Oxidation Method Research Articles

Selective SERS Detection of TATB Explosives Based on Hydroxy-Terminal Nanodiamond-Multilayer Graphene Substrate.

Selective surface-enhanced Raman scattering (SERS) detection of target explosives with good reproducibility is very important for monitoring soldiers' health and ecological environment. Here, the specific charge transfer pathway was constructed between a stable nanodiamond-multilayer graphene (MGD) film substrate and the target explosives. Two-step wet chemical oxidation methods of H2O2 (30%) and HNO3 (65%) solutions were used to regulate the terminal structure of MGD films. The experimental results showed that the hydroxyl (-OH) functional groups are successfully modified on the surface of MGD thin films, and the MGD-OH substrates having good selectivity for 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) explosive in mixed solutions of the TATB, 2,2-dinitroethene-1,1-diamine, 2,4,6-trinitrotoluene, and 1,3,5-trinitroperhydro-1,3,5-triazine explosives compared with MGD substrates were demonstrated. Finally, first-principles density functional theory simulations revealed that the SERS enhancement of the MGD-OH substrate is mainly attributed to the transferred electrons between the -NO2 groups of TATB and the -OH groups of the MGD-OH substrate.

Surface-Assisted Selective Air Oxidation of Phosphines Adsorbed on Activated Carbon.

Trialkyl- and triarylphosphines readily adsorb onto the surface of porous activated carbon (AC) even in the absence of solvents through van der Waals interactions between the lone electron pair and the AC surface. This process has been proven by solid-state NMR techniques. Subsequently, it is demonstrated that the AC enables the fast and selective oxidation of adsorbed phosphines to phosphine oxides at ambient temperature in air. In solution, trialkylphosphines are oxidized to a variety of P(V) species when exposed to the atmosphere, while neat or dissolved triarylphosphines cannot be oxidized with air. When the trialkyl- and triarylphosphines PnBu3 (1), PEt3, (2), PnOct3 (3), PMetBu2 (4), PCy3 (5), and PPh3 (6) are adsorbed in a mono- or submonolayer on the surface of AC, in the absence of a solvent and at ambient temperature, they are quantitatively oxidized to the adsorbed phosphine oxides, 1ox-6ox, once air is admitted. No formation of any unwanted P(V) side products or water adducts is observed. The phosphine oxides can then be recovered in good yields by washing them off of the AC. The oxidation is likely facilitated by a radical activation of molecular oxygen due to delocalized electrons on the aromatic surface coating of AC, as proven by ESR. This easy and inexpensive oxidation method renders hydrogen peroxide or other oxidizers unnecessary and is broadly applicable to sterically hindered and even to air-stable triarylphosphines. Phosphines adsorbed at lower surface coverages on AC oxidize at a faster rate. All oxidation reactions were monitored by solution- and solid-state NMR spectroscopy.

Tailoring Ni 3d orbitals in Ni-Fe/Ni foam heterostructures for enhanced H* adsorption and boosted electrocatalytic nitrate reduction performance

The electrochemical nitrate (NO3−) reduction (ENR) in wastewater, a promising remediation strategy, is often impeded by the essential use of costly noble metals. This study introduces an innovative non-noble Ni-Fe/Ni foam cathode fabricated via one-step electrodeposition technique. Efficient nitrate removal (99.4 %) was achieved with the selectivity of 83.6 % to NH3. The exceptional performance can be ascribed to the augmented active sites and the synergistic interaction between Ni and Fe. The leftward shift of the 3d orbitals density of Ni and the elevation of density at the Fermi level on Ni foam heterostructures, consequent to Fe doping, enhance the adsorption of H*. The addition of reactive chlorine species, generated through anodizing in Cl− mediated system, further improves N2 selectivity by oxidizing intermediate NH4+ product. The coupled anodic oxidation method employed herein achieves nearly 100 % removal efficiency of total nitrogen (TN) for initial concentration of 100 mg/L within 180 min, under the conditions of 1.5 g/L Cl− concentration and a current density of 25 mA cm−2. The findings underscore the potential of the Ni-Fe/Ni foam cathode within a Cl− mediated electrocatalytic framework for nitrate wastewater treatment, providing novel insights into the design of cathode catalysts and anodic coupling strategies for efficient TN removal.

Photocatalytic activity of polyaniline‐potassium doped nickel oxide nanocomposites: A comprehensive investigation on multifaceted properties

AbstractPolyaniline‐potassium doped nickel oxide nanocomposites (PANI/KNO) were efficiently synthesized via an in situ chemical oxidation method, meticulously confirmed by comprehensive x‐ray diffraction, Fourier transformation infrared spectroscopy, energy dispersive x‐ray spectroscopy, selected area electron diffraction, and x‐ray photoelectron spectroscopy analyses. The crystallite size and strain exhibited distinct behaviors, while field emission scanning electron microscopy revealed a blend of irregular spherical shapes and nanofibers, further confirmed by high resolution transmission electron microscopy. These composites exhibited significantly enhanced thermal stability, surpassing PANI by 1.39 times, and showcased a band gap exceeding 3 eV, along with multiple photoluminescence peaks at room temperature (RT). Moreover, their RT AC conductivity experienced a remarkable surge by 4.91 times compared to pure polyaniline. Jonscher's Power Law model and the Havriliak–Negami relaxation model are employed to elucidate the electrical properties of composite materials. The composites displayed nonDebye relaxation behavior with increased conductivity, as observed through impedance analysis, electrical modulus evaluation, and dielectric constant assessment. Additionally, evident superparamagnetic properties and multiple magnetic domains further contributed to their effectiveness. The PANI/KNO composite demonstrated photocatalytic efficiency, achieving over 90% degradation of methylene blue dye across four cycles, thus highlighting its superior photostability. Furthermore, investigations into its response to pH variations and scavenger activity underscored its immense potential for highly effective photocatalytic applications.

Recycling lithium-ion battery graphite: Synthesis of adsorbent materials for highly efficient removal of dye and metal ions from wastewater

The fate of residual graphite derived from hydrometallurgical treatment of spent Lithium-ion batteries remains uncertain. This study dwells on the aim of identifying the potentialities of recycling residual graphite for wastewater treatment. Graphite was recovered hydrometallurgically, and new adsorption materials: graphite oxide (GO) and graphene oxide (GrO) were synthesized from the residual graphite using the chemical oxidization method. Synthesized materials showed higher interlayer spacings (GO = 0.81 nm, GrO = 0.78 nm) than the commercially available similar materials. Adsorption studies revealed higher adsorption capacities for both dye (>550 mg/g in all cases) and metal ions (highest ∼93 mg/g for Ni2+ and lowest ∼68 mg/g for Zn2+). GrO showed superior results than GO due to its high surface area and porosity despite GO having more functional groups. Moreover, produced materials showed about 97 % removal of dye and about 94 % removal of contaminated metals which are higher performance than existing commercial or similar materials. These findings highlight the promising recycling capabilities of waste graphite and suggest its potential as a substitute for natural graphite.

Arc erosion resistance of Al2O3–Cu/35Mo composites reinforced by trace graphene oxide

In this study, Al2O3–Cu/35Mo composites were prepared by rapid hot-press sintering-internal oxidation method, and the materials were modified by adding trace amounts of graphene oxide (GO). The results show that the relative densities of the composites are above 99%, the γ-Al2O3 generated by internal oxidation is diffusely distributed on the copper matrix. The incorporation of GO produced a small number of hard MoC particles at the interface, which facilitated the interfacial bonding of the composites. In the 30 V DC, 10–30 A electrical contact test, the anode mass of the composites increases, while the cathode mass decreases. And GO reduces the total mass loss of the electric contact by 63.6%, 38.9%, 51.3% and 20.9%, respectively. A comparison of the electrical contact properties of the two materials showed that the addition of GO dispersed the concentrated erosion of the arc. At 10 A and 30 A, the arc energy is reduced by 75.5% and 12.5%, respectively. With the gradual increase in electric current, GO makes the Al2O3–Cu/35Mo composites more stable during the electric contact process, improves the anti-welding ability of the contact and reduces contact resistance.

Photocatalytic Removal of Emerging Contaminants from Water using Metal Oxide-based Nanoparticles

Abstract: Water contamination resulting from industrial and anthropogenic activities is a major problem in many countries throughout the world. Effective water treatment technologies are necessary to address this issue. Emerging pollutants (EPs) are reaching the aquatic environments from point and diffuse sources constantly. These are the substances that are not regularly monitored, yet have the potential to infiltrate the environment and harm the ecosystem and human health. Because of their ecological and sustainable properties, interest in improved photocatalytic technologies based on metal oxide-based nanomaterials has grown tremendously over the years to address this water contamination. Pollutant degradation, water splitting, carbon dioxide reduction, nitrogen reduction, and microbial inactivation are just a few of the applications of photocatalysis. However, to maintain its environmentally favourable status, new solutions must be found to assure long-term viability. Here we review, emerging organic pollutants, conventional water treatment, advanced oxidation methods, photocatalytic mechanisms, photocatalyst support materials, synthesis, and characterization of metal oxides and metal oxide nanoparticles in the removal of emerging contaminants. The purpose of this review is to reach a broader readership by giving a simple comprehension of the fundamentals and advances of metal-oxide-driven photocatalysis for environmental clean-up.

Effect of the pre-oxidation process on the surface properties of the Ti6Al4V and the wettability of sealing glass

Ti6Al4V is widely used in industrial fields due to its many excellent properties, but it still has the disadvantages of poor wear resistance. In order to broaden its application range, it needs to be connected with other materials with complementary properties. The method of sealing glass to connect dissimilar materials is widely used because of its low cost and low difficulty. In this study, Ti6Al4V was pre-oxidized by thermal oxidation method, and it was found that the oxidation temperature and holding time had a significant effect on the surface morphology and properties of the alloy. The wetting behavior between bismuthate sealing glass and Ti6Al4V under atmospheric conditions was investigated by sessile drop method. The effect of pre-oxidation temperature on the wettability of the alloy surface was studied by high temperature contact angle measuring instrument during the dynamic heating process. Combined with interface analysis, it was found that the sealing glass reacted with the Ti6Al4V alloy to form Bi4Ti3O12, and the reaction degree of Ti4+ and Bi3+ was the main reason for the wetting of the glass on the alloy surface. It was concluded that the higher the proportion of TiO2 on the surface, the better the wettability.

Effect of electric mode of micro-arc oxidation on structural and phase state of calcium-phosphate coating

The micro-arc oxidation method has been used to obtain calcium-phosphate coatings on titanium surface, expected to have bioactive properties. The effect of the pulse current duty cycle and voltage of micro-arc oxidation on the morphology, elemental and phase composition of the coating has been studied. Decrease in the pulse duty cycle during micro-arc oxidation results in the formation of flake, spheroidal and lamellar structures. It has been shown that the Ca/P ratio and surface roughness of the coating increases regardless of the pulse duty cycle with increase of applied voltage. Depending on the application mode, the Ca/P ratio and the roughness of calcium phosphate coatings ranged from 0.44 to 0.67 and from 4.2 to 6.8 μm, respectively. It was found that change of the pulse current duty cycle and increase of the voltage up to 600 V results in the formation of the main crystalline phases Ca(H2PO4)2(H2O) and CaPO3(OH) in the coatings.

Research and Development of Online Monitoring Protection Sensors for Paper Books Based on TiO2 NT/MoS2

NO2 is a prevalent environmental pollutant, and its reaction with water produces nitric acid, which is one of the main factors contributing to the degradation of books and paper. Therefore, it is crucial to develop a real-time monitoring system for NO2 gas content in the air and establish timely response measures to delay book aging and provide effective protection. In this study, TiO2 nanotubes (NTs) were fabricated using the anodic oxidation method, followed by the preparation of TiO2 NT/MoS2 composites through hydrothermal synthesis. It was observed that flaky MoS2 is attached to the surface of TiO2 nanotubes, forming aggregated structures resembling flower balls. The TiO2 NT/MoS2 nanocomposites were found to exhibit a rapid response with a 5 s response time and an 80 s recovery time towards 367 ppm NO2 at 260 °C. The gas response to 100 ppm NO2 vapor was 3.3, which is higher than all the other gases under the same concentration. Our experimental results demonstrate that compared to pure TiO2 NTs, TiO2 NT/MoS2 composites exhibit a larger specific surface area along with higher sensitivity and faster response times towards various concentrations of NO2 gas.

Exploring the potential of selective oxidation in bioconjugation of collagen with xyloglucan carboxylates

Xyloglucan (XG), as a natural biopolymer, possesses a sound biocompatibility and an impressive biodegradability, which are usually featured with abundant hydroxyl groups available for the bioconjugation with a bioactive moiety, suggesting a promising or unique value possibly applied in the field of biomedicine. In this study, XG was extracted from Tamarind seeds and subjected to four regioselective oxidation methods to introduce carboxyl groups onto the XG molecules for a bioconjugation with collagen. Galactose oxidase and reducing end aldehyde group oxidation mainly resulted in a low carboxylate content at ∼0.34 mmol/g, whereas the primary and secondary hydroxyl group oxidations would lead to a high carboxyl content at ∼0.84 mmol/g. The number-average molar mass (Mn) and weight-average molar mass (Mw) of XG were 8.8 × 105 g/mol and 1.1 × 106 g/mol, respectively. The oxidized XGs were then subjected to a further biofunctionalization with the collagen through EDC/NHS coupling, which exhibited a degree of conjugation rate, ranged from 50 % to 72 %. The collagen-conjugated at the C6 position of XGs exhibited the highest cell viability recorded at 168 % in promoting cell growth and proliferation after 72 h of culture, surpassing that of pure collagen recorded at 138 %, which may indeed suggest a promising value in a biomedical application.

Simulation of dimethyl ether production as LPG substitute using LNG from Arun terminal with tri-reforming and direct synthesis method

Increased demand for LNG compels Indonesia to import to meet these needs. Substituting LNG with alternative fuel emerges as a strategy to reduce LPG imports. One such alternative can be used for LPG substitution is Dimethyl Ether. Dimethyl ether is a colorless compound possesses a heating value of 30,5 MJ/kg and an energy equivalency with LPG ranging between 1,56 – 1,76. Dimethyl ether can be directly synthesized from synthetic gas produced through natural gas reforming. Production of synthetic gas from natural gas employs the tri-reforming method which integrating steam reforming, dry reforming, and partial oxidation methods in a single reactor offering optimal energy utilization advantages and minimal environmental impact. Dimethyl ether production from synthetic gas is using direct synthesis method, combining methanol synthesis and dehydration in a single reactor providing high conversion advantages compared to indirect synthesis method. Simulation was carried out using process simulator program ASPEN Plus V11. Based on the simulation results, dimethyl ether yield and selectivity is 99.62%.

Endogenous advanced oxidation process with peracetic acid for recycling spent LiFePO4 batteries

LiFePO4 batteries are becoming more widely used due to their low cost and high stability advantages, which means that many spent batteries are generated. Designing green and efficient recycling methods for used batteries is strategically significant for the sustainable development of the new energy industry. This study innovatively proposes a self-activated advanced oxidation process with peroxyacetic acid for recycling spent LiFePO4, selectively releasing Li+ while converting LiFePO4 to FePO4. Quenching tests show that the de-embedding of Li+ is mainly caused by the rapid attack from HO• and R-O• radicals. Furthermore, the recycled products Li2CO3 and FePO4 are employed to regenerate LiFePO4 cathode materials, forming a closed-loop recycling process. Compared with traditional hydrometallurgy and hydrogen peroxide oxidation methods, this technology has obvious advantages in terms of process complexity, energy consumption, reagent consumption, recovery profit, and environmental friendliness. This work opens up a new way for the recycling of spent lithium-ion batteries.

Interface interaction mediated surface plasmon resonance enhancement promoted visible-light-driven CO2 reduction with water

The conversion of carbon dioxide (CO2) into fuel using solar energy holds significant promise. However, the inefficient use of light and poor production activity have hindered its development. Here, we propose a simple in situ annealing oxidation method by coating a layer of TiO2 outside TiN, a material with a favorable price and localized surface plasmon resonance (LSPR) effect, to create an L-TiNO composite. The yield of CO over L-TiNO (50.8 μmol g−1 h−1) is 56.4 times that over TiO2 (0.9 μmol g−1 h−1) under visible light irradiation in pure aqueous environment, with a selectivity of 95.98%. In-situ Fourier transform infrared (FTIR) measurements reflect the CO2-COOH*-CO conversion route happening on L-TiNO. Characterizations like the Kelvin probe force microscopy (KPFM) technique confirm the generation of built-in electric field, which facilitates efficient carrier separation and migration. Density functional theory (DFT) calculations support that L-TiNO with LSPR effect alters the shape of absorbed CO2 to facilitate generation COOH* via forming hydroxyl end group (Ti-OH) and promotes CO* desorption to CO(g). This work provides valuable insights into the coupling of plasmonic materials with semiconductors to achieve efficient solar energy utilization.

Complete recovery of valuable metals from chlorinated titanium-white waste acids: Focus on solvent extraction for recovery and preparation of battery-grade manganese sulfate (MnSO4·H2O) from lab to pilot scale

Chlorination titanium-white waste acid (CTWA) is known to contain a substantial number of valuable metals, including Mn, which can be utilized in the manufacturing of high-value battery cathode materials. Based on the concept of complete resource recovery and zero pollution, a novel process for metal recovery from CTWA has been developed. D2EHPA was used to extract Sc, V from CTWA. Al was completely removed by slowly adding 1.5 mol/L NaOH until the solution pH reached 4.20 and stabilized for 0.5 h. This process resulted in a limited loss of 11 % for Fe and 5 % for Mn. An oxidative precipitation method was proposed to process the Al-free solution to preparate a pure and easily filterable FePO4 product, which can be used in the production of battery materials. Additionally, the loss of Mn in this process was less than 0.5 %. After removing Fe and Al, the pre-extraction feed has an O/A ratio of 2.5:1, a temperature of 40 °C, and an equilibrium pH of 4.5 ∼ 5.0, it is possible to extract Mn at over 99.50 % using a 5-stage extraction. The loaded phase is scrubbed with 5 g/L H2SO4, O/A = 5:1. It is then cyclically stripped with 75 g/L H2SO4, O/A = 8:1, to obtain a battery-grade MnSO4 solution. The stripped solution can be 100 % crystallized to obtain battery-grade MnSO4·H2O products after removing heavy metals using BaS and removing oil with activated carbon. The recovery of Mn in the extraction process was 97.59 %. The pilot test was conducted to demonstrate that the extraction process can be efficiently and continuously produced. The process achieved the recovery of valuable metals from CTWA and the preparation of corresponding products. This process is comprehensive and environmentally friendly, which has an industrial foundation.

Covalent vs. Non covalent chemical modification of multiwalled carbon nanotubes based-nanofluids: Stability and thermal conductivity steadiness over temperature

Thermal conductivity enhancement coupled to nanoparticle dispersion stability over time are the two main conflicting requirements to overcome to develop carbon nanomaterial-based nanofluids. Both covalent and non-covalent approaches, having their own advantages and disadvantages, are commonly used for carbon nanotube based nanofluids development. However, they are rarely compared regarding their impact on stability and thermal conductivity performances for the same kind of nanofluid. In this work, multiwalled carbon nanotubes have been chemically modified by both covalent and non-covalent functionalization. For the covalent functionalization, a simple oxidation method is applied. It consists of refluxing the powdered MWCNTs in H2SO4/HNO3 at 5 M concentration. For the non-covalent approach, both an anionic (sodium dodecyl sulfate) and a non-ionic (Pluronic P123, comprising poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) in an alternating linear fashion, PEO-PPO-PEO) surfactants were employed at a concentration of 1 wt%. Nanofluids were prepared with multiwalled carbon nanotubes at a fixed concentration of 0.2 wt% for both chemical modification approaches. The oxidation reaction occurs without significant structure damaging as shown by transmission electron microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. UV–visible spectrophotometry analysis shows a remarkable stability with temperature in the 293.15–303.15 K range over one-week and for a longer period of 49 days for all the three types of nanofluids. Their thermal conductivity has been investigated in the same temperature range. For all the three nanofluid series prepared with a fixed concentration of carbon nanomaterials, a thermal conductivity enhancement compared to that of the base fluid has been observed. The thermal conductivity evolution with temperature is different for each type of nanofluid. The covalently oxidized multiwalled carbon nanotube based nanofluids showed the better thermal conductivity enhancement steadiness (around 7 %) with temperature. The discussion on the surfactant-based nanofluid behavior proposes the possible involved mechanisms as temperature increases for each surfactant.

Innovative Application of Polyether Amine as a Recyclable Catalyst in Aerobic Thiophenol Oxidation

Polyether amines are versatile compounds characterized by a flexible structure, consisting of polyoxypropylene and polyoxyethylene as the backbone, with amine groups at each end. They have widespread applications in various industrial processes and daily life. Despite their versatility, the utilization of polyether amines as base catalysts is rare. In this study, one kind of three-arm polyether amine 1 was employed as an environmentally friendly, cost-effective catalyst for the aerobic oxidation of thiophenols, leading to the synthesis of disulfides. The oxidative coupling of thiols serves as a fundamental pathway for the production of disulfides, which are vital in both chemical and biological processes. In contrast to known methods for thiol oxidation, this polyether amine-based catalytic process eliminates the need for expensive stoichiometric oxidants and minimizes the formation of over-oxidized by-products. Using a mere 0.5 mol % of the polyether amine 1 as the catalyst, a remarkable > 96% yield was achieved for all 16 tested substrates, encompassing a diverse range of functional groups, under the catalytic aerobic oxidation conditions. Furthermore, it is noteworthy that over 90% of the polyether amine catalyst can be efficiently recovered for reuse without loss of activity, making this a sustainable and cost-effective catalytic approach.

Functional carbon nanoparticles modified poly(3,4-ethylenedioxythiophene) nanocomposites with enhanced dielectric and antibacterial properties

The importance of nanocomposites with tailored properties is growing due to their applications in various fields. In the present study, poly(3,4-ethylenedioxythiophene) (PEDOT) and functionalized carbon nanoparticles (f-CNPs) are synthesized by in-situ chemical oxidative polymerization and pyrolysis methods, respectively. The f-CNPs-PEDOT nanocomposites are prepared by varying the concentration of PEDOT (i.e., 1, 2.5, 5, 10, and 20 wt%), and the thermal stability, dielectric properties and antibacterial activities of f-CNPs-PEDOT nanocomposites were evaluated. The dielectric studies indicated that the addition of PEDOT has enhanced the dielectric properties due to interfacial polarization effect, whereas decreased the thermal stability due to degradation of PEDOT in the nanocomposite, however, it is higher than the pure PEDOT. The antimicrobial potential of synthesized f-CNPs-PEDOT nanocomposites was studied against two different bacterial strains, namely Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli. The findings of this research have potential to open new opportunities for employing f-CNPs-PEDOT nanocomposites in physical sciences and antimicrobial applications.

Research Progress in Preparation of Oxidized Cellulose

Cellulose is the most abundant natural polymer material in the world. Cellulose is difficult to dissolve because it contains a large number of inter molecular hydrogen bonds. Therefore, the modification of natural cellulose by chemical oxidation can expand its application field. The oxidation process of cellulose is focused on, the oxidation methods and research progress of cellulose are introduced, and further development direction of oxidized cellulose is prospected.

Synthesis of novel conducting triblock copolymer poly(thiophene-co-pyrrole-co-aniline) by chemical oxidative polymerization method for gas sensor application

The conducting triblock copolymer P(Th-co-Py-co-Ani) of thiophene (Th), pyrrole (Py), and aniline (Ani) has been synthesized by chemical oxidative polymerization method using anhydrous iron (III) chloride (FeCl3) as an oxidizing agent in presence of acetonitrile solvent at 0–8°C. Characterizations of the synthesized copolymer were performed by Attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectroscopy, powder X-ray diffraction analysis (PXRD), UV-Vis spectroscopy, elemental analysis (CHNS), Thermogravimetric analysis (TGA) and Scanning electron microscopy (SEM). Notably, UV-Vis spectroscopy revealed that triblock copolymers exhibit highly conjugated conducting polymer backbone, essential for its electrical conductivity and suitability for various applications. The prepared P(Th-co-Py-co-Ani) material was investigated for the gas sensing property of several gases such as ammonia, acetone, carbon monoxide, ethanol and methane. The gas sensing study revealed that P(Th-co-Py-co-Ani) demonstrates promising gas sensing capabilities, particularly at room temperature.