Search Results (165)

In this study, the advanced oxidation system of peroxymonosulfate (PMS) was activated by molybdenite supported on biochar (Molybdenite@BC), and the degradation efficiency, influencing factors and degradation mechanism of sulfamethoxazole (SMX) were explored through experiments. Molybdenite@BC, a composite material used in the study, was prepared by pyrolysis at high temperature. The optimum pyrolysis temperature was 700 °C, and the mass ratio of molybdenite to biochar (BC) was 1:3. By changing dosage of Molybdenite@BC, pH value, initial concentration of PMS, and the types and concentration of inorganic anions, the effects of various factors on SMX degradation were systematically studied. The optimum reaction conditions of the Molybdenite@BC/PMS process were as follows: Molybdenite@BC dosage was 100 mg/L, PMS concentration was 0.2 mM, pH value was 6.9 ± 0.2, and initial SMX concentration was 6 mg/L. Under these conditions, the degradation rate of SMX was 97.87% after 60 min and 99.06% after 120 min. The material characterization analysis showed that Molybdenite@BC had a porous structure and rich active sites, which was beneficial to the degradation of pollutants. After the composite material was used, the peaks of MoO₂ and MoS₂ became weaker, which indicated that there was some loss of molybdenum from the material structure. Electron paramagnetic resonance (EPR) and radical quenching experiments revealed that Molybdenite@BC effectively catalyzed PMS to generate various reactive oxygen radicals and non-free radicals, including singlet oxygen (¹O₂), hydroxyl radical (^•OH), sulfate radical (SO₄^•−) and superoxide radical (^•O₂⁻). ¹O₂ played a leading role in the degradation of SMX, while ^•OH and SO₄^•− had little influence. The intermediate products of the degradation of SMX in Molybdenite@BC/PMS system were analyzed by liquid chromatography–tandem mass spectrometry (LC–MS). The results showed that there were nine main intermediate products in the process of degradation, and the overall toxicity tended to decrease during the degradation of SMX. The degradation path analysis showed that with the gradual ring opening and bond breaking of SMX, small molecular compounds were generated, which were finally mineralized into H₂O, CO₂, CO₃²⁻, H₂SO₄ and other substances. The research results confirmed that the Molybdenite@BC/PMS process provided a feasible new method for the degradation of SMX in water. Full article

Methoxy radicals (CH₃O•), formed as intermediates during methane oxidation, may play an underexplored but locally significant role in the atmospheric oxidation of dimethyl sulfide (DMS), a key sulfur-containing compound emitted primarily by marine phytoplankton. This study presents a comprehensive computational investigation of the reaction mechanisms and kinetics of DMS oxidation initiated by CH₃O•, using density functional theory B3LYP-D3(BJ)/6-311++G(3df,3pd), CCSD(T)/6-311++G(3df,3pd), and UCBS-QB3 methods. Our calculations show that DMS reacts with CH₃O• via hydrogen atom abstraction to form the methyl-thiomethylene radical (CH₃SCH₂•), with a rate constant of 3.05 × 10⁻¹⁶ cm³/molecule/s and a Gibbs free energy barrier of 14.2 kcal/mol, which is higher than the corresponding barrier for reaction with hydroxyl radicals (9.1 kcal/mol). Although less favorable kinetically, the presence of CH₃O• in localized, methane-rich environments may still allow it to contribute meaningfully to DMS oxidation under specific atmospheric conditions. While the short atmospheric lifetime of CH₃O• limits its global impact on large-scale atmospheric sulfur cycling, in marine layers where methane and DMS emissions overlap, CH₃O• may play a meaningful role in forming sulfur dioxide and downstream sulfate aerosols. These secondary organic aerosols lead to cloud condensation nuclei (CCN) formation, subsequent changes in cloud properties, and can thereby influence local radiative forcing. The study’s findings underscore the importance of incorporating CH₃O• driven oxidation pathways into atmospheric models to enhance our understanding of regional sulfur cycling and its impacts on local air quality, cloud properties and radiative forcing. These findings provide mechanistic insights that improve data interpretation for atmospheric models and extend predictions of localized variations in sulfur oxidation, aerosol formation, and radiative forcing in methane-rich environments. Full article

This study explores the application of a cobalt–manganese oxide catalyst supported on coal gangue (CoMnOx@CG) for peroxymonosulfate (PMS) activation to degrade phenol in coal chemical wastewater (CCW). The synthesized CoMnOx@CG catalyst demonstrated remarkable catalytic activity, achieving above 90% phenol removal within 10 min at pH 9 and 11. More importantly, the catalyst exhibited excellent stability and reusability, maintaining over 85% phenol removal efficiency after four consecutive cycles and cobalt leaching below 100 μg/L. Quenching experiments and electron paramagnetic resonance (EPR) analyses revealed that singlet oxygen (¹O₂), sulfate radicals (SO₄·⁻), and hydroxyl radicals (·OH) contributed to the degradation process. When treating actual CCW, the system significantly reduced both phenol and fluorescent dissolved organic matter, demonstrating its effectiveness for complex wastewater matrices. CoMnOx@CG provides a sustainable and practical solution for alkaline refractory wastewater remediation. Full article

This study investigated the antioxidant and antiadipogenic activities of sulfated polysaccharide (SPs) from the red seaweed Gracilaria caudata. First, sulfated polysaccharide-rich extracts (SPREs) from fifteen tropical seaweeds were screened to evaluate both their chemical composition and antioxidant potential. Among all samples, G. caudata exhibited the highest total antioxidant capacity, which justified its selection for detailed characterization. Sequential acetone precipitation produced three SPs (F1.5, F2.0, and F3.0), differing in sulfate content, monosaccharide composition, and molecular weight. In vitro assays revealed that F1.5 had the highest total antioxidant capacity and strong iron-chelating activity, while F2.0 exhibited the most effective hydroxyl radical scavenger. Importantly, F1.5 was the only SP that was non-cytotoxic to non-tumor cell lines. In 3T3-L1 preadipocytes, F1.5 attenuated H₂O₂-induced oxidative stress by reducing ROS and MDA levels and restoring GSH and SOD activity, achieving effects comparable to those of quercetin. Moreover, F1.5 inhibited adipogenic differentiation in a dose-dependent manner, as evidenced by decreased Oil Red O staining and reduced glycerol release. Collectively, these findings indicate that F1.5 exerts both antioxidant and antiadipogenic activities, highlighting G. caudata as a promising natural source of bioactive polysaccharides with potential nutraceutical applications. Nonetheless, further studies are required to elucidate the molecular mechanisms underlying these effects, validate the efficacy in vivo, and assess bioavailability and safety before clinical translation can be considered. Full article

Sulfamethazine (SMT) contamination in aquatic environments and its propensity to induce antibiotic resistance pose critical risks to ecosystems and public health, necessitating effective remediation strategies. Here, we develop a MOF-derived copper core–shell activator, Cu-MOFs400@PSN, by coating a calcined Cu-MOF derivative (Cu-MOFs400) with a nitrogen/phosphorus/sulfur-doped shell and systematically evaluate its peroxymonosulfate (PMS) activation performance toward SMT degradation. Comprehensive characterization confirms successful N/P/S incorporation and the formation of a smooth spherical core–shell architecture that enhances chemical stability; the Cu-MOFs400@PSN/PMS system achieves complete SMT removal within 120 min and maintains 99.33% efficiency after five reuse cycles. Bicarbonate markedly promotes degradation, whereas chloride, nitrate, and phosphate exert negligible interference, indicating strong tolerance to common background ions. Radical-quenching tests identify singlet oxygen (¹O₂) and superoxide (•O₂⁻) as the dominant reactive species, with minor contributions from sulfate and hydroxyl radicals; the system facilitates complete SMT mineralization and reduces resistance-inducing intermediates. These results highlight Cu-MOFs400@PSN as a robust and reusable PMS activator for practical remediation of SMT-contaminated waters and mitigation of antibiotic-resistance risks. Full article

Iron-based catalysts for peroxymonosulfate (PMS) and peroxydisulfate (PDS) activation represent a cornerstone of advanced oxidation processes (AOPs) in environmental remediation, prized for their cost-effectiveness, environmental compatibility, and high catalytic potential. These catalysts, including zero-valent iron, iron oxides, and iron-organic frameworks, activate PMS/PDS through heterogeneous and homogeneous pathways to generate reactive species such as sulfate radicals (SO₄•⁻) and hydroxyl radicals (•OH). However, their large-scale implementation is constrained by inefficient iron cycling, characterized by sluggish Fe³⁺/Fe²⁺ conversion and significant iron precipitation, leading to catalyst passivation and oxidant wastage. This comprehensive review systematically dissects innovative strategies to augment iron cycling efficiency, encompassing advanced material design through elemental doping, heterostructure construction, and defect engineering; system optimization via reductant incorporation, bimetallic synergy, and pH modulation; and external field assistance using light, electricity, or ultrasound. We present a mechanistic deep-dive into these approaches, emphasizing facilitated electron transfer, suppression of iron precipitation, and precise regulation of radical versus non-radical pathways. The performance in degrading persistent organic pollutants—including antibiotics, per- and polyfluoroalkyl substances (PFASs), and pesticides—in complex environmental matrices is critically evaluated. We further discuss practical challenges related to scalability, long-term stability, and secondary environmental risks. Finally, forward-looking directions are proposed, focusing on rational catalyst design, integration of sustainable processes, and scalable implementation, thereby providing a foundational framework for developing next-generation iron-persulfate catalytic systems. Full article

The non-oxidizing antimicrobial 2-Methyl-4-Isothiazolin-3-one (MIT) poses a significant environmental risk given its frequent detection in municipal wastewater. This study showed that the combination of Vacuum UV/UV (VUV/UV) and persulfate (PDS) efficiently achieved the rapid transformation and removal of 10 μM MIT within 90 s, which is much faster than UV, UV/PDS, and VUV/UV. Increasing the PDS dosage improved MIT degradation, whereas changes in pH between 4 and 10 had little effect. Radical quenching experiments showed that 93% of the MIT oxidation was attributable to the hydroxyl radical (•OH) and the sulfate radical (SO₄•⁻). SO₄•⁻ and •OH at concentrations of 8.6 × 10⁻¹² M and 1.5 × 10⁻¹² M accounted for 32% and 61% of the MIT degradation, respectively, and the greater contribution of •OH was attributed to its higher reaction rate constant with MIT compared to SO₄•⁻. Sulfate had a negligible impact on the radical concentrations. Chloride (1 mM) reduced the SO₄•⁻ and •OH concentrations by 61% and 27%, respectively. And the SO₄•⁻ contribution to MIT degradation fell to 19%. Nitrate (5 mM) readily quenched •OH but minimally affected SO₄•⁻. The •OH concentration decreased by 79%, reducing its contribution to 27%. Bicarbonate/carbonate (5 mM) simultaneously reduced the SO₄•⁻ and •OH by 26–30% and had little effect on their contributions. Because of the quenching effect of organic matter and inorganic anions on radicals, secondary effluent inhibited the degradation of MIT. After a 120 s treatment, the total organic carbon, UV₂₅₄, and fluorescence regional integration were reduced by 5%, 8%, and 17–24%, respectively. This study provides a quantitative analysis of how inorganic ions alter the concentrations and contributions of •OH and SO₄•⁻, elucidating the MIT removal mechanisms in VUV/UV/PDS for sustainable wastewater reclamation. Full article

Removing toxic formaldehyde (HCHO) from environmental water is crucial for human health and the ecosystem. Perovskite-type Lanthanum cobalt oxide (LaCoO₃) has achieved great success in a wide range of catalytic processes; however, this concept has been rarely applied to the degradation of HCHO. Here, we prepared perovskite-type catalysts with different La/Co molar ratios, and the time for HCHO oxidation degradation at room temperature was shortened by 12 times (10 min vs. 119 min) compared to other heterogeneous catalysts. LaCoO₃ exhibits superior catalytic activity for HCHO degradation at room temperature when the La/Co molar ratio is 1:1 compared to lanthanum cobalt oxides with other molar ratios. The X-ray photoelectron spectroscopy (XPS) test results show that increasing the La/Co molar ratio reduces the Co²⁺ content in the catalyst, while Co²⁺ plays the most important role in the catalyst. Quencher experiments indicated that sulfate radicals (SO₄·⁻) and hydroxyl radicals (·OH) were the primary reactive species for the removal of HCHO. This finding suggests that the catalytic oxidation reaction involving HCHO operates as a heterogeneous Fenton-like oxidation reaction. Full article

The degradation of Brilliant Coomassie Blue G-250 (BCB) was investigated using the thermally activated persulfate (TAP) process in deionized water. A kinetic model incorporating both hydroxyl (^●OH) and sulfate (SO₄^●–) radicals was developed to predict pseudo-first-order rate constants (kₒ) for the interaction of BCB with these radicals. Experimental results demonstrated efficient BCB degradation under TAP treatment. A parametric study examining the effects of initial conditions such as solution pH, persulfate concentration, initial BCB concentration, and temperature revealed that higher persulfate dosages, lower BCB concentrations, and alkaline pH enhanced degradation performance. Complete removal of BCB was achieved within 20 min under optimal conditions ([BCB]₀ = 10 mg/L, [PS]₀ = 2 mg/L, neutral pH). The kinetic model showed strong agreement with experimental data across a broad range of pH and persulfate concentrations. The rate constants for BCB reactions with ^●OH and SO₄^●– were determined through simulation to be 4.731 × 10⁹ M⁻¹s⁻¹ and 1.07 × 10⁹ M⁻¹s⁻¹, respectively. The selectivity analysis results revealed that SO₄^●– radicals played a dominant role in the degradation process across the various initial persulfate concentration scenarios. The remaining degradation was attributed to the contribution of ^●OH radicals. These findings are linked to the higher reactivity of BCB with SO₄^●– compared to ^●OH. Overall, the results demonstrate that TAP process is an effective method for the removal of emerging contaminants such as BCB from water. Full article

The widespread presence of bisphenol A (BPA), a persistent endocrine-disrupting pollutant, in aquatic environments poses significant ecological and health risks, necessitating its effective removal. However, conventional remediation technologies are often hampered by catalysts with narrow pH adaptability and poor stability. In this study, a novel catalyst, Zeolite-supported Cu₃Mn-layered double hydroxide (LDH), was fabricated using the co-precipitation method. The synthesized catalyst was applied to activate peroxymonosulfate (PMS), effectively enabling decomposition of BPA by advanced oxidation processes. The composite material was characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy (TEM), which confirmed the successful synthesis of the zeolite-supported Cu₃Mn-LDH. The catalyst exhibited high activity in both neutral and strongly alkaline environments, achieving complete degradation of 10 mg⋅L⁻¹ bisphenol A (BPA) within 40 min and a 98% total organic carbon (TOC) removal rate when both the PMS and catalyst were dosed at 0.15 g⋅L⁻¹. Singlet oxygen was detected as the primary reactive species responsible for BPA degradation, as verified by quenching experiments and EPR analysis, which also identified the presence of sulfate (SO₄^•−), hydroxyl (•OH), and superoxide (•O₂⁻) radicals. The catalyst exhibited excellent reusability, maintaining high catalytic efficiency over two consecutive cycles with minimal performance loss. Gas chromatography-mass spectrometry (GC-MS) analysis revealed five intermediate products, enabling the proposal of potential BPA degradation pathways. This work not only presents a novel synthetic approach for zeolite-supported LDH composites, but also offers a promising strategy for the efficient removal of BPA from aqueous systems through AOPs. Full article

In this study, we investigated the performance of iron-loaded biochar (Fe-BC) derived from mulberry branches in activating persulfate (PS) for the efficient degradation of sulfamethoxazole (SMX). The Fe-BC/PS system exhibited superior catalytic activity towards SMX degradation, achieving 97% removal within 60 min. The degradation efficiency was found to be highly dependent on preparation conditions, including calcination temperature, the type of iron salt, and biomass feedstock. Reactive species such as hydroxyl radicals (^•OH), sulfate radicals (SO₄^•−), and iron (IV) (Fe(IV)) were identified as key contributors to SMX degradation, with Fe(IV) playing a dominant role. The influence of water quality parameters, such as inorganic ions, pH, and natural organic matter (NOM), on the degradation of SMX was also examined. Proposed degradation pathways revealed the stepwise oxidation of SMX into smaller intermediates, ultimately leading to mineralization. Our findings highlight the potential of Fe-BC/PS systems as a sustainable and effective approach for the remediation of sulfonamide antibiotics in aquatic environments. Full article

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of synthetic fluorinated compounds widely used in industrial and consumer products due to their exceptional thermal stability and hydrophobicity. However, these same properties contribute to their environmental persistence, bioaccumulation, and potential adverse health effects, including hepatotoxicity, immunotoxicity, endocrine disruption, and increased cancer risk. Traditional water treatment technologies, such as coagulation, sedimentation, biological degradation, and even advanced membrane processes, have demonstrated limited efficacy in removing PFAS, as they primarily separate or concentrate these compounds rather than degrade them. In response to these limitations, photoassisted processes have emerged as promising alternatives capable of degrading PFAS into less harmful products. These strategies include direct photolysis using UV or VUV irradiation, heterogeneous photocatalysis with materials such as TiO₂ and novel semiconductors, light-activated persulfate oxidation generating sulfate radicals, and photo-Fenton reactions producing highly reactive hydroxyl radicals. Such approaches leverage the generation of reactive species under irradiation to cleave the strong carbon–fluorine bonds characteristic of PFAS. This review provides a comprehensive overview of emerging photoassisted technologies for PFAS removal from water, detailing their fundamental principles, degradation pathways, recent advancements in material development, and integration with hybrid treatment processes. Moreover, it discusses current challenges related to energy efficiency, catalyst deactivation, incomplete mineralization, and scalability, outlining future perspectives for their practical application in sustainable water treatment systems to mitigate PFAS pollution effectively. Full article

Amitriptyline (AMT), a widely prescribed antidepressant, and its metabolites have emerged as significant environmental contaminants, posing substantial risks to aquatic organisms and human health. Systematic and in-depth investigations into advanced anode materials, coupled with a profound elucidation of their electrochemical mechanisms, are imperative for the development of efficacious technologies for AMT removal. In this study, a series of amorphous carbon-encapsulated zinc oxide (C@ZnO) modified anodes were systematically synthesized and incorporated into a persulfate-based electrochemical system (CZ-PS) to comprehensively elucidate the catalytic mechanisms and mass transfer efficiencies governing the degradation of AMT via electroperoxidation. Notably, the CZ-PS system achieved a 97.5% degradation for 5.0 mg/L AMT within 120 min under optimized conditions (200 C@ZnO electrode, pH 7.0, current density 20 mA/cm², PS concentration 0.5 mM), significantly outperforming the single PS system (37.8%) or the pure electrocatalytic system. Quenching experiments and EPR analysis confirmed hydroxyl radicals (•OH) and sulfate radicals (SO₄•⁻) as the dominant reactive species. Both acidic and neutral pH conditions were demonstrated to favorably enhance the electrocatalytic degradation efficiency by improving adsorption performance and inhibiting •OH decomposition. The system retained >90% degradation efficiency after 5 electrode cycles. Three degradation pathways and 13 intermediates were identified via UPLC–MS/MS analysis, including side-chain demethylation and oxidative ring-opening of the seven-membered ring to form aldehyde/carboxylic acid compounds, ultimately mineralizing into CO₂ and H₂O. It demonstrates strong engineering potential and provides a green, high-efficiency strategy for antibiotic wastewater treatment. Full article

This study investigates Fenton-based processes for textile dye degradation, focusing on Direct Red 28 (DR28), Reactive Blue 19 (RB19), and Reactive Black 5 (RBk5). Results reveal varying effectiveness of catalyst–radical combinations, with copper and peroxydisulfate consistently performing well, especially on RBk5 with 100% and 98.5% decolorization and total organic carbon (TOC) reduction, respectively. Iron faces limitations with DR28 due to sediment formation, resulting in 3.5% and 52.7% TOC removal when paired with hydroxyl and peroxydisulfate radicals, correspondingly. Unexpectedly, cobalt shows notable capabilities with RBk5, reaching 87.2% TOC removal, but performs poorly on the other two dyes, with less than 20% TOC removal when paired with hydroxyl radicals. Cost analysis highlights the cost-effectiveness of the standard photo-Fenton process for easy-to-degrade dyes with a cost of $0.174/g TOC removed, while copper emerges as a viable option for recalcitrant dyes, costing $0.371/g TOC removed. Overall, this research enhances understanding of catalyst–radical interactions on various dyes, a topic that is scarcely discussed in other research, and expands upon it by using techno-economic analysis for Fenton-based technologies for textile wastewater treatment, as a consideration for technology selection in actual application. Full article

The increasing presence of tetracycline antibiotics (TCs) in water sources poses significant environmental and public health risks, necessitating effective treatment technologies. This study investigates the degradation of three types of TCs in water—Tetracycline (TC), Oxytetracycline (OTC), and Chlortetracycline (CTC)—using nonthermal plasma (NTP) coupled with the persulfate (PS) process. The combined NTP/PS system was optimized for various operational parameters, including PS concentration, pH, and reaction time, to achieve maximum degradation and mineralization efficiency. The results showed that the NTP/PS system achieved over 90% degradation of all TCs under optimal conditions, outperforming plasma alone treatment. The degradation kinetics followed a pseudo-first-order model, indicating a rapid initial breakdown of TCs. The degradation mechanism was elucidated through the identification of intermediate byproducts using liquid chromatography-mass spectrometry (LC-MS/MS). Free radicals, such as sulfate (SO₄^•−) and hydroxyl (^•OH) radicals, were identified as the primary reactive species responsible for TCs degradation. This study demonstrates the potential of the NTP/PS system as an efficient and sustainable solution for the removal of antibiotic contaminants from water. Further research on the scalability and application in real wastewater conditions is recommended. Full article