Oxidation Method Research Articles

Structure and magnetic properties of (Ni,Fe)Fe2O4 derived from nickel slag via molten oxidation

The large amount of nickel-iron resources in nickel slag urgently needs to be recycled. In this study, (Ni,Fe)Fe2O4 was prepared by phase reconstruction of the nickel slag by molten oxidation method. The thermodynamic conditions and feasibility of the formation of (Ni,Fe)Fe2O4 during molten oxidation were analyzed by combining thermodynamic calculation and experimental research. The influence of the different NiO contents on the cation distribution and magnetic properties of (Ni,Fe)Fe2O4 was analyzed. Additionally, the mechanism governing Ni incorporation within the (Ni,Fe)Fe2O4 lattice was elucidated. The results show that the sulfide phase and silicate phase of Fe and Ni in the nickel slag were finally transformed into (Ni,Fe)Fe2O4 phase, which was preferentially precipitated during the cooling process. (Ni,Fe)Fe2O4 is formed by the replacement of Fe2+ at the octahedral site in Fe3O4 by Ni2+. As more Fe2+ is replaced by Ni2+, (Ni,Fe)Fe2O4 solid solution exhibits high permeability and low coercivity. The recoveries of Fe and Ni are up to 77.89 % and 80.8 % via the molten oxidation process, respectively. This work not only provided a theoretical foundation for the preparation of (Ni,Fe)Fe2O4 by molten oxidation but also promoted the recovery of valuable metal resources in nickel slag.

Effects of Ta and Nb on high-temperature oxidation properties of Ti-6Al-3.5Sn-4Hf-0.4Si-X alloys

In previous studies, we identified Ta and Nb as the crucial elements affecting the high-temperature oxidation resistance of titanium alloys. To investigate their impact on microstructure evolution and oxidation resistance, we employed a constant temperature oxidation method at 700°C. The results demonstrate that Ta and Nb elements effectively inhibit oxygen diffusion and adsorption on the alloy surface, promote the formation of Al2O3 in the oxide film, and enhance its density. Notably, Ti-6Al-3.5Sn-4Hf-0.4Si-3Ta alloy exhibits exceptional antioxidation performance with an oxidation weight gain of only 0.4884 mg/cm2 after 100 hours of constant temperature oxidation at 700°C, an oxide film thickness of merely 1.047 μm, and a significant proportion (36.29 %) of O atoms combined with Al in the oxide film. The statement is in line with our previous computational findings and serves as a research foundation for the advancement of high-temperature titanium alloys.

One-step thermal oxidation synthesis of carbon-doped TiO2 with enhanced photocatalytic activity using CO2 as the carbon source

The study proposed a simplified carbon doping synthesis strategy to enhance the photocatalytic activity of titanium dioxide (TiO2). Utilizing CO2 gas as the carbon source, the material was directly synthesized onto a titanium substrate through a one-step thermal oxidation method. Raman and XPS analyses indicated that with the increase in CO2 partial pressure, the influence of the carbon source was amplified, resulting in carbon doping in a graphite-like structure and the induction of oxygen vacancies. Electrochemical impedance spectroscopy and UV–vis spectra demonstrated that the introduced carbon species acted as a photosensitizer, augmenting the transfer of photogenerated carriers. Photoluminescence spectra suggested that oxygen vacancies could enhance the non-radiative scattering of photogenerated carriers. These two effects synergistically improved the photocatalytic activity of TiO2 significantly, although the degree of enhancement was dependent on the optimized ratio of carbon content to oxygen vacancy content. Only with optimal carbon content and oxygen vacancy levels could the undesired radiative recombination of photogenerated carriers be prevented, ensuring that the energy derived from visible light was effectively utilized to drive chemical reactions. Under these optimal conditions, the TC-O5 and TC-O10 samples exhibited excellent photocatalytic degradation performance of methyl orange under visible light, with degradation rates of 86.27% and 82.54%, respectively, and displayed outstanding cycling stability, with the degradation rate remaining above 90% for three cycles. This method proved to be simple, efficient, and easily operable, offering significant advantages for industrial-scale preparation.

Supported nano-sized precious metal catalysts for oxidation of catalytic volatile organic compounds.

Volatile organic compounds (VOCs) are common contaminants found as indoor as well as outdoor pollutants, which can induce acute or chronic health hazards to the human physiological system. The catalytic oxidation method is widely considered as one of the effective methods for removing VOCs, and the development of highly effective catalysts is highly urgent for booming this interesting field. This review focuses on the recent progress of VOC oxidation catalyzed by supported nano-sized precious metal catalysts, and discusses the effects of metal composition, supports, size, and morphology on the catalytic activity. In addition, the roles played by both nano-sized precious metals and supports in enhancing the performance of catalytic VOCs are also systematically discussed, which will guide the further development of more advanced VOC catalysts.

Ultrafast Solid-Phase Oxidation of Aldehydes to Carboxylic Acids by Atmosphseric Plasma Treatment.

Although atmospheric plasma treatment is an industrially widespread, scalable, and environmentally friendly method, it has been generally used for surface modification, decontamination, or sterilization. In this paper, a novel, sustainable, green, and ultrafast oxidation method is described for aldehydes on a preparative thin-layer chromatographic plate as a solid support. The plasma treatment has proven to be suitable for producing the corresponding carboxylic acids by using only air as a reactant source under mild reaction conditions, while the isolation of the products is also directly integrated into the oxidation process. Extensibility to other reaction types is not explored yet, but we are sure that this novel synthesis conception carries a lot of possibilities.

An antifouling electrochemical biosensor based on oxidized bacterial cellulose and quaternized chitosan for reliable detection of involucrin in wound exudate

The monitoring of biomarkers in wound exudate is of great importance for wound care and treatment, and electrochemical biosensors with high sensitivity are potentially useful for this purpose. However, conventional electrochemical biosensors always suffer from severe biofouling when performed in the complex wound exudate. Herein, an antifouling electrochemical biosensor for the detection of involucrin in wound exudate was developed based on a wound dressing, oxidized bacterial cellulose (OxBC) and quaternized chitosan (QCS) composite hydrogel. The OxBC/QCS hydrogel was prepared using an in-situ chemical oxidation and physical blending method, and the proportion of OxBC and QCS was optimized to achieve electrical neutrality and enhanced hydrophilicity, therefore endowing the hydrogel with exceptional antifouling and antimicrobial properties. The involucrin antibody SY5 was covalently bound to the OxBC/QCS hydrogel to construct the biosensor, and it demonstrated a low limit of detection down to 0.45 pg mL−1 and a linear detection range from 1.0 pg mL−1 to 1.0 μg mL−1, and it was capable of detecting targets in wound exudate. Crucially, the unique antifouling and antimicrobial capability of the OxBC/QCS hydrogel not only extends its effective lifespan but also guarantees the sensing performance of the biosensor. The successful application of this wound dressing, OxBC/QCS hydrogel for involucrin detection in wound exudate demonstrates its promising potential in wound healing monitoring.

Dual-carbon isotope analysis of benzene polycarboxylic acids for tracking black carbon across different environments

Black carbon (BC) is ubiquitous in the environment and is a significant component of the refractory carbon pool. However, its sources, biogeochemical processes, and environmental residence times are poorly understood. One important reason is that the technical protocols for isolating/analyzing BC vary across different matrices, thereby bringing inconsistency among studies on BC in different environment media. Benzene polycarboxylic acids (BPCA), produced by nitric acid oxidation of the condensed aromatic structure that is common in BC and BC-like substances, has been proven to be a useful molecular proxy for tracking BC in the Earth's surface. Here, we introduce a new technical approach for the compound-specific dual-carbon isotope (δ13C and Δ14C) analysis of BPCA. The BPCA compounds are isolated using preparative liquid chromatography, in which trifluoroacetic acid is used in the mobile phase instead of phosphoric acid. This allows complete removal of solvent from the isolated BPCA fraction, so that conversion of BPCA isolates into CO2 can be done by conventional oxidation methods for off-line Δ14C analysis with accelerator mass spectrometry. Liquid chromatography (void column)-stable carbon isotope ratio mass spectrometry is employed to measure δ13C of the isolated BPCA, leaving as much BPCA carbon amount as possible for 14C analysis. Blockage of oxidation chamber due to incomplete oxidation of other organic acids in the samples is avoided thanks to preliminary isolation of BPCA. We tested the approach by applying it to solid and dissolved BC species in a suite of environmental reference materials, including maize char, coal, riverine natural organic matter (NOM 2R101N), marine sediment (SRM 1941b), urban dust (SRM 1649b), and coke-polluted soils. We assessed the offsets of BPCA-δ13C and BPCA-Δ14C values caused by procedural carbon contaminations to correct measured carbon isotopic values. Paired δ13C-Δ14C data of individual BPCA were plotted to validate and demonstrate the ability of this dual carbon isotope technique in tracking BC across different environmental matrices. We observed slightly different δ13C-Δ14C signatures among individual BPCA, indicating that the less condensed BC may have younger apparent radiocarbon ages.

Efficient Visible‐Light‐Driven Aromatic Alcohol Oxidation Using PI‐TiO2 Composite Photocatalyst

AbstractSynthesizing fine chemicals and valuable pharmaceutical intermediates through selective catalytic oxidation of alcohols is indispensable and crucial. However, the conventional methods of alcohol oxidation have inevitable drawbacks, including harsh reaction conditions and environmental pollution. Thus, it is imperative to develop efficient catalytic oxidation systems for alcohols. Herein, we successfully synthesized a 15 wt %PI‐TiO2 composite by a one‐step solid‐state heating polymerization technique. This catalyst exhibits excellent responsiveness to visible light and demonstrates remarkable catalytic activity. Furthermore, TEMPO was introduced as a cocatalyst to construct a PI‐TiO2/TEMPO/O2 system for the catalytic oxidation of alcohols. In comparison to the individual effects of PI or TiO2, this system showcases improved catalytic activity and broader substrate applicability. As a result, the conversion efficiency of benzyl alcohol increases by 3.44 times and 2.26 times, respectively. This research not only introduces a novel approach for preparing visible light‐active PI‐TiO2 catalysts but also indicates the significance of establishing an efficient electron transfer process in alcohol catalytic oxidation.

PTFE-g-GMA graft copolymer synthesis promoted by oxidative gamma-rays method and characterization

The functionalization of polymeric matrices through graft polymerization offers various advantages by providing new properties, allowing for additional chemical reactions that the matrix alone could not undergo or that would require drastic chemical conditions to occur. In this work, epoxy groups were incorporated through a graft polymer of poly(glycidyl methacrylate), using a prefunctionalization with peroxide groups in the polytetrafluoroethylene matrix through gamma radiation. These peroxide groups were subsequently used as radical chemical initiators in the graft polymerization reaction of glycidyl methacrylate. The graft polymerization reaction was studied based on the absorbed dose, monomer concentration, reaction time, and temperature.Graphical abstract

The Enhanced Photoluminescence Properties of Carbon Dots Derived from Glucose: The Effect of Natural Oxidation.

The investigation of the fluorescence mechanism of carbon dots (CDs) has attracted significant attention, particularly the role of the oxygen-containing groups. Dual-CDs exhibiting blue and green emissions are synthesized from glucose via a simple ultrasonic treatment, and the oxidation degree of the CDs is softly modified through a slow natural oxidation approach, which is in stark contrast to that aggressively altering CDs' surface configurations through chemical oxidation methods. It is interesting to find that the intensity of the blue fluorescence gradually increases, eventually becoming the dominant emission after prolonging the oxidation periods, with the quantum yield (QY) of the CDs being enhanced from ~0.61% to ~4.26%. Combining the microstructure characterizations, optical measurements, and ultrafiltration experiments, we hypothesize that the blue emission could be ascribed to the surface states induced by the C-O and C=O groups, while the green luminescence may originate from the deep energy levels associated with the O-C=O groups. The distinct emission states and energy distributions could result in the blue and the green luminescence exhibiting distinct excitation and emission behaviors. Our findings could provide new insights into the fluorescence mechanism of CDs.

Electrochemical Synthesis of Ferrate (VI): Factors Influencing Synthesis and Current Research Trends

Ferrate(VI) emerges as a multifaceted substance endowed with a substantial redox potential, showcasing considerable potential for utilization in realms such as battery materials and advancements in water treatment technologies. There are primarily three methods for preparing Ferrate(VI), including peroxide heating method, hypochlorite oxidation method and electrochemical synthesis method. This review centrally delves into the electrochemical synthesis of ferrate(VI), given its mild reaction conditions, emerges as a highly potent means to synthesize Ferrate(VI) with substantial potential for industrial applications.The intricacies of influencing factors, including anode materials, electrolyte composition, electrolyte additives, reaction temperature, current density, membranes (ion-exchange membranes), and reactor types, are meticulously detailed, all of which exert a discernible influence on the synthesis process. A comprehensive exposition of the current research landscape and prevailing trends in the electrochemical synthesis of ferrate(VI) is presented. However, the current discourse on the electrochemical synthesis of Ferrate(VI) remains insufficient. Addressing these issues not only demands the optimization of reaction conditions but also necessitates the exploration of novel methodologies. For instance, incorporating the contextual application of Ferrate(VI) and achieving in-situ synthesis for immediate utilization are pivotal directions for future research and development.

XPS analysis of molecular contamination and sp2 amorphous carbon on oxidized (100) diamond

The efficacy of oxygen (O) surface terminations on diamond is an important factor for the performance and stability for diamond-based quantum sensors and electronics. Given the wide breadth of O-termination techniques, it can be difficult to discern which method would yield the highest and most consistent O coverage. Furthermore, the interpretation of surface characterization techniques is complicated by surface morphology and purity, which if not accounted for will yield inconsistent determination of the oxygen coverage. We present a comprehensive approach to consistently prepare and analyze oxygen termination of surfaces on (100) single-crystalline diamond. We report on x-ray photoelectron spectroscopy (XPS) characterization of diamond surfaces treated with six oxidation methods that include various wet chemical oxidation techniques, photochemical oxidation with UV illumination, and steam oxidation using atomic layer deposition (ALD). Our analysis entails a rigorous XPS peak-fitting procedure for measuring the functionalization of O-terminated diamond. The findings herein have provided molecular-level insights on oxidized surfaces in (100) diamond, including the demonstration of clear correlation between the measured oxygen atomic percentage and the presence of molecular contaminants containing nitrogen, silicon, and sulfur. We also provide a comparison of the sp2 carbon content with the O1s atomic percentage and discern a correlation with the diamond samples treated with dry oxidation which eventually tapers off at a max O1s atomic percentage value of 7.09 ± 0.40%. Given these results, we conclude that the dry oxidation methods yield some of the highest oxygen amounts, with the ALD water vapor technique proving to be the cleanest technique out of all the oxidation methods explored in this work.

Enhanced Conductive and Optical Properties of TiO2/PANI Composites Synthesized by in-situ Chemical Oxidation Polymerization Route

Abstract Polyaniline titania composites have been investigated due to their unique chemical and physical properties. This study synthesized several PANI/TiO2 composites with different mol% of PANI using in-situ oxidative polymerization methods. TiO2 was obtained by coprecipitation methods. The functional group analysis carried out using Fourier transform Infrared reflectance, it was found that PAni/TiO2 had been successfully created, which was indicated by the absence of new peaks. Based on the results of measuring absorbance in the Ultraviolet-Visible wavelength, it was found that the composite material made had a wider absorption range compared to its constituents. The electrical conductivity of composites was shown to have a higher value than TiO2. From these results, it was found that the PANI/TiO2 composite material has greater photoactivity than TiO2.

Improved thermoelectric performance in polypyrrole/Cu2SnS3 composites

Polypyrrole (PPy) is a promising thermoelectric organic material due to low thermal conductivity, higher electrical conductivity, easy preparation and stability. However, its thermoelectric performance is limited by the intrinsic low Seebeck coefficient. In this paper, PPy/xCu2SnS3 (x = 0–5 wt%) composites with enhanced thermoelectric properties were prepared through chemical oxidation method using iron chloride (FeCl3) as oxidant and methyl orange (MO) as soft template. The obtained composites were investigated by X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Raman spectroscopy. The Cu2SnS3 increased the carrier density and electrical conductivity, meanwhile, thanks to the energy filtering effect and phonon scattering at the organic-inorganic interface of PPy and Cu2SnS3, the Seebeck coefficient increased and thermal conductivity decreased for PPy/ xCu2SnS3 (x > 0) composites. The highest electrical conductivity (74.571 S/cm) and Seebeck coefficient (11.165 μV/K) at 300 K were obtained from PPy/xCu2SnS3 (x = 1 wt%), resulting in a maximum figure of merit (ZT) of 1.646×10−3, which is 8.5 times higher than that of pure PPy.

Construction of Fe(III) Active Sites on Phenanthroline-Grafted g-C3N4: Reduced Work Function and Enhanced Intramolecular Charge Transfer for Efficient N2 Photofixation.

Photocatalytic nitrogen fixation is one of the important pathways for green and sustainable ammonia synthesis, but the extremely high bonding energy of the N≡N triple bond makes it difficult for conventional nitrogen fixation photocatalysts to directly activate and hydrogenate. Given this, we covalently grafted the phenanthroline unit onto graphitic carbon nitride nanosheets (CN) by the simple thermal oxidation method and complexed it with transition metal Fe3+ ions to obtain stable dispersed Fe active sites, which can significantly improve the photocatalytic activity. The Fe(III)-4-P-CN photocatalyst morphology consists of porous lamellar structures internally connected by nanowires. The special morphology of the catalysts gives them excellent nitrogen fixation performance, with an average NH3 yield of 492.9 μmol g-1 h-1, which is 6.5 times higher than that of the pristine CN, as well as better photocatalytic cycling stability. Comprehensive experiments and density-functional theory results show that Fe(III)-4-P-CN is more favorable than pristine CN for *N2 activation, effectively lowering the reaction energy barrier. Moreover, other byproducts (such as nitrate and H2O2) are also produced during the photocatalytic nitrogen fixation process, which also provides a new way for nitrogen-fixing photocatalysts to achieve multifunctional applications.

Synthesis and characterization of yttrium iron oxide/PPy nanocomposites for supercapacitor application by chemical oxidative polymerization method

ABSTRACT Polypyrrole (PPy)/Yttrium Iron oxide (YIG) nanocomposite was synthesized by the chemical oxidation polymerization method. Yttrium iron oxide is also known as iron yttrium oxide or yttrium iron garnet denoted as YIG (Y3Fe5O12). YIG is a familiar material among the rare earth garnets and is also commonly used in electronic devices. Fourier transform infrared (FT-IR) spectroscopy analysis reveals the strong interaction between PPy and YIG nanoparticles. The crystal structure for the PPy and PPy nanocomposites is observed by X-ray Diffraction (XRD) and the average crystalline size calculated by Scherrer’s formula for PPy/n-YIG is 27.47 nm. Surface morphology of the samples identified by scanning electron microscopy. Optical properties were studied by UV–Vis spectroscopy. From the 2-probe method, AC electrical conductivity for n-YIGPPy is found to be 1.05 × 10−5 S/cm, higher than that of the polypyrrole. The electrochemical performance of PPy and YIG/PPy nanocomposites was observed by cyclic voltammetry (CV). The combination of optical, electrical properties of YIG/PPy nanocomposites suits supercapacitor applications.

Development of Technology for the Bioleaching of Uranium in a Solution of Bacterial Immobilization

This study presents findings regarding the kinetics of ferrous iron oxidation in solution mediated by Acidithiobacillus ferrooxidans bacteria within a continuous-flow bioreactor employing diverse types of immobilizers. The objective is to augment the rate of ferrous iron oxidation in solutions utilizing an immobilizer for Acidithiobacillus ferrooxidans strains. Immobilization represents a promising avenue for enhancing the efficiency of Fe2⁺ oxidation via acidophilic ferrooxidizing bacteria, leading to a several-fold increase in oxidation rate. A comparative analysis was conducted to evaluate the efficacy of different types of immobilizer in facilitating iron oxidation within a continuous-flow bioreactor, including the application of wood chips coated with Fe(OH)3. The results indicate that wood chips coated with iron hydroxide serve as effective type of immobilizer, facilitating the robust attachment of Acidithiobacillus ferrooxidans via electrostatic interactions between negatively charged bacteria and positively charged surfaces. Experimental investigations were conducted using novel immobilization matrices in pilot-scale tests simulating the underground borehole leaching (UBL) of uranium. The bioactivation of leaching solutions enhances the efficiency and environmental compatibility of UBL compared to conventional chemical oxidation methods. The relationships between redox potential and ferric iron content in bioactivated solutions during the UBL of uranium were delineated. The significance of this study lies in its elucidating the pivotal role of Fe2⁺ oxidation in uranium extraction processes, particularly in the context of UBL. By employing bioactivation mediated by Acidithiobacillus ferrooxidans, the study demonstrates not only enhanced uranium extraction efficiency, but also markedly improved environmental sustainability compared to traditional chemical oxidation methods. The findings reveal crucial correlations between redox potential and ferric iron concentration in bioactivated solutions.

Adhesion and Cohesion of Three-Dimensional Porous Calcium Phosphate Coatings on Titanium Deposited by Ultrasound-Assisted Micro-Arc Oxidation Method

Adhesion and Cohesion of Three-Dimensional Porous Calcium Phosphate Coatings on Titanium Deposited by Ultrasound-Assisted Micro-Arc Oxidation Method

Tailoring the selective generation of oxidative organic radicals for toxic-by-product-free water decontamination

Peracetic acid (PAA) is emerging as a versatile agent for generating long-lived and selectively oxidative organic radicals (R-O•). Currently, the conventional transition metal-based activation strategies still suffer from metal ion leaching, undesirable by-products formation, and uncontrolled reactive species production. To address these challenges, we present a method employing BiOI with a unique electron structure as a PAA activator, thereby predominantly generating CH3C(O)O• radicals. The specificity of CH3C(O)O• generation ensured the superior performance of the BiOI/PAA system across a wide pH range (2.0 to 11.0), even in the presence of complex interfering substances such as humic acids, chloride ions, bicarbonate ions, and real-world water matrices. Unlike conventional catalytic oxidative methods, the BiOI/PAA system degrades sulfonamides without producing any toxic by-products. Our findings demonstrate the advantages of CH3C(O)O• in water decontamination and pave the way for the development of eco-friendly water decontaminations based on organic peroxides.

Polyaniline/titanium phosphate as a biosensor detection of glucose performance

In this study, we have prepared titanium phosphate (TiPO4) by photolysis-hydrothermal method, and then incorporated it with polyaniline (PANI) by oxidative polymerization method. FTIR, XRD and XPS confirmed the formation of nanocomposite. TGA analysis were also carried out for thermal stability characterization. The TiPO4/PANI nanocomposite has been employed as a biosensor for glucose disclosure via immobilization with glucose oxidase enzyme. Amperometry, cyclic voltammetry (CVs) and chemical impedance (EIS) were carried out for sensing of glucose. The linear range of glucose detection was noted from 20 to 100 μM by using amperometric analysis, and the LOD was found to be 5.44 μM.