of milk, but the best results in reducing the microorganism count were obtained from samples containing low levels of fat.

A modified quick, easy, cheap, effective, rugged, and safe method for determination of by-products originating from ozonation of chlorpyrifos and diazinon spiked in cherry tomato and perilla leaf

In this study, sample pretreatment methods have been developed for the determination of chlorpyrifos, diazinon, and their by-products present in cherry tomato and perilla leaf using liquid chromatography-tandem mass spectrometry. To optimize a quick, easy, cheap, effective, rugged, and safe method, the recoveries at each step were evaluated. The steps improved the recoveries of chlorpyrifos, chlorpyrifos oxon, diazinon, diazoxon, and 2-isopropyl-6-methyl-4-pyrimidinol up to 80% or more by removing interferents, but diethyl phosphate was almost lost during the partition procedure, and the 3,5,6-trichloro-2-pyridinol recovery was below 65%. Therefore, the compounds were evaluated using different solvent compositions based on a quick polar pesticides method; note that 100% methanol showed acceptable extraction results. The optimized method provided method detection limits ranging from 0.03 to 1.22 ng/g and good linearities (R²  > 0.996). The recovery values were between 82.1 and 113.3%. The intra- and interday reproducibility was evaluated to be within 8.6 and 9.9%, respectively. The method was applied to determine the degradation efficiency of chlorpyrifos and diazinon and their by-products formed during plasma treatment.

Advanced oxidation processes for waste water treatment: from laboratory-scale model water to on-site real waste water

A process combining three steps has been developed as a tertiary treatment for waste water in order to remove micropollutants not eliminated by a conventional waste water treatment plant (WWTP). These three processes are ozonation, photocatalysis and granulated activated carbon adsorption. This process has been developed through three scales: laboratory, pilot and pre-industrial scale. At each scale, its efficiency has been assessed on different waste waters: laboratory-made water, industrial waste water (one from a company cleaning textiles and another from a company preparing culture media, both being in continuous production mode) and municipal waste water. At laboratory scale, a TiO₂-based photocatalytic coating has been produced and the combination of ozonation-UVC photocatalytic treatment has been evaluated on the laboratory-made water containing 22 micropollutants. The results showed an efficient activity leading to complete or partial degradation of all compounds and an effective carbon for residual micropollutant adsorption was highlighted. Experiments at pilot scale (100 L of water treated at 500 L/h from a tank of 200 L) corroborated the results obtained at laboratory scale. Moreover, tests on municipal waste water showed a decrease in toxicity, measured on Daphnia Magma, and a decrease in micropollutant concentration after treatment. Finally, a pre-industrial container was built and evaluated as a tertiary treatment at the WWTP Duisburg-Vierlinden. It is shown that the main parameters for the efficiency of the process are the flow rate and the light intensity. The photocatalyst plays a role by degrading the more resistant micropollutants. Adsorption permits an overall elimination >95% of all molecules detected.

Preparation of a Cage-Type Polyglycolic Acid/Collagen Nanofiber Blend with Improved Surface Wettability and Handling Properties for Potential Biomedical Applications

Electrospun biobased polymeric nanofiber blends are widely used as biomaterials for different applications, such as tissue engineering and cell adhesion; however, their surface wettability and handling require further improvements for their practical utilization in the assistance of surgical operations. Therefore, Polyglycolic acid (PGA) and collagen-based nanofibers with three different ratios (40:60, 50:50 and 60:40) were prepared using the electrospinning method, and their surface wettability was improved using ozonation and plasma (nitrogen) treatment. The effect on the wettability and the morphology of pristine and blended PGA and collagen nanofibers was assessed using the WCA test and SEM, respectively. It was observed that PGA/collagen with the ratio 60:40 was the optimal blend, which resulted in nanofibers with easy handling and bead-free morphology that could maintain their structural integrity even after the surface treatments, imparting hydrophilicity on the surface, which can be advantageous for cell adhesion applications. Additionally, a cage-type collector was used during the electrospinning process to provide better handling properties to (PGA/collagen 60:40) blend. The resultant nanofiber mat was then incorporated with activated poly (α,β-malic acid) to improve its surface hydrophilicity. The chemical composition of PGA/collagen 60:40 was assessed using FTIR spectroscopy, supported by Raman spectroscopy.

Contemporary Techniques for Remediating Endocrine-Disrupting Compounds in Various Water Sources: Advances in Treatment Methods and Their Limitations

Over the years, the persistent occurrence of superfluous endocrine-disrupting compounds (EDCs) (sub µg L⁻¹) in water has led to serious health disorders in human and aquatic lives, as well as undermined the water quality. At present, there are no generally accepted regulatory discharge limits for the EDCs to avert their possible negative impacts. Moreover, the conventional treatment processes have reportedly failed to remove the persistent EDC pollutants, and this has led researchers to develop alternative treatment methods. Comprehensive information on the recent advances in the existing novel treatment processes and their peculiar limitations is still lacking. In this regard, the various treatment methods for the removal of EDCs are critically studied and reported in this paper. Initially, the occurrences of the EDCs and their attributed effects on humans, aquatic life, and wildlife are systematically reviewed, as well as the applied treatments. The most noticeable advances in the treatment methods include adsorption, catalytic degradation, ozonation, membrane separation, and advanced oxidation processes (AOP), as well as hybrid processes. The recent advances in the treatment technologies available for the elimination of EDCs from various water resources alongside with their associated drawbacks are discussed critically. Besides, the application of hybrid adsorption–membrane treatment using several novel nano-precursors is carefully reviewed. The operating factors influencing the EDCs’ remediations via adsorption is also briefly examined. Interestingly, research findings have indicated that some of the contemporary techniques could achieve more than 99% EDCs removal.

Characterisation of Some Phytochemicals Extracted from Black Elder (Sambucus nigra L.) Flowers Subjected to Ozone Treatment

Elderflowers are a well-known source of bioactive compounds. The amount of isolated bioactive compounds may be increased by applying various abiotic and biotic factors. Gaseous ozone (10 and 100 ppm) was used in the process of preparing flowers. Next, the flowers were treated with sugar syrup to extract bioactive compounds. It was shown that this treatment, including the influence of extraction temperature, significantly affects the contents of polyphenols (liquid chromatography-mass spectrometry (LC-MS) methods) and vitamin C, as well as the antioxidant potential (cupric reducing antioxidant capacity (CUPRAC method)), the profile of volatile substances (head space-solid-phase microextraction (HS-SPME methods)) and the colour of the syrup (Commission Internationale de l'Eclairage (CIE) L*a*b* methods). The findings show that an increased dose of ozone and higher extraction temperature applied in the process of syrup production resulted in higher contents and different compositions of bioactive compounds. The highest contents of bioactive compounds were identified in syrup obtained from raw material treated with ozone for 15 min (concentration = 10 ppm) and extraction with sugar syrup at a temperature of 60 °C.

Fate of natural organic matter and oxidation/disinfection by-products formation at a full-scale drinking water treatment plant

This paper investigates the fate of natural organic matter (NOM) during the full-scale drinking water treatment plant supplied by Danube river bank filtration. After the recent reconstruction of the plant, special attention was devoted to the effects of ozone dose and granulated activated carbon (GAC) filtration on the formation and behaviour of oxidation by-products (carbonyl compounds and bromate), as well as carbonaceous and nitrogenous chlorination by-products. For the oxidation of aromatic NOM moieties that absorb light at UV₂₅₄, a lower ozone dose (1.0 g O₃/m³) is sufficient, whereas to achieve a measurable reduction (about 20%) of total organic carbon, an ozone dose of 1.5 g O₃/m³ is required. The content of carbonyl compounds in the water after ozonation increases relative to the content before oxidation treatment, and is up to 12 times higher in the case of aldehydes and up to 2 times higher in the case of carboxylic acids. Seasonal variations, including changes in temperature and the amount of precipitation, were also shown to affect the content of organic matter in the raw water, with slight effects on the quality of the treated water. In the winter, the organic matter content is slightly higher, meaning their transformation products aldehydes and carboxylic acids, are also higher during the winter than the summer.

Efficiency of Fe3O4 Nanoparticles with Different Pretreatments for Enhancing Biogas Yield of Macroalgae Ulva intestinalis Linnaeus

In this work, different pretreatment methods for algae proved to be very effective in improving cell wall dissociation for biogas production. In this study, the Ulva intestinalis Linnaeus (U. intestinalis) has been exposed to individual pretreatments of (ultrasonic, ozone, microwave, and green synthesized Fe3O4) and in a combination of the first three mentioned pretreatments methods with magnetite (Fe3O4) NPs, (ultrasonic-Fe3O4, ozone-Fe3O4 and microwave-Fe3O4) in different treatment times. Moreover, the green synthesized Fe3O4 NPs has been confirmed by FTIR, TEM, XRD, SEM, EDEX, PSA and BET. The maximum biogas production of 179 and 206 mL/g VS have been attained when U. intestinalis has been treated with ultrasonic only and when combined microwave with Fe3O4 respectively, where sediment were used as inoculum in all pretreatments. From the obtained results, green Fe3O4 NPs enhanced the microwave (MW) treatment to produce a higher biogas yield (206 mL/g VS) when compared with individual MW (84 mL/g VS). The modified Gompertz model (R2 = 0.996 was appropriate model to match the calculated biogas production and could be used more practically to distinguish the kinetics of the anaerobic digestion (AD) period. The assessment of XRD, SEM and FTIR discovered the influence of different treatment techniques on the cell wall structure of U. intestinalis.