Search Results (119)

Fibrate pharmaceuticals (fibrates), as a widespread class of emerging contaminants, pose potential risks to both ecological systems and human health. The photocatalytic system based on nitrogen (N) and fluorine (F) co-doped TiO₂ nanotube arrays (NF-TNAs) provides a renewable solution for fibrate pharmaceutical removal from water, powered by inexhaustible sunlight. In this study, the degradation of two typical fibrates, i.e., bezafibrate (BZF) and ciprofibrate (CPF), under simulated sunlight irradiation through NF-TNAs were investigated. The photocatalytic degradation of BZF/CPF was achieved through combined radical and non-radical oxidation processes, while the generation and reaction mechanisms of associated reactive oxygen species (ROS) were examined. Electron paramagnetic resonance detection and quenching tests confirmed the existence of h⁺, •OH, O₂^•−, and ¹O₂, with O₂^•− playing the predominant role. The transformation products (TPs) of BZF/CPF were identified through high-resolution mass spectrometry analysis combined with quantum chemical calculations to elucidate the degradation pathways. The influence of co-existing ions and typical natural organic matters (NOM) on BZF/CPF degradation were also tested. Eventually, the ecological risk of BZF/CPF transformation products was assessed through quantitative structure–activity relationship (QSAR) modeling, and the results showed that the proposed photocatalytic system can largely alleviate fibrate toxicity. Full article

This study presents the development of a novel Cu–Co–O-codoped graphitic carbon nitride (g-C₃N₄) catalyst for efficient peroxymonosulfate (PMS) activation to degrade sulfamethoxazole (SMX) in aqueous environments. The synthesized Cu–Co–O-g-C₃N₄ catalyst demonstrated exceptional catalytic performance, achieving 90% SMX removal within 10 min—significantly outperforming pristine g-C₃N₄ (14%) and O-doped g-C₃N₄ (22%)—with a reaction rate constant of 0.63 min⁻¹. The superior activity was attributed to the synergistic effects of Cu-Co bimetallic doping and oxygen incorporation, which enhanced the active sites, stabilized metal ions, and minimized leaching. Mechanistic studies revealed a dual-pathway degradation process: (1) a radical pathway dominated by sulfate radicals (SO₄•⁻) and (2) a non-radical pathway driven by singlet oxygen (¹O₂), with the latter identified as the dominant species through quenching experiments. The catalyst exhibited broad pH adaptability and optimal performance at neutral to alkaline conditions. Characterization techniques (XRD, FTIR, XPS) confirmed successful doping and revealed that oxygen incorporation modified the electronic structure of g-C₃N₄, improving charge carrier separation. This work provides a sustainable strategy for antibiotic removal, addressing key challenges in advanced oxidation processes (AOPs), and highlights the potential of multi-heteroatom-doped carbon nitride catalysts for water purification. Full article

The emergence of antifungal-resistant Aspergillus fumigatus (A. fumigatus) became a serious public health concern, underscoring the need for new effective antifungal agents. Here, we present a strategy based on the in situ generation of radical species that are toxic to the pathogen. The synthesis of an alkoxyamine linked to a peptide substrate recognized by A. fumigatus-secreted dipeptidyl peptidase is described. Kinetic experiments show a stable prodrug prior to enzymatic activation. Ensuing peptide cleavage and spontaneous homolysis resulted in the generation of a stable nitroxide and a reactive alkyl radical moiety. Next, the exposure of A. fumigatus spores to the prodrug lead to pathogen growth inhibition in a compound concentration-dependent fashion (e.g., 42% inhibition at 10 µg/L). Importantly, the designed alkoxyamine inhibited not only the growth of a clinical voriconazole-susceptible A. fumigatus strain, but also the growth of a strain resistant to this azole. To determine the antifungal importance of the reactive alkyl radical, its substitution with a non-radical structure did not prevent A. fumigatus growth. Furthermore, the introduction of succinic group in the peptide substrate resulted in the loss of alkoxyamine antifungal properties. Our work reports a novel chemical strategy for antifungal therapy against A. fumigatus based on the pathogen enzyme-mediated generation of toxic radicals. Significantly, these findings are timely since they could overcome the emerged resistance to conventional drugs that are known to target defined pathogen biologic mechanisms such as ergosterol synthesis. Full article

This study explores biochar-based catalysts made from hardwood (HW) and wheat straw (WS) biomass for activating persulfate (PS) in the removal of lindane and β-endosulfan from water. The effects of pyrolysis temperature, solution pH, and PS concentration were investigated. The results indicated that both feedstock and pyrolysis temperature are key factors influencing biochar composition. Biochars pyrolyzed at 700 °C exhibited higher surface areas compared to those pyrolyzed at 400 °C, suggesting more effective interactions with the target pesticides. Changes in pH had a minimal impact on pesticide removal, while increasing the PS concentration from 0.5 to 3 mM accelerated degradation. However, further increases in PS concentration slowed the degradation of both pesticides. Under optimal conditions (pH of 7.0 ± 0.2 and PS concentration of 3 mM), the HW700/PS and WS700/PS systems achieved > 90% removal of pesticides within 4 h. Quenching experiments confirmed that non-radical species (¹O₂), generated through persulfate activation by biochar, were the key factor in lindane degradation in both systems, supporting the catalytic role of biochar rather than mere adsorption. In the HW700/PS system, SO₄^•−, HO^•, and ¹O₂ acted synergistically to enhance the degradation of β-endosulfan, whereas in the WS700/PS system, the degradation was mainly driven by SO₄^•− and ¹O₂. Notably, HW700 biochar maintained its activation efficiency during β-endosulfan degradation even after five cycles. This research offers new insights into the potential of biochar-activated PS as a green, cost-effective, and efficient method for water treatment, addressing pesticide-contaminated surface water and promoting agricultural waste recycling. Full article

Rapid industrialization has escalated environmental pollution caused by organic compounds, posing critical challenges for wastewater treatment. Advanced oxidation processes based on peroxymonosulfate (PMS) suffer from metal leaching and catalyst recycling challenges. To address these limitations, this study developed a nitrogen-doped biochar aerogel (NBA) derived from poplar wood powder as an eco-friendly and easily recoverable PMS activator. The NBA catalyst, optimized by tuning the calcination temperature to achieve a specific surface area of 297.5 m² g⁻¹, achieved 97% bisphenol A (BPA) removal within 60 min with a catalyst dosage of 0.3 g/L and 1.0 mM PMS under mild conditions. The material exhibited broad pH adaptability (pH 3.5–9), recyclability (>94% efficiency after thermal treatment), and versatility in degrading seven pollutants (BPA, phenol, 4-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, rhodamine 6G, and levofloxacin) through synergistic radical (•OH, SO₄^•−, O₂^•−) and non-radical (¹O₂) pathways. X-ray photoelectron spectroscopy (XPS) analyses revealed that nitrogen doping enhanced PMS activation by optimizing electronic structures. This study highlights the potential of waste biomass-derived carbon aerogels as eco-friendly, efficient, and reusable catalysts for advanced oxidation processes in wastewater treatment. Full article

Bimetallic catalysts can effectively enhance the catalytic degradation efficiency of peroxymonosulfate (PMS), which is usually attributed to the enhancement of electron transfer, but currently, there is no clear explanation of the mechanism of how the electron transfer is enhanced. A nitrogen-doped Fe/Mn composite biochar (FeMn-NBC) was co-constructed by hydrothermal synthesis and high-temperature calcination. The FeMn-NBC activated PMS more efficiently than the monometallic one due to the enhanced electron transfer between Fe and Mn. The FeMn-NBC/PMS system activated PMS with Mn as the active center, and the high oxidation state of Mn⁴⁺ promoted the acceleration of the PMS adsorption of the generation of Mn²⁺/Mn³⁺. This gaining effect accelerated the electron cycling between Fe²⁺/Fe³⁺ and Mn²⁺/Mn³⁺/Mn⁴⁺, which enhanced the PMS catalysis to generate free radicals (•OH, SO₄^•− and •O₂⁻) and non-radicals (¹O₂) for the efficient degradation of diisobutyl phthalate (DIBP). Benefiting from this gaining effect, the degradation rate of DIBP by the FeMn-NBC/PMS system was increased by 2.43 and 3.38 times compared to Fe-NBC and Mn-NBC. The bimetallic-enhanced electron transfer mechanism proposed in this study facilitated the development of efficient catalysts for more efficient and selective removal of organic pollutants. Full article

Heterogeneous electro-Fenton (HEF) technology utilizing iron-based cathode catalysts has emerged as an efficient advanced oxidation process for wastewater treatment, demonstrating outstanding performance in degrading emerging organic contaminants (EOCs) while maintaining environmental sustainability. The performance of this technology is governed by two critical processes: the accumulation of H₂O₂ and the electron transfer mechanisms governing the Fe(III)/Fe(II) redox cycle. This review comprehensively summarizes recent advances in understanding the electron transfer mechanisms in iron-based HEF systems and their applications for EOC degradation. Five representative catalyst categories are critically analyzed, including zero-valent iron/alloys, iron oxides, iron-carbon/nitrogen-doped carbon composites, iron sulfides/phosphides, and iron-based MOFs, with a particular focus on their structural design, catalytic performance, and electron transfer mechanisms. A particular focus is placed on strategies enhancing Fe(III)/Fe(II) cycling efficiency and the interplay between radical (^•OH) and non-radical (¹O₂) oxidation pathways, including their synergistic effects in complex wastewater systems. Major challenges, including catalyst stability, pH adaptability, and selective oxidation in complex matrices, are further discussed. Potential solutions to these limitations are also discussed. This review provides fundamental insights for designing high-efficiency iron-based HEF catalysts and outlines future research directions to advance practical applications. Full article

Sludge-derived biochar (SDB) synthesized by the pyrolysis of sludge is gaining enormous interest as a sustainable solution to wastewater treatment and sludge disposal. Despite the proliferation of general biochar reviews, a focused synthesis on SDB-specific advances, particularly covering the recent surge in multifunctional wastewater treatment applications (2020–2025), receives little emphasis. In particular, a critical analysis of recent trends, application challenges, and future research directions for SDB is still limited. Unlike broader biochar reviews, this mini-review highlights the comparative advantages and limitations of SDB, identifies emerging integration strategies (e.g., bio-electrochemical systems, catalytic membranes), and outlines future research priorities toward enhancing the durability and environmental safety of SDB applications. Specifically, this review summarized the advances from 2020 to 2025, focusing exclusively on functional modifications, and practical applications of SDB across diverse wastewater treatment technologies involved in adsorption, catalytic oxidation, membrane integration, electrochemical processes and bio-treatment systems. Quantitative comparisons of adsorption capacities (e.g., >99% Cd2+ removal, >150 mg/g tetracycline adsorption) and catalytic degradation efficiencies are provided to illustrate recent improvements. The potential of SDB in evaluating traditional and emerging contaminant degradation among the Fenton-like, persulfate, and peracetic acid activation systems was emphasized. Integration with membrane technologies reduces fouling, while electrochemical applications, including microbial fuel cells, yield higher power densities. To improve the functionality of SDB-based systems in targeting contamination removal, modification strategies, i.e., thermal activation, heteroatom doping (N, S, P), and metal loading, played crucial roles. Emerging trends highlight hybrid systems and persistent free radicals for non-radical pathways. Despite progress, critical challenges persist in scalability, long-term stability, lifecycle assessments, and scale-up implementation. The targeted synthesis of this review offers valuable insights to guide the development and practical deployment of SDB in sustainable wastewater management. Full article

Background: Several mitochondrial abnormalities such as defective energy production, depletion of energy stores, Ca²⁺ accumulation, generation of reactive oxygen species, and impaired intracellular signaling are associated with cardiac dysfunction during the development of different heart diseases. Methods: A narrative review was compiled by a search for applicable literature in MEDLINE via PubMed. Results: Mitochondria generate ATP through the processes of electron transport and oxidative phosphorylation, which is used as energy for cardiac contractile function. Mitochondria, in fact, are the key subcellular organelle for the regulation of intracellular Ca²⁺ concentration and are considered to serve as a buffer to maintain Ca²⁺ homeostasis in cardiomyocytes. However, during the development of heart disease, the excessive accumulation of intracellular Ca²⁺ results in mitochondria Ca²⁺-overload, which, in turn, impairs mitochondrial energy production and induces cardiac dysfunction. Mitochondria also generate reactive oxygen species (ROS), including superoxide anion radicals and hydroxyl radicals as well as non-radical oxidants such as hydrogen peroxide, which promote lipid peroxidation and the subsequent disturbance of Ca²⁺ homeostasis, cellular damage, and death. Conclusion: These observations support the view that both oxidative stress and intracellular Ca²⁺-overload play a critical role in mitochondrial disruption during the pathogenesis of different cardiac pathologies. Full article

The functionalization of nitrogen-doped graphene with β-Cyclodextrin (designated β/N-rGO) was employed to enhance the dispersibility of graphene materials and to establish an adsorption-catalytic oxidation system using peroxymonosulfate (PMS) for the removal of trace antibiotics from water. The experimental results indicated that β-Cyclodextrin was effectively dispersed on the support structure of nitrogen-doped graphene, which enhanced the specific surface area and dispersibility of the material. The adsorption-catalytic oxidation system comprising β/N-rGO and PMS degraded 92.35% of sulfamethoxazole within 12 min and exhibited significant removal efficiency for sulfonamides, quinolones, macrolides, tetracyclines, β-lactams, and chloramphenicol antibiotics across a pH range of 3–12. The reaction time was reduced by over 10% compared to the unmodified material, with a more pronounced improvement in treatment efficiency, particularly under low-pH conditions. The activation energy of β/N-rGO was estimated to be approximately 4.5 kJ/mol, and elevated temperatures accelerated the reaction, with the removal rate remaining above 85% after five regeneration cycles. Quenching experiments and EPR spectra confirmed that the primary pathway for PMS activation by β/N-rGO was a non-radical process dominated by singlet oxygen. These findings broaden the research and application scope of cyclodextrin–graphene interactions and provide a feasible approach for the removal of trace antibiotics from water. Full article

Carbonaceous materials (CMs) have gained great attention as heterogeneous catalysts in water treatment because of their high efficiency and potential contribution to achieving carbon neutrality. Expanded graphite (EG) is ideal for studying CMs because the reactivity in CMs largely depends on graphitic structures, and most surface of EG is exposed, minimizing mass transfer resistance. However, EG is poor in adsorption and catalysis. In this study, EG was modified by simple thermal treatment to investigate the effects of characteristics of graphitic structures on reactivity. Tetracycline (TC) removal rate via activating peroxydisulfate (PDS) by the EG treated at 550 °C (EG550) was more than 10 times that of EG. The thermal modification did not significantly increase surfaces but led to increases in damaged, rough surfaces, graphitization degree, C content, defects, and C=O. Radical and non-radical pathways, such as SO₄^•−, O₂^•−, ¹O₂, and electron transfer, were involved in TC removal in EG550+PDS. TC degradation in EG550+PDS was initiated by hydroxylation, followed by demethylation, dehydroxylation, decarbonylation, and ring-opening. The ions ubiquitous in water systems did not significantly affect the performance of EG550+PDS, except for H₂PO₄⁻ and HCO₃⁻, suggesting the high potential of practical applications. This study demonstrated that graphitic structure itself and surface area are not detrimental in the catalytic reactivity of CMs, which is different from previous studies. Rather, the reactivity is governed by the characteristics, i.e., defects and functional groups of the graphitic structure. It is thought that this study provides valuable insights into the development of highly reactive CMs and the catalytic systems using them. Full article

To address the issues of poor Co²⁺ regeneration and limited interfacial electron transfer in heterogeneous catalytic systems, this study proposes the synthesis of highly efficient and stable Co₃O₄/ZnO composites through the pyrolysis–oxidation reaction of Co/Zn MOFs for the degradation of rhodamine B (RhB) using activated peroxymonosulfate (PMS). The results confirmed that the catalyst exhibited a high electron transfer capacity, and the synergistic effect between the bimetals enhanced the reversible redox cycle of Co³⁺/Co²⁺. Under optimal conditions, complete removal of RhB was achieved in just 6 min using the Co₃O₄/ZnO composite, which demonstrated excellent stability after five cycles. Furthermore, the catalyst exhibited a high degradation efficiency in real water samples with a total organic carbon (TOC) removal rate of approximately 65% after 60 min. The electrochemical measurements, identification of active species, and X-ray photoelectron spectroscopy (XPS) analysis revealed that non-radicals (¹O₂ and direct charge transfer) played a major role in the degradation of RhB. Finally, the potential mechanisms and degradation pathways for RhB degradation using this catalyst were systematically investigated. This study opens new avenues for the development of efficient and stable PMS catalysts, and provides insights into the preparation of other emerging metal oxides. Full article

Coke (AC) was modified and activated with sodium hydroxide (NaOH) and potassium hydroxide (KOH) to produce AC-Na and AC-K, respectively, and applied as a persulfate (PS) activator to promote phenol (Ph) removal in water. Under the given experimental conditions, compared to AC/PS (Ph removal effect was 77.09%), the Ph removal effects were 94.46% and 88.73% for AC-K/PS and AC-Na/PS, respectively. AC-K proved to be a more effective activator than AC-Na and was used for all the subsequent experiments. When PS/phenol molar ratio was 6.26:1:00, the initial system pH was 7 and the system temperature was 25 °C; the AC-K/PS system could effectively remove Ph (98.75%) from the simulated wastewater. After that, the stability of AC-K was verified. Electron paramagnetic resonance (EPR) and quenching analysis confirmed the hydroxyl free radical (•OH) to be predominant within this system. EPR combined with X-ray photoelectron spectroscopy (XPS), Fourier-transformed infrared (FTIR) spectroscopy, and Raman spectroscopy indicated that the sulfate radical (SO₄^•−) and •OH were generated due to the defects in AC-K, thereby enhancing the PS activation potency of AC-K. Additionally, the radical quenching experiments showed that the superoxide (O₂⁻) radical is a key intermediate product promoting SO₄^•− and •OH, which aided Ph removal. Both radical (SO₄^•− and •OH) and non-radical (¹O₂) pathways were found to co-exist during the removal process. The Ph removal rate of the AC-K/PS system could still reach 29.50%, even after four repeated cycles. These results demonstrate that the unique AC-K/PS system has a potential removal effect on organic pollutants in water. Full article

The growing diversity and prevalence of contaminants of emerging concern (CECs) in aquatic environments present significant risks to human health and ecosystems, necessitating the development of effective remediation strategies. Advanced oxidation processes (AOPs) have emerged as a promising solution due to their ability to produce highly reactive species that efficiently degrade persistent contaminants. Among the various oxidizing agents, peracetic acid (PAA) has attracted significant attention in the field of water treatment for its powerful oxidative properties, environmentally safe decomposition, and ease of use. This article is designed to offer a comprehensive overview of the latest trends in PAA-based AOPs. The discussion begins with an overview of the intrinsic performance of PAA, emphasizing its oxidation potential and degradation mechanisms. Subsequently, the effectiveness of PAA-based AOPs in remediating CECs is explored, focusing on transition metal-mediated activation (Fe, Co, Mn), UV irradiation, and carbon-based catalysts, all of which enhance the generation of reactive species (RS). Next, the determination of RS in PAA-based AOPs is examined, distinguishing between free radical (organic and inorganic) and non-radical (singlet oxygen and high-valent metal) mechanisms that govern pollutant degradation. Then, key factors affecting the removal of CECs in PAA-based AOPs, including initial PAA concentration, catalyst dosage, and pH, are also addressed. Following that, the potential by-products and hazard assessments associated with PAA oxidation are discussed. Finally, current challenges and future research directions are proposed to facilitate the large-scale application of PAA-based AOPs in water remediation. Full article

The reliance on acidic working environments presents a significant bottleneck in the development and widespread application of peroxymonosulfate (PMS)-activated high-valent iron-oxo systems and iron-based catalysts. In this study, we present a system of non-homogeneous activation of peroxymonosulfate that is capable of overcoming the acidic environment in heterogeneous to generate continuous non-radicals for the selective degradation of organic pollutants such as sulfamethoxazole. The system takes advantage of amphiprotic hydroxides to create a homogeneous neutral pH microenvironment at the heterogeneous interface of the catalyst. The generation of the neutral pH microenvironment is capable of inducing the formation of high-valent iron-oxo species and a more stable cycling of iron ions in the iron-based material., promoting sustained catalytic activity A series of design quenching experiments, electron paramagnetic resonance (EPR) experiments, and three-dimensional excitation-emission matrix fluorescence spectroscopy (3D-EEM) which were conducted to assess the selectivity of FeCo-LDH/PMS under high salt or natural organic conditions, as well as its effectiveness in treating real wastewater. These findings offer a novel approach to overcoming pH limitations and enhancing the selectivity of target pollutants in advanced oxidation processes (AOPs). Full article