Search Results (101)

Heterogeneous catalytic ozonation has attracted increasing research attention as a strategy for advanced wastewater polishing; yet the recent literature has advanced the attribution of non-radical pathways at a pace that has outstripped rigorous demonstration of their practical process advantage. This article constitutes an evidence-centered critical review—rather than a formal systematic review—organized around a central evaluative question: under what conditions are non-radical mechanistic claims in catalytic ozonation sufficiently persuasive, wastewater-relevant, and defensible to warrant consideration for process translation. Recent studies, drawn primarily from the period 2023–2026, are evaluated through an explicit evidence-grading framework that distinguishes among radical, singlet-oxygen-mediated, surface-bound oxygen-transfer, direct electron-transfer, and high-valent metal-oxo pathways. The review further examines whether reported parent-compound removal is corroborated by complementary lines of evidence encompassing bromate formation, transformation product characterization, effluent toxicity assessment, catalyst leaching quantification, operational durability, and reactor-scale performance. The synthesis reveals that single-atom catalysts currently provide the most robust active-site mechanistic evidence; however, even these systems remain constrained by their reliance on simplified aqueous matrices, incomplete transformation byproduct accounting, and unresolved long-term stability. Accordingly, the article proposes standardized reporting protocols and benchmark performance metrics—including a bromate-normalized treatment benefit index—to delineate mechanistic elegance from process realism. Full article

The textile and clothing industry exerts a significant environmental impact in the EU, contributing heavily to water, land, and resource depletion, with waste generation expected to rise sharply due to fast fashion trends. Accelerating circularity and closed-loop production is critical to reduce the sector’s ecological footprint. This study investigates newer approaches for the removal of indigo prints from cotton (CO) and polyester (PES) textiles using aqueous-based solutions and/or ozone treatment. Aqueous alkaline solutions containing reducing agents and surfactants were evaluated, as well as dry and wet ozone treatments. The efficacy of colour removal was assessed via spectrophotometric analysis [colour strength (K/S) and colour difference (ΔE)] and the fabrics were tested for dimensional stability and tensile strength before and after treatment. Results reveal that surfactant-assisted aqueous treatments enable effective pigment removal and maintain textile properties, supporting subsequent reprinting for textile upcycling. Wet ozone treatment also promoted substantial decolourisation, particularly in cellulosic substrates. Although PES samples exhibited better mechanical resistance, they revealed limited pigment extraction upon ozone treatment. These findings demonstrate the potential of chemical treatments using aqueous-based solutions and surfactants for circular textile applications, facilitating pigment removal without compromising substrate integrity, and boosting the upcycling. Full article

The onset of the COVID-19 pandemic prompted the rapid development and deployment of novel strategies and methodologies to manage the dissemination of microorganisms. Understanding the crucial role that contaminated surfaces play in the spread of viruses highlights the importance of having effective cleaning and disinfection protocols in place for inanimate objects. A variety of antimicrobial agents have shown strong effectiveness against the SARS-CoV-2 virus. Various factors can impact on the performance of these agents. As a result, technologies utilizing ozone’s microbicidal effects have been developed or improved for cleaning indoor areas, surfaces, and materials, despite ozone’s diverse uses being known for years. Ozone offers the advantage of adaptability for both gaseous and aqueous use, depending on the nature of the decontaminated surfaces. Moreover, ozone-infused water is ecologically benign, possesses microbial-fighting capabilities, and synergistically reinforces the biocidal action of other chemical disinfectants. This review aims to summarize the efforts dedicated to harnessing gaseous and aqueous ozone as a valuable means to eliminate the SARS-CoV-2 virus from environments, surfaces, clinical equipment, and office supplies. This review sourced evidence-based articles from electronic databases, including MEDLINE (via PubMed), EMBASE, the Cochrane Library (CENTRAL), and preprint repositories. The findings illustrated that ozone could serve as an additional tool for curbing the proliferation of COVID-19 and other viral infections. Additionally, we elucidated the operational attributes of ozone, the variables that influence its disinfection potency, and the mechanisms of its virucidal action. Notably, this review does not encompass the disinfection of the COVID-19 virus in wastewater. Full article

To address the low efficiency of tetracycline (TC) ozonation caused by low ozone solubility, short aqueous half-life, and mass-transfer limitations, an ozone micro-nano bubble (O₃-MNBs) oxidation system was designed and systematically compared with conventional ozone sparging (Conv-O₃). Thus, this study assessed the bubble size distribution, zeta potential, ozone dissolution and decay behaviors in water, ·OH concentration, and TC oxidation products, elucidating the degradation pathways and underlying mechanisms enabled by O₃-MNBs. Relative to Conv-O₃, O₃-MNBs increased the steady-state dissolved ozone concentration by 2.57–4.33 times, reduced the ozone decay rate constant by 41.3%, and enhanced ·OH generation by 2.3 times. TC degradation in the O₃-MNB system exhibited a distinct two-stage kinetic behavior, following second-order kinetics in the initial period (0–30 s) and first-order kinetics thereafter (30–120 s). Accordingly, the TC removal efficiency of O₃-MNBs reached 96.25% within 120 s, which was 81.25% higher than that of Conv-O₃. Notably, TC removal under Conv-O₃ obeyed first-order kinetics throughout, with an apparent rate constant only 7.14% of that obtained with O₃-MNBs. These improvements were attributed to the sustained and efficient supply of oxidants, high dissolved ozone and ·OH radicals, promoting the conversion of TC intermediates toward low m/z small-molecule end products, with greater ring opening and skeletal fragmentation. Our findings suggest that the enhanced biodegradability results in a markedly reduced burden and environmental risk for subsequent biological or advanced treatment processes. Therefore, this study highlights the potential of O₃-MNBs to enhance ozone utilization and oxidation intensity, providing mechanistic insights and technical support for rapid pretreatment of antibiotic-containing wastewater. Full article

Microbiological contamination of drinking water remains a significant public health concern worldwide, necessitating the development of efficient and environmentally friendly disinfection technologies. This study investigated the effectiveness and physicochemical mechanisms of water treatment using high-frequency electrical discharge plasma. Experimental research was conducted employing a laboratory dielectric barrier discharge reactor operating at 10–30 kHz and 10–25 kV, with treatment durations ranging from 5 to 20 min. Plasma exposure resulted in pronounced physicochemical changes in the aqueous medium, including a decrease in pH from 7.1–7.3 to 5.4–6.0 and an increase in electrical conductivity from 280–340 µS/cm to 480–620 µS/cm. The formation of reactive oxygen species, including hydroxyl radicals, ozone, and hydrogen peroxide, was confirmed, with hydrogen peroxide concentrations varying between 0.35 and 1.20 mg/L. Microbiological analysis demonstrated a reduction in microbial concentration from approximately 10⁵–10⁶ CFU/mL to 10²–10³ CFU/mL, corresponding to 3–4 log inactivation. The results indicated that microbial reduction was strongly associated with the generation of reactive species and treatment duration. Energy density within the range of 0.3–1.2 kWh/m³ was found to support effective disinfection performance. The findings demonstrated that high-frequency plasma treatment established a strong oxidative environment leading to microbial membrane disruption and cellular damage. Overall, the study confirmed the potential of high-frequency electrical discharge plasma technology as a promising approach for drinking water disinfection and provided a basis for further optimization and scale-up investigations. Full article

Recycled carbon fibres frequently exhibit degraded surface functionality owing to prior matrix removal processes, limiting their compatibility with contemporary epoxy resin systems. This study proposes a nanobubble-based surface treatment route designed to restore and enhance the surface characteristics of recycled carbon fibres without aggressive chemical oxidation. The study generated ozone and carbon dioxide nanobubbles in aqueous media and experimentally investigated the effects of nanobubble treatment on the surface properties and adhesive behaviour of recycled carbon fibres. Surface chemical changes were examined using X-ray photoelectron spectroscopy, which revealed an increase in oxygen-containing functional groups due to the nanobubble treatment, indicating improved surface polarity and potential for chemical interaction with epoxy networks. The practical effectiveness of the treatment was assessed via a pinhole pull-out test that served as an indirect measure of interfacial adhesion with epoxy resin, especially the combination of ozone nanobubbles and recycled carbon fibres. Notably, the nanobubble-treated recycled carbon fibres exhibited an increase in the adhesion compared with untreated recycled carbon fibres, rising from 84.5 ± 11.5 MPa to 138.5 ± 14.8 MPa, reflecting enhanced wetting behaviour and stronger fibre–matrix interfacial bonding. Overall, the proposed nanobubble processing route offers a mild, scalable, and environmentally favourable method for restoring surface reactivity in recycled carbon fibres, supporting their reintegration into high-performance composite applications. Full article

In order to reduce fungal contamination in grapes and increase the dehydration rate for producing raisins, the development of alternative technologies that do not compromise product safety and quality is required. This study examined the impact of innovative pre-drying methods using aqueous ozone (10 min-4.1 mg O₃ L⁻¹) and UV-C light (30.3 kJ m⁻² UV-C) on the incidence of Aspergillus carbonarius, as well as on air-drying kinetics and ultrastructure of epicuticular waxes in Sultanina grapes, when applied either individually or sequentially. The effect of the pre-treatments on the colour of the dehydrated grapes was also assessed. Grapes pre-treated with 30.3 kJ m⁻² UV-C and 10 min-4.1 mg O₃ L⁻¹ + 30.3 kJ m⁻² UV-C showed a lower incidence of A. carbonarius in storage at 20 ± 1 °C than those exposed to aqueous ozone (30 and 8% lower infection compared to the non-pretreated fruit at 15-day storage, respectively). Although the combined pre-treatment did not significantly improve the fungus inhibition with respect to the individual UV-C application, it allowed a higher dehydration rate during the drying process at 60 ± 1 °C. The drying time was reduced by ~31% compared to non-pretreated fruit, a result slightly lower than that achieved with the traditional chemical pre-treatment of ethyl oleate-K₂CO₃ (~39%). This enhancement in drying rate was partly attributed to marked alterations in the grape’s epicuticular wax layer. UV-C and the combined pre-treatment helped in reducing the browning of raisins. Therefore, the combined application of ozone and UV-C light could be an environmentally friendly alternative for both improving the microbiological quality of grapes and accelerating the drying process. Full article

Oily sludge is a complex emulsified waste consisting of water, oil, and solid particles. Conventional treatments are often inefficient, energy-intensive, and prone to causing secondary pollution. This study proposes a green demulsification technology based on ozone micro–nanobubbles (O₃MNBs) by constructing an experimental system to analyze its effects and mechanisms of action on oily sludge treatment. The O₃MNBs exhibited a mean particle size of 831 nm and generated a substantial amount of hydroxyl radicals (·OH, 250.4 μmol·L⁻¹) in situ. Compared with conventional aeration, the dissolved ozone concentration and residence time in water of O₃MNBs increased by 192% and 213%, respectively. During bubble collapse, intense pressure waves and high-speed microjets were generated to disrupt sludge aggregates, promoting the dispersion of sludge particles while simultaneously stripping oil films. Thus, the oil removal rate reached 41.5%, demonstrating the high demulsification efficiency of O₃MNBs. Furthermore, ozone and ·OH attacked alkane C-H bonds in the oil phase, oxidizing hydrophobic films into hydrophilic products and decomposing surfactants that stabilize emulsions. This process promoted oil droplet coalescence and degradation into small organic molecules. After O₃MNB treatment, the absorption peak of alkane C-H bonds gradually reduced, while a new C=O absorption peak appeared. This study provides a theoretical foundation and technical support for environmentally sustainable treatment of oily sludge by O₃MNB application, offering an effective alternative to chemical demulsification without secondary pollution. Full article

Recent studies on novel protein sources unveiled lupins as a promising substitute for meat consumption. However, lupin cultivation and processing include significant safety concerns, such as quinolizidine alkaloids (QAs) and the possible growth of toxigenic fungi as Diaporthe toxica, which produces the mycotoxin phomopsin-A (PHO-A). Therefore, this study aims to assess the influence of gaseous and aqueous ozone on lupin beans as environmentally sustainable methods for detoxifying QAs and PHO-A mycotoxins, thereby addressing both these safety challenges. Three distinct aqueous and gaseous ozone treatments (4, 6, and 8 h, at 7.00 ppm O₃ concentration) were applied on lupin seeds inoculated with D. toxica DSM 1894. A good effectiveness of aqueous O₃ in the reduction in PHO-A (about 20%) was demonstrated, independently of the treatment duration, along with the reduction in some QAs typically encountered in lupin. Additionally, a significant reduction in D. toxica count was observed after 4 h treatment with aqueous O₃. In contrast, results for gaseous O₃ treatments did not show any significant effectiveness on either PHO-A or QAs. Conversely, none of the treatments applied significantly affected lupin color. In conclusion, aqueous ozone treatment demonstrated significant potential for the reduction in PHO-A and QAs, and the insights acquired from this work may aid in mitigating the dangers associated with lupin intake. Nevertheless, additional research is required to cover current knowledge gaps. Specifically, toxicological assays on PHO-A degradation by-products or O₃ combination with other hurdles is required to enhance treatments and preserve lupins’ nutrients. Full article

This review summarizes recent applications of carbon-based materials as catalysts in the ozonation of wastewater contaminated with persistent organic pollutants. Methods available for production of commonly used inexpensive carbonaceous materials such as biochar and hydrochar are presented. Differences between production methods of active carbon and biochar or hydrochar are discussed. Interestingly, biochar, in a role of rather simple and cheap charcoal, is catalytically active and increases the rate of oxidative degradation of nonbiodegradable aqueous contaminants such as drugs or textile dyestuffs. This review documents that even the addition of biochar to the ozonized wastewater increases the rate of removal of persistent organic pollutants. Cheap bio-based carbonaceous materials such as biochar work as adsorbent of dissolved pollutants and catalysts for ozone-based degradation of organic compounds via the formation of reactive oxygen species (ROS). Low-molecular-weight degradation products produced by ozonation of pharmaceuticals and textile dyes are presented. The combination of air-based ozone generation, together with application of biochar, represents a sustainable AOP-based wastewater treatment method. Full article

Biodegradable bioplastics have emerged as a promising sustainable alternative to minimize the environmental impact of traditional plastics. Nevertheless, many of them degrade slowly under natural or industrial conditions, raising concerns about their practical biodegradability. This fact is related to the high-order structure of the polymer backbones, i.e., high molar mass and high crystallinity. Research efforts are being devoted to the development of technologies capable of reducing the length of polymer segments by accelerated chain scission, which could help improve biodegradation rates upon disposal of bioplastic products. The objective of this review is to examine the current state of the art of abiotic degradation techniques, physically driven by temperature, mechanical stress, UV/gamma/microwave irradiation, or plasma or dielectric barrier discharge, and chemically induced by ozone, water, or acidic/basic solutions, with the aim of enhancing the subsequent biodegradation of bioplastics in controlled valorization scenarios such as composting and anaerobic digestors. Particular attention is given to pretreatment degradation technologies that modify surface properties to enhance microbial adhesion and enzymatic activity. Technologies such as ozonation and plasma-driven treatments increase surface hydrophilicity and introduce functional groups with oxygen bonds, facilitating subsequent microbial colonization and biodegradation. Irradiation-based techniques directly alter the chemical bonds at the polymer surface, promoting the formation of free radicals, chain scission, and crosslinking, thereby modifying the polymer structure. Pretreatments involving immersion in aqueous solutions may induce solution sorption and diffusion, together with hydrolytic chain breakage in bulk, with a relevant contribution to the ulterior biodegradation performance. By promoting abiotic degradation and increasing the accessibility of biopolymers to microbial systems, these pretreatment strategies can offer effective tools to enhance biodegradation and, therefore, the end-of-life management of bioplastics, supporting the transition toward sustainable cradle-to-cradle pathways within a biocircular economy. Full article

Spirulina extract holds significant promise for food applications, but its characteristic odor limits consumer acceptance. This study evaluated ozone (5, 10, and 25 ppm) and activated carbon (AC; 10, 30, and 50% w/v) treatments for their effects on selected volatile organic compounds (VOCs) in spirulina aqueous extracts, as well as on protein content, bioactive compounds, and antioxidant activities. Neither treatment adversely affected protein content. Ozone treatments significantly increased total phycobiliprotein content (172.5–181.1 mg/g; p < 0.05), whereas AC treatments significantly reduced it (138.5–159.0 mg/g; p < 0.05). Both treatments decreased chlorophyll (13.9–30.6%) and carotenoid (44.6–72.3%) levels, while DPPH and ABTS antioxidant activities varied according to treatment and concentration. AC treatments were more effective than ozone in reducing total VOCs (74.1–79.9% vs. 30.3–55.5% reduction), but 25 ppm ozone achieved the most favorable sensory profile as assessed by trained panelists. Treatments with 25 ppm ozone and 10% AC provided the best compromise between deodorization and retention of bioactive compounds. These findings indicate that both ozone and AC treatments can substantially reduce the undesirable odor of spirulina extracts, thereby improving their sensory quality and application potential in odor-sensitive food and functional products. Full article

Pea starch, often obtained as a by-product of pea protein isolation, is increasingly available and economically attractive. Consequently, the industry is seeking new applications of pea starch, both in its native and modified forms. This paper highlights the topic of pea and potato starch oxidation with ozone in aqueous suspension and evaluates the effect of process time, retention volume and solids content on pasting, texture, and flow behavior, benchmarking against a commercial hypochlorite-oxidized product. Moreover, obtained preparations were studied for their molecular mass distribution and hydrodynamic parameters. It was found that the oxidation of both potato and pea starch with ozone in an aqueous suspension is an effective method of obtaining this type of starch preparations. The extent of modification was dependent on all variables considered in the research. The depolymerization of both starch varieties progressed gradually, but the oxidation effects were more noticeable for potato starch compared to pea starch, which was found to be related to the gelling characteristic of those preparations. Full article

The development of efficient and sustainable advanced oxidation processes (AOPs) for organic pollutant removal is of great significance for water purification. In this study, a CoFeNi-layered double hydroxide (CoFeNi-LDH) catalyst was synthesized and applied for the simultaneous activation of peroxymonosulfate (PMS) and ozone to degrade rhodamine B (RhB) in aqueous solution. The CoFeNi-LDH/PMS/ozone system achieved a remarkable RhB removal efficiency of 95.2 ± 1.2% within 8 min under neutral pH conditions. Systematic parametric studies revealed that synergistic interactions among CoFeNi-LDH, PMS, and ozone contributed to the generation of reactive oxygen species (ROS), primarily sulfate radicals (SO₄^•−) and singlet oxygen (¹O₂), as confirmed by EPR and quenching experiments. Density functional theory (DFT) calculations demonstrated that ozone enhanced PMS adsorption and activation at CoFeNi catalytic sites. The catalyst exhibited robust magnetic recyclability and structural stability after repeated use. This work highlights a synergistic catalytic strategy for PMS/ozone activation, offering an effective and environmentally friendly platform for dye wastewater remediation. Full article

This study explores the adsorption and catalytic degradation of 2,4,6-trinitrotoluene (TNT) from aqueous solutions, using montmorillonite-based catalysts. Commercially, montmorillonite K10 was modified through aluminum pillaring (K10-Al-PILC), followed by vanadium intercalation (K10-Al-PILC-V) and ozone activation. A novel aspect of this work is the use of naturally contaminated water as the TNT source. The selected sample, collected from the Plaiul Arșiței–Cireșu–Leșunț region (Oituz, Bacau, Romania), originated from an area historically exposed to explosive residues, where TNT traces were previously identified. The adsorption performance of the materials was evaluated by varying adsorbent dosage, contact time, and solution pH. Catalytic ozonation experiments were conducted under different catalyst masses, ozone concentrations, and reaction times to assess degradation efficiency. The results demonstrated that aluminum pillaring significantly enhanced the adsorption capacity of the clay, while vanadium incorporation further improved both adsorption and catalytic activity. The vanadium-modified material exhibited superior performance in TNT removal, both through adsorption and oxidative degradation. Additionally, the catalytic ozonation process led to the formation of degradation products with reduced toxicity, confirming the potential of these materials for environmental remediation of nitroaromatic pollutants in real water systems. Full article