Hydrogen Peroxide In Aqueous Medium Research Articles

Synthesis and Characterization of MCM-41 Nanomaterials Containing Titanium and Application for Catalytic Oxidation of BTEX

The TiO<sub>2</sub>/MCM-41 nanomaterials were synthesized by impregnation with an excess solvent with different percentages of titanium dioxide. They were used for catalytic degradation of Benzene Toluene Ethylbenzene and Xylenes (BTEX) in the presence of hydrogen peroxide in aqueous media. The obtained materials were characterized by X-ray Diffraction, nitrogen adsorption-desorption using the BET method and Fourier Transform Infrared Spectroscopy. The nanostructured phase of the hexagonal ordered materials was obtained even after modification with titanium oxide and calcination. The characterizations have proven the effectiveness of the synthesis method used to incorporate titanium with anatase structure impregnated in the nanoporous of the MCM-41 material. Anatase is the main active phase of TiO<sub>2</sub> to oxidize organic compounds. The catalytic evaluation wascarried out in a semi-bath reactor with 20 mL of a mixture containing BTEX (100 mg/L), hydrogen peroxide (2.0 mol/L) and TiO<sub>2</sub>/MCM-41 (2.0 g/L) in aqueous media. The reactions were carried out at a temperature of 60°C for 5 hours, and the analyses were performed by gas chromatography with a photoionization detector and headspace sampler. The catalytic tests showed satisfactory results with more than 95% of conversion, where the catalyst 48%TiO<sub>2</sub>/MCM-41 presented higher performance.

Mild and selective catalytic oxidation of 5-HMF to 2,5-FDCA over metal loaded biomass derived graphene oxide using hydrogen peroxide in aqueous media

Biomass-derived graphene oxide-supported metal catalysts (Ru@S-GO, Pd@ S-GO, and Pd/Ru@ S-GO) were produced in a tube furnace with a metal loading of 1 weight percent. All the synthesised nano catalysts were well characterised by XRD, FESEM-EDS, ICP-OES, XPS and FTIR, and applied for the oxidation of 5-hydroxymethylfurfural (5-HMF) to 2,5-furan dicarboxylic acid (FDCA). Hydrogen peroxide was utilized as the liquid oxidant due to its reduced mass transfer resistance. 5-HMF used in this study was also obtained from biomass. All the operational parameters, such as temperature of the reaction, amount of oxidant, base concentration, and catalyst loading were optimized using Response surface methodology (RSM) based on central composite design (CCD). Ru@S-GO was found to have greater activity and selectivity towards FDCA under benign reaction conditions, and complete conversion of 5-HMF to 2,5-FDCA was accomplished (98.8% yield) over 5 hours of reaction time in an aqueous medium with a lower catalyst loading and reduced metal content.

Mechanochemical synthesis of an AIE-TICT-ESIPT active orange-emissive chemodosimeter for selective detection of hydrogen peroxide in aqueous media and living cells, and solid-phase quantitation using a smartphone

We report herein the design and mechanochemical synthesis of a chemodosimeter, benzothiazole-derived unsymmetrical azine protected by 4-bromomethylphenylboronic acid (BTPAB), an orange aggregation-induced emission (AIE), for the selective detection of H2O2 in a turn-on manner.

Efficient Assay for the Detection of Hydrogen Peroxide by Estimating Enzyme Promiscuous Activity in the Perhydrolysis Reaction

AbstractHydrogen peroxide is an ideal oxidant in view of its availability, atom economy, or green aspects. Furthermore, it is produced by the cell mitochondria and plays a meaningful role in controlling physiological processes, but its unregulated production leads to the destruction of organs. Due to its diverse roles, a fast and selective method for hydrogen peroxide detection is the major limitation to preventing the negative effects caused by its excess. Therefore, we aimed to develop an efficient assay for the detection of H2O2. For this purpose, we combined the enzymatic method for the detection of hydrogen peroxide with the estimation of the promiscuity of various enzymes. We estimated the activity of an enzyme in the reaction of p‐nitrophenyl esters with hydrogen peroxide resulting in the formation of peracid. To our knowledge, there is no example of a simple, multi‐sensor demonstrating the promiscuous activity of an enzyme and detecting hydrogen peroxide in aqueous media.

Green synthesis of novel phosphonate derivatives using ultrasonic irradiation

A novel and efficient procedure for the generation of quinazolinone phosphonate derivatives employing the reaction of euparin, isatin or its derivatives, primary amines, dialkyl acetylenedicarboxylates, trimethyl phosphite or triphenyl phosphite, and acidic solution of hydrogen peroxide in aqueous media at ambient temperature under ultrasonic irradiation was developed. Without ultrasonic irradiation, the reaction does not proceed and agitation of the reaction mixture is difficult. Some advantages of this procedure are: short time of reaction, high yields of products, easy isolation of products.

Iodoamination of Alkenyl Sulfonamides by Potassium Iodide and Hydrogen Peroxide in Aqueous Medium

AbstractA procedure for the iodoamination of unfunctionalized olefins tethered to a tosyl‐protected NH‐group has been developed. The combined use of KI and H2O2 in aqueous medium was effective for the preparation of iodomethyl‐substituted nitrogen‐containing heterocycles. The selective exo‐trig iodocyclization provided 1,2‐bifunctional 5‐, 6‐, and 7‐membered cyclic skeletons.

苦味酸介导CdSe/ZnS量子点用于水环境双氧水的测定

苦味酸介导CdSe/ZnS量子点用于水环境双氧水的测定

Green Synthesis of CoFe2O4 and Investigation of its Catalytic Efficiency for Degradation of Dyes in Aqueous Medium

Abstract The catalytic wet oxidation is one the methods used for elimination of dyes from aqueous medium in which various metal based materials can be used as heterogeneous catalysts. Bimetallic oxides as heterogeneous catalysts have gained much attention as bimetallization improve the catalytic properties of the resulting particles. The biosynthetic green method is the most viable and simple method for synthesis of bimetallic oxides nanoparticles. Here, we report the green synthesis of CoFe2O4 particles using Azadirachata indica leaves extract as reducing and stabilizing agent. The synthesized particles were characterized using X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared spectroscopy and scanning electron microscopy. The synthesized CoFe2O4 particles were tested as a catalyst for mineralization of rhodamine B and methylene blue dyes in the presence of hydrogen peroxide in aqueous media. More than 95% dyes degraded in 120 min. The reaction kinetics was described in terms of Langmuir–Hinshelwood mechanism which suggests that molecules of dye and hydrogen peroxide adsorbed surface of CoFe2O4 and then react together.

Gold Nanoparticles Supported on Magnesium Oxide Nanorods for Oxidation of Alcohols.

Gold nanoparticles supported on magnesium oxide nanorods (Au-MgO) have been synthesised by a solution based chemical reduction method. Au-MgO nanorods were found to be an efficient heterogeneous catalyst for oxidation of alcohols with hydrogen peroxide in aqueous medium at room temperature. To find out the best reaction conditions for oxidation, optimization of catalyst quantity, solvent, mole equivalence of hydrogen peroxide were carried out. The scope of the reaction was extended to several aromatic and aliphatic alcohols, product yields were quantified by gas chromatography (GC) and GC/mass spectroscopy. Heterogeneity and reusability tests were performed. The use of water as a solvent and hydrogen peroxide as co-catalyst at room temperature makes the reaction interesting from sustainable development point of view.

Membraneless fuel cells using Pt-Ru-Sn/C catalystsfor methanol oxidation

In the present work, the continuous flow operation of membraneless methanol fuel cell (MLMFC) using Pt-Ru-Sn/C electrocatalysts with different atomic ratios were prepared by alcohol-reduction process. In this membraneless fuel cell, methanol is used as a fuel, sodium percarbonate is used as an oxidant and sulphuric acid is used as the electrolyte. Sodium percarbonate affords hydrogen peroxide in aqueous medium. The synthesized electrocatalysts were characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) analyses. The electrocatalytic activities of the catalysts were characterized by cyclic voltammetry (CV) and chronoamperometry (CA). During the experiments performed on single membraneless fuel cells, Pt-Ru-Sn/C (70:20:10) performed better among all the catalysts prepared with power density of 36.5 mWcm-2. The better performance of ternary Pt-Ru-Sn/C catalysts may be due to the formation of a ternary alloy and the smaller particle size.

Study and modeling of the organophosphorus compound degradation by photolysis of hydrogen peroxide in aqueous media by using experimental response surface design

This work was designed to study the effectiveness of hydrogen peroxide photolysis on the degradation of malathion pesticide in an aqueous medium. Experiments were performed in a static reactor with a low-pressure mercury vapor lamp at initial organophosphorus concentrations of 10−3. The first result obtained showed that the system H2O2/UV can completely oxidize the organophosphorus compound. The oxidation yields obtained using the static reactor depended on the reaction time, the initial concentration of H2O2, and the initial pH solution. However, the oxidation efficiency may be reduced by the presence of radical traps in the reaction medium. Moreover, a model of the hydrogen peroxide photocatalysis is also presented in this paper. The use of experimental design and in particular the response surface methodology (RSM) in addition to the full factorial design allowed the determination of the influence of the simultaneous effects and interaction of the operating parameters on the performance of the photo degradation Demim et al. Ecol. Eng. 57 (2013) 302; Ecol. Eng. 61 (2013) 426; Boudjema et al. Desalin. Water Treat. 1065. 10.1080/19443994.2015.449. Indeed, the operating parameters studied in this research work were the initial concentration of malathion, H2O2 catalyst volume and the pH of the solution. The results found showed that the application of the RSM allowed describing correctly the effect of these three operating parameters on the treatment efficacy. The optimal parameter values giving a maximum yield (100%) were determined.

Electrochemical Oxidation of Hydrazine in Membraneless Fuel Cells

This paper describes the continuous flow operation of membraneless sodium perborate fuel cell using acid/alkaline bipolar electrolyte. Here, hydrazine is used as a fuel and sodium perborate is used as an oxidant under Alkaline-acid media configuration. Sodium perborate affords hydrogen peroxide in aqueous medium. In our operation, the laminar flow based microfluidic membranleless fuel cell achieved a maximum power density of 27.2 mW cm �2 when using alkaline hydrazine as the anolyte and acidic perborate as the catholyte at room temperature with a fuel mixture flow rate of 0.3 mL min -1 . The simple planar structured membraneless sodium perborate fuel cell enables high design flexibility and easy integration of the microscale fuel cell into actual microfluidic systems and portable power applications.

Colorimetric Sensor Based on Silver Nanoparticle – Embedded Polymethacrylate Matrix

Silver nanoparticles synthesized by a reagent less method involving only thermal treatment have been used in colorimetric assay for the detection of hydrogen peroxide. The silver nanoparticles were directly synthesized in polymethacrylate matrix (PMM) by method based on the reduction of the inorganic precursor AgNO3, which was pre-adsorbed by PMM from solution, through thermal treatment. These silver nanoparticles were characterized using absorption spectroscopy. It was shown that the silver nanoparticles in PMM (Ag – PMM) had ability for reduction of hydrogen peroxide with silver oxidation. As a result, the yellow color of Ag – PMM samples was gradually changed to transparent color depending on the hydrogen peroxide concentrations. Hence, the silver nanoparticles in PMM could be used as colorimetric sensor for hydrogen peroxide in aqueous medium.

Glassy carbon electrode modified with a graphene oxide/poly(o-phenylenediamine) composite for the chemical detection of hydrogen peroxide

Conducting poly(o-phenylenediamine) (POPD)/graphene oxide (GO) composites were prepared using a facile and efficient method involving the in-situ polymerization of OPD in the presence of GO in an aqueous medium. Copper sulfate was used as an oxidative initiator for the polymerization of OPD. Scanning electron microscopy and transmission electron microscopy images showed that POPD microfibrils were formed and distributed relatively uniformly with GO sheets in the obtained composites. X-ray diffraction results revealed the highly crystal structure of POPD. This composite exhibited good catalytic activity and stability. These results highlight the potential applications of POPD/GO composites as excellent electrochemical sensors. The composites were used to modify glass carbon electrodes for the chemical detection of hydrogen peroxide in aqueous media.

The use of copper and cobalt phthalocyanines as electrocatalysts for the oxygen reduction reaction in acid medium

Direct electrochemical generation of hydrogen peroxide in aqueous medium represents an attractive method for the production of the oxidizing agent. This paper describes the development of electrocatalysts comprising Printex L6 carbon black containing 0 to 10% (w/w) of copper or cobalt phthalocyanine (CuPc and CoPc, respectively) as modifier. Formation of H2O2 by the ORR in acidic medium was investigated by linear voltammetry using a rotating ring-disc electrode, whose glassy carbon disc contained a microporous layer of the catalyst. Incorporation of CuPc into Printex decreased the current efficiency for H2O2 formation [i(H2O2)%] from 75.4% for unmodified Printex to a minimum of 53.3% when 10% of the modifier was present. However, i(H2O2)% increased when CoPc was employed as modifier, and a maximum value of 92.3% was attained with Printex containing 1.0% CoPc. Moreover, a shift of +340mV (relative to unmodified Printex) was observed in the overpotential required for the generation of H2O2 when 10% of CoPc was present. SECM demonstrated that, at a potential of -0.2V, Printex with 10% CoPc produced larger amounts of H2O2 compared with unmodified Printex. It is concluded that the use of the CoPc modifier is promising for the electrogeneration of H2O2 on a large scale.

A Development of Ethanol/Percarbonate Membraneless Fuel Cell

The electrocatalytic oxidation of ethanol on membraneless sodium percarbonate fuel cell using platinum electrodes in alkaline-acidic media is investigated. In this cell, ethanol is used as the fuel and sodium percarbonate is used as an oxidant for the first time in an alkaline-acidic media. Sodium percarbonate generates hydrogen peroxide in aqueous medium. At room temperature, the laminar-flow-based microfluidic membraneless fuel cell can reach a maximum power density of 18.96 mW cm−2 with a fuel mixture flow rate of 0.3 mL min−2. The developed fuel cell features no proton exchange membrane. The simple planar structured membraneless ethanol fuel cell presents with high design flexibility and enables easy integration of the microscale fuel cell into actual microfluidic systems and portable power applications.

Perborate as novel fuel for enhanced performance of membraneless fuel cells

This paper presents the development of membraneless sodium perborate fuel cell using acid/alkaline electrolyte. In the acid/alkaline electrolyte, perborate works both as an oxidant as well as reductant. Sodium perborate affords hydrogen peroxide in aqueous medium. The cell converts the energy released by H2O2 decomposition with H+ and OH− ions into electricity and produces water and oxygen. Such a novel design eliminates the need of a membrane, in which acid and alkaline electrolytes contact with each other. At room temperature, the laminar flow-based microfluidic membraneless fuel cell can reach a maximum power density of 34 mW/cm2 with the molar ratio of [Perborate]/[NaOH] = 1 as fuel and [Perborate]/[H2SO4] = 2 as oxidant. The paper reports for the first time the use of sodium perborate as the oxidant and reductant. The developed fuel cell emits no CO2, features no proton exchange membrane, inexpensive catalysts, and simple planar structure, which enables high design flexibility and easy integration of the microscale fuel cell into actual microfluidic systems and portable power applications.

Analysis of Membraneless Methanol Fuel Cell Using Percarbonate as an Oxidant

This paper presents the continuous flow operation of membraneless sodium percarbonate fuel cell using acid/alkaline bipolar electrolyte. In this membraneless fuel cell, methanol is used as a fuel and sodium percarbonate is used as an oxidant for the first time under “multi-media” configuration. Sodium percarbonate affords hydrogen peroxide in aqueous medium. At room temperature, the laminar flow based microfluidic membraneless fuel cell can reach a maximum power density of 22.25 mW cm−2 with a fuel mixture flow rate of 0.3 mL min−1. The developed fuel cell features no proton exchange membrane. The simple planar structured membraneless sodium percarbonate fuel cell enables high design flexibility and easy integration of the microscale fuel cell into actual microfluidic systems and portable power applications.

Facile synthesis of carbon quantum dots and thin graphene sheets for non-enzymatic sensing of hydrogen peroxide

Carbon quantum dots (CQDs) and two dimensional (2D) graphene sheets were prepared from formic acid by microwave mediated thermal method. Microwave irradiation followed by thermal evaporation of formic acid produces fluorescent CQDs. The fluorescence emission of CQDs in water can be tuned between 310 and 820 nm by changing the excitation wavelengths. These quantum dots are found to be sensitive towards hydrogen peroxide in aqueous medium due to quenching of fluorescence. The large area graphene sheets are formed on a solid substrate due to self assembly and 2D growth of CQDs. Graphene sheets modified glassy carbon electrode showed fast electron transfer kinetics for Fe(CN)63−/4− couple. Moreover, these modified electrodes can be used as a highly sensitive and selective metal free, non-enzymatic electrochemical sensor for hydrogen peroxide. The low detection limit was found to be 300 nM.

Organic–inorganic polyoxometalate based salts as thermoregulated phase-separable catalysts for selective oxidation of thioethers and thiophenes and deep desulfurization of model fuels

Synthesis of various organic–inorganic polyoxometalate based salts composed of sulfonated pyridinum cations and the Keggin tungstophosphate anion (PW12O403−) and their subsequent application in the oxidation of methyl phenyl sulfide with hydrogen peroxide in aqueous media was reported. Special attention was paid to the temperature-dependent solubility of the salts as a function of the organic cation in water. Cyclic voltammetry was further used for the investigation of the redox behavior of these catalysts. Based on these properties, a novel thermoregulated phase-separable catalyst was introduced and successfully used for the selective oxidation of thioethers and thiophenes to the corresponding sulfoxides or sulfones. Catalytic oxidation of the sulfur-containing model oil (methyl phenyl sulfide, dibenzothiophene and thiophene) was also studied under optimized conditions. In both cases, excellent conversion and selectivity were obtained in relatively short reaction times. This novel catalyst showed the characteristic of homogeneous reaction at ambient temperatures and phase-separation at lower temperatures. By simple decantation, the catalyst could be easily separated from the products upon cooling of the reaction mixture and could be reused several times with high recycling efficiency.