Oxidation Procedure Research Articles

Virus removal from drinking water using modified activated carbon fibers.

Activated carbon (AC) exhibits superior sorption properties compared to other porous materials, due to well-developed porous structures and high surface areas. Therefore, it is widely applied in its various forms in water purification to remove a diverse range of contaminating species. The presence of viruses in fresh water bodies poses a serious issue for human health. However, AC has not yet been commonly applied to waterborne virus removal. In this study, we present oxidation and copper impregnation treatment procedures of activated carbon fibers (ACFs) that resulted in porous structure and surface chemistry modifications. The effect of these modifications on virus removal was investigated by experimental flow studies and revealed up to 2.8 log10 reduction value (LRV) and 3.6 LRV of MS2 bacterio-phages for non-modified and oxidized ACFs, respectively, emphasizing the advantages of ACF surface functionalization. Copper modified fibers demonstrated a high sensitivity to media composition, resulting in a release of metal and therefore limited virucidal capacity.

Electron-transfer oxidation of Organo-cuprates with Benzophenone: Synthesis of Biaryls

A mild and simple way to synthesize Biaryls from aryl bromides via formation of organo-cuprate complexes has been developed. The Organo-cuprates {Ar2CuMgBr.Mg(I)Br}, generated from Arylmagnesium bromide and half equivalent of copper(I) iodide in dry THF at lower temperature under nitrogen, underwent electron-transfer oxidation with an aryl ketone benzophenone producing homo-coupled Biaryls in moderate yields. Aryl bromides either with electron-donating or with electron-withdrawing substituents were smoothly transformed into the corresponding Biaryls through formation of aryl Grignard reagents and Organo-cuprate complexes in a one pot reaction under this electron-transfer oxidation procedure.

Rapid wet-chemical oxidative activation of graphite felt electrodes for vanadium redox flow batteries.

To boost the performance of vanadium redox flow batteries, modification of the classically used felt electrodes is required to enable higher cycling performance and longer life cycles. Alternative approaches to the standard thermal oxidation procedure such as wet chemical oxidation are promising to reduce the thermal budget and thus the cost of the activation procedure. In this work we report a rapid 1 hour activation procedure in an acidified KMnO4 solution. We show that the reported modification process of the felt electrodes results in an increase in surface area, density of oxygenated surface functionalities as well as electrolyte wettability, as demonstrated by N2-physisorption, XPS, Raman spectroscopy as well as contact angle measurements. The activation process enables battery cycling at remarkably high current densities up to 400 mA cm−2. Stable cycling at 400 mA cm−2 over 30 cycles confirms promising stability of the reported activation procedure.

Assessment of the Oxidative Desulfurization of Middle Distillate Surrogate Fuels with Spectroscopic Techniques.

The oxidative desulfurization of five (5) model sulfur compounds and eleven (11) surrogate blends was investigated using the hydrogen peroxide (H2O2)-acetic acid (CH3COOH) system. Consequently, extractive desulfurization was carried out using conventional solvents. The model sulfur compounds, as well as the solvent, are present in petroleum middle distillates. The selection of the compounds was made so that they represent various kinds of sulfur compounds. The goal of this study was the implementation of a simple and economical oxidative and extractive system for the desulfurization of surrogate mixtures with an intermediate sulfur concentration 1% w/w, at the mild temperature of 70°C, and without the use of supplementary and assisting methods such as heterogeneous catalysis or ultrasound irradiation. The sulfur content was estimated using X-ray fluorescence. The progress of the oxidation reaction was monitored using liquid FT-IR. The solid sediments of the oxidation procedure were identified with solid-state FT-IR and 1H NMR spectroscopy.

Selective Oxidation of Ethane to Acetic Acid Catalyzed by a C-Scorpionate Iron(II) Complex: A Homogeneous vs. Heterogeneous Comparison

The direct, one-pot oxidation of ethane to acetic acid was, for the first time, performed using a C-scorpionate complex anchored onto a magnetic core-shell support, the Fe3O4/TiO2/[FeCl2{κ3-HC(pz)3}] composite. This catalytic system, where the magnetic catalyst is easily recovered and reused, is highly selective to the acetic acid synthesis. The performed green metrics calculations highlight the “greeness” of the new ethane oxidation procedure.

Motivated surface reaction thermodynamics on the bismuth oxyhalides with lattice strain for enhanced photocatalytic NO oxidation

Understanding and establishing a specific relationship between modified structures and photocatalytic reaction process has a profound significance for designing catalysts with preferable activity. In this study, we have favorably synthesized the bismuth oxyhalides (BiOClxBr1-x, 0 ≤ x ≤ 1) photocatalysts by utilizing the ethylene glycol assisted solvothermal method and the calcination procedure for photocatalytic nitric oxide oxidation. By regulating the halogen proportion in anions layer, the lattice strain has been induced in the structure, specifically the tensile strain in c axis. By virtue of in situ DRIFTS and DFT calculation, we found that the optimized surface reaction thermodynamic process should be the main factors response for prominent enhanced photocatalytic activity, rather than the light absorption and separation of carriers. The bismuth oxyhalides with Cl/Br ratios of 3:1 (BiOClxBr1-x-3:1) possess the lowest thermodynamic energy barrier for photocatalytic nitric oxide oxidation reaction, whilst both associative and dissociative reaction process exist in the initial elementary reaction about oxygen reduction. Finally, we develop a feasible strategy to depress thermodynamic energy barriers via tuning the ratio of halogen in anions layer and bringing the lattice strain, as well build relationship between the adjusted structures and surface reaction process.

Electrical properties of (Pb0.6Gd0.2 Bi0.2)(Fe0.4Ti0.6)O3 material

A gadolinium modified BiFeO 3 -PbTiO 3 electronic sample with chemical composition of (Pb 0.6 Gd 0.2 Bi 0.2 )(Fe 0.4 Ti 0.6 )O 3 is processed by exploiting high-temperature mixed oxide procedure. The prepared materials’s dielectric, loss tangent, electric modulus, impedance as well as conudctivity features are studied in different testing conditions to reveal resistive, conducting and capacitive performance. The impedance investigation indicates non-Debye type of relaxation mechanism. The material entails a relatively large dielectric constant with low loss tangent. The preliminary investigation depicts the electrical properties which props up this material for functional device applications.

Synthesis of an Azabicyclo[3.1.0]hexanone-Containing Inhibitor of NF-κΒ Inducing Kinase via Catalytic C–H Activation

AbstractThe synthesis of an azabicyclo[3.1.0]hexanone-containing inhibitor of the nuclear factor-κB inducing kinase (NIK) is reported. The initial route to this compound was streamlined from 13 to 7 linear steps through the use of a catalytic, enantioselective C–H activation step. A procedure for lactam oxidation was identified that avoided use of peroxides on scale. These synthetic improvements allowed for the synthesis of multigram quantities of the desired NIK inhibitor for in vivo profiling.

Self-arranged polythiophene on multi-walled carbon nanotube templated composites: Synthesis and application in rechargeable aluminium battery

This work demonstrates the application of polythiophene/multi-walled carbon nanotube (PTh/MWCNT) composite as electrode material for rechargeable aluminium battery (RAB) consisting Al plate as negative electrode. Chemical in-situ oxidative synthetic procedure was followed for obtaining PTh/MWCNT composite, which defines one-dimensional morphology of as synthesized mixture, deciphered through FESEM and HRTEM analysis. The polymer's successful nanocomposite formation was confirmed through FTIR analysis and EDS elemental mapping. Further application of PTh/MWCNT as cathode against Al anode in 1.5:1 molar ratio of AlCl3:[EMIm]Cl signify the positive electrochemical behaviour. Cyclic voltammetry of the cells show well-defined redox-peaks, demonstrating the possible chloroaluminate ions doping/de-doping at the active electrode. Galvanostatic charge-discharge analysis of the cell yields high specific capacity of ~216mAh/g, retaining ~100% coulombic efficiency. The cells have shown excellent reversible cycling over different C-rates. XPS analysis of the cycled PTh/MWCNT electrode shows the existence of multi-polaron state associated with S from thiophene of polymer unit affirming the de/-doping chloroaluminate ions occurred. The positive prospect of PTh in its pristine or composite form defines a promising electrode material that deserves intensive study and further development.

Enhanced Sorption of Radionuclides by Defect-Rich Graphene Oxide.

Extremely defect graphene oxide (dGO) is proposed as an advanced sorbent for treatment of radioactive waste and contaminated natural waters. dGO prepared using a modified Hummers oxidation procedure, starting from reduced graphene oxide (rGO) as a precursor, shows significantly higher sorption of U(VI), Am(III), and Eu(III) than standard graphene oxides (GOs). Earlier studies revealed the mechanism of radionuclide sorption related to defects in GO sheets. Therefore, explosive thermal exfoliation of graphite oxide was used to prepare rGO with a large number of defects and holes. Defects and holes are additionally introduced by Hummers oxidation of rGO, thus providing an extremely defect-rich material. Analysis of characterization by XPS, TGA, and FTIR shows that dGO oxygen functionalization is predominantly related to defects, such as flake edges and edge atoms of holes, whereas standard GO exhibits oxygen functional groups mostly on the planar surface. The high abundance of defects in dGO results in a 15-fold increase in sorption capacity of U(VI) compared to that in standard Hummers GO. The improved sorption capacity of dGO is related to abundant carboxylic group attached hole edge atoms of GO flakes as revealed by synchrotron-based extended X-ray absorption fine structure (EXAFS) and high-energy resolution fluorescence detected X-ray absorption near edge structure (HERFD-XANES) spectroscopy.

Surface Oxidation of Nano-Silicon as a Method for Cycle Life Enhancement of Li-ion Active Materials.

Among the many studied Li-ion active materials, silicon presents the highest specific capacity, however it suffers from a great volume change during lithiation. In this work, we present two methods for the chemical modification of silicon nanoparticles. Both methods change the materials’ electrochemical characteristics. The combined XPS and SEM results show that the properties of the generated silicon oxide layer depend on the modification procedure employed. Electrochemical characterization reveals that the formed oxide layers show different susceptibility to electro-reduction during the first lithiation. The single step oxidation procedure resulted in a thin and very stable oxide that acts as an artificial SEI layer during electrode operation. The removal of the native oxide prior to further reactions resulted in a very thick oxide layer formation. The created oxide layers (both thin and thick) greatly suppress the effect of silicon volume changes, which significantly reduces electrode degradation during cycling. Both modification techniques are relatively straightforward and scalable to an industrial level. The proposed modified materials reveal great applicability prospects in next generation Li-ion batteries due to their high specific capacity and remarkable cycling stability.

Towards new routes to increase the electrocatalytic activity for oxygen reduction reaction of n-doped graphene nanofibers

A facile preparation of nitrogen doped graphene nanofibers (GNF) is required in order to promote an easy scalable method for the production of batteries using this material as catalyst support. In this work, two simple oxygen pretreatments were developed in order to maximize the nitrogen amount on the structure of the carbon nanomaterial. In that sense, a mild-term oxidation with acid and a high oxidative procedure using potassium permanganate were developed. After that, the two oxidized fibers and the raw ones were doped using a hydrothermal method which use 2-chlorethyl amine as nitrogen donor. All the materials have been deeply studied by SEM, RAMAN, FTIR, CHNS, Zeta potential, XRD, N2 adsorption-desorption and, TGA analysis. The characterization of the material showed that its structure after the treatments was more defective, significantly varying the surface area of the final material. After the hydrothermal treatment different amounts of N atoms (1.2–5.5%) were introduced in the structure depending on the oxidative treatment. The introduction of the nitrogen atoms increases the activity on oxygen reduction reaction (ORR) in almost all the cases, increasing further in the case of the GNF pretreated with acids which increase the electrochemical activity considerably.

Catalytic conversion of pure glycerol over an un-modified H-ZSM-5 zeolite to bio-based aromatics

The catalytic conversion of pure glycerol to bio-aromatics (bio-BTX) over an un-modified H-ZSM-5 (SiO2/Al2O3 molar ratio of 23) via an ex-situ catalytic pyrolysis approach in a continuous tandem-micro reactor at a scale of 1 g glycerol h−1 was investigated. A BTX peak carbon yield of 28.1 ± 0.2 % was obtained at a pyrolysis temperature of 400 °C, catalytic upgrading temperature of 500 °C, atmospheric pressure and a WHSV of 1 h−1. About 70 % of the bound oxygen in glycerol was converted to water. The latter was mainly formed in the catalytic upgrading unit (70 %), though conversion of glycerol to other oxygenates with water formation was also observed in the pyrolysis unit. Catalyst deactivation occurs at a time scale of hours and is mainly due to coke deposition (12.0 wt.%) on the catalyst surface. An oxidative regeneration procedure to remove coke was applied and 5 cycles of reaction-regeneration were performed successfully, though a drop in activity was observed after each cycle due to irreversible catalyst deactivation. Characterization of the fresh, deactivated and regenerated catalysts by various techniques revealed dealumination of the H-ZSM-5 framework and resulted in a dramatic decrease in Brønsted acidity of the catalyst. Dealumination mainly occurred in the catalytic upgrading reactor and to a by far lesser extent during catalyst regeneration. This information is relevant for a better understanding of the process on a molecular level but also for scale-up studies, e.g. for the design of pilot plants.

Microplastics in wastewater outlets of Bandar Abbas city (Iran): A potential point source of microplastics into the Persian Gulf

Wastewater discharge is considered to be a significant point source of microplastic (MPs) release into the marine environment. This study is the first attempt to quantify MPs released from the wastewater outfall from Bandar Abbas City into the Persian Gulf. Two wastewater discharge stations at Gursuzan and Suru were sampled. MPs were isolated by an oxidative procedure and subsequent density separation using ZnCl2 solution. The average MP concentration in wastewater and sludge were 70.66 (±14.12, SD) MP.35 L−1 and 6070 (±807.25) MPs.kg−1, respectively at Confidence Level (CL) (95.0%). The most commonly recovered polymers were polyethylene (PE) and polypropylene (PP) in all size classes. Our findings provides a baseline of MP concentration in wastewater streams and slurry that is discharged from the Bandar Abbas wastewater treatment facility into the Persian Gulf. This highlights the need to undertake more studies at water treatment plants in the region for a realistic assessment of MP discharge into the Persian Gulf.

Biomimetic anchoring of Fe3O4 onto Ti3C2 MXene for highly efficient removal of organic dyes by Fenton reaction

MXene has emerged as one of the most interest two-dimensional layered materials that has been extensively explored for various applications. In this work, a novel biomimetic method has been developed for the first time to fabricate Ti3C2 MXene based magnetic Fe3O4 composites that relied on the self-polymerization of dopamine and subsequent mild temperature pyrolysis. We demonstrated that many organic dyes could be rapidly degraded by the MXene-MNPs composites through Fenton reaction with extremely high efficiency. The degradation efficiency could be greater than 97 % under the optimized experimental conditions. Moreover, the catalysts displayed a good recyclable property after five continuous cycles. Electron paramagnetic resonance analysis and quenching results indicated that both OH and O2− were the reactive species and involved in the degradation process. Owing to the universality and mild reaction conditions of mussel-inspired biomimetic method, many other multifunctional composites with great research interest could also be fabricated. We also believe that this work will provide some new insights for fabrication of highly efficient catalysts for advanced oxidation processes and exploring the critical roles of polydopamine in advanced oxidation procedures.

Thermokinetic Model for the Formation and Oxidation of Carbon Nanoforms

A thermokinetic model for the formation and decomposition of layered carbon nanoforms (LCNFs) has been proposed. The model relies on the fundamental dependence of discrete temperature component in the CO (Boudouard–Meyer) disproportionation reaction. Reversible reduction–oxidation reactions for individual LCNFs superpose in the range 820–1070 K. The superposition of reaction package has two thermokinetic components: rapid (discrete) and slow (continuous). The rate vred/ox C of the continuous process is 10–8–10–7 mole/sec. The activation parameter Ea ox C of the first-order reaction (smoldering) has been determined as 35 ± 5 kJ/mole. The rate of rapid oxidation processes exponentially depends on temperature, and vred/ox C is 10–6–10–5 mole/sec in the range 1073–1473 K. The activation energies for oxidation (combustion) of most nanoforms are in the range ~173 ± 5 kJ/mole. The oxidation temperatures for carbon nanoforms have been found. The following carbon nanoforms are mainly synthesized or oxidized in a CO or oxygen atmosphere: nanoonions at 823 K, graphite nanoplatelets at 873 K, stacked nanofibers at 923 K, conical nanofibers at 973 K, coiled nanofibers at 1013 K, multiwall nanotubes at 1033 K, and single-wall nanotubes at 1173 K. Carbon polymerization is driven by free radicals. The polymerization is catalytically promoted by three types of primary paramagnetic carbon radicals with one to three free electrons. The concentrations of radicals represent superposed Gaussian curves on the promoter’s acceptor surface in the range 820–1070 K. Primary radicals give rise to three nanoforms: spherical, lamellar, and tubular. The reactions are reversible as a function of environment and temperature. When equilibrium precipitation of the LCNFs and ‘carbon sludge’ is achieved, the reaction package is eventually converted to a S-shaped curve similar to the temperature dependence of CO partial pressure. The chemical properties of nanoforms combine two topological interactions: peripheral hydrophilic and surface hydrophobic. The synthesis and up-stop-up oxidation procedures in the qualification and selective determination of carbon nanoforms in mixtures are discussed.

A suitable and effective stepwise oxidative refolding procedure for highly‐cationic tetrameric avidin in nucleic acid free conditions

Optimized conditions are needed to refold recombinant proteins from bacterial inclusion bodies into their biologically active conformations. In this study, we found two crucial requirements for efficient refolding of cationic tetrameric chicken avidin. The first step is to eliminate nucleic acid contaminants from the bacterial inclusion body. The electrostatic interactions between the remaining nucleic acids and proteins strongly enhanced protein aggregation during the refolding process. The cysteine specific reversible S-cationization procedure was successfully employed for large-scale preparation of nucleic acid free denatured protein without purification tag system. The second step is the intramolecular disulfide formation prior to refolding in dialysis removing denaturant. Disulfide intact monomeric avidin showed efficient formation of biologically active tetrameric conformation during the refolding process. Using this optimized refolding procedure, highly cationic avidin derivative designed as an intracellular delivery carrier of biotinylated protein was successfully prepared.

Laser-Induced Mesoporous Nickel Oxide as a Highly Sensitive Nonenzymatic Glucose Sensor

In this paper, we present a novel laser-induced oxidation procedure for in-situ formation of nickel oxide nanoporous structures directly onto the nickel surface as highly sensitive non-enzymatic gl...

Effect of particles addition to solution of plasma electrolytic oxidation (PEO) on the properties of PEO coatings formed on magnesium and its alloys: A review

Abstract The plasma electrolytic oxidation (PEO) procedure is utilized in order to amend the surface properties of Mg and its alloys. This procedure creates a ceramic coating on the surface applying high-voltage. The presence of deep pores and porosities in the surface that affect the corrosion resistance of the coatings is one of the PEO procedure limitations. One of the useful methods to decrease porosities of coating and improve its final properties is changing electrolyte conditions based on the presence of micro- and nanoparticles. The present paper reviews the mechanisms of particle adsorption and composition in PEO thin films in addition to the effect of particle addition on the microstructure, composition and corrosion behavior of coatings that were applied on magnesium alloys.

Amide Bond Formation Strategies: Latest Advances on a Dateless Transformation

The synthesis of amides remains one of the most important transformations and it is one of the more frequently performed reactions. In the pharmaceutical industry, the formation of the amide group is pivotal and among the more important transformations in the design of the synthetic plan. This review presents an overview of only very recent contributions, published in the last three years, to highlight the latest progress in this “dateless” reaction, with a special focus on metal‐free methodologies. New, more efficient and/or greener stoichiometric methods, as well as catalytic strategies, have been discussed, either for the “classic” coupling approach between an amine and a carboxylic acid (or its activated equivalent) or for more innovative approaches, mainly involving oxidation procedures to generate amides starting from amines.