Reactive Species Research Articles

Nanogalvanic Cells Release Highly Reactive Electrons in Tumors to Effectively Eliminate Tumors.

External stimuli triggering chemical reactions in cancer cells to generate highly reactive chemical species are very appealing for cancer therapy, in which external irradiation activating sensitizers to transfer energy or electrons to surrounding oxygen or other molecules is critical for generating cytotoxic reactive species. However, poor light penetration into tissue, low activity of sensitizers, and reliance on oxygen supply restrict the generation of cytotoxic chemical species in hypoxic tumors, which lowers the therapeutic efficacy. Here, we present galvanic cell nanomaterials that can directly release highly reactive electrons in tumors without external irradiation or photosensitizers. The released reactive electrons directly react with surrounding biomolecules such as proteins and DNA within tumors to destroy them or react with other surrounding (bio)molecules to yield cytotoxic chemical species to eliminate tumors independent of oxygen. Administering these nanogalvanic cells to mice results in almost complete remission of subcutaneous solid tumors and deep metastatic tumors. The results demonstrate that this strategy can further arouse an immune response even in a hypoxic environment. This method offers a promising approach to effectively eliminate tumors, similar to photodynamic therapy, but does not require oxygen or irradiation to activate photosensitizers. This article is protected by copyright. All rights reserved.

Biomedical Applications of Cold Atmospheric Plasma: Cancer Therapy and Virus Inactivation

Cold atmospheric plasma (CAP), known for its ability to generate Reactive Oxygen Species (ROS) and Reactive Nitrogen Species (RNS), has emerged as a promising tool in many biomedical applications, including cancer therapeutics and virus inactivation. In cancer therapy, ROS and RNS induced by plasma have been shown to selectively target cancer cells, triggering apoptosis and inhibiting tumor growth while sparing healthy cells. This selective cytotoxicity makes plasma an attractive option for localized cancer treatment with minimal side effects. Additionally, the antimicrobial properties of ROS and RNS make plasma an effective agent for virus inactivation. By connecting the dots between cancer therapy and virus disinfection, this review paper sheds light on the potential of plasma-generated ROS and RNS as versatile tools in medical applications, offering a dual benefit of targeted cancer treatment and effective virus control. Specifically, this review explores the effects of CAP treatment on B16 melanoma cells, assessing changes in cell viability, proliferation, apoptosis and oxidative stress response. Dichloroacetate (DCA), a mitochondrial modulator, has shown promise in inducing apoptosis in melanoma cells. However, its clinical use is limited by side effects related to its neurotoxicity and suspected carcinogenicity. The potential of CAP in enhancing the therapeutic efficacy of DCA on B16-F10 melanoma apoptosis is also explored. CAP therapeutics for other types of cancers are also explored in this review. Alongside its implications in oncology, CAP has gathered substantial attention for its extraordinary potential in neutralizing viruses. CAP’s exceptional precision in targeting viral envelopes, genetic material and structural components disrupts their integrity and vital functions. This orchestrated mechanism offers a swift and efficacious route to render viruses inactive, encompassing both enveloped and nonenveloped viral types. In parallel pursuit, this review examines CAP-generated reactive species’ proficiency in deactivating SARS-CoV-2 across various surfaces. The inquiry entails subjecting surfaces to CAP treatment, succeeded by quantifying viral load and scrutinizing viral integrity. The outcomes gleaned from these investigations provide pivotal insights into CAP’s potential as a robust surface disinfection strategy, poised to combat the propagation of viral transmission.

In vitro susceptibility of grass carp fish (Ctenopharyngodon idella) to oxidized myosin on structural change of protein secondary structure associated with reactive oxygen species (ROS) treatment

This study aimed to investigate the in vitro susceptibility of grass carp (Ctenopharyngodon idella) oxidized myosin, with the treatment of H2O2 levels being 0, 25, 50, and 100 μmol/L, respectively. The results showed that in vitro oxidation of myosin, reactive oxidative species promoted protein modifications that propagated the conformation changes on myosin secondary structure, leading to a significant increase (P < 0.05) in the protein carbonyl content in the high oxidation treatment, when compared to the low and medium treatments. The results of the Western blot analysis and sodium-polyacrylamide amide-dodecyl sulfate gel electrophoresis demonstrated that in vitro oxidation actively promoted the degradation of protein molecular weight and Desmin (53 kDa) deterioration in the sample with the highest concentration treatment of H2O2. Circular dichroism spectra showed a decrease in α-helix content from 70.1% to 29.8% and an increase in β-sheet percentage from 5.6% to 17.4%. Meanwhile, cysteine and methionine as the free amino acids were most susceptible to oxidative change due to their high sensitivity to the reaction of the sulfur group of amino acids. Protein degradation induced by oxidation resulted in significant changes to the protein secondary structure, as evidenced by the observation of oxidized myosin under different H2O2 levels.

Glycated LDL generates reactive species that damage cell components, oxidize hemoglobin and alter surface morphology in human erythrocytes

Low-density lipoprotein (LDL) transports cholesterol to various tissues via the blood. Glycation of LDL occurs during hyperglycemic condition which is characterised by persistently high blood glucose level. Circulating erythrocytes can come in direct contact with glycated LDL (G-LDL). The objective of this study was to investigate the effect of G-LDL on human erythrocytes, specifically on hemoglobin, intracellular generation of reactive species and the antioxidant defence system. Isolated erythrocytes were incubated with G-LDL (3 and 6 mg/ml) and native LDL (6 mg/ml) at 37 °C for 24 h. Native LDL and G-LDL untreated erythrocytes were similarly incubated at 37 °C and served as control. G-LDL treatment increased hemolysis compared to control and native LDL-treated erythrocytes. Incubation of erythrocytes with G-LDL led to an increase in protein oxidation and lipid peroxidation while greatly decreasing the total sulfhydryl content. It also significantly enhanced hemoglobin oxidation, heme degradation, and the release of free iron moiety. Treatment with G-LDL led to an appreciable increase in the production of reactive oxygen and nitrogen species. The antioxidant power and activities of major antioxidant enzymes were drastically reduced, while critical membrane-bound enzymes were inhibited. The surface morphology of G-LDL-treated erythrocytes was altered leading to the formation of echinocytes. Importantly, treatment of erythrocytes with native LDL did not significantly affect the above-mentioned parameters and values were similar to the corresponding controls. Thus, G-LDL is cytotoxic to human erythrocytes and causes oxidative damage to cell components. This can reduce the oxygen-transporting ability of blood and also result in red cell senescence and anemia.

E. Coli inactivation by humidified air barrier discharge plasmas and the chemical stability of amino acids

Abstract In this study, we use atmospheric air dielectric barrier discharge (DBD) plasma to inactivate Escherichia coli (E. coli) by changing the air humidity levels. In order to analyze the inactivation process of E. coli during the humidified air DBD plasma treatment, we analyze the byproducts of 12 representational amino acids and compare their chemical stability. The experimental results show that the E. coli surface density (CFU/cm2) on a steel disc decreased significantly when the air humidity was increased from 20% to 60%, and humidified air DBD plasma at 60% humidity is very effective in inactivating E. coli. A consistently potent deactivation effect on E. coli can be seen in plasma afterglow treatment experiments over a storage time of two minutes, indicating that plasma-activated long-lived reactive oxygen and nitrogen species play a crucial role in controlling the E. coli inactivation. Compared to the low humidity (20%) condition, the concentration of reactive species produced by the plasma at high humidity (60%) increased 2-fold for 2-hydroxyterephthalic acid and 5-fold for hydrogen peroxide while ozone production was halved. Amino acid experiments showed that amino acids may be oxidized, hydroxylated and nitroxylated by reactive species. The reduction of amino acids by air DBD plasma was even more pronounced at high air humidity compared to low air humidity. Our analysis indicates that the significant inactivation of E. coli by humified air DBD plasma is related to the chemical instability of amino acids.&amp;#xD;

Plasma-deposited reactive species assisted synthesis of colloidal zinc-oxide nanostructures

A surface-wave microwave discharge is applied to deposit reactive oxygen and nitrogen species (RONS) into the liquid subsequently used as a medium for laser ablation of a Zn metallic target. It is shown that during laser ablation in plasma-treated liquids the H2O2 concentration decreases, while in deionized water (DIW) significant H2O2 is produced. Meanwhile, the pH—initially adjusted by applying reductive metals—increases in the acidic liquids and decreases in the alkaline ones. During months of storage the pH of colloids stabilize around pH 6, which insures the long-term stability of RONS. It is demonstrated that in DIW metallic Zn NPs are created, which gradually oxidize during storage, while in the plasma-treated liquids ZnO NPs are produced with the mean size of 18 nm. In the alkaline plasma-treated liquid the NPs form large aggregates, which slows the dissolution of NPs. In the acidic and neutral solutions besides NPs nanosheets are also formed, which during storage evolve into nanosheet networks as a result of the dissolution of NPs. The band gap of the colloidal ZnO is found to decrease with the formation of aggregates and nanosheet networks. The ZnO NPs ablated in plasma-treated liquids exhibit a high-intensity visible emission covering the green-to-red spectral region. The photoluminescence spectra is dominated by the orange-red emission—previously not detected in the case of laser-ablated ZnO NPs and attributed to the interstitial Zn and oxygen sites—and the yellow emission, which can be attributed to the OH groups on the surface. It is shown that during months of storage, due to the dissolution of NPs and formation of nanosheets, the intensity of the visible emission decreases and shifts to the blue-green spectral region.

Peracetic acid-induced nanoengineering of Fe-based metallic glass ribbon in application of efficient drinking water treatment

This study presents a novel approach utilizing Fe-Si-B metallic glass-based advanced oxidation processes (AOPs) with peracetic acid (PAA) exposure to mitigate disinfection by-products (DBPs) formation in drinking water treatment. Under optimal conditions, it achieved a 98.21% removal of natural organic matter (NOM) and an 80.64% reduction in DBPs formation. The efficacy is attributed to the galvanic cell effect induced by nanoflower structures on the ribbon surface, produced via PAA exposure, thereby enhancing degradation efficiency. High-valent iron Fe(IV) was identified as the primary reactive species, showing robust cycling efficiency under near-neutral conditions. Continuous flow experiments and toxicity assessments using luminescent bacteria further validated the method, demonstrating minimal metal leaching (<0.146 mg/L) and reduced biotoxicity with a 37.68% inhibition rate decrease in 24 h. These findings underscore the promising potential of PAA-integrated Fe-based amorphous alloys for comprehensive water disinfection and purification.

Propagation of nanosecond discharge in an air gap containing a water droplet: modelling and comparison with time-resolved images

The plasma-water interface is a complex medium characterized by interesting physical and chemical phenomena useful for many applications such as water processing or material synthesis. In this context, optimizing the transport of reactive species from plasma to water is crucial, and it may be achieved by increasing the surface-to-volume ratio of the processed object. Herein, we study the characteristics of a streamer produced by nanosecond discharge in air gap with a droplet of deionized water. The discharge is characterized experimentally by electrical measurements as well as by 1 ns-intergated ICCD images. To report plasma properties that are not accessible through experiment, such as the spatio-temporal evolution of electron density, electric field, and space charge density, a 2D fluid model is developed and adapted to the experimental geometry. Due to the fast propagation of the ionization front, the droplet is considered as a solid dielectric. The model solves Poisson’s equation as well as the drift-diffusion equation for electrons, positive ions, and negative ions. The utilized transport coefficients are tabulated as a function of the reduced electric field. Helmholtz equations are also included in the model to account for photoionization. The electron impact ionization source obtained from the model is compared to experimental 1 ns-integrated ICCD images, and a good agreement is observed. Finally, the model is used to investigate the influence of droplet dielectric permittivity and wetting angle (the angle between a liquid surface and a solid surface) on the properties of the discharge. Overall, the data reported herein demonstrate that the model can be used to investigate plasma properties under different conditions.

Quantitative estimation of ·OH-radical density from fluorescence decay behavior near the plasma-liquid interface by incident microscopic LIF spectroscopy

The formation and transportation of short-lived species on/within the plasma-liquid interfacial layer plays a crucial role in various applications because of their high chemical reactivity. However, the experimental detection and quantification of these short-lived species, such as ˙OH radicals, at the gas–liquid interface still pose formidable challenges. This study confronts this challenge by employing incident microscopic laser-induced fluorescence (mLIF) method to capture the OH-LIF signals on the interfacial layer at different time moments of the post-discharge phase under high spatial resolution. The temporal evolution of ˙OH density is subsequently quantified by fitting the OH-LIF decay behavior to a reaction-dissolution model. Results reveal that increasing the pulse width serves better to enhance ˙OH generation on liquid surface, reaching a density of 1.25 × 1016 cm−3. Furthermore, the cathode-solution interface demonstrates significantly enhanced ˙OH production compared to the anode-solution interface. These results underscore the efficacy of incident mLIF in quantitatively probing short-lived ˙OH-radical production at the interfacial layer in pulsed-driven plasma-solution interactions, with potential applicability to other reactive species.

Tailoring Ni 3d orbitals in Ni-Fe/Ni foam heterostructures for enhanced H* adsorption and boosted electrocatalytic nitrate reduction performance

The electrochemical nitrate (NO3−) reduction (ENR) in wastewater, a promising remediation strategy, is often impeded by the essential use of costly noble metals. This study introduces an innovative non-noble Ni-Fe/Ni foam cathode fabricated via one-step electrodeposition technique. Efficient nitrate removal (99.4 %) was achieved with the selectivity of 83.6 % to NH3. The exceptional performance can be ascribed to the augmented active sites and the synergistic interaction between Ni and Fe. The leftward shift of the 3d orbitals density of Ni and the elevation of density at the Fermi level on Ni foam heterostructures, consequent to Fe doping, enhance the adsorption of H*. The addition of reactive chlorine species, generated through anodizing in Cl− mediated system, further improves N2 selectivity by oxidizing intermediate NH4+ product. The coupled anodic oxidation method employed herein achieves nearly 100 % removal efficiency of total nitrogen (TN) for initial concentration of 100 mg/L within 180 min, under the conditions of 1.5 g/L Cl− concentration and a current density of 25 mA cm−2. The findings underscore the potential of the Ni-Fe/Ni foam cathode within a Cl− mediated electrocatalytic framework for nitrate wastewater treatment, providing novel insights into the design of cathode catalysts and anodic coupling strategies for efficient TN removal.

Quantum dots and their potential biomedical applications

Quantum dots (QDs) are semiconductor-based nanocrystals. These nanoparticles have exhibited their unique optical and electronic properties. With these characteristics, QDs attracted scientists interest in biomedical areas such as bioimaging, drug delivery and biosensors apart from other applications like photocatalysis, light-emitting, and solar cells in recent years, and plenty of QDs and QD-based materials have exhibited their unique properties in their applications of biomedical areas. Nevertheless, the potential toxicity of QDs becomes the limitation of QDs application in biomedical areas. The toxicity of QDs might come from: the toxicity core material of QDs; the toxicity substances from the surface of QDs; the free radicals or reactive species released from QDs; the biological environment induced QDs toxicity. In this article, we review the properties of QDs, the applications of QDs in different biomedical fields, how QDs cause toxicity, and how to reduce or prevent QDs potential toxicity. In the future, we expect the improvement and further application of QDs in biomedical areas.

Enhanced tetracycline degradation through nonradical processes by modulating the exposure of active sites on the iron nanoconfined catalysts

There is an urgent need to develop effective and sustainable methods for reducing water pollution. Non-homogeneous Fenton catalysts are commonly used to eliminate pollutants from water. However, the effectiveness of these catalysts is limited by the restricted availability and accessibility of the active site (AS). In this work, we presented a strategy for modulating the exposure of active nanometallic particles to fully expose the AS at the nanoscale. We also confined the AS in carbon frameworks with micropores and mesopores to enhance the effectiveness of AS utilization in Fenton-like reactions. The experimental results indicate that the Fe-out@N-C/PMS system achieved complete degradation of tetracycline within 10 min and maintained an efficient degradation rate of over 91% after five consecutive cycles. The degradation of contaminants was due to an effective non-radical mechanism, as shown by free radical quenching experiments, EPR reactive species capture tests, in situ Raman, and PMSO probe experiments. Furthermore, density-functional theory (DFT) calculations revealed that iron nanoparticles supported on nitrogen-doped carbon acted as active sites, enhancing electron transfer capacity (N-C (0.24 e) vs. Fe-out@N-C (0.69 e)). Finally, the intermediates have a limited environmental impact because of their extremely low concentrations, despite having a high relative toxicity. The exposed metal nanoparticle catalysts provide a new approach for effectively activating PMS to efficiently degrade organic contaminants with a high mineralization rate via the non-radical pathway.

Protein Oxidation in Aging and Alzheimer’s Disease Brain

Proteins are essential molecules that play crucial roles in maintaining cellular homeostasis and carrying out biological functions such as catalyzing biochemical reactions, structural proteins, immune response, etc. However, proteins also are highly susceptible to damage by reactive oxygen species (ROS) and reactive nitrogen species (RNS). In this review, we summarize the role of protein oxidation in normal aging and Alzheimer’s disease (AD). The major emphasis of this review article is on the carbonylation and nitration of proteins in AD and mild cognitive impairment (MCI). The oxidatively modified proteins showed a strong correlation with the reported changes in brain structure, carbohydrate metabolism, synaptic transmission, cellular energetics, etc., of both MCI and AD brains compared to the controls. Some proteins were found to be common targets of oxidation and were observed during the early stages of AD, suggesting that those changes might be critical in the onset of symptoms and/or formation of the pathological hallmarks of AD. Further studies are required to fully elucidate the role of protein oxidation and nitration in the progression and pathogenesis of AD.

Highly Reactive Peroxide Species Promoted Soot Oxidation over an Ordered Macroporous Ce0.8Zr0.2O2 Integrated Catalyzed Diesel Particulate Filter.

Particulate matter, represented by soot particles, poses a significant global environmental threat, necessitating efficient control technology. Here, we innovatively designed and elaborately fabricated ordered hierarchical macroporous catalysts of Ce0.8Zr0.2O2 (OM CZO) integrated on a catalyzed diesel particulate filter (CDPF) using the self-assembly method. An oxygen-vacancy-enriched ordered macroporous Ce0.8Zr0.2O2 catalyst (VO-OM CZO) integrated CDPF was synthesized by subsequent NaBH4 reduction. The VO-OM CZO integrated CDPF exhibited a markedly enhanced soot oxidation activity compared to OM CZO and powder CZO coated CDPFs (T50: 430 vs 490 and 545 °C, respectively). The well-defined OM structure of the VO-OM CZO catalysts effectively improves the contact efficiency between soot and the catalysts. Meanwhile, oxygen vacancies trigger the formation of a large amount of highly reactive peroxide species (O22-) from molecular oxygen (O2) through electron abstraction from the three adjacent Ce3+ (3Ce3+ + Vö + O2 → 3Ce4+ + O22-), contributing to the efficient soot oxidation. This work demonstrates the fabrication of the ordered macroporous CZO integrated CDPF and reveals the importance of structure and surface engineering in soot oxidation, which sheds light on the design of highly efficient PM capture and removal devices.

Exploring enzyme inhibition and comprehensive mechanisms of antioxidant/prooxidative activity of natural furanocoumarin derivatives: A comparative kinetic DFT study

This study aimed to explore the antioxidant and prooxidative activity of two natural furanocoumarin derivatives, Bergaptol (4-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, BER) and Xanthotoxol (9-Hydroxy-7H-furo [3,2-g] [1]benzopyran-7-one, XAN). The collected thermodynamic and kinetic data demonstrate that both compounds possess substantial antiradical activity against HO• and CCl3OO• radicals in physiological conditions. BER exhibited better antiradical activity in comparison to XAN, which can be attributed to the enhanced deprotonation caused by the positioning of the –OH group on the psoralen ring. In contrast to highly reactive radical species, newly formed radical species BER• and XAN• exhibited negligible reactivity towards the chosen constitutive elements of macromolecules (fatty acids, amino acids, nucleobases). Furthermore, in the presence of O2•─, the ability to regenerate newly formed radicals BER• and XAN• was observed. Conversely, in physiological conditions in the presence of Cu(II) ions, both compounds exhibit prooxidative activity. Nevertheless, the prooxidative activity of both compounds is less prominent than their antioxidant activity. Furthermore, it has been demonstrated that anionic species can engage in the creation of a chelate complex, which restricts the reduction of metal ions when reducing agents are present (O2•─ and Asc─). Moreover, studies have demonstrated that these chelating complexes can be coupled with other radical species, hence enhancing their ability to inactivate radicals. Both compounds exhibited substantial inhibitory effects against enzymes involved in the direct or indirect generation of ROS: Xanthine Oxidase (XOD), Lipoxygenase (LOX), Myeloperoxidase (MPO), NADPH oxidase (NOX).

Experimental study of the influence of O2 content on electrical and optical characteristics of He/CF4 APPJ

CF4 is an important source of reactive F-containing species (RFS) so that it is used to mix with inert gas as the working gas of atmospheric pressure plasma jet (APPJ) for material surface fluoridation modification. The addition of a small amount of O2 can increase the density of RFS in He/CF4 APPJ. Therefore, the hydrodynamic, electrical and optical properties of He/CF4/O2 APPJ interacting with the dielectric are experimentally investigated in this paper. Meanwhile, the influence of the excitation source on plasma discharge is discussed in detail and the internal mechanism of the experimental phenomenon in this paper is analyzed using the simulation results based on the model established in the previous paper. It is found that the addition of a small amount of O2 can increase the intensity and accelerate the axial propagation speed of He/CF4 APPJ due to the low ionization energy of O2 and the increase of the Penning ionization between metastable He and O2. With the increase of O2 content, the stability of the discharge is gradually enhanced due to the electron attachment reaction of O2 and the position of the primary current pulse in each half voltage cycle gradually approaches the position of the peak voltage because the increase in O2 content raises the breakdown threshold in dielectric barrier discharge region. In the presence of downstream dielectric, the addition of 0.1%O2 does not significantly change the radial development radius of APPJ due to the higher electron attachment rate and electron collision excitation loss power. The discharge pulse intensity is generally reduced compared to the absence of dielectric and the glow discharge in the strict sense no longer exists. The continuous spectrum intensity of RFS increases with the addition of a small amount of O2 while decreases significantly when O2 content is too high.

Insights into atomic arrangement in CuMnO2 with tailored exposed crystal facets for effectively micropollutant oxidation via peroxymonosulfate activation

Crystal facet engineering of bimetallic ABO2 oxides is regarded as decisive strategy for regulation of catalytic activity, whereas precisely identifying the intrinsic mechanism of facet-dependent activity are still significant challenging. Herein, crednerite CuMnO2 nanoflake material with tailored crystal facets were synthesized and identified as efficient peroxymonosulfate (PMS) activators, in which CuMnO2-160 catalyst with exposed (201) facet exhibited more superior catalytic efficiency compared to CuMnO2-80 with (020) facet towards p-hydroxybenzoic acid (HBA) oxidation. Notably, CuMnO2-160 demonstrated substantial activity across a wide pH range even under high concentration inorganic anions and humic acid (HA). Quenching experiments and EPR spectra elucidated the crucial reactive species of •OH and SO4•-, with 1O2 playing an auxiliary role in HBA degradation. Computational analysis and characterization results collectively revealed that PMS molecules adopted two distinct adsorption modes on different CuMnO2 facets, and the PMS adsorption-activation behavior was significantly altered by detailed atom arrangement of CuMnO2 in tailored exposed facets, thereby lowering the charge transfer energy barrier to favor PMS bonding interaction on (201) facet. This study systematically underscores the catalyst microstructure and crystal facet dominated PMS activation behavior and oxidation mechanism, providing valuable and novel insights for further understanding of crystal facets and the morphology control relied catalytic mechanism.

Heterogeneous Organocatalysts for Light-Driven Reactions in Continuous Flow

Within the realm of organic synthesis, photocatalysis has blossomed since the beginning of the last decade. A plethora of classical reactivities, such as selective oxidation of alcohol and amines, redox radical formation of reactive species in situ, and indirect activation of an organic substrate for cycloaddition by EnT, have been revised in a milder and more sustainable fashion via photocatalysis. However, even though the spark of creativity leads scientists to explore new reactions and reactivities, the urgency of replacing the toxic and critical metals that are involved as catalysts has encouraged chemists to find alternatives in the branch of science called organocatalysis. Unfortunately, replacing metal catalysts with organic analogues can be too expensive sometimes; however, this drawback can be solved by the reutilization of the catalyst if it is heterogeneous. The aim of this review is to present the recent works in the field of heterogeneous photocatalysis, applied to organic synthesis, enabled by continuous flow. In detail, among the heterogeneous catalysts, g-CN, polymeric photoactive materials, and supported molecular catalysts have been discussed within their specific sections, rather than focusing on the types of reactions.

Biochar-Supported FeCo-MOF derivative catalyzes PDS-Mediated degradation of tetracycline

Bimetallic metal–organic framework (MOF) has gained wide attention in the field of advanced oxidative processes (AOPs), however, the agglomeration problem severely limits its active sites and its activation mechanism still needs to be further explored. This study developed the BC@CoFe composite material, utilizing biochar (BC) to support FeCo-MOF derivatives, effectively alleviating their agglomeration and structural collapse. The results of the BC@CoFe activated peroxydisulfate (PDS) system for the degradation of tetracycline (TC) revealed an excellent degradation efficiency up to 97.7 % in 2 h for TC solution (20 mg/L, degradation rate constants k = 7.066 mM-1min−1). Furthermore, the BC@CoFe/PDS system exhibits exceptionally high cyclic stability (73.23 % degradation efficiency after 12 h continuous degradation), a wide range of pH (3–11) and temperature tolerance (20-60℃), resistance to background ion interference (SO42-, H2PO4-, NO3– and HA), and reduced toxicity of the degradation products. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) analyses show that the exceptional catalytic performance of BC@CoFe primarily stems from the synergistic effect between Fe(II)/Co(III) and Fe(III)/Co(II). Regarding the reactive active species involved in TC degradation, the contribution rates of 1O2, SO4•- and ·OH were measured and calculated to be 73.6 %, 14.9 %, and 11.5 %, respectively. Thus, the BC@CoFe/PDS system exhibits outstanding catalytic activity and has broad practical applications in water treatment.

Efficient activation of peracetic acid by cobalt modified nitrogen-doped carbon nanotubes for drugs degradation: Performance and mechanism insight

Peracetic acid (PAA) has garnered significant attention as a novel disinfectant owing to its remarkable oxidative capacity and minimal potential to generate byproducts. In this study, we prepared a novel catalyst, denoted as cobalt modified nitrogen-doped carbon nanotubes (Co@N-CNTs), and evaluated it for PAA activation. Modification with cobalt nanoparticles (∼4.8 nm) changed the morphology and structure of the carbon nanotubes, and greatly improved their ability to activate PAA. Co@N-CNTs/PAA catalytic system shows outstanding catalytic degradation ability of antiviral drugs. Under neutral conditions, with a dosage of 0.05 g/L Co@N-CNT-9.8 and 0.25 mM PAA, the removal efficiency of acyclovir (ACV) reached 98.3% within a mere 10 min. The primary reactive species responsible for effective pollutant degradation were identified as acetylperoxyl radicals (CH3C(O)OO•) and acetyloxyl radicals (CH3C(O)O•). In addition, density functional theory (DFT) proved that Co nanoparticles, as the main catalytic sites, were more likely to adsorb PAA and transfer more electrons than N-doped graphene. This study explored the feasibility of PAA degradation of antiviral drugs in sewage, and provided new insights for the application of heterogeneous catalytic PAA in environmental remediation.