Reagent For Oxidation Research Articles

Challenges in Raman Spectroscopy of (micro)Plastics: The interfering role of colourants

Rising plastic consumption leads to widespread microplastic (MP) contamination. Raman spectroscopy is widely used for MP identification due to its ability to analyse particles as small as 1 μm. However, it faces challenges such as interference from pigments and additives. In this study, we aim to assess the accuracy of Raman micro-spectroscopy in identifying coloured plastic samples by applying various oxidative treatments to eliminate the possible interference effect caused by colourants associated with the sample. Standard and coloured microplastics were analysed using a Raman imaging microscope. Coloured plastics were treated with H2O2 30%, Sodium hypochlorite 5%, and Fenton reagent ( H2O2 30% and Ferrous sulphate 0.2 M) for 24, 48, and 72 hours. The Raman spectra were acquired after treatment to assess the impact of the treatment procedure on the polymer identification. Our results revealed that colourants significantly impact Raman spectra by peak broadening and/or fluorescence effects, which reduces identification accuracy and match scores Red pigments particularly obscure polymer identification. Treatments like oxidation and Fenton's reagent showed limited effectiveness. Additives in plastic samples can affect the accuracy of polymer identification by the Raman spectroscopy technique. Common treatment procedures do not improve the accuracy of identification. In order to improve the reliability of Raman analysis, essential factors such as utilizing multiple excitation lasers and appropriate CCD detectors, establishing a comprehensive reference library of colourants and additives, and employing advanced techniques like time-gated Raman spectroscopy or Surface-Enhanced Raman Spectroscopy (SERS) should be considered.

Extraction of gold from gravity-flotation concentrates via surfactant and oxidation reagents

The focus of this work is to establish a hydrometallurgical technique for efficiently extracting gold from the aggregated gold-rich concentrate produced by a mining facility in one of Kazakhstan's deposits. The leaching techniques applied to gravity-flotation concentrates include hydrometallurgical gold recovery processes using the surfactant sulfanol and the oxidizing reagent trichloroisocyanuric acid (TCCA). The findings indicate the effectiveness of leaching gravity-flotation concentrates with oxidizing (accelerating) reagents. Gold extraction through cyanidation of the blended concentrate, ground to 89–90% passing 10 µm with TCCA, averaged 84.0%, compared to 65.76–67.8% with conventional direct cyanidation. The advantage of employing chlorine-based oxidants, such as TCCA, in hydrometallurgical processing lies in their applicability in both acidic and alkaline environments, whereas other oxidants are constrained by specific technological conditions. Technical trichloroisocyanuric acid (TCCA), a chlorine-containing oxidizer with the formula C3O3N3Cl3, containing 25–30% calcium hypochlorite as an impurity, proved to be the most effective in enhancing gold leaching techniques. Apart from improving the efficiency of the leaching process, the use of TCCA is economically viable. The wholesale cost of technical TCCA is ~ $700 per ton, significantly lower than many other oxidants commonly used in gold hydrometallurgical production. With its higher active chlorine content, TCCA consumption per ton of gold-bearing raw material is nearly half that of hypochlorite or peroxide. Additionally, TCCA use minimizes the formation of unwanted impurities in both the pulp and the productive solution.

A Multicomponent [2+2+1] Cascade Cyclization to Synthesize Thiazol-2(3H)-one.

A multicomponent [2+2+1] tandem cyclization of alkynones with amines and water using potassium thiocyanate as electrolyte and raw material to access thiazol-2(3H)-ones has been developed. This transformation proceeded smoothly via electrocatalytic oxidative C-H bond thiolation, and nucleophilic cascade cyclization to build the (C-S/C-N) bonds to construct the C-O bond. The reaction avoided using transition metal catalysts or oxidation reagents, making it more sustainable and renewable.

Visible-Light-Driven Method for the Selective Synthesis of Amides and N-Acylureas from Carboxylic Acids and Thioureas.

In this work, we developed a visible-light-driven method for the selective synthesis of amides and N-acylureas from carboxylic acids and thioureas. This protocol was featured as avoidance of additional oxidants and transition metal catalysts, simple manipulations, low cost, broad substrate scope, and good functional group tolerance. As only oxygen serves as the oxidation reagent, this method provides a promising synthesis candidate for the formation of N-aryl amides and N-acylureas, including late-stage functionalization of complex pharmaceutical molecules and biologically active molecules.

High-efficiency electrospun PVDF@MXene composite membrane with covalent bonding and well-dispersed internal materials for solar-driven seawater desalination

Environmentally friendly and efficient solar-driven interfacial evaporation (SDIE) has been increasingly applied to seawater desalination, and the easy-to-operate electrospinning technology has attracted more and more attention. However, photothermal materials such as MXene are often combined with polymers suitable for spinning through ordinary blending. The inherent difficult dispersion of it may lead to the instability of spinning and decrease the performance of evaporators, further hindering their production and application. To address these challenges, this work designs a covalent bonding PVDF@MXene composite as the spinning raw material. Using the electrospinning technology, the high-efficiency membrane-based evaporator with well-dispersed internal materials and strong homogeneity is successfully fabricated. The membrane performance is optimal when the MXene content is 25 %, achieving an evaporation rate of 1.88 kg·m−2·h−1 and an efficiency of 94.06 % under one sun. Besides, it exhibits remarkable salt resistance, maintaining an evaporation rate of 1.81 kg·m−2·h−1 even at the salinity of up to 20 wt%. More importantly, the membrane can be immersed in oxidative reagents for 24 h without degradation or reduced performance, demonstrating its good environmental stability. Overall, this research not only provides a rational idea for addressing the dispersion issue of MXene, but also presents a potential solution to deal with the global freshwater shortage emergency.

Continuous oxidation of organic contaminates in soil by polylactic acid-coated KMnO4

Potassium permanganate (KMnO4), as a versatile and safe solid source of MnO4-, received substantial attention from researchers as a potential soil oxidant reagent. In this study, we prepared polylactic acid (PLA)-coated KMnO4 (KMnO4@PLA) to control MnO4- release. The experimental results indicated that the optimal preparation scheme for KMnO4@PLA was a particle size of 1–2 mm, a solid-liquid ratio of 1:3, and a core-shell ratio of 1:3. And the release lifetimes of MnO4- from KMnO4@PLA in aqueous and quartz sand media were 200 hours and 310 hours, respectively, which were 2400 and 33 times longer than the release lifetimes of raw KMnO4. The controlled release of MnO4- from KMnO4@PLA was achieved through the hydrolysis of PLA. And the release process adhered to first-order reaction kinetics and displayed Fickian diffusion characteristics. Moreover, the removal of phenol by KMnO4@PLA in aqueous, quartz sand, and soil media were investigated through batch and flow column experiments. Compared with the raw KMnO4, the KMnO4@PLA exhibited a stronger ability to degrade phenol, due to the mildly acidic nature of the PLA shell. These findings demonstrated that KMnO4@PLA has significant advantages for the remediation of organically contaminated soils.

Recent Development on the Heterocycles Derived From In Situ Formation of Aryl Glyoxals by Iodine/DMSO Mediated Oxidation of Methyl Ketones

ABSTRACTControlled oxidation of methyl‐ketones to aryl glyoxals using Selenium dioxide and iodine is one of the useful transformation. Regardless the availability of many oxidation reagents, Iodine/DMSO system is very efficient and flexible. This system efficiently allows in situ formation of α‐halo ketones and subsequently transforming them directly to useful products. The Iodine/DMSO system allows the selective CI and CO bond formation, substantially useful for converting them to other bond forming reactions and heterocycles useful in the synthetic and medicinal chemistry. Iodine/DMSO system could be an important alternative strategy due to sustainability, metal‐free conditions, allowing multiple/linear domino reactions. This review will focus on heterocyclic systems smartly developed/manipulated by Wu group from methyl‐ketones. The scope and limitations of this method and selected examples of applications for the synthesis of interesting molecules are discussed herein.

Using CO2 in pyrolysis to neutralise toxic aromatic compounds derived from blended textile waste

Blended textiles are favoured for their enhanced properties, combining the strengths of constituent fibres (typically synthetic fibres integrated with natural cellulosic fibres). However, the presence of aromatic components in blended textile waste (BTW) complicates its disposal and raises environmental concerns due to the release of toxic chemicals. To resolve this issue, this study suggests a pyrolysis system as a strategy to neutralise toxic aromatic compounds derived from BTW. Carbon dioxide (CO2) was used as the partial oxidative reagent. The characterisation of BTW revealed its composition, containing rayon and polyester. The complex composition of BTW, particularly the recalcitrant nature of polyester, leads to the massive generation of toxic aromatic chemicals, such as terephthalic acid and its analogues, during thermolysis. However, introducing CO2 to pyrolysis facilitates interacting with these toxic compounds, converting them into carbon monoxide (CO). The effectiveness of CO2 for the suppression of toxic aromatic formations was further enhanced when adopting a nickel-based catalyst. CO2-assisted catalytic pyrolysis achieved a 64.87 % reduction in toxic aromatic chemicals and an 11.36-fold increase in CO production compared with conventional pyrolysis. This study presents a promising approach for the sustainable disposal of BTW, emphasising the oxidative functionality of CO2 in neutralising toxic aromatic chemicals into detoxified products, especially CO.

Polycyclic aromatic hydrocarbons (PAHs) in crude oil-contaminated water and soil and their removal using locally available plant materials

ABSTRACT The presence of polycyclic aromatic hydrocarbons (PAHs) in water and soil can be harmful to human life when ingested. PAHs are determined in the water and soil of the B-Dere community of Rivers State, Nigeria. The concentration level, source identification, and treatment were carried out. The water samples were treated with garlic and Moringa seed extracts, while the soil samples were treated with garlic and Fenton oxidation reagents. PAHs were extracted before and after treatment. The gas chromatograph mass spectrometer analyses showed 13 PAHs in the water and 10 PAHs in the soil. The highest concentration in water was recorded for benzo(ghi)perylene, with a mean value of 27.7 ± 0.25 ngL−1, while that of soil was recorded for benz(a)anthracene, with a mean value of 14.4 ± 0.631 ngkg−1. The source of PAHs in water was pyrogenic, while that of soil was petrogenic. Garlic extract removed 100% of benz(a)anthracene and benzo(b)fluorothane from the water, while Moringa removed 100% biphenylene from the water. However, garlic extract removed 2.59% of acenaphthylene, while Fenton reagents removed 100% of anthracene, phenathrene, and chrysene from the soil. Moringa seed and garlic extracts can be used in PAH's polluted water treatment.

CATALYTIC OXIDATION OF AROMATIC ALDEHYDES TO CARBOXYLIC ACIDS IN MILD CONDITIONS WITH NaClO2

This study aimed to improve the conditions for the oxidation of benzaldehyde to benzoic acid using chlorine dioxide generated from sodium chlorite, across various pH ranges and different catalysts. The powerful oxidation capability of chlorine dioxide played a crucial role in enhancing the kinetic efficiency of the reactions. In our research, we examined various reaction conditions, including sodium dihydrogen phosphate, sodium dihydrogen phosphate together with sodium chlorite, sodium dihydrogen phosphate combined with sodium chlorite and potassium permanganate, and sodium dihydrogen phosphate with sodium chlorite and V2O5. Additionally, different oxidation combinations were tested, such as sodium chlorite with sodium tripolyphosphate (STPP), 1-hydroxyethylidene-1,1-diphosphonic acid (HEDP), and formic acid, as well. The stabilized chlorine dioxide solution was also used directly as an oxidation reagent. The role of chlorine dioxide in these combinations significantly impacted the selectivity and yield in terms of product. Furthermore, some Mn (III) complexes (Cat.1 and Cat.2) were used as catalysts in this study, and the findings revealed that chlorine dioxide is an effective oxidant in the selective oxidation of aromatic aldehydes to aromatic acids. For the catalytic application in buffer solutions, a leveling effect was observed. When Mn (III) complexes were used, it showed a similar leveling effect in buffer solutions with a pH >1, which was resulting in slow ClO₂ formation. With these findings it was found that the use of Mn (III) complexes in NaH2PO4+NaClO2 combination provided the highest yield in the oxidation of aromatic aldehydes to acids. These results underscore the importance of chlorine dioxide as a powerful oxidant in chemical transformation processes.

I2/CAN as an efficient reagent for the direct oxidation of tertiary Csp3-H to Csp3-OH: Synthesis of bis(N-methyl-7-azaindol-3-yl) (phenyl) methanol from 3,3′-(phenyl methylene)-bis(N-methyl-7-azaindole)

I2/CAN has emerged as a powerful and efficient oxidizing agent for direct tertiary CH oxidation of 3,3′-(phenyl methylene) bis(N-methyl-7-azaindole) under mild conditions to form bis(N-methyl-7-azaindol-3-yl) (phenyl)methanol in quantitative yield. Further, based on control experiments, a plausible mechanism and characterization of products including XRD are described. Synthetic transformation for bis(N-methyl-7-azaindol-3-yl) (phenyl) methanol is achieved by thionation.

Synergetic recycling of permanent magnet and Li-ion battery cathode material for metals recovery

Rare earth elements (REEs)-based (NdFeB) magnets and lithium−ion batteries (LIBs) are critical for a low−carbon economy. Their production depends on critical elements like REEs, Li, Co and Ni. Recycling of these products have been explored separately as a potential solution. Conventional methods for recycling NdFeB magnets and LIBs face challenges like high energy consumption, lengthy processing, excessive reagent usage, and waste generation. In this study, a novel synergetic recycling methodology is proposed to minimize these challenges. The idea is based on using waste ferrous sulfate solution generated during magnet leaching as a reducing and leaching reagent for battery recycling thereby eliminating the need for additional reagents for oxidation of iron in NdFeB and reduction of cathode material in LIBs. The magnet is leached in diluted H2SO4 at 70 °C followed by double sulfate precipitation for REEs with Na2SO4. The REE-depleted but acidic ferrous solution is then used for reductive leaching of cathode material at 90 °C. The overall recovery rates of REEs, Li, Co, Ni, and Mn in this process are >95%. The iron from magnet material is recovered as crystalline and easily-filterable iron compound that can be converted to goethite and used as a byproduct. This synergetic approach not only reduces reagent consumption and waste generation aligning with the principles of circular economy but also offers improved efficiency, resource conservation, and environmental sustainability.

Catalytic Hydroxyethylation of Phenols with Renewable Ethylene Glycol Diester as an Alternative to Ethylene Oxide

AbstractPolyol esters are abundant bio‐based resources. Integration of polyol esters into the production chain of fine chemicals would reduce carbon emissions and improve the sustainability of the chemical industry. An efficient synthetic route to phenoxyethanols was developed through catalytic hydroxyethylation of phenols with ethylene glycol diacetate as the reagent. This method showed the potential of ethylene glycol diester as a safe and sustainable substitute for ethylene oxide, a useful but toxic reagent. A variety of phenoxyethanol esters were produced in high yield under simple catalytic conditions. Mechanistic studies revealed that the reaction underwent a neighboring group participation process.

A Low-Cost Ecofriendly Oxidation Process to Manufacture High-Performance Polymeric Biosurfactants Derived from Municipal Biowaste.

Biosurfactants account for about 12% of the global value of the surfactant market, which is currently dominated by synthetic surfactants obtained from fossil sources. Yet, the production of biosurfactants from renewable feedstock is bound to increase, driven by the increasing pressure from both society and governments for chemistry-based industries to become more ecofriendly and economically sustainable. A photo-chemical oxidation process is reported here, yielding new biosurfactants from urban biowaste in water that perform as a solvent and terminal oxidant reagent at room temperature without the addition of conventional oxidants and catalysts. Products with 200-500 kDa molecular weight are obtained. They lower the surface tension of water down to 34 mN/m at 0.5-2 g/L concentration. The estimated cost is rather low (0.1-1.5 EUR/kg), which is competitive with the cost of synthetic surfactants but much lower than the cost of the best-performing bacterial surfactants. For the implementation of the photo-chemical oxidation process at the industrial level, the results suggest that the new biosurfactants obtained in the present work may not reach the performance level of the best-performing bacterial surfactants capable of lowering the surface tension of water down to 28 mN/m. Yet, the biosurfactants produced by the photo-chemical process have a greater chance of being marketed on large scales.

Poly-3,4-dihydroxybenzylidenhydrazine, a different analogue of polydopamine

Abstract In this article, 3,4-dihydroybenzylidenehydrazine is synthesized for the first time, and its properties as a dopamine analogue for polymerization are investigated. Using an oxidative polymerization reaction, the reaction mechanism as well as the coating ability of the new polymer is determined and compared to that of polydopamine. The polymerization reactions were performed in a mixture of methanol–water with NaIO4 as an oxidation reagent. The polymer was used as a coating on both glass surfaces with a thickness of ∼5 nm as determined by AFM, as well as on TiO2 nanoparticles. For the latter, SEM/TEM and the pH-dependent variation of zeta potential were measured. As a free polymer, poly-3,4-dihydroxybenzylidenhydrazine was investigated by UV-Vis, ss-NMR, and FTIR, and a variety of monomeric units were found in the polymer matrix. The solubility in methanol or DMSO of the monomer and the slight solubility of the polymer allowed us to study the fluorescence and cyclic voltammetry properties for both the monomer and polymer.

Manganese(III) Nitrate Complexes as Bench-Stable Powerful Oxidants.

We report herein a convenient one-pot synthesis for the shelf-stable molecular complex [Mn(NO3)3(OPPh3)2] (2) and describe the properties that make it a powerful and selective one-electron oxidation (deelectronation) reagent. 2 has a high reduction potential of 1.02 V versus ferrocene (MeCN) (1.65 vs normal hydrogen electrode), which is one the highest known among readily available redox agents used in chemical synthesis. 2 exhibits stability toward air in the solid state, can be handled with relative ease, and is soluble in most common laboratory solvents such as MeCN, dichloromethane, and fluorobenzene. 2 is substitutionally labile with respect to the coordinated (pseudo)halide ions enabling the synthesis of other new Mn(III) nitrato complexes also with high reduction potentials ranging from 0.6 to 1.0 V versus ferrocene.

(Diazomethyl)dimethylphosphine Oxide - A Diazoalkane Reagent for [3+2] Cycloadditions.

A safe and efficient method for the in-situ preparation of (diazomethyl)dimethylphosphine oxide - a hereto unexplored diazoalkane reagent - is developed. The method is based on the diazotization of the corresponding P(O)Me2-substituted amine (readily available in multigram quantities) in non-aqueous media. The protocol provides the target product as ca. 1.5 M CHCl3 solution which is stable at -18 °C. The utility of the synthesized diazoalkane is illustrated by its [3+2] cycloaddition with electron-poor alkynes and alkenes providing the corresponding P(O)Me2-substituted pyrazoles and pyrazolines with moderate to good efficiency. In this view, the title compound represents and an important extension of medicinally relevant phosphine oxide reagents.

Oxidative cyclization reagents reveal tryptophan cation-π interactions.

Methods for selective covalent modification of amino acids on proteins can enable a diverse array of applications, spanning probes and modulators of protein function to proteomics1-3. Owing to their high nucleophilicity, cysteine and lysine residues are the most common points of attachment for protein bioconjugation chemistry through acid-base reactivity3,4. Here we report a redox-based strategy for bioconjugation of tryptophan, the rarest amino acid, using oxaziridine reagents that mimic oxidative cyclization reactions in indole-based alkaloid biosynthetic pathways to achieve highly efficient and specific tryptophan labelling. We establish the broad use of this method, termed tryptophan chemical ligation by cyclization (Trp-CLiC), for selectively appending payloads to tryptophan residues on peptides and proteins with reaction rates that rival traditional click reactions and enabling global profiling of hyper-reactive tryptophan sites across whole proteomes. Notably, these reagents reveal a systematic map of tryptophan residues thatparticipate in cation-π interactions, including functional sites that can regulate protein-mediated phase-separation processes.

The effect of the significant acid and alkaline environment and oxidation agent on the microplastic integrity

The research examined the ability of each treatment to recover a known quantity of particles and the impact on identifying polymer type using a microscope. By conducting extensive research on the changes induced in the chemical structures and morphologies of microplastics (MPs) there is potential for enhancing the detection and analysis of MPs by incorporating pre-treatment methods in the future. When treating environmental matrices with high organic content, chemical digestion treatment is required to get rid of microplastics and release particles. This type of treatment involves using a range of chemical agents, including acids, bases, and oxidizing agents. Unfortunately, there has been limited research into the chemical resistance of various types of microplastics to these substances. To address this issue, a study was conducted to examine the chemical resistance of four species of microplastics high-density polyethylene (HD-PE), low-density polyethylene (LD-PE), polypropylene (PP) and polyethylene terephthalate (PET) to hydrogen peroxide (H2O2), potassium hydroxide (KOH), nitric acid (HNO3) and acetic acid (CH3COOH). The results showed that acidic and alkaline substances were the most destructive to microplastics, while oxidative reagents resulted in fewer changes to plastic properties. These findings provide valuable insights into the properties of MPs and their response to strong acids, bases and oxidizing agents, which can serve as a reference for future studies on MP pre-treatment. In addition, used as a guideline to update current protocols and ensure that microplastics can be treated without causing damage.

Reduction of Irreversible Capacity in Lithium-ion Batteries

This article is focused on a research of negative materials for Lithium-ion batteries. In the research are considered methods, which can lead to enhance capacity of Lithium-ion batteries. The increase of the battery capacity is based on reduction of irreversible capacity. The majority of Li-ion batteries which are used in this time has negative electrode make from graphite. On interface between electrolyte and graphite electrode originates the SEI layer (Solid-Electrolyte Interphase), this layer is the cause of irreversible capacity of graphite. This layer is indispensable for appropriate battery function but for creating this layer is consumed almost one-third potential capacity of Li-ion cell. In our research we attempted to prepare the material which would reduce these capacity losses. Was designed a concept where n-butyllithium (C4H9Li) reagent behaves as the source of lithium atoms and graphite acts like acceptor of lithium atoms. This process is called „lithiation“, our conception presents n-butyllithium like oxidative reagent which is able to reduce graphite material by Li atoms. Lithium atoms are intercalated between graphite sheets (as at charging process), resulting of this process is new lithiated electrode material which can be used for prepare of negative electrode for Li-ion cells.