Oxidation Process Research Articles

Влияние проантоцианидинов на физиологическое состояние стерляди Acipenser ruthenus (Linnaeus, 1758) и антиоксидантную активность комбикорма

The effect of grape seed extract (GSE), containing 95% proanthocyanidins, on the physiological state of sterlet grown in conditions of closed water supply system is investigated. Additionally, the changes in the antioxidant activity of compound feed with the introduction of GSE (in dry and water-dissolved) after 1, 3 and 24 hours are analyzed. It is established that the greatest total amount of water-soluble antioxidants (TAWSA) is observed in the Russian compound feed with introduction of water solution of GSE (95% proanthocyanidins). The introduction of 50 mg of GSE per 1 kg of compound feed for 63 days promotes changes in the biochemical parameters of blood and organs of the experimental sterlet group. The total amount of water-soluble antioxidants in the liver increases by 25% (p < 0.05) compared to the control group. There is a tendency to increase the level of total protein (0.05 ≤ p ≤ 0.1), increase in albumin level by 36.47% (p ≤ 0.01) and the alkaline phosphatase enzyme activity by 25.45% (p ≤ 0.01) in serum. There is also a significant decrease in glucose levels in the experimental group of 60.22% (p < 0.01). There are no differences in the chemical and mineral composition of meat (p ≥ 0.1). It is assumed that in sterlet of the experimental group metabolism is intensified and oxidative processes in the liver are reduced. It is proposed to use GSE containing 95% proanthocyanidins in a dosage of 50 mg/kg as an additive in compound feed for juvenile sterlet to prevent oxidative stress and stimulate metabolic processes in the body.

The 24-kDa subunit of mitochondrial complex I regulates growth, microsclerotia development, stress tolerance, and virulence in Verticillium dahliae

BackgroundThe complete mitochondrial respiratory chain is a precondition for maintaining cellular energy supply, development, and metabolic balance. Due to the evolutionary differentiation of complexes and the semi-autonomy of mitochondria, respiratory chain subunits have become critical targets for crop improvement and fungal control. In fungi, mitochondrial complex I mediates growth and metabolism. However, the role of this complex in the pathogenesis of phytopathogenic fungi is largely unknown.ResultsIn this study, we identified the NADH: ubiquinone oxidoreductase 24-kDa subunit (VdNuo1) of complex in vascular wilt pathogen, Verticillium dahliae, and examined its functional conservation in phytopathogenic fungi. Based on the treatments with respiratory chain inhibitors, the mitochondria-localized VdNuo1 was confirmed to regulate mitochondrial morphogenesis and homeostasis. VdNuo1 was induced during the different developmental stages in V. dahliae, including hyphal growth, conidiation, and melanized microsclerotia development. The VdNuo1 mutants displayed variable sensitivity to stress factors and decreased pathogenicity in multiple hosts, indicating that VdNuo1 is necessary in stress tolerance and full virulence. Comparative transcriptome analysis demonstrated that VdNuo1 mediates global transcriptional effects, including oxidation and reduction processes, fatty acid, sugar, and energy metabolism. These defects are partly attributed to impairments of mitochondrial morphological integrity, complex assembly, and related functions. Its homologue (CgNuo1) functions in the vegetative growth, melanin biosynthesis, and pathogenicity of Colletotrichum gloeosporioides; however, CgNuo1 does not restore the VdNuo1 mutant to normal phenotypes.ConclusionsOur results revealed that VdNuo1 plays important roles in growth, metabolism, microsclerotia development, stress tolerance, and virulence of V. dahliae, sharing novel insight into the function of complex I and a potential fungicide target for pathogenic fungi.

The Removal of Organic Pollutants and Ammonia Nitrogen from High-Salt Wastewater by the Electro-Chlorination Process and Its Mechanism

Electro-chlorination (E-Cl) is an emerging and promising electrochemical advanced oxidation technology for wastewater treatment with the advantages of high efficiency, deep mineralization, a green process, and easy operation. It was found that the mechanism of pollutant removal by electro-chlorination mainly involves an indirect oxidation process, in which pollutant removal is mainly driven by the intermediate active species, especially RCS and chlorine radicals, with a strong oxidization ability produced at the anodes. In this work, we summarized the principles and pathways of the removal/degradation of pollutants (organic pollutants and ammonia nitrogen) by E-Cl and the major affecting factors including the applied current density, voltage, electrolyte concentration, initial pH value, etc. In the E-Cl system, the DSA and BDD electrodes were the most widely used electrode materials. The flow-through electrode reactor was considered to be the most promising reactor since it had a high porosity and large pore size, which could effectively improve the mass transfer efficiency and electron transfer efficiency of the reaction. Of the many detection methods for chlorine radicals and RCS, electron paramagnetic resonance (EPR) and spectrophotometry with N, N-diethyl-1,4-phenylenediamine sulfate (DPD) as the chromogenic agent were the two most widely used methods. Overall, the E-Cl process had excellent performance and prospects in treating salt-containing wastewater.

A Hybrid Photo-Catalytic Approach Utilizing Oleic Acid-Capped ZnO Nanoparticles for the Treatment of Wastewater Containing Reactive Dyes

In pursuit of overcoming Fenton oxidation limitations in wastewater treatment, an introduction of a heterogeneous photocatalyst was developed. In this regard, the current work introduces ZnO nanocrystals that were successfully prepared via a thermal decomposition technique and then capped with oleic acid (OA). The synthesized ZnO-OA and the pristine ZnO were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and field emission scanning electron microscopy (FE-SEM). Then, the study introduces the application of such materials in advanced oxidation processes, i.e., a Fenton reaction to treat dye-containing wastewater. Synthetic wastewater that was prepared using Reactive Blue 4 (RB4) was used as a simulated textile wastewater effluent. Fenton’s oxidation was applied, and the system parameters were assessed using the modified Fenton’s system. The synthesized samples of ZnO were characterized by a recognized wurtzite hexagonal structure. The surface modification of ZnO with oleic acid (OA) resulted in an increase in crystallite size, lattice parameters, and cell volume. These modifications were linked to the efficient capping of ZnO nanoparticles by OA, which further improved the dispersion of the nanoparticles, as demonstrated through SEM imaging. The optimum conditions of ZnO- and ZnO-OA-synthesized modified Fenton composites showed 400 mg/L and 40 mg/L for H2O2 and the catalyst, respectively, at pH 3.0, and within 90 min under UV irradiation the maximal dye oxidation reached 93%. The catalytic performance at its optimal circumstances was in accordance with a pseudo-second-order kinetics model for both ZnO-OA- and the pristine ZnO-based Fenton’s systems. The thermodynamic parameters, including the enthalpy (ΔH′), the entropy (ΔS′), and Gibbs free energy (ΔG′) of activations, were also checked, and their values settled that both ZnO and ZnO-OA Fenton systems are non-spontaneous in nature. Furthermore, the reaction signified for processing at a low energy barrier condition (10.38 and 31.38 kJ/mol for ZnO-OA- and the pristine ZnO-based Fenton reactions, respectively).

Antibiotic amoxicillin degradation by electrochemical oxidation process: effects of process parameters and degradation pathway at environmentally relevant concentrations.

Amoxicillin (AMX) is a common antibiotic used in both human and veterinary medicine in order to both cure and avoid bacterial infections. Traces of AMX have been found in ground and surface water, urban effluents, water, and wastewater treatment facilities due to its widespread use. The level of hazard and disposal of this class of micropollutants is the reason for concern. Advanced technology is required since conventional wastewater treatment plants are ineffective at eliminating these emerging contaminants. Electrochemical oxidation is a promising method of treating wastewater, which uses electrogenerated radicals to mineralize organic pollutants. This work investigated the detailed process mechanism for AMX degradation utilizing a low-cost, thin, flexible graphite sheet with lower AMX concentrations, initial pH value, voltage, electrolyte concentration, and wastewater matrix. The degradation of AMX by in situ generated hydroxyl radicals is a function of applied voltage and follows pseudo-first-order reaction kinetics. The removal efficiencies of AMX have been achieved up to 99% within 3h. Moreover, intermediate by-products have been identified using liquid chromatography-mass spectrometry, and a plausible pathway has been proposed. This study could serve as a process reference for controlling AMX wastewater contamination via the electrochemical oxidation technique.

Kinetics of decomposition of 1,1-diamino-2,2-dinitroethylene (fox-7). 5. Vapor pressure and reaction in the gas phase

The pressure of β-FOX-7 vapors in the temperature range 140–160 °C was determined by the manometric method. The correlation dependence of logPvap on 1/T has been established, which makes it possible to estimate the value of Pvap with satisfactory accuracy in the temperature range of 100–200°C. The kinetics of the reaction in the gas phase was measured at temperatures of 200–230 °C and m/V = 10–3–10–4 g/cm3. It was found that under these conditions, in parallel with the usual monomolecular isomerization reaction into aci-form, a chain process of direct oxidation of FOX-7 by NO2 proceeds. The consequence of this reaction is a significant decrease in the activation energy observed and the appearance of rate dependence on the experimental conditions. The scheme of the main stages of the chain reaction is presented and the conditions necessary for the manifestation of this reaction are determined.

Transformation of persistent organic micropollutants by UV and UV/H2O2 in wastewater treatment plant effluent

ABSTRACT Photochemical and advanced oxidation processes (AOPs) are promising options to simultaneously disinfect wastewater treatment plant (WWTP) effluent and degrade organic micropollutants (OMPs). In the present study, kinetic experiments with UV alone and the combination of UV and hydrogen peroxide (H2O2) as an AOP were conducted in WWTP effluent (with and without ultrafiltration) to assess the degradation of 24 OMP, 13 of which were examined for the first time, in a flow-through batch reactor setup. Four parameters were systematically varied to quantify their impacts on OMP degradation: H2O2 concentrations, UV source, water matrix, and flow rate. Most of the studied OMPs (e.g., trimethylammonium, 1,3-di-o-tolylguanidine, carbamazepine) were only significantly degraded in the presence of UV radiation and H2O2. The highest pseudo-first-order rate constants were found for diclofenac, acesulfame, diatrizoate, and sulfamethoxazole. The experiment with the highest degradation also showed the strongest abatement of UV absorbance at 254 nm. Only three of the 24 substances (cyanoguanidine, melamine, and oxipurinol) were not degraded; UV alone even increased their concentrations. Overall, upgrading a UV disinfection to an AOP using H2O2 allows the degradation of a wide range of OMP, making it an interesting process for water reuse.

Oxidative stress and metabolic syndrome in Alzheimer’s disease: the search for a relationship

The article addresses the problem of Alzheimer’s disease (AD) from the perspective of the interaction between two important pathological processes: oxidative stress and metabolic disorders. Although histopathological changes in early and senile dementia are similar, and both variants are attributed to AD, individuals with early-onset AD (EOAD) demonstrate a more aggressive course of the disease with rapid cognitive decline and fewer concomitant morphological changes. The development of late-onset AD (LOAD) depends on multiple environmental factors, lifestyle, and, among other things, the functioning of general adaptation mechanisms, including redox, immunological, and hormonal systems.The article pays special attention to the role of metabolic syndrome (MS) as an important risk factor not only for cardiovascular and cerebrovascular diseases but also for AD. The presence of MS in individuals over 60 years of age increases the risk of developing dementia by 13% under the age of 60 and by 8% between the ages of 60 and 70. The article emphasizes the importance of oxidative stress (OS), which causes oxidation of biomolecules and tissue damage, in the pathogenesis of metabolic disorders and the development of MS. Possible mechanisms of the relationship between oxidative stress processes and metabolic disorders are described. Understanding the mechanisms of AD and MS development, as well as their interrelation, is key to developing effective methods for preventing and treating these diseases.

Kinetic and Mechanistic Study of the Oxidation of Some Para-substituted Benzhydrols by Cetyltrimethylammonium Bromochromate using Spectrophotometric Technique

Objectives: This study investigates the oxidation of para-substituted benzhydrols by cetyltrimethylammonium bromochromate (CTMABC) in dimethylsulfoxide (DMSO), aiming to elucidate the reaction kinetics and solvent effects. Methods: The oxidation was carried out under pseudo-first-order conditions, showing first-order kinetics for both CTMABC and benzhydrols. The role of hydrogen ions in catalysis was examined, and the reaction was analyzed in 19 different organic solvents. Solvent effects were quantified using Kamlet’s and Swain’s multi-parametric equations. Findings: The reaction produced the corresponding benzophenones and demonstrated a first-order dependence on both reactants. The presence of hydrogen ions accelerated the reaction. Solvent studies indicated that solute-solvent interactions significantly influenced reactivity. Novelty: This research provides a comprehensive kinetic and mechanistic understanding of benzhydrol oxidation, utilizing a novel multi-parametric approach to analyze solvent impacts, offering new insights into solute-solvent interactions in oxidation processes. Keywords: Kinetics, Mechanism, Cetyltrimethylammonium bromochromate, Benzhydrol, Solvent effect

Influence of the Reduction Rate of Slag from Oxidation Process of Cu–Fe–Pb Alloy During Reduction (De-coppering) on Its Viscosity

AbstractThe production of copper based on a direct-to-blister flash smelting process made it necessary to introduce the technology for the reduction of flash smelting slag and subsequent refining of the resulting Cu–Fe–Pb alloy. Refining of Cu–Fe–Pb alloy produces a converter slag containing 7 ÷ 25 wt pct Cu, 3 ÷ 20 wt pct Fe , and 15 ÷ 45 wt pct Pb. This material is directed to the reduction (de-coppering) process, which allows the recovery of copper in the form of Cu–Pb alloy as well as the removal of lead from the copper material cycle in the form of lead-bearing material. The copper recovery rate in the form of Cu–Pb alloy depends on a number of factors, of which one of the primary ones is the viscosity of the medium (slag), which determines the rate of coalescence and sedimentation of the reduced metal droplets. The investigations on how the degree of reduction of metal oxides from the converter slag affects its viscosity are presented in the study. Viscosity tests were conducted in the range of 1000 ÷ 1450 °C and showed that the main factor affecting viscosity is the Cu2O content in the slag. Slags directed to the reduction process with a high Cu2O content have a lower viscosity than slags after the reduction process, which is due to a decrease in the copper oxide content of the slag. The viscosity of slags after reduction depends on the PbO content, the higher the PbO content the lower the slag viscosity. Furthermore, studies have shown that the viscosity of slags can be reduced by adding CaO to the slag.

UV-Activated and Fe2+-Catalyzed H2O2 for the Treatment of Dye-Contaminated Water: Kinetics, Mechanism and Toxicity Investigations

This study investigated the removal of methylene blue (MB) by different UV, UV-catalyzed H2O2 (UV/H2O2) and UV-and-iron-catalyzed H2O2 (UV/H2O2/Fe2+)-based advanced oxidation processes. At pH 6.0, the removal of MB (15 mg/L) was found to be 6.31% at 60 min for UV only. However, the combination of H2O2 (5 mM) with UV greatly enhanced the removal efficiency as 96.44% degradation of MB was found in the UV/H2O2 process at 60 min. Furthermore, the UV/H2O2/Fe2+ process was observed to be even more efficient than UV/H2O2, achieving 99.11% MB degradation at 30 min of treatment under the experimental conditions of [MB]0 = 15 mg/L, [H2O2]0 = 2 mM, [Fe2+]0 = 0.5 mg/L, and pH0 = 3.0. Furthermore, the removal of TOC was found to be 59 and 71% for UV/H2O2 and UV/H2O2/Fe2+, respectively. The pH did not change the efficiency of the UV/H2O2 process significantly; however, it greatly affected the efficiency of the UV/H2O2/Fe2+ system. The results demonstrate that both UV/H2O2 and UV/H2O2/Fe2+ could be used for the effective degradation and mineralization of MB.

Pyrite depression by sodium metabisulfite and dextrin with xanthates: contact angle, floatability, zeta potential and IR spectroscopy studies

The individual and combined depressive action of metabisulfite and dextrin on pyrite in the presence and absence of amyl xanthate has been studied through contact angle, zeta potential, microflotation, and IR spectroscopy analyses. The combined application of depressants significantly reduces the contact angle of pyrite compared with that of galena, with this effect being enhanced when the pulp is oxygenated during conditioning with metabisulfite, facilitating pyrite surface oxidation. Zeta potential measurements demonstrate the role of the oxidation process in decreasing the magnitude of the negative electric charge on the pyrite surface. These results were further corroborated by IR spectroscopy studies, which confirmed the oxidation of the pyrite surface in the presence of metabisulfite, as well as the co-adsorption of dextrin and amyl xanthate. In microflotation experiments, pyrite and galena exhibited contrasting flotation behaviors, with pyrite being effectively depressed at pH 8 when a combination of air, metabisulfite, and dextrin was used.

The Potential of Flavonoid Antioxidants in Dragon Fruit Skin (Selenicereus undatus) for Cardiovascular Health

This study aims to examine the potential of flavonoid antioxidants found in dragon fruit peel (Selenicereus undatus) in supporting cardiovascular health. Flavonoids, as bioactive compounds with antioxidant properties, have an important role in protecting the body from oxidative stress that can damage cells and tissues, including the cardiovascular system. With a qualitative approach through literature studies and library research, this study analyzes secondary data from various scientific sources to explore the effects of flavonoids on reducing the risk of cardiovascular disease. Studies show that the flavonoid content in dragon fruit peel is able to suppress the lipid oxidation process, lower cholesterol levels, and inhibit inflammation which is a major risk factor for cardiovascular disease. In addition, the high antioxidant activity of these flavonoids has the potential to strengthen the walls of blood vessels and improve blood circulation, so that it can prevent atherosclerosis and hypertension. The results of this study support the use of dragon fruit peel as a source of natural antioxidants that have the potential to be used as a supplement in the prevention of cardiovascular diseases. A further recommendation is to conduct clinical research to test the effectiveness of flavonoids from dragon fruit peel in cardiovascular health applications in more depth.

Comparison of UV/PAA and VUV/PAA Processes for Eliminating Diethyl Phthalate in Water

Diethyl phthalate (DEP) is a commonly utilized plasticizer that has gained significant attention due to its widespread occurrence in the environment and its harmful impact on human health. The primary objective of this study was to evaluate and compare several (ultraviolet) UV-(peracetic acid) PAA advanced oxidation processes based on hydroxyl radicals to degrade DEP. The effect of UV-LEDs incorporating PAA at different UV ranges (UV-A, λ = 365 nm; UV-C, λ = 254 nm and VUV, λ = 254 nm) was evaluated. The results demonstrated that DEP was successfully degraded in both the UVC/PAA (removal rate 98.28%) and VUV/PAA (removal rate 97.72%) processes compared to the UVA/PAA process (removal rate of 2.71%). The competitive method evaluated the contribution of R-O•, which were 24.08% and 33.92% in UVC/PAA and VUV/PAA processes, respectively. We also evaluated the effects of peroxymonosulfate (PMS) dosages, UV irradiation, pH and anion coexistence on the removal of DEP. In the UVC/PAA system, DEP degradation was particularly effective (removal rate about 95.52%) over a wider pH range (3–9). As the concentration of HCO3− ions increased, there may have been some inhibition of DEP removal. The inhibitory effect of HA and Cl− ions on DEP removal were negligible. Analysis of the intermediates revealed that DEP degradation primarily occurred via two pathways: hydrolysis and hydroxylation reactions. This study presents a potential mnethod for the removal of phthalates and offers some guidance for the selection of appropriate disinfection technologies in drinking water treatment.

Combination of Biochar and Advanced Oxidation Processes for the Sustainable Elimination of Pharmaceuticals in Water

The presence of pharmaceuticals in aquatic ecosystems is an issue of increasing concern. Regardless of the low concentration of pharmaceuticals in water, they can have a toxic effect on both humans and aquatic organisms. Advanced oxidation processes (AOPs) have been described as a promising technique for eliminating pharmaceuticals due to their high efficiency. However, the cost associated with the application of these processes and their high reagents and energy requirements have affected the implementation of AOPs at large scales. Biochar has been suggested to be used as a catalyst in AOPs to overcome these limitations. Biochar is considered as an alternative heterogeneous catalyst thanks to its physicochemical characteristics like its specific surface area, porous structure, oxygen-containing functional groups, electrical conductivity, persistent free radicals (PFRs), modifiable properties, and structure defects. This carbonaceous material presents the capacity to activate oxidizing agents leading to the formation of radical species, which are needed to degrade pharmaceuticals. Additionally, AOP/biochar systems can destroy pharmaceutical molecules following a non-radical pathway. To enhance biochar catalytic performance, modifications have been suggested such as iron (Fe) impregnation, heteroatom doping, and supporting semiconductors on the biochar surface. Although biochar has been efficiently used in combination with several AOPs for the mineralization of pharmaceuticals from water, further research must be conducted to evaluate different regeneration techniques to increase biochar’s sustainable applicability and reduce the operational cost of the combined process. Moreover, operational conditions influencing the combined system are required to be evaluated to discern their effect and find conditions that maximize the degradation of pharmaceuticals by AOP/biochar systems.

A green synthetic approach to construct C2‐quaternary indolin‐3‐ones at room temperature via regioselective oxidative dearomatization of indoles

A new synthetic strategy for the construction of C2‐quaternary indole for the formation of Indolin‐3‐ones has been explored via indium(III) trifluoromethansulphonate catalyst at room temperature with TBHP as a green oxidant in water. This approach for the oxidative dearomatization process allows to produce natural product Halichrome A and a broad range of C2‐arylated Indolin‐3‐ones under a milder condition in very good yields. The oxidative self‐dimerization and self‐trimerization of various indole derivatives have also been achieved under the same conditions.

From molecules to droplets: The Fog and Aerosol InteRAction Research Italy (FAIRARI) 2021/22 campaign

Abstract The Italian Po Valley is one of the most polluted regions in Europe. During winter, meteorological conditions favor long and dense fogs, which strongly affect visibility and human health. In spring, the frequency of nighttime fogs reduces while daytime new particle formation events become more common. This transition is likely caused by a reduction in PM2.5, leading to a decrease in the relevant condensation sink. The physics and chemistry of fog and aerosol have been studied at the San Pietro Capofiume site since the 1980s, but the detailed processes driving the observed trends are not fully understood. Hence, during winter and spring 2021/22, the Fog and Aerosol InteRAction Research Italy (FAIRARI) campaign was carried out, using a wide spectrum of approaches, including in-situ measurements, outdoor chamber experiments, and remote sensing. Atmospheric constituents and their properties were measured ranging from gas molecules and molecular clusters to fog droplets. One unique aspect of this study is the direct measurement of the aerosol composition in- and outside of fog, showing a slightly greater dominance of organic compounds in the interstitial compared to the droplet phase. Satellite observations of fog provided a spatial context and agreed well with in-situ measurements of droplet size. They were complemented with in-situ chamber experiments, providing insights into oxidative processes and revealing a large secondary organic aerosol forming potential of ambient air upon chemical aging. The oxidative potential of aerosol and fog water inferred the impact of aerosol-fog interactions on particle toxicity.

Structure-based drug design of pre-clinical candidate nanopiperine: a direct target for CYP1A1 protein to mitigate hyperglycaemia and associated microbes

ABSTRACT Diabetes is attributed to an increased vulnerability to bacterial infection linked to unregulated hyperglycaemia. The present study highlights the formulation of nanoparticles with phyto-compound piperine (PIP) encapsulated within non-toxic biodegradable polymer poly-lactide co-glycolide (PLGA) which showed a variety in surface functionality, biocompatibility, and the ability to tailor an optimized release rate from its polymeric enclosure. The observations revealed that nanopiperine (NPIP) pre-treatment in mice inhibited alteration in hepatic tissue architecture and hepato-biochemical parameters in diabetes and its associated bacterial infections. NPIP also decreased the propensity of lipids to undergo an oxidation process and stabilized the membrane lipids in vivo, thereby lowering oxidative stress and preventing enzymatic activation of CYP1A1. This result is corroborated with the in silico molecular docking study where PIP binding with CYP1A1 gave −11.32 Kcal/mol dock score value. The antibacterial activity of PIP was further demonstrated by the in silico PIP and Ef-Tu protein-binding efficacy revealing −6.48 Kcal/mol score value which was coupled with the results of in vitro studies where the zone of inhibition assay with NPIP against Staphylococcus aureus and Escherichia coli. Thus, NPIP could serve as a potential drug candidate in modulating targeted proteins to inhibit the progression of hyperglycaemia and its associated microbes.

Modulated Fe Central Spin State in FeCu4 Alloy Nanoparticles for Efficient and Selective Activation of H2O2

AbstractIn advanced oxidation processes, the efficient activation of H2O2 and the selective production of reactive oxygen species are the key steps to achieve the removal of organic pollutants in the water environment. Studies have shown that the precise regulation of catalyst metal active sites can break through the limitation of H2O2 activation and realize the efficient selective conversion of H2O2. Therefore, FeCu bimetallic active sites are developed by constructing FeCu4 alloy nanocluster metal catalyst (FeCu/NC). The introduction of Cu metal sites realized charge redistribution, promoted rapid electron transfer, reduced the spin state of Fe in the catalyst, diminished the interaction between Fe and O, weakened the strong and persistent adsorption between Fe center and *H2O2, lowered the energy barrier of intermediate products in hydroxyl radicals (·OH) generation process, achieved efficient activation of H2O2 and selective generation of ·OH. In addition, a complete electron circulation path is formed between FeCu active sites and the substrate, breaking the contradiction between single metal and H2O2 redox relationship, promoting efficient reduction of Fe3+ to Fe2+. The first‐order kinetic constant (kobs) of FeCu/NC is 0.081 min−1, which is 3.68 and 7.36 times higher than those of single Fe metal species (FeFe/NC) and single Cu metal species (CuCu/NC) catalysts, respectively, and has excellent catalytic performance).

A Study on Gas‑sensing Behavior of Reduced Graphene Oxide (rGO) Green Method, Enhansing the Performance of Green-synthesized Reduced Graphene Oxide

This paper presents a comparative study on gas-sensing behavior of reduced graphene oxide (rGO) synthesized by chemical and green synthesis route. GO is synthesized by Hummers method and then reduced employing two reducing agents hydrazine hydrate [represented by (rGO)1] and L-citrulline [represented by (rGO)2]. Synthesized products were then obtained in the form of thin films, and tested for 10 ppm NO2 and CO at operating temperatures of 50, 100, and 150 °C. The green-synthesized reduced graphene oxide (rGO)2 exhibits higher relative response of 254.7% as compared to conventionally synthesized (rGO)1 (93.9%) and GO (22.7%) for 10 ppm NO2 at operating temperature of 150 °C. Furthermore, a switching of conductivity from usual p-type behavior to n-type on exposure of NO2 is observed at all operating temperatures (50, 100, and 150 °C) for GO, (rGO)1, and (rGO)2. The XRD, FTIR, and Raman confirm the oxidation and reduction process. (rGO)2 shows high thermal stability as observed through TGA. FESEM and TEM images show wrinkled sheet structure for GO as well (rGO)1 and (rGO)2. The data observed from the characterization of resultant products have made it possible to explain better reduction of GO through green-reducing agent and enhanced gas-sensing performance of green-synthesized reduced graphene oxide.