Search Results (169)

The purpose of this study was to investigate the effectiveness and mechanism of iron-based catalysts in the treatment of phenolic wastewater by catalyzing ozone oxidation. The removal rates of phenolics and COD were systematically examined using simulation experiments with water and actual wastewater, which involved analyzing the effects of reaction time, pH, ozone dosage, catalyst dosage, and initial concentration. The phenol and COD removal rates in the simulated wastewater were 95.9% and 93.5%, respectively, respectively, while the ozone dosage was 16 mg/L/min, pH was 6.7–6.8, and catalyst dosage was 0.3 g/L. The phenol and COD removal rates in the actual wastewater were 68.6% and 68.0%, respectively. The reaction time was 30 min. The system’s efficient removal ability for phenolic compounds, polycyclic aromatic hydrocarbons, and others was confirmed through three-dimensional fluorescence and ultraviolet spectroscopy. The iron-based catalyst generates ·OH through three pathways: adsorption of activated ozone on surface active sites, continuous production of free radicals by Fe²⁺/Fe³⁺ cycling, and direct activation of ozone by Fe²⁺. This mechanism analysis showed that the catalyst generates ·OH. These pathways convert pollutants into small molecules or mineralized by attacking the aromatic rings and conjugated structures of pollutants. Technical references for the deep treatment of phenol-containing wastewater are provided in this study. Full article

Ce-Ni@WSA (WSA = water-resistant silica–alumina gel) ozone catalyst was prepared with an impregnation–calcination method using WSA as the support and characterized by SEM, XRD, BET, XRF, and XPS analyses. The operating conditions and reaction mechanism of the Ce-Ni@WSA catalytic ozonation of norfloxacin (Nor)-simulated wastewater were systematically studied. A data-envelopment analysis model (DEA-B²C) was then established to evaluate the catalytic ozonation process. Under the optimal conditions of initial pH 7.42 (raw water), ozone dosage = 0.4 g/L/h, catalyst-filling ratio = 5%, humic acid dosage = 0 mg/L, the removal rates of chemical oxygen demand (COD) and Nor reached 84.95% and 93.52%, respectively. Ce-Ni@WSA retained its high catalytic performance and mechanical strength after 50 cycles of repeated use. Mechanistic studies showed that •OH oxidation was dominant in the catalytic-ozonation system, and Nor can be degraded into small molecules through three different pathways and eventually mineralized. The DEA-B²C model analysis showed that the treatment cost was low and the catalytic efficiency was high under the optimal operating conditions. Full article

To in situ and efficiently degrade irreversible membrane contaminants under mild conditions, SiC ceramic membranes (CMs) were imparted a catalytic ozonation functionality. A spinel-type CoFe₂O₄ catalyst was fabricated via a citrate-assisted sol–gel method and subsequently impregnated into the macropores of SiC ceramic membranes through a urea-assisted one-step combustion technique. The as-prepared catalytic membranes (CoFe₂O₄-CM) were systematically characterized by SEM, EDS, XRD and XPS techniques, and the catalytic ozonation performance was evaluated in an integrated catalytic ozonation–membrane separation system (CoFe₂O₄-CM/O₃). A flux recovery rate (FRR) of 93.33% was achieved at an ozone concentration of 70.27 mg·L⁻¹ within 30 min, indicating that a catalytic self-cleaning membrane was successfully developed. The possible catalytic reaction mechanism was elucidated by identifying reactive oxygen species generated using free radical quenching tests and electron paramagnetic resonance (EPR) analysis. This study offers a promising and environmentally friendly strategy for ceramic membrane cleaning in various membrane separation fields. Full article

Increasing water demand and the rising complexity of wastewater matrices, driven by pharmaceuticals, personal care products, and recalcitrant industrial contaminants, require advanced catalytic solutions capable of efficient mineralization under sustainable conditions. Solar-driven processes have attracted growing attention; however, ultraviolet disinfection, heterogeneous photocatalysis, and photo-Fenton systems are commonly treated as independent approaches without mechanistic integration. This review presents a unified photonic–thermal catalytic framework for solar-driven wastewater treatment, emphasizing the interplay between photon absorption, charge-carrier separation, reactive oxygen species generation, and radical-mediated oxidation pathways. The contributions of ultraviolet, visible, and infrared radiation are analyzed in terms of catalyst activation, persulfate and ozone activation mechanisms, and temperature-enhanced reaction kinetics governed by Arrhenius behavior. Particular attention is given to photothermal effects that modulate surface reaction rates, mass transfer, and catalyst stability. By integrating mechanistic insights with reactor-level considerations, this work provides a rational basis for the design of robust solar catalytic systems with enhanced activity, selectivity, and scalability for real wastewater applications. Full article

Advanced oxidation technology utilizing ozone as the oxidant shows great potential for the efficient purification of wastewater. However, the efficiency of ozone decomposition remains a significant bottleneck limiting the performance of ozone-based advanced oxidation processes. Catalytic ozone decomposition technology is a highly effective approach to enhancing ozone utilization efficiency; nevertheless, the competing adsorption of water molecules results in low catalytic reaction efficiency and catalyst deactivation. In this study, NiFe layered double hydroxide (LDH) was prepared successfully through the hydrothermal method. In situ DRIFTS with isotope labeling revealed that ozone combines with surface H atoms to produce H₂O, whereas the oxidation of high-valence metals destroys H₂O, producing H atoms that return to the surface of NiFe LDH. The unique structure of NiFe LDH allows water to participate in the surface H atom cycle process, and the charge exchange between Ni and Fe atoms accelerates the recovery of surface H atoms, which avoids the deactivation of the active site caused by competitive adsorption of water molecules, achieving a catalytic ozone decomposition efficiency of 99% for 80 h and 59.0% for simulated wastewater containing polyacrylamide as a model pollutant. This work presents a fresh insight into surface H cycling of LDH materials to improve the wet resistance of the catalysts. Full article

Catalytic ozonation often suffers from a low ozone utilization rate and incomplete mineralization of organic pollutants. To address these challenges, we designed and prepared a novel catalyst via a one-step thermal polymerization method, anchoring single-atom manganese on a glucose-derived carbon network-modified C₃N₅ framework (Mn/C-C₃N₅). Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (AC-HAADF-STEM) on an FEI Titan Themis Z microscope confirmed the atomic dispersion of Mn sites, while Raman spectroscopy using a Renishaw inVia Reflex laser micro-Raman spectrometer verified the successful incorporation of a graphitic carbon network within the C₃N₅ matrix. Moreover, electrochemical analyses, including electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) performed on a Bio-Logic SP-150 electrochemical workstation, demonstrated that the integration of the conductive carbon matrix substantially enhanced the interfacial charge transfer capability. The optimized Mn/C-C₃N₅ catalyst demonstrated exceptional performance in phenol mineralization, achieving a 97% total organic carbon (TOC) removal within 60 min, a remarkable improvement compared to pristine C₃N₅ (30%). Furthermore, the catalyst exhibited excellent operational stability, preserving more than 95% of its original activity over five repeated runs. Mechanistic investigations, including electron paramagnetic resonance (EPR) spectroscopy and radical quenching experiments, revealed that the Mn/C-C₃N₅ system accelerated the generation of multiple oxidizing radicals (•O₂⁻, ¹O₂, and •OH), with •OH identified as the predominant reactive species responsible for complete mineralization. This work establishes an integrated catalytic platform and provides fundamental insights into electronic structure modulation for designing advanced oxidation catalysts. Full article

Gas-phase oxidation of volatile organic compounds (VOCs) with the aid of ozone can be an attractive, energy-efficient way of treating exhaust gas streams in a low-temperature process, enabling the sustainable operation of industrial installations in a natural environment. This work is focused on the efficiency and kinetics of toluene oxidation with ozone towards CO₂ and H₂O in the presence of a SiO₂-supported cobalt catalyst. A kinetic model is proposed based on a simplified reaction mechanism, with the parameters determined from measurements carried out in a fixed-bed reactor at 40–65 °C under conditions ensuring negligible mass transfer resistance. The proposed model provided satisfactory agreement between the predicted and measured toluene and ozone conversion rates and the formation rate of CO₂, as well as in conditions when mass transfer resistance due to internal diffusion in the catalyst pellet was necessary to consider. The discussed results provide an assessment of the space velocity and ozone usage necessary to achieve a given degree of toluene conversion and mineralization to CO₂. The proposed model can be used for the design of a sustainable, low-temperature ozone-assisted catalytic process of VOC abatement. 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

Environmental pollution from ozone and wastewaters containing dyes from various industries is an important problem for humanity. In this study, novel composite catalysts based on manganese carbonate ore from the Obrochishte deposit, Bulgaria, were used successfully in two environmentally relevant catalytic processes—the ozone decomposition and photocatalytic decolourization of Malachite Green (MG) dye under UV illumination. Manganese carbonate ore/NiO, manganese oxides, and silver-containing composites were synthesized via co-precipitation, followed by calcination at 500 °C or hydrothermal treatment at 160 °C, and then thermal treatment. The phase and elemental composition, structure, morphology, and textural characteristics of the obtained composites were investigated using powder X-ray diffraction analysis, wavelength-dispersive X-ray fluorescence, Fourier-transform infrared spectroscopy, scanning electron microscopy, nitrogen adsorption–desorption isotherms, and the BET method. The materials exhibit a mesoporous structure. The results established that the thermally treated MnCO₃ ore/NiO, manganese oxides, and Ag-containing composites demonstrate a higher catalytic efficiency for the removal of ozone (85%, 93%, and 99%) in comparison with hydrothermally treated analogues—79%, 66%, and 98%, respectively. The thermally treated manganese carbonate ore/silver-containing composite exhibits the highest photocatalytic ability (83% degree of decolourization of MG dye) compared to the other investigated catalysts. Full article

Catalytic ozonation has been widely utilized in environmental applications, such as the removal of pharmaceutical active compounds (PHACs) from wastewater, due to its outstanding catalytic efficiency. To further enhance its performance and expand its practical application, ozone-based hybrid processes have been investigated, including ultraviolet radiation/ozonation, hydrogen peroxide/ozonation, ultrasonication/ozonation, and biological treatment/ozonation. Ozone degrades pollutants via two primary pathways: direct oxidation (via molecular ozone) and indirect oxidation (via reactive intermediates). Enhancing ozone decomposition into various reactive oxygen species (ROS), predominantly hydroxyl radicals, can significantly augment the degradation efficiency of pollutants. The surface adsorption and electron transfer processes of catalysts can promote ozone activation and decomposition into ROS to achieve the efficient degradation and mineralization of pollutants. Among catalysts, Mn-based catalysts have been extensively studied in past research. They have demonstrated exceptional performance when combined with other metals, such as Mn/Ce, Mn/Fe, and Mn/Co, etc., due to synergistic effects arising from bimetallic interactions. The inherent characteristics of catalyst supports may also influence the generation process of ROS. Choosing an appropriate support is conducive to promoting the uniform distribution of catalytic active sites on the catalyst surface and avoiding the agglomeration of metal particles, and it is also beneficial for the recovery and reuse of the catalyst. Furthermore, coupling catalytic ozonation processes with techniques like high-gravity technology, jet reactor systems, and micro–nano-bubbles can improve the utilization efficiency of ozone by exploiting gas cavitation effects. In this paper, we summarize the research progress in the degradation of PHACs using catalytic ozonation and discuss strategies for improving the mass transfer efficiency of ozone in water. Finally, the challenges and opportunities associated with applying catalytic ozonation in practical applications are also discussed. Full article

Naproxen (NPX), a nonsteroidal anti-inflammatory drug, is considered an emerging contaminant due to its persistence and potential environmental risks. In this study, NPX degradation was investigated through ozonation using nickel–iron foam (NiFeF) and NiO-modified NiFeF (NiO/NiFeF). The effect of the foam size was investigated using three configurations: S1 (1 cm × 2.5 cm), S2 (2 cm × 2.5 cm), and S3 (2 cm × 5 cm). Complete NPX removal was achieved in all systems, with degradation times of 4 min for ozonation alone, 2 min for NiFeF-S1, and 1 min for NiO/NiFeF-S2 and NiO/NiFeF-S3. The NiO/NiFeF catalyst was synthesized via ultrasonic spray pyrolysis, resulting in a porous structure with abundant active sites. Compared with conventional ozonation, NiO/NiFeF-S1 improved the total organic carbon (TOC) removal rate by 6.2-fold and maintained 87.5% of its activity after five reuse cycles, demonstrating excellent stability. High-resolution mass spectrometry revealed that catalytic ozonation generated fewer by-products (22 vs. 27 for ozonation alone) and promoted more selective pathways, including demethylation, ring-opening oxidation, and partial mineralization to CO₂ and H₂O. This enhanced performance is attributed to the synergy between NiO and NiFeF, which facilitates reactive oxygen species generation and electron transfer. These results demonstrate the potential of NiO/NiFeF as an efficient and stable catalyst for pharmaceutical removal from water. Full article

Nitrogen oxides (NO_x), one of the major air pollutants, not only are key substances in forming acid rain and photochemical smog, but can also enter the stratosphere and damage the ozone layer to some extent. The selective catalytic reduction (NH₃-SCR) technology has been widely utilized in industrial flue gas treatment for its efficient removal of NO_x. In recent years, nitrogen-doped carbon materials (NC) have emerged as a novel type of environmentally friendly catalyst, showing outstanding performance in the low-temperature NH₃-SCR reaction. This paper reviews the application advancements of nitrogen-doped carbon materials in the NH₃-SCR reaction, with a focus on the catalytic mechanisms, modification strategies, and stability issues. This paper analyzes multiple improvement ideas, such as regulating metal types and distributions to achieve synergy effects, optimizing carrier loading, and designing morphology structures, and discusses how these measures jointly act to enhance the overall performance of the catalyst. Finally, solutions to the deactivation problem of NC catalysts are proposed, and the future research directions are explored to meet the increasingly stringent environmental protection requirements and promote the development of related technologies. Full article

To promote sustainable wastewater treatment, this study developed an eco-friendly and low-cost ozone catalyst using natural zeolite for the advanced treatment of petrochemical wastewater. The Ca-Cu/zeolite catalyst (0.75 mol/kg Ca and 0.25 mol/kg Cu) demonstrated high efficiency in catalytic ozonation, achieving 55.52% TOC removal under optimized conditions (ozone dosage: 108.0 mg/(L·h), catalyst dosage: 406.0 g/L, reaction time: 90 min). Compared to ozonation alone, the catalyst enhanced oxidation rates by 10 times, promoting ozone decomposition into reactive oxygen species (e.g., OH and ¹O₂) while improving gas–liquid–solid mass transfer for efficient pollutant mineralization. Remarkably, the natural zeolite-based catalyst exhibited superior sustainability: compared to conventional alumina-based catalysts, its production cost (4000–4500 CNY/ton) is 44–53% lower, while its carbon footprint (533.7 kg CO₂/ton) is reduced by 45.4%. This work presents a sustainable, low-carbon, and economically viable catalytic ozonation solution, contributing to the development of green and cost-effective industrial wastewater treatment technologies. Full article

Biologically treated swine farm wastewater still contains high levels of refractory organics, humic substances and antibiotic residues, posing environmental risks and limiting opportunities for water reuse. Wastewater treatment by ozonation alone suffers from low mass transfer efficiency and selective oxidation. To overcome these limitations, a catalytic ozonation process (O₃/Fe²⁺/H₂O₂) was applied and optimized using Response Surface Methodology (RSM) based on single-factor experiments and Central Composite Design (CCD) for advanced swine farm wastewater treatment. The optimal conditions ([O₃] = 25.0 mg/L, [Fe²⁺] = 25.9 mg/L, [H₂O₂] = 41.1 mg/L) achieved a COD removal of 44.3%, which was 86.8% higher than that of ozonation alone, and increased TOC removal to 29.5%, indicating effective mineralization. Biodegradability (BOD₅/COD) of swine farm wastewater effluent increased from 0.01 to 0.34 after the catalytic ozonation treatment. Humic-like and fulvic-like substances were removed by 93.7% and 95.4%, respectively, and antibiotic degradation was significantly accelerated and enhanced. The synergistic process improved ozone utilization efficiency by 33.1% and removed 53.95% of total phosphorus through Fe³⁺-mediated coprecipitation. These findings demonstrate that with catalytic ozone decomposition and production of hydroxyl radicals, the O₃/Fe²⁺/H₂O₂ system effectively integrates enhanced ozone utilization efficiency, radical synergy, and simultaneous pollutant removal, providing a cost-effective and technically feasible strategy for advanced swine farm wastewater treatment and safe reuse. 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