Radical Oxidation Research Articles

Hydroxyl radical-mediated synthesis of carbonyl functionalized graphene quantum dots-like as enzyme mimics with tunable fluorescence emission

The synthesis of graphene quantum dots-like enriched with specific oxygenated groups (o-GQDs) exhibiting great catalytic performance offers a promising tool for diagnosis and biomedicine, but introducing specific oxygen groups remains a challenge. Here, we propose a mild synthetic protocol for producing regulated fluorescence emission (from blue to yellow) carbonyl functionalized GQDs with double catalytic function through Fe3O4-catalyzed hydroxyl radical (·OH) oxidation the precursors like graphene oxide, polyaniline (PANI) and polydopamine (PDA). The method can be carried out at room temperature than the traditional high-temperature oxidation in concentrated acid. Interestingly, o-GQDs exhibit excellent peroxidase (POD)- and ascorbate oxidase-like activity. XPS characterization showed a significant increase in carbonyl content in o-GQDs compared to the precursor, even a 14-fold increase in blue-emitting iron-doped GQDs (b-Fe-GQDs). The introduction of Fe3O4 during the synthesis process results in a minor degree of Fe doping, which enhances the catalytic activity of b-Fe-GQDs through coordination with N. Based on this feature, highly sensitive single-signal and ultra-selective dual-signal methods for alkaline phosphatase detection were developed. This low cost and safe synthesis strategy paves the way for practical usage of o-GQDs.

A high-flux atomically dispersed MIL-100 (Fe) incorporated PMS-based LDH catalytic membrane for the removal of micropollutants from secondary effluent wastewater

This study fabricated a CoFe layered double hydroxide (CoFeLDH) membrane incorporating the metal–organic framework (MOF) MIL(100)Fe, tailored for a peroxymonosulfate (PMS) based system. Among various combinations of MOF and LDH nanosheets on a PVDF substrate, the highest water flux, reaching 1900 L/m2/hr/bar, was achieved with an LDH/MOF ratio of 5:1 and an MOF concentration of 0.025 M. The optimized membrane exhibited exceptional performance, achieving 99 % degradation of ranitidine at 0.1 mM PMS. The LDH MOF catalytic membrane exhibited excellent treatment performance in real water matrices and demonstrated long-term operational efficiency. The effective removal of ranitidine by this catalytic membrane was attributed to a synergistic combination of radical (SO4− and OH) and non-radical (singlet 1O2 and electron transfer O2) oxidation pathways, with SO4− and singlet 1O2 playing a predominant role. Post-activation, 40 % of surface Co2+ and 65 % of Fe2+ in the LDH MOF membrane were found in the + III oxidation state, highlighting the significance of metal catalytic sites and the reusability potential of the membrane. The durability of the membrane was evident through 10 cycles, achieving a flux recovery ratio of 95 % in the first cycle and sustaining efficient performance across pH variations (3 to 9) and exposure to various anions. Importantly, negligible metal leaching was observed for the real water samples, ensuring suitability for large-scale applications.

Study of the neuroprotective properties of metformin in rats with type 2 diabetes mellitus and brain injury induced by intracerebral hemorrhage

The aim of this study was to study the effect of metformin (Met) on the formation of the conditional passive avoidance skills, markers of neurogenesis and oxidative stress in the brain of rats with acute intracerebral hemorrhage (ICH) in the setting of streptozotocin-nicotinamide-induced diabetes. Type 2 diabetes mellitus (T2DM) was induced in rats via the intraperitoneal injection of streptozotocin (STZ) and nicotinamide (NA), ICH – by microinjection of bacterial collagenase into the striatum. Rats were randomly divided into four groups: 1 – intact animals (n=8), 2 – T2DM (n=9); 3 – T2DM+ICH (n=7); 4 – T2DM+ICH+Met (n=7). The passive avoidance test was used to evaluate behavioural activity. Advanced oxidation protein products (AOPP) and lactate were measured by spectrophotometry, advanced glycation end products (AGEs) by quantitative fluorescence, level of 8-hydroxy-2-deoxyguanosine (8-OHdG) was assessed by enzyme-linked immunosorbent assay (ELISA). Histopathological examination was performed using general histological staining techniques and immunohistochemical methods for assessment of expression of endothelial NO-synthase (eNOS), Growth Associated Protein 43 (GAP43), Hypoxia-inducible factor 1-alpha (HIF-1α), neural cadherine (N-cadherine) and vascular endothelial cadherine (VE-cadherine). In this study, metformin had nootropic (anti-amnestic) activity and decreased oxidative stress markers (AGEs, AOPPs and 8-OHdG) levels by 29.1% (p<0.001), 24.9% (p<0.015) and 29.3% (p<0.05) respectively, which indicates its positive impact on the course of free radical oxidation reactions intensified by both diabetes and intracerebral hemorrhage. The study provides additional information on neuroprotective properties of metformin and the emphasizes possibility of using metformin in diabetic patients at risk of hemorrhagic stroke. Considering the increase in VE-cadherin expression by the drug, it is possible to predict its positive effect on the function of blood-brain barrier. This study may serve as a reference for the feasibility of studying the clinical efficacy of metformin under these conditions.

ANALYSIS OF ANTIOXIDANT SYSTEM OF TEST ANIMALS IN THE DYNAMICS OF THE WOUND PROCESS AT LOCAL APPLICATION OF HYDROGEL DRESSINGS

Introduction. The development of the inflammatory process is always accompanied by the activation of lipid peroxidation, which is caused by tissue hypoxia. This, in turn, catalyzes a change in the physiological parameters of the antioxidant system. The aim of the study is to analyze the dynamics of the antioxidant balance of wounds in an experiment using hydrogels saturated with silver ions and an antioxidant drug for the local treatment of inflammatory processes. Object and research methods. The experimental study was carried out on 80 Wistar rats weighing 150 to 200 grams. Animals were removed from the experiment. for 3, 7, 10, 14 days. Catalase activity in the dynamics of the wound process was determined. Research results and their discussion. The content of catalase on the 7th day in the third experimental group is 0.51±0.03 μKat/l. On the 10th day, the indicator of the antioxidant system in the second (0.44±0.05 μKat/l) and third experimental groups was 0.42±0.02 μKat/l. At the final stage of the study on the 14th day, the analysis of catalase content showed that in all animals with a simulated inflammatory process, the indicator of antioxidant activity had no significant differences between themselves and, importantly, with the indicators of intact animals (0.33±0.01 μKat /l). The indicators of the control (0.33±0.04 μKat/l) and experimental groups were as follows: the first experimental group – 0.32±0.06, the second experimental group – 0.36±0.04, the third experimental group – 0, 38±0.06 μKat/l. Antioxidant protection was supplemented by local release of a drug with antioxidant action from the hydrogels, which contributed to a reduction in the intensity of free radical oxidation processes. That is, in almost all groups of animals, which were simulated purulent-inflammatory wounds, indicators of catalase activity approached the level of intact animals already on the 14th day. Conclusions. Application for local treatment of hydrogel bandages saturated with an antioxidant drug, which is released into the wound surface for a long time, promotes the activation of antioxidant protection and suppresses the processes of free radical formation.

Graphene/MoS2-assisted alum sludge electrode induces selective oxidation for organophosphorus pesticides degradation: Co-oxidation and detoxification mechanism

Designing an electrode that can generate abundant free radicals and 1O2, which can effectively degrade and detoxify organophosphorus pesticides (OPPs) through a co-oxidation pathway, is important. In this study, we prepared a electrode GO/MoS2@AS by supporting MoS2 on alum sludge (AS) under graphene oxide (GO) nanoconfinement. The results show that the dominant role of 1O2 at the cathode and •OHads at the anode for degradation, in addition to the involvement of 1O2 in the cathodic degradation mechanism, can be attributed to the abundant precursor •O2– and H2O2. Furthermore, calculations using density functional theory and toxicity prediction of products show that the energy (∆E) requirements of •OHfree to break the C–O bond of the pyridine ring and phosphate group are higher than that required for 1O2, and this non-radical oxidation plays a key role in detoxification. In contrast, accelerating ring opening and oxidation processes are attributed to radical oxidation. Above all, the cathodic detoxification is more effective than anodic detoxification. Three prevalent OPPs, chlorpyrifos, glyphosate, and trichlorfon, were degraded in the GO/MoS2@AS system by over 90 %, with mineralization rates of 76.66 %, 85.46 %, and 82.18 %, respectively. This study provides insights into the co-oxidation degradation and detoxification mechanism mediated by 1O2 and •OHfree.

Co@C Nanocatalyst: Enhanced Activation of Peroxymonosulfate for Paracetamol Degradation

A core–shell Co@C composite catalyst was prepared, characterized and used to activate peroxymonosulfate (PMS) for the degradation of paracetamol in water. Hybridized structures containing Co and graphitized carbon act as independent active sites for PMS activation initiating both radical and nonradical oxidation. A 91.57% paracetamol removal was reached in the Co@C/PMS system at 60 min. Radical quenching and electron paramagnetic resonance (EPR) tests show that nonradical 1O2 played predominant roles in the advanced oxidation process, while the other three radicals [Formula: see text], •OH and [Formula: see text]. also played a certain role in paracetamol degradation. After four cycles, the degradation could still reach 70%, which proves that the Co@C composite catalyst exhibits good stability.

Reaction mechanism of antioxidant inhibition of hydroxyl radical in coal oxidation.

To solve the problem of unclear targeted inhibition of key free radicals by antioxidants, this paper took the hydroxyl radical with the highest oxidation activity of coal as the inhibition target and selected five antioxidants such as ethylene diamine tetraacetic acid, tea polyphenol, citric acid, vitamin C, and proanthocyanidins. Based on the theory of quantum chemistry, the characteristics and oxidation pathway of antioxidants inhibiting coal oxidation of hydroxyl radical were analyzed. Analyze the influence characteristics of antioxidants on the evolution of free radicals in coal through an electron paramagnetic resonance experiment (ESR). The results showed that the electron density of antioxidants was mainly distributed in the functional groups of carboxyl and hydroxyl, which played a key inhibitory role, and the vicinity of carboxyl and hydroxyl and other functional groups was positive potential, which was the active site of inhibiting hydroxyl radical. The order of inhibitory capacity of the five antioxidants was determined as GTP > PC > EDTA > CA > VC. It is concluded that the energy barrier of hydroxyl radical inhibition by citric acid is much lower than that of EDTA. For the hydrogen extraction reaction, VC inhibited the hydroxyl radical pathway with a higher energy barrier than the other three antioxidants. The mechanism of five antioxidants inhibiting •OH reaction was comprehensively analyzed. It was found that tea polyphenols have more active sites that can react with •OH to quench it, so the inhibition of tea polyphenols should be the most significant. When antioxidants inhibit coal spontaneous combustion, the type, complexity, concentration, and linewidth of free radicals in coal molecules are lower than those in raw coal, with GTP antioxidants having the best inhibitory effect. The research results have important theoretical and practical significance for revealing the mechanism of coal spontaneous combustion inhibition and developing directional coal spontaneous combustion inhibition technology.

Electrochemically-induced metal–oxygen bond Cu(II)-[rad]SO5− on novel CuBi2O4 anode for efficient peroxymonosulfate activation

Transition metal oxide catalysts had the limitation of a slow electron transfer rate in activating peroxymonosulfate (PMS) during wastewater treatment. In this work, we developed a novel copper bismuthate (CuBi2O4) anode using a catalyst drop casting method to efficiently activate PMS through electrochemically induced metal–oxygen bonds for herbicide prometon (PMT) degradation. The PMT removal rate in the EC/CuBi2O4 anode/PMS system was 74.60 %, which was much greater than the simple superposition of CuBi2O4 catalyst-activated PMS alone (4.88 %) and FTO anode electrically activated PMS (32.15 %). The CuBi2O4 fixed on the anode surface accelerated the electron transfer efficiency between the interface employing the electric field, showing stronger PMS activation performance than the equivalent three-dimensional particle electrode system. The free radical quenching experiments illustrated that the degradation of PMT mainly proceeded through the free radical oxidation pathway dominated by SO4− and OH. In the EC/CuBi2O4 anode/PMS system, the traditional Cu+/Cu2+ cycle did not dominate the activation of PMS in the CuBi2O4 anode reaction. Raman experiment and open circuit potential results proved that the introduction of an electric field caused PMS to form the metal–oxygen bond Cu(II)-SO5− at the CuBi2O4 anode interface, and converted it into activated state PMS (PMS*), accelerating the interface electron transfer. The PMS* was more readily further activated by electrons and promoted water dissociation to form OH for pollutants degradation. The EC/CuBi2O4 anode/PMS system manifested stable purification performance for COD and emerging pollutants in high-salt pesticide wastewater, coupled with its superior economic benefits, possessing broad application prospects.

Enhanced Orange II Removal Using Fe/Mn/Mg2-LDH Activated Peroxymonosulfate: Synergistic Radical Oxidation and Adsorption

In this study, Fe/Mn/Mg2-LDH was utilized for the first time as a catalyst for peroxymonosulfate (PMS) activation to facilitate the removal of Orange II. This composite was characterized using various techniques, such as XRD, FTIR, SEM-EDS, BET, and XPS. The results revealed a well-defined lamellar structure of Fe/Mn/Mg2-LDH with a metal molar ratio of Fe/Mn/Mg at 1:1:2. Moreover, the structural stability of Fe/Mn/Mg2-LDH was confirmed through the XRD, FTIR, and SEM. Fe/Mn/Mg2-LDH exhibited a good adsorption capacity towards Orange II and highly efficient PMS activation. The optimal removal efficiency of Orange II (98%) was achieved under the conditions of pH 7.0, [PMS] = 1.0 mmol L−1, [Fe/Mn/Mg₂-LDH] = 1.6 g L−1, and [Orange II] = 50 μM. Additionally, this system demonstrated good adaptability across a wide pH range. The presence of Cl− and humic acids (HA) did not significantly inhibit Orange II removal, whereas inhibitory effects were observed in the presence of CO32− and PO43−. The removal mechanism of Orange II was attributed to a synergy of adsorption and oxidation processes, wherein the generated surface radicals (SO4•−ads and HO•ads) on the surface of the Fe/Mn/Mg2-LDH played a predominant role. Furthermore, the Fe/Mn/Mg2-LDH exhibited good reusability, maintaining a removal rate of 90% over five cycles of recycling. The Fe/Mn/Mg2-LDH/PMS system shows promising potential for the treatment of wastewater contaminated with refractory organic pollutants.

Plasma-catalytic synergistic oxidation of NO in the non-thermal plasma system: Insight into the active sites effect

Superoxide radicals-dominated oxidation plays a crucial role in the removal of NOx in gas treatment schemes, especially in the catalytic oxidation of NO at room temperature. However, the specific mechanism underlying radical oxidation processes remains unclear. In this study, a series of transitional metal (Mn, Co, Cr) catalysts anchored on graphitic carbon nitride (g-C3N4) were prepared and then introduced into non-thermal plasma (NTP) system to produce highly reactive superoxide free radicals (•O2-) for deep oxidation of NO. Experimental results revealed that the optimized CrCN catalyst, in combination with the NTP technique, exhibited an impressive oxidation efficiency of up to 100 %, which was 10 % and 30 % higher than that of MnCN and CoCN, respectively. Moreover, it was 1.56 times higher than that of NTP alone, indicating a synergistic effect of the NTP system and catalysis. The characterization results demonstrated that CrCN catalyst, with higher specific surface area and smaller grain sizes, was beneficial to increase the chemisorbed oxygen content and produce superoxide free radicals, which were proved by XPS, ESR technologies. Furthermore, the possible catalytic mechanism was proposed, which provided a basis for further understanding of the catalytic oxidation activity.

Degradation of Atrazine by Flow-Through UV-Based Advanced Oxidation Processes: Roles of Light Source and Chlorine Addition

Understanding the degradation kinetics and mechanisms of trace organic contaminants (TrOCs) by UV-based advanced oxidation processes (UV-AOPs) are pivotal in realizing their efficient application in water treatment. However, the relevant knowledge in practical flow-through reactors remains a void, compared with that of commonly used batch reactors. To fill the knowledge gaps, the current work investigated the degradation of atrazine (ATZ) in flow-through UV-AOP systems with different light sources and chlorine additions. The results showed that UV/Cl2 in the reactors (with a diameter of 50 mm) was not very efficient in ATZ degradation while the pseudo-first order degradation rate constant was elevated by over 2.7 times with vacuum UV (VUV)/UV. In contrast to observations in the batch reactors, the addition of chlorine to the flow-through VUV/UV system unexpectedly decreased the rate constant by about 39%. The analysis of the relative contributions of different degradation pathways revealed that the inhibitory effect of the chlorine addition arose from the transformation of HO• to reactive chlorine species (e.g., ClO•) which had low reaction rate constants with ATZ. The baffle implementation promoted the ATZ degradation by 12–58%, mainly due to an enhanced mixing that facilitated the radical oxidation. The energy costs of the UV-AOPs in ATZ removal ranged within 0.40–1.11 kWh m−3 order−1. The findings of this work are helpful in guiding efficient VUV/UV and VUV/UV/Cl2 processes in drinking water treatment.

Enhanced degradation of acid orange 74 via anodic activation of peroxydisulfate using a silver nanoparticle-modified carbon paper anode

In this study, peroxydisulfate (PDS) was activated using silver nanoparticle-modified carbon paper (AgNPs@CP) anode for the efficient degradation of acid orange 74 (AO 74) in wastewater. The AgNPs@CP anode degraded AO 74 at a 4.96-fold higher rate than the unmodified CP anode, where the degradation efficiency depended mainly on radical oxidation, with ·OH accounting for 63.50% and SO4·− accounting for 16.02%. The current density and PDS concentration were the most important parameters affecting the activation efficiency, and the degradation rate could be quantitatively controlled by adjusting these parameters. In terms of the effect of water matrices, Cl− considerably improved the electrochemical activation efficiency, whereas CO32− and PO43− inhibited it. After five cycles of reuse, the AO 74 degradation efficiency decreased to 88.39%, and the corresponding degradation rate decreased to 30.56% of the original value. However, the AO 74 degradation efficiency was still substantially higher than that achieved by the unmodified CP anode. The main reason for the deactivation of the AgNPs@CP electrode was the formation of Ag2+ during electrochemical activation. Generally, the anodic activation of PDS using the AgNPs@CP anode is an efficient method for degrading refractory organic pollutants.

Chemical oxidation co-coagulation-flocculation for the flotation wastewater treatment of lead-zinc oxide ore from Lanping mine

The flotation wastewater produced by "lead preferred flotation-zinc flotation" all-open process with aids of mixed depressants and cationic-anionic collectors has a high turbidity and multitude of reagent contaminants, and fails to meet the discharge standards. This study objective is to remove fine solid particles and flotation reagents in this wastewater by chemical oxidation co-coagulation-flocculation process. Results of chemical oxidation tests indicate peroxymonosulfate (PMS) exhibits superior performance on decreasing COD, and the COD remarkably decreases to 71.8 mg·L<sup>-1</sup> with 100 mg·L<sup>-1</sup> PMS addition after 120 min. Moreover, the combined oxidation of radicals (SO<sub>4</sub><sup>•-</sup> and •OH) are responsible for degradation of flotation reagents (Na<sub>2</sub>S, DCCH, xanthates and amine) in the wastewater. Results of experimental factors confirm that the turbidity of wastewater decreases significantly from 124796 to 71.4 NTU, and the yield of water reaches above 90% with combined usage of lime (500 mg·L<sup>-1</sup>) and polyacrylamide (PAM, 50 mg·L<sup>-1</sup>). Besides, the contents of S, P, N, Zn Pb and Fe decrease, and meet the discharge standards. Results of zeta potential analysis suggest lime reduces the electrostatic repulsion between particles, and PAM plays a bridge link role between particles, accelerating the precipitation of suspended particle.

Synchronously enhanced dual oxidation pathways via engineered Co-Nx/Co3O4 for high-efficiency degradation of versatile antibiotics

Developing efficient and eco-friendly technologies for treating the antibiotic wastewaters is crucial. At present, the catalysts with metal-nitrogen (M-Nx) coordination showed excellent Fenton-like performance but were always difficult to realize practical antibiotics degradation because of their complicated preparation methods and inferior stability. In this work, the Co-Nx configuration was facilely reconstructed on the surface of Co3O4 (Co-Nx/Co3O4), which exhibited superior catalytic activity and stability towards various antibiotics. DFT results indicated that stronger ETP oxidation will be triggered by the electron-donating pollutants since more electrons can be easily migrated from these pollutants to the Co-Nx/Co3O4/PMS complex. The Co-Nx/Co3O4/PMS system could maintain superior oxidation capacity, high catalytic stability and anti-interference due to (i) the strong nonradical ETP oxidation with superior degradation selectivity in Co-Nx/Co3O4/PMS system, and (ii) the synchronously enhanced radical oxidation with high populations of non-selective radicals generated via activating PMS by the Co-Nx/Co3O4. As a result, the synergies of synchronously enhanced dual oxidation pathways guaranteed the self-cleaning properties, maintaining 98 % of activity after eight cycles and stability across a wide pH range. Basically, these findings have significant implications for developing technologies for purifying antibiotic wastewater.

Effects of hydroxyl radical oxidation on the stability and biochemical functions of rex rabbit meat

Reactive oxygen species (ROS)-generating system in muscle food is an important factor as it greatly influences shelf life and quality of meat. In this study, whole muscle homogenate was used as the research object, and the Fenton reaction system as an inducer was established for analyzing the effect of oxidation on Chuanbai Rex and Hyla rabbits meat. The homogenates were exposed to varying concentrations of hydrogen peroxide (H2O2, 0, 2, 4, 6, 8, and 10 mmol/L), the level of lipid oxidation of both breeds increased with the increased H2O2 concentration, while Hyla rabbits was higher. Oxidation and molecular aggregation of myofibrillar protein (MP) was observed in both breeds, including formation of carbonyl compounds, depleted sulphydryl, and increased hydrophobicity while fluorescence decreased. After oxidation, the loss of amino acids was higher in Hyla (16%) than in Rex rabbits (11%). Cys content was identified as the most discriminant parameter capable of elucidating the variations between the two breeds under this oxidation system.

ДОСЛІДЖЕННЯ АНТИОКСИДАНТНИХ ВЛАСТИВОСТЕЙ ЕКСТРАКТІВ ВІДКАСНИКА БЕЗСТЕБЛОВОГО (Carlina acaulis L.), АРНІКИ ГІРСЬКОЇ (Arnica montana L.) ТА КАЛЕНДУЛИ ЛІКАРСЬКОЇ (Calendula officinalis L.)

The intensity of lipid peroxidation (LPO) and oxidative modification of proteins (OMP) was investigated under the influence of 40 % and 70 % aqueous-ethanol plant extracts (PE) of the root of Carlina acaulis L., flowers of Arnica montana L. and Calendula officinalis L. on rat liver hepatocytes under conditions of free radical oxidation initiation in vitro. Investigated plant extracts reduce the formation of free radicals in proteins and lipids, which is evidently associated with the presence of phenolic compounds, flavonoids, and polyphenols in the extracts. The best results were demonstrated by the plant extracts of arnica and calendula. Arnica extract at a concentration of 40 % exhibited better antioxidant properties than its 70 % extract.

Comparative study of organic removal by pre-adsorption oxidation and synchronous adsorption oxidation processes: Performance and mechanism

Both adsorption and oxidation occur and contribute to organics removal in carbonaceous materials based advanced oxidation processes, while the correction of adsorption and oxidation, and the role of adsorption in the veritable removal of organic are not clear. Herein, we investigated the performance of carbamazepine (CBZ) removal by peroxymonosulfate (PMS) activated by magnetic Fe-doped biochar through two models of pre-adsorption oxidation and synchronous adsorption oxidation processes. The adsorption process was better fitted by pseudo-second-order kinetic model and the adsorption mechanism was obtained by comprehensive analysis of equilibrium adsorption capacities, surface functional groups, specific surface area, pore volume, and ID/IG value. It is noted that pre-adsorption highly inhibited the further oxidation of CBZ in 0.5Fe@LSBC700/PMS system due to the occupied catalytic active sites. Total CBZ removal in pre-adsorption oxidation (45 %) was inferior to synchronous adsorption oxidation (∼100 %), as well as the veritable CBZ oxidation removal of 27 % for pre-adsorption oxidation vs ∼100 % in synchronous adsorption oxidation at 30 min. Oxidation degradation of CBZ based on radical oxidation was identified by quenching experiments and electron paramagnetic resonance measurements. This work is conducive to identifying the role of adsorption during the removal of organics in the adsorption-oxidation process, as well as veritable adsorption and oxidation removal of organics.

Molecular Electrocatalysis under Finite Diffusive Mass Transport Conditions. An Analytical Approach

AbstractMolecular electrocatalysis has emerged as a crucial branch of molecular electrochemistry, finding applications across various fields such as energy generation, electroanalysis, and electrosynthesis. In recent years, the study of these processes within confined spatial domains, has been increasingly frequent. However, a significant gap exists in the theoretical understanding of the interplay between different kinetics (redox and chemical) and mass transport under these conditions, and how their combined effects influence the electrochemical response. As a first step to address the aforementioned gap, this manuscript presents a theoretical expression for the current‐potential‐time response of a catalytic reaction occurring under finite diffusive conditions. The results indicate that, when the chemical kinetics is not fast, there are significant differences in electrochemical responses due to mass transport influences. Thus, in the case of bounded finite diffusion, a loss of efficiency in the process is observed, resulting in lower currents compared to those corresponding to semi‐infinite diffusive conditions. The validity of well‐known methods, such as the analysis of the current plateau or the foot of the wave under stationary conditions, is discussed. Experimental validation of these results is also provided through the study of the oxidation of Solketal mediated by the oxidation of TEMPO radical.

Dual single atomic Fe-Ni sites in N‑doped nanoporous carbon for high-efficiency potassium periodate activation toward pollutant abatement

Diatomic catalysts (DACs) with atomically isolated metal pairs hold the potential for activating potassium periodate (PI) in sustainable pollution control, yet their synthesis poses a significant challenge. In this study, Fe/Ni species anchored to a nitrogen-doped carbon as diatomic catalysts (FeNi-NC DACs) were precisely synthesized by direct carbonization of metal–organic frameworks (MOFs) assembled by Fe/Ni-doped ZnO nanoparticles and used for the effective decomposition of organic pollutants through PI activation. As anticipated, FeNi-NC exhibited superior catalytic properties due to the abundance of adjacent bimetallic active sites (Fe/Ni-Nx), rich doped nitrogen, high specific surface area, and electron transport conductivity, surpassing single-atom Fe-NC and Ni-NC, as well as nonmetallic NC catalysts. Free radical quenching, electron paramagnetic resonance, and electrochemical experiments have shown that the FeNi-NC/PI system can oxidize organic compounds through non-free radical oxidation pathways, including singlet oxygen (1O2) oxidation and mediated electron transfer processes. Electron transfer mediated by FeNi-NC/PI* complexes is the primary mechanism for organic oxidation. Additionally, the FeNi-NC catalyst demonstrated remarkable stability in both inorganic-containing and real water samples, as well as in continuous-flow microreactors. This study introduces a novel approach for designing highly efficient DACs and offers fundamental insights into the mechanism of PI-activated oxidation of organic pollutants.

The Effects of Antioxidants and Hyperbaric Oxygenation at Severe Thermal Injury: a Prospective Study

INTRODUCTION. Severe thermal injury (STI) characterized, among others, by hypoxia and oxidative stress (OS). The possibility of maintaining the antioxidant system through the antioxidants usage is proposed, but their effectiveness and duration are debatable issues. On the other hand, correction of OS at STI is theoretically possible by hyperbaric oxygenation (HBO) sessions, but there is a need to assess the benefit-risk ratio. AIM. Investigate the effect of antioxidants and hyperbaric oxygenation sessions on the course of oxidative stress at severe thermal injury. MATERIALS AND METHODS. This study involved conditionally healthy individuals (n = 25), and patients with STI (n = 31), randomized into 3 groups: standard methods (n = 11), supplemented with antioxidants (daily injecting of 250 g vitamin C, 1.494 g “Cernevit” and 10 ml “Addamel N” during 14 days, n = 11) or HBO sessions (50–60 minutes in pressure chambers BLKS-30, BLKS-307/1 in the “low dose” at 1.3 Ata, n = 9). Plasma and erythrocytes were evaluated for free radical oxidation (FPO) and total antioxidant activity, malonic dialdehyde (MDA) concentration, activity of superoxide dismutase (SOD), catalase, and glutathione reductase. RESULTS AND DISCUSSION. At the antioxidant usage was found SOD activity increase by 11 % (p 0.01) on the second day, a decrease in FROer by 13 % (p = 0.012) on the 9th day, and MDAer by 13 % (p = 0.036) on the 6th day. In the HBO group, there was 9 % increase in SOD activity (p = 0.038) after the first session, an increase in glutathione reductase activity by 15 % (p = 0.028) by the 9th day. Thus, it is possible to pre-limit the period of potentially favorable use of antioxidants and HBO, which contributes to the maximum therapeutic effect. The negative consequences caused by the use of antioxidants or HBO have not been identified in this work. CONCLUSION. The antioxidant usage at STI contributes to the growth of the antioxidant protection of erythrocytes. The HBO usage leads to an improvement in cellular respiration and antioxidant enzymes activity and does not cause a deepening of OS. The optimal duration of prescribing antioxidants is the first 6–8 days, HBO — 9–11 days from the beginning of therapy.