Reagent For Oxidation Research Articles

Polyaniline-Ag Nanocomposite Containing Silane Ligand: Synthesis, Characterization and Electroactivity Behavior

In this work, polyaniline-Ag nanocomposite containing modified silane ligand was synthesized via the reduction of AgNO3 with hydrazine on the surface of the emeraldine-base polyaniline containing modified silane ligand. The latter was prepared through chemical polymerization of aniline in the presence of thiol-terminated silane ligand by ammonium peroxydisulfate as an oxidant reagent under ultrasonic waves. Then it was used as a template in the synthesis of Ag NPs. Resultant nanocomposite displayed high dispersity in polar organic solvents and aquous media. Nanocomposite was characterized by UV–Vis and FTIR spectroscopy, X-ray diffraction studies, scanning electron microscopy, energy dispersive analysis of W-ray and transmission electron microscopy. The results confirmed the presence of Ag NPs in nanocomposite and also the successful convertion of emeraldine-salt to emeraldine-base polyaniline. Finally, the electroactivity behavior of initial polymer and resultant nanocomposite was investigated by cyclic voltammetry method.

Redox-Mediated Endocytosis of a Receptor-Like Kinase during Distal Stem Cell Differentiation Depends on Its Tumor Necrosis Factor Receptor Domain.

Cellular redox status plays critical roles in cell division and differentiation, but the underlying mechanism is unclear. Here we explored the effect of redox status on stem cell identity in distal stem cells (DSCs) of Arabidopsis (Arabidopsis thaliana) roots. Treatment with the reductive reagent glutathione and the oxidative reagent H2O2 inhibited DSC differentiation, as did endogenously altering reactive oxygen species production via various mutations. This suggests that both highly reductive and oxidative environments inhibit specification of stem cell identity. In our observations of mutant components of the CLAVATA3/ENDOSPERM SURROUNDING REGION 40 (CLE40)-ARABIDOPSIS CRINKLY4 (ACR4)/CLAVATA1 (CLV1)-WUSCHEL RELATED HOMEOBOX5 (WOX5) module, both reductive and oxidative reagents influenced DSC differentiation in wox5-1 and clv1-1, but not in acr4-2 or cle40 mutant plants. The stability of the receptor-like kinase ACR4 is modulated by redox status through endocytosis in root tips. ACR4 with multiple Cys mutations in the tumor necrosis factor receptor (TNFR) extracellular domain failed to undergo endocytosis. ACR4 with a complete deletion of the TNFR domain was localized directly to endosomes, bypassing the plasma membrane. Both mutations affected DSC differentiation, but not seed filling. Conversely, the intracellular domain of the ACR4 protein is partially required for seed filling, but not for DSC differentiation. Our study uncovers an important biological role of the TNFR domain in redox-mediated endocytosis of ACR4 in root DSC differentiation.

Multiplex Quantitative Glycomics Enabled by Periodate Oxidation and Triplex Mass Defect Isobaric Multiplex Reagents for Carbonyl-Containing Compound Tags.

Glycosylation is one of the most important post-translational modifications (PTMs) with essential physiological functions, including protein folding, cell signaling, and immune response. Thus, various qualitative and quantitative glycomics analysis strategies have been developed. Recently, the isobaric multiplex reagents for carbonyl-containing compound (SUGAR) tag was developed for quantitative glycomics with multiplexing capacity and increased reporter ion yield. To further improve quantification efficiency and enable quantifying low-abundance species, the mass defect based triplex SUGAR (mdSUGAR) tag has been designed. In addition, we also introduce additional reaction sites for mdSUGAR at the terminal sialic acid by periodate oxidation of the polyhydroxy chain to extend the mass difference and lower the requirement for resolving power. As a result, mdSUGAR tags show complete labeling efficiency, improved fragmentation pattern, and accurate quantification. Moreover, the quantitative performance of the mdSUGAR tags in a complex system has been systematically evaluated and demonstrated reliable results.

Anaerobic digestion of aqueous phase from pyrolysis of biomass: Reducing toxicity and improving microbial tolerance

Among the products of pyrolysis is an aqueous phase (AP), which contains a significant fraction of carbon but is too dilute to make recovery of this organic content cost-effectively. This study was to explore the use of AP for anaerobic digestion. Different treatment methods including overliming, Fenton's reagent oxidation, bleaching and activated carbon adsorption were investigated to reduce toxicity of AP. Overliming treatment increased biogas production up to 32-fold compared to non-treated AP. Enhancing the tolerance of the bacterial and archaeal community to the AP toxicity was also attempted with a directed evolution method, resulting the microbes’ tolerance to AP from 5% to 14%. Directed evolution resulted a major bacterial taxa as Cloacimonetes, Firmicutes, and Chloroflexi, while shifted the predominant archaea shifted from acetoclastic to hydrogenotrophic methanogens. Collectively, the results demonstrated that combining feedstock treatment and directed evolution of the microbial community is an effective way for AP anaerobic digestion.

Regioselective Ortho Amination of an Aromatic C-H Bond by Trifluoroacetic Acid via Electrochemistry.

A trifluoroacetic acid-facilitated ortho amination of alkoxyl arene has been established via anodic oxidation in an undivided cell. In the absence of any additional metal or oxidant reagents, a series of aromatic and heteroaromatic amine derivatives have been synthesized in good to excellent yields. Our findings reveal the possibility of achieving complete ortho-selective amination of a simple arene, which emerges as an efficient route for facile and large-scale organic synthesis.

Modelling input data interactions for the optimization of artificial neural networks used in the prediction of pitting corrosion

Purpose This paper aims to predict the localized corrosion resistance by the application of artificial neural networks. It emphasizes the importance to take into account the relationships between the physical parameters before presenting them to the network. Design/methodology/approach The work was conducted in two phases. At the beginning, the authors executed an experimental program to measure pitting corrosion resistance of carbon steel in an aqueous environment. More than 900 electrochemical experiments were conducted in chemical solutions containing different concentrations of pitting agents, corrosion inhibitors and oxidant reagents. The obtained results were collected in a table where for a combination of the experimental parameters corresponds a pitting potential Epit obtained from the corresponding electrochemical experiment. In the second step, the authors used the experimental data to train different artificial neuron networks for predicting pitting potentials. Findings In this step, the authors considered the relationships that the chemical parameters are likely to have between them. Two types of relationships were taken into account: chemical equilibria which are controlled by the pH and the synergistic relationships that some corrosion inhibitors may have when they are in the presence of a chemical oxidant. Originality/value This comparative study shows that adjusting the input data by considering the physical relationships between them allows a better prediction of the pitting potential. The quality of the prediction, quantified by a regression factor, is qualitatively confirmed by a statistical distribution of the gap between experimental and calculated pitting potentials.

Recovery of Arsenic from Arsenic-Bearing Cobalt/Nickel Residue Using Sodium Persulfate

Cobalt/nickel residue has a high content of arsenic, and it poses a great threat to humans. It is absolutely necessary to treat the residue. In this study, the leaching of cobalt/nickel residue using alkali at atmospheric pressure was reported. The results showed that the optimum condition was as follows: 16 g of oxidant reagent, alkali concentration of 5 mol/L, reaction temperature of 80°C and reaction time of 2 h. Under those conditions, the leaching ratios of arsenic and zinc reached about 99% and 87%, whereas cobalt, copper and nickel remained non-dissolved. Based on thermal analysis and kinetics calculation, the activation energy of the leaching process was 42.06 kJ/mol, and the reaction order was 2.77. This work effectively recovered arsenic from this hazardous residue, greatly reducing environmental pollution. It also laid a solid foundation for further comprehensive recovery of valuable metals from the zinc metallurgy process.

Synthesis of 1,2,3-Triazolo-Fused Allocolchicine Analogs via Intramolecular Oxidative Biaryl Coupling.

A novel series of 1,2,3-triazolo-fused allocolchicine analogs is described. The strategy to prepare these analogs involves two steps: The first step is the synthesis of 1,2,3-triazole derivatives using our previously reported triazolization method, and in the second step, cyclization between two aromatic rings occurs by using the combination of PIFA and BF3·Et2O as an oxidative coupling reagent. Furthermore, the diversity of aromatic rings and functional groups is explored in order to obtain seven- and eight-membered ring systems with medicinal chemistry interest.

Colorimetric Determination of Amoxicillin in Pure and some Pharmaceutical Formulations Via Reaction with Potassium Permanganate as Oxidant Reagent

We proposed two simple, rapid, and convenient spectrophotometric methods are described for the determination of Amoxicillin in bulk and its pharmaceutical preparations. They are based on the measurement of the flame atomic emission of potassium ion (in first method) and colorimetric determination of the green colored solution for manganite ion at 610 nm formed after reaction of Amoxicillin with potassium permanganate as oxidant agent (in the second method) in basic medium. The working conditions of the methods were investigated and optimized. Beer's law plot showed a good correlation in the concentration range of 5-45 μg/ml. The detection limits and relative standared deviations were (2.573, 2.814 μg/ml) (2.137, 2.498) for the flame emission photometric method and (1.844, 2.016 μg/ml) (1.645,1.932) for colorimetric methods for capsules and suspensions respectively. The methods were successfully applied to the determination of Amoxicillin in capsules and suspensions, and the obtained results were in good agreement with the label claim. No interference was observed from the commonly encountered additives and expectancies.

Extraction of Aqueous Metabolites from Cultured Adherent Cells for Metabolomic Analysis by Capillary Electrophoresis-Mass Spectrometry.

Metabolomic analysis is a promising omics approach to not only understand the specific metabolic regulation in cancer cells compared to normal cells but also to identify biomarkers for early-stage cancer detection and prediction of chemotherapy response in cancer patients. Preparation of uniform samples for metabolomic analysis is a critical issue that remains to be addressed. Here, we present an easy and reliable protocol for extracting aqueous metabolites from cultured adherent cells for metabolomic analysis using capillary electrophoresis-mass spectrometry (CE-MS). Aqueous metabolites from cultured cells are analyzed by culturing and washing cells, treating cells with methanol, extracting metabolites, and removing proteins and macromolecules with spin columns for CE-MS analysis. Representative results using lung cancer cell lines treated with diamide, an oxidative reagent, illustrate the clearly observable metabolic shift of cells under oxidative stress. This article would be especially valuable to students and investigators involved in metabolomics research, who are new to harvesting metabolites from cell lines for analysis by CE-MS.

Pd-based Catalysts by Colloid Synthesis Using Different Reducing Reagents for Complete Oxidation of Methane

Here, without using any organic stabilizer, via two-steps process, Pd-based catalysts supported on La-modified Al2O3 by a new colloid synthesis method using different reducing reagents were prepared. It was found that the reducibility and structure of reducer controlled the rate of nucleation and growth of Pd in its precursor solution supported on the modified Al2O3. The surface OH groups of alumina can stabilize the formed Pd nanoparticles and enhance Pd dispersion. The catalyst obtained by using the mild reducing reagent, ethylene glycol, had the highest dispersion (32.6%) and largest active metal surface area. This catalyst showed the best catalytic performance among the five as-synthesized catalysts for removing pollutants in a simulated natural gas vehicles (NGVs) exhaust. Compare to its counterpart by common impregnation method, the light-off temperature over the catalyst by colloid synthesis method can be significantly decreased by 39 °C for CH4 and 27 °C for NO, respectively. The study may provide a general method to control the formation of metal (oxide) nanoparticles for heterogeneous catalysis, especially for emission abatement of NGVs.

Using porous iron composite (PIC) material to immobilize rhenium as an analogue for technetium

Technetium (99Tc), a uranium-235 (235U) and plutonium-239 (239Pu) fission product, is a primary risk driver in low level radioactive liquid waste at U.S. Department of Energy sites. Previous studies have shown success in using Zero Valent Iron (ZVI) to chemically reduce and immobilize redox sensitive groundwater contaminants. Batch and column experiments were performed to assess the ability of a novel porous iron composite material (PIC) to immobilize Tc(VII) in comparison with two commercial Fe oxide sorbents and reagent grade ZVI in the presence and absence of NO3−, a competing oxidized species that is often found in high concentrations in liquid nuclear waste. Perrhenate (ReO4−) was used as a non-radioactive chemical analogue for pertechnetate (TcO4−) under both oxic and anoxic test conditions. The PIC powder was the most effective at immobilizing Re(VII) under all batch test conditions. The presence of nitrate (NO3−) slowed the removal of ReO4− from solution, presumably through chemical reduction and precipitation. Even so, the PIC and ZVI were effective at removing both Re(VII) and NO3− completely from solution. Nitrate was reduced to NH3 with very little nitrite (NO2−) buildup during equilibration. Significant Re immobilization was observed in the column tests containing PIC sorbent, even though inlet solutions were in equilibrium with O2. The presence of NO3− hastened Re breakthrough, while NO3− reduction to NH3 was observed. The results suggest that PIC and ZVI would be the most effective at the removal of TcO4− from contaminated groundwater sites.

Effects of oxidant and catalyst on the transformation products of rocket fuel 1,1-dimethylhydrazine in water and soil

Existing methods for cleanup of wastewaters and soils polluted with the extremely toxic rocket fuel unsymmetrical dimethylhydrazine (UDMH) are mainly based on the treatment with various oxidative reagents. Until now, the assessment of their effectiveness was based on the residual content of UDMH and did not take into account the possibility of the formation of a large number of potentially dangerous nitrogen-containing transformation products (TPs). In this study, using the recently developed approach based on high-resolution Orbitrap mass spectrometry, the comprehensive characterization of UDMH TPs formed by the action of air oxygen and different oxidants (Fenton's reagent, KMnO4, HOCl, H2O2 in the presence of Cu2+ and [Fe (EDTA)]– catalysts) typically used to detoxify spill sites was performed. The range of the identified molecular formulas of TPs comprised 303 compounds of various classes. Among them, there is a number of major products not previously described in the literature. It was established that none of the investigated oxidative reagents ensures complete conversion of rocket fuel to safe compounds. The hydrogen peroxide based reagents, particularly H2O2 + Na [Fe (EDTA)] system currently used in Kazakhstan, give the greatest number of TPs, for many of which a toxicity was not characterized so far. The majority of the compounds found in model solutions was detected in extracts of soil from the crash site of the Proton carrier rocket, which was subjected to the on-site reagent treatment. During successive treatments, along with the decrease in the number of detectable UDMH TPs, their ratios change in favor of amines.

Applications of Advanced Oxidation Technologies for Sludge Treatment

Treatment of sludge is an important issue in water treatment. At present, the traditional sludge treatment process still faces problems such as high sludge production and low solid content, and it is impossible to achieve environmental and economic benefits. Advanced oxidation technology can not only reduce sludge dry base production, but also improve sludge dewatering performance, which has attracted much attention in the field of sludge treatment. On the basis of a brief description of Fenton reagent oxidation, ozone oxidation, wet air oxidation and supercritical water oxidation mechanism, the effects of several advanced oxidation techniques on sludge dry yield and dewatering performance are discussed, and various oxidation methods are introduced. Finally, the advantages and disadvantages of various advanced oxidation technologies are discussed, and the main research directions of advanced sludge oxidation are pointed out.

Effect of various chemical oxidation reagents on soil indigenous microbial diversity in remediation of soil contaminated by PAHs

Chemical oxidation is a promising pretreatment step coupled with bioremediation for removal of polycyclic aromatic hydrocarbons (PAHs). The effectiveness of Fenton, modified Fenton, potassium permanganate and activated persulfate oxidation treatments on the real contaminated soils collected from a coal gas plant (263.6 ± 73.3 mg kg−1 of the Σ16 PAHs) and a coking plant (385.2 ± 39.6 mg kg−1 of the Σ16 PAHs) were evaluated. Microbial analyses showed only a slight impact on indigenous microbial diversity by Fenton treatment, but showed the inhibition of microbial diversity and delayed population recovery by potassium permanganate reagent. After potassium permanganate treatment, the microorganism mainly existed in the soil was Pseudomonas or Pseudomonadaceae. The results showed that total organic carbon (TOC) content in soil was significantly increased by adding modified Fenton reagent (1.4%–2.3%), while decreased by adding potassium permanganate (0.2%–1%), owing to the nonspecific and different oxidative properties of chemical oxidant. The results also demonstrated that the removal efficiency of total PAHs was ordered: permanganate (90.0%–92.4%) > activated persulfate (81.5%–86.54%) > modified Fenton (81.5%–85.4%) > Fenton (54.1%–60.0%). Furthermore, the PAHs removal efficiency was slightly increased on the 7th day after Fenton and modified Fenton treatments, about 14.6%, and 14.4% respectively, and the PAHs removal efficiency only enhanced 4.1% and 1.3% respectively from 1st to 15th day after potassium permanganate and activated persulfate treatments. The oxidants greatly affect the growth of soil indigenous microbes, which cause further influence for PAHs degradation by bioremediation.

Extraction of Potassium from Biotite by Ca2+/K+ Ion Exchange and the Structural Transformation

In order to alleviate the contradiction between supply and demand of potassium resources in China, we extracted potassium from biotite by Ca2+/K+ ion exchange. Soluble potassium salts were obtained from the filtrate by hydrothermal reaction of biotite with oxidant, ion exchanger and other reagents at 80 ℃. The extraction rate of potassium and the structure change of biotite during the process of potassium exchange were determined by atomic absorption spectrophotometer and X-ray diffraction. The results showed that the layered silicate structure of biotite after ion exchange had not been destroyed, the base-plane spacing has expanded from 1.012 nm to 1.4288 nm, and most of the interlayer potassium ions have been extracted after 24 hours. The potassium extraction rate is 89%.

One-Pot Oxidative Coupling/Decyanation of 6,7-Diphenylindolizine-5-carbonitriles and 2,3-Diphenylquinolizine-4-carbonitriles.

The one-pot oxidative coupling/decyanation reactions of 6,7-diphenylindolizine-5-carbonitriles and 2,3-diphenylquinolizine-4-carbonitriles were investigated using aryl-aryl oxidative coupling reagents. The phenanthroindolizidinones and phenanthroquinolizidinones were produced in 52-89% yields under VOF3/trifluoroacetic acid or [bis(trifluoroacetoxy)iodo]benzene/BF3-mediated conditions. This represents a mild and efficient approach to construct these types of pentacyclic skeletons from the corresponding cyano group-activated aza-Diels-Alder cycloadducts. A plausible mechanism of the one-pot oxidative coupling/decyanation reaction was proposed.

Development of customized 3D printed stainless steel reactors with inline oxygen sensors for aerobic oxidation of Grignard reagents in continuous flow

Development of 3D printed stainless steel reactors for the oxidation of Grignard reagents in continuous flow.

Crystalline Structure Study of Double Perovskites Sr2FeNb1-xMoxO6 Synthesized by the Molten Salts Method

Abstract Sr2FeNb1-xMoxO6 compounds (x = 0.0, 0.2, 0.3, 0.4) were synthesized by the molten salts methodin air atmosphere. Rietveld refinements of the X-ray diffraction patterns for those samples indicate that the molybdenum ions occupy niobium sites,inducing to decreasein the lattice parameterlengths and (Fe1,2/Nb1,2)–O bond length. As a consequence, the octahedral distortion increases for (Fe1/Nb1)O6 while decreases for (Nb2/Fe2)O6.The secondary phases are less than 10%,theycould be attributed to the fact that oxidation of reagents is faster than the main reaction, even though the molten salt method increases the reaction rate.

Безвакуумный метод получения кубического карбида титана в плазме низковольтного дугового разряда постоянного тока

AbstractThe results of a study on the production of cubic titanium carbide in direct-current arc discharge plasma initiated in open air are presented. A feature of the method is its implementation without the use of gas or liquid protective media preventing the oxidation of products and initial reagents with air oxygen. According to the X-ray diffraction data, graphite gC, hexagonal titanium α-Ti, and cubic titanium carbide TiC are identified in the composition of the powder product. The TiC particles are represented by objects with a regular characteristic cut and sizes from units to tens of micrometers.