Hydrogen Peroxide In Acid Solution Research Articles

Rotating disc method to study the dissolution kinetics of copper metal in citric acid and hydrogen peroxide

This study reports the kinetics of copper metal dissolution in citric acid-hydrogen peroxide solution using the rotating disc method. The effect of the concentration of citric acid as well as hydrogen peroxide, stirring speed, disc surface area, and temperature was investigated. The concentration of hydrogen peroxide (0.25–1.5 mol/L) has a strong effect on the dissolution rate (mg/min) of copper with a reaction order of 0.92, compared to a reaction order of 0.42 with respect to the concentration of citric acid (0.125–1.5 mol/L). The reaction rate is directly proportional to the disc area (A) and square root of the disc rotation speed (ω1/2), as expected from the Levich equation. The activation energy of 33 kJ/mol, in the temperature range 30-60 °C is also comparable with the values reported in previous studies.

Effect of High-Temperature Hydrothermal Treatment on the Cellulose Derived from the Buxus Plant.

Cellulose has attracted considerable attention as the most promising potential candidate raw material for the production of bio-based polymeric materials. In the last decade, significant progress has been made in the production of biopolymers based on different cellulose forms. In this study, cellulose was obtained in an innovative and environmentally friendly way, using boxwood powder. Crude cellulose was obtained by treating Buxus powder with an ethanol–acetic acid–water mixture. Refined cellulose was then obtained by treatment with an acidic sodium hypochlorite solution and alkaline hydrogen peroxide solution. The novel chemistry of cellulose prepared by this method promises to be not only green, but also highly desirable, because of its lower emissions and low cost. It is crucial for the future of the global polymer industry. The refined cellulose was subjected to a high-temperature hydrothermal treatment under two temperatures and time conditions, with temperature gradients of 120, 140, and 160 °C, and time gradients of 1, 2, and 3 h. The samples were subjected to infrared and thermogravimetric analyses. The cellulose undergoes dehydration and thermal degradation reactions during the heat treatment process, and the thermal stability of the residual is enhanced, compared with that of virgin cellulose. Between 120 and 140 °C, the hydroxyl and hypomethyl groups on the surface of cellulose are shed. Groups in the amorphous region of the polymer are the first to be shed. The dehydration reaction reduces the number of free hydroxyl groups on the surface of the cellulose molecules. The dehydration reaction was accelerated by an increase in temperature. Between 140 and 160 °C, the β-(1,4)-glycosidic bond begins to slowly break and some furans are generated. The structure of cellulose undergoes reorganization during thermal treatment. The thermal stability of the modified material is greater than that of untreated cellulose.

Inactivation of SARS-CoV-2 and influenza A virus by dry fogging hypochlorous acid solution and hydrogen peroxide solution

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19), is transmitted mainly by droplet or aerosol infection; however, it may also be transmitted by contact infection. SARS-CoV-2 that adheres to environmental surfaces remains infectious for several days. We herein attempted to inactivate SARS-CoV-2 and influenza A virus adhering to an environmental surface by dry fogging hypochlorous acid solution and hydrogen peroxide solution. SARS-CoV-2 and influenza virus were air-dried on plastic plates and placed into a test chamber for inactivation by the dry fogging of these disinfectants. The results obtained showed that the dry fogging of hypochlorous acid solution and hydrogen peroxide solution inactivated SARS-CoV-2 and influenza A virus in CT value (the product of the disinfectant concentration and contact time)-dependent manners. SARS-CoV-2 was more resistant to the virucidal effects of aerosolized hypochlorous acid solution and hydrogen peroxide solution than influenza A virus; therefore, higher concentrations of disinfectants or longer contact times were required to inactivate SARS-CoV-2 than influenza A virus. The present results provide important information for the development of a strategy that inactivates SARS-CoV-2 and influenza A virus on environmental surfaces by spatial fogging.

Electrochemical and leaching studies to better understand the role of ethylene glycol in the oxidative acid dissolution of chalcopyrite

It has been demonstrated that the combined use of organic compounds and acidic peroxide solutions greatly improves the dissolution kinetics of chalcopyrite. Among the additives employed, ethylene glycol (EG) is one of the most attractive for operating at moderate temperatures (20–50 °C). However, the role of EG in the leaching process is still not clearly understood, which limits optimization and industrial scale-up. For this reason, in this investigation, an electrochemical study was undertaken, using both a solid chalcopyrite (SE-Cp) electrode coupled to a rotating disk, as well as a chalcopyrite concentrate carbon paste electrode (CPE-CCp). Leaching experiments were also performed with EG and several other organic compounds, comparing the copper dissolved in each case. The results, in the mixed potential range of 0.55–0.75 V, showed that the presence of EG did not increase chalcopyrite oxidation. However, EG adsorption on the surface of the sulfide is sufficient to hinder hydrogen peroxide dismutation, the main cause of H2O2 decomposition in EG-free acidic solutions; at the same time, decreasing the interfacial tension favors chalcopyrite contact with the solution. Finally, the formation of similar products on the chalcopyrite surface, suggest that the organics additives do not alter the dissolution mechanism.

A synchrotron radiation photoelectron spectroscopy study on atomic-scale wet etching of InAs (111)-A and (111)-B in acidic peroxide solutions: surface chemistry versus kinetics

Anisotropy in the wet-chemical surface oxidation of indium arsenide (InAs) (111) in HCl/H2O2 and H2SO4/H2O2 was investigated. The atomic-scale etching kinetics was determined by inductively coupled plasma mass spectrometry and the surface chemistry, and electronic property transformation was probed by post operando synchrotron X-ray photoelectron spectroscopy. The oxidation rate is found to be larger for the (111)-B surface (As-terminated) than for the (111)-A surface (In-terminated). HCl/H2O2 solution has shown lower InAs etch rates than H2SO4/H2O2. The nature of etchant plays a role in the band bending, which is attributed to the formation of different species (sulfates/sulfides, chlorides, and hydroxides) on the surface.

Free-Radical and Non-Free-Radical Based Reaction Pathways of Iodide Oxidation by Hydrogen Peroxide in Acid Solution–Ab Initio Calculations

Free-Radical and Non-Free-Radical Based Reaction Pathways of Iodide Oxidation by Hydrogen Peroxide in Acid Solution–Ab Initio Calculations

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.

Preparation of Polycrystalline Silicon from Rice Husk by Thermal Decomposition and Aluminothermic Reduction

Polycrystalline silicon was extracted from rice husk by thermal decomposition and aluminothermic methods. Rice husk was thermally decomposed under various heat treatments and acid purifications. High purity silica of 99.81% was obtained by subsequent rice husk washing, pressure cooking in mixed chloride acid peroxide solution, and burning at 500oC for one hour. Aluminothermic reduction of silica was conducted at various calcination temperatures. It is found that 78.6% of silica was converted to silicon for calcination temperature of 800oC. Leaching the reduction product with strong hydrochloric and hydrofluoric acids produced silicon polycrystalline with a purity of 99.91%.

Green leaching of tungsten from synthetic scheelite with sulfuric acid-hydrogen peroxide solution to prepare tungstic acid

Synthetic scheelite are considered as an important source of tungsten. In this study, an environment-friendly medium, H2SO4-H2O2 solution, was used to decompose synthetic scheelite. In the leaching process, tungsten was completely dissolved in peroxytungstic acid and separated from the insoluble CaSO4·nH2O. The solution containing tungsten was then treated by thermal decomposition to produce tungstic acid. The effects of the leaching and thermal decomposition parameters were investigated with the optimum conditions obtained as follows: leached at temperature of 50 °C, H2SO4 concentration of 2.0 mol/L, H2O2 concentration of 2.5 mol/L and L/S of 6 mL/g for 60 min; thermal decomposed at 90 °C for 4 h. Under the optimum conditions, 98.0% of tungsten was leached from CaWO4 and 99.3% of tungsten was precipitated from lixivium. Mineralogical characterization of the residue shows that solid CaSO4·nH2O dispersedly distributes in the residue and does not wrap the unreacted CaWO4, thus CaWO4 can be leached effectively.

Study on Pre-oxidation of a High-Arsenic and High-Sulfur Refractory Gold Concentrate with Potassium Permanganate and Hydrogen Peroxide

For arsenic-containing refractory gold concentrate, gold recovery by leaching is extremely difficult due to the encapsulation of gold in arsenopyrite and pyrite. In this work, the pre-oxidation of a high-arsenic and high-sulfur refractory gold concentrate in the acidic potassium permanganate or hydrogen peroxide solutions has been investigated. The studied parameters include pre-oxidation time, acidity, pre-oxidation temperature, ethylene glycol addition and oxidant concentration. When potassium permanganate of 0.25 mol/L is used as oxidant, 61.4% of arsenic and 51.8% of iron can be removed, respectively. The results of kinetics analysis indicate that the oxidative dissolution of arsenopyrite during the pre-oxidation process is controlled by the product layer diffusion, with an activation energy of 7.92 kJ/mol. The stability of hydrogen peroxide can be significantly improved by increasing both sulfuric acid concentration and ethylene glycol addition when hydrogen peroxide is used as oxidant. Under optimum conditions, arsenic removal ratio of 57.2% and iron removal ratio of 51.9% have been achieved with hydrogen peroxide of 2.5 mol/L, sulfuric acid of 0.75 mol/L and ethylene glycol of 30 mL/L. The gold extraction of refractory concentrate is only 11.5% in the copper–ammonia–thiosulfate leaching solutions without pre-oxidation. A gold extraction of 71.8% and significant decrease in thiosulfate consumption from 28.2 to 5.7% have been observed for the concentrate after pre-oxidation.

Studies on the suitability of oxidizing agents for discolouring lime and poplar wood in the first stage of transparent wood forming process

Studies on the suitability of oxidizing agents for discolouring lime and poplar wood in the first stage of transparent wood forming process. Series of lime and poplar wood samples were prepared and subjected to oxidising agent in order to decolourise wood in bulk. Sodium chlorite solution in the environment of diluted acetic acid and alkaline hydrogen peroxide solution were used as different treating agents, followed by intense rinsing in water and drying the samples. The effect of wood delignification conditions such as time of treatment and reagent used was investigated. Changes in mass and dimensions of the samples were measured, and thus density changes were calculated. Colour changes were measured with colorimeter in CIE Lab colour space. In the case of lime wood swelling of the samples was observed at the first stage, along with mass loss, leading to density decrease by 10 % after 20 h exposure. In the case of poplar wood, shrinking of the samples was observed, but due to severe mass loss, final density was similar to lime wood. Colour changes correlated mainly with lightness parameter of the samples. Significant colour differences were found even at the shortest time of treatment.

Performance characteristics of a passive direct ethylene glycol fuel cell with hydrogen peroxide as oxidant

A passive direct ethylene glycol fuel cell is proposed and tested, which does not contain external liquid pumps, gas blowers/compressors or any other auxiliary devices. Therefore, comparing to the active fuel cells, the volumetric energy density is improved. In this work, ethylene glycol in alkaline solution is employed as fuel in this fuel cell, while hydrogen peroxide in acid solution is employed as oxidant, and a cation exchange membrane is employed to transport cations. The theoretical voltage of this type of fuel cell is as high as 2.47 V, which exhibits a promising potential in practical applications. The operating conditions can influence the performance of this fuel cell system, including species concentrations in both fuel and oxidant, thicknesses of membranes, and operating temperatures. In addition, the open-circuit voltage and the peak power density of this fuel cell are as high as 1.58 V and 65.8 mW cm−2 at 60 °C, respectively. Comparing to a fuel cell system with a similar setting but using oxygen as oxidant, the higher voltage output and power output are attributed to the easier and faster reduction reaction of hydrogen peroxide, which makes contributions to the impressive performance improvement of this fuel cell. Moreover, the effect of the released heat caused by the hydrogen peroxide self-decomposition to the cell performance is studied as well.

Nanoscale etching of III-V semiconductors in acidic hydrogen peroxide solution: GaAs and InP, a striking contrast in surface chemistry

In this study of nanoscale etching for state-of-the-art device technology, the importance of surface chemistry, in particular the nature of the surface oxide, is demonstrated for two III-V materials. Striking differences in etching kinetics were found for GaAs and InP in sulphuric and hydrochloric acidic solutions containing hydrogen peroxide. Under similar conditions, etching of GaAs was much faster, while the dependence of the etch rate on pH, and on H2O2 and acid concentrations also differed markedly for the two semiconductors. Surface analysis techniques provided information on the product layer present after etching: strongly non-stoichiometric porous (hydr)oxides on GaAs and a thin stoichiometric oxide that forms a blocking layer on InP. Reaction schemes are provided that allow one to understand the results, in particular the marked difference in etch rate and the contrasting role of chloride in the dissolution of the two semiconductors. A critical factor in determining the surface chemistry is considered to be the ease with which a proton can be removed from the group V hydroxide, which is formed in the initial etching step (the breaking of the III-V surface bond).

Electrosynthesis of Н2О2 from О2 in a Gas-Diffusion Electrode Based on Mesostructured Carbon CMK-3

Mesostructured carbon CMK-3 (Carbon Mesostructured by KAIST) synthesized by the template method is studied as the electrocatalyst for electrosynthesis of Н2О2 from О2 in a gas-diffusion electrode (GDE) in alkaline and acidic solutions. The texture characteristics of the original material and its mixture with hydrophobizer (polytetrafluoroethylene) are studied by the method of low-temperature nitrogen adsorption. The rate constants for hydrogen peroxide decomposition on these materials in alkaline and acidic solutions are calculated. Kinetic parameters of oxygen reduction in alkaline and acidic solutions are determined as well as the capacitance of gas-diffusion electrodes based on mesocarbon. The selectivity of the electrocatalyst is estimated by finding the current fracture γ consumed in oxygen reduction to hydrogen peroxide. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis of Н2О2 from О2 are obtained. The acidic solution of hydrogen peroxide with the concentration more than 3 M is obtained with the current efficiency higher than 80%.

A Method for Preparation of Ordered Porous Silicon Based on a 2D SiO2 Template**Supported by the National Natural Science Foundation of China under Grant Nos 10804026 and 51101049, the Natural Science Foundation of Hebei Province under Grant Nos A2013205101 and A2014205051, and the Hebei Talent Cultivation Foundation under Grant No A201400119.

A new method for fabricating ordered porous silicon is reported. A two-dimensional silica nanosphere array is used as a template with a hydrofluoric acid–hydrogen peroxide solution for etching the nanospheres. The initial diameter and distribution of the holes in the resulting porous silicon layer are determined by the size and distribution of the silica nanospheres. The corrosion time can be used to control the depths of the holes. It is found that the presence of a SiO2 layer, formed by the oxidation of the rough internal surface of the hole, is the primary reason allowing the corrosion to proceed. Ultraviolet reflection and thermal conductivity measurements show that the diameter and distribution of the holes have a great influence on properties of the porous silicon.

Sulphur removal from Artvin-Yusufeli lignite with acidic hydrogen peroxide solutions

In this study, the optimisation of sulphur removal by H2O2/H2SO4 solutions, and a limited kinetic measurements by H2O2/HCl solutions have been carried over Artvin/Yusufeli lignite. In kinetic measurements, only the effect of temperature on removal of sulphur has been investigated. By keeping all other parameters constant, with increments in temperature at different times, it has been seen that removal of sulphur is increased. A statistical experimental arrangement which has six parameters and for each parameter there is twenty five experiments with five levels. In generally, pyritic sulphur, total sulphur, organic sulphur and ash removal rates have been determined. According to carried out variance analysis, in removal of pyritic and total sulphur, all parameters are effective, but, in removal of organic sulphur, acid concentration and particle size are not effective, and in removal of ash, only, acid concentration is not effective, however, all other parameters are effective.

Hardness, friction and wear studies on hydrogen peroxide treated bovine teeth

A possible problem with peroxide based tooth whitening is the loss of tooth hardness and higher susceptibility to enamel surface wear. This study focussed on the effects of acidic and neutral hydrogen peroxide solutions (6 and 30% w/v) on hardness, friction and wear of bovine enamel. The experiments showed that treatments with neutral peroxide reduced wear and the loss of enamel hardness up to 2–3 times. In addition, further investigation on remineralisation with amorphous calcium phosphate showed an increase in hardness after treatment. Friction coefficients of teeth against steel varied between 0.25 and 0.7, and wear coefficients ranged between ≈10−6 and 10−7mm3/Nm. From this study, it is possible to explain the wear behaviour of HP treated enamel with changes in hardness.

The leaching and adsorption of gold using low concentration amino acids and hydrogen peroxide: Effect of catalytic ions, sulphide minerals and amino acid type

The leaching of gold using alkaline amino acids–hydrogen peroxide solutions at low concentrations has been studied. The application of alkaline amino acid–hydrogen peroxide system may offer an alternative and environmentally benign process for gold leaching, particularly in the context of leaching low grade gold ores in an in-situ or in heap leach processes. In the presence of an oxidant or oxidants, it was found that amino acids can dissolve gold at alkaline condition at low and moderate temperature. Heating the leach solution between 40 and 60°C was found to enhance the gold dissolution significantly in alkaline amino acid–peroxide solutions. It was also found that gold dissolution increases by increasing amino acid concentration, peroxide and pH. Amino acids acts synergistically to dissolve gold. Although glycine showed the highest gold dissolution as a single amino acid compared to histidine and alanine, histidine was found to enhance gold dissolution when used in equimolar amounts with glycine. The presence of Cu2+ ion enhances gold dissolution in the glycine–peroxide solutions. The process will propose an environmentally benign process for gold treatment in order to replace the use of cyanide in heap or in-situ leaching. In the presence of pyrite, the amount of gold leached was lower due to the peroxide consumption in sulphide oxidation.

3D morphological analysis of copper foams as current collectors for Li-ion batteries by means of X-ray tomography

Abstract As-received and chemically treated copper foams were characterized by means of laboratory X-ray tomography with a resolution of 0.5 μm. 3D image processing and analysis allowed the morphological parameters (size, sphericity, tortuosity etc.) of the pores and copper skeleton to be determined. The chemical dissolution of the Cu foam in an acid hydrogen peroxide solution results in an increase of the open pore size (from 54 to 93 μm) and a decrease of the foam thickness (from 140 to 115 μm). With an open porosity of 81.8% and a specific surface area as high as 280,000 (49,000) m2/m3 of Cu (foam), the chemically-treated Cu foam appears very attractive for use as a 3D current collector for metal (e.g. Si) based anodes for Li-ion batteries.

Leaching of major and minor elements during the transport and storage of coal ash obtained in power plant.

In power plant, coal ash obtained by combustion is mixed with river water and transported to the dump. Sequential extraction was used in order to assess pollution caused by leaching of elements during ash transport through the pipeline and in the storage (cassettes). A total of 80 samples of filter ash as well as the ash from active (currently filled) and passive (previously filled) cassettes were studied. Samples were extracted with distilled water, ammonium acetate, ammonium oxalate/oxalic acid, acidic solution of hydrogen-peroxide, and a hydrochloric acid. Concentrations of the several elements (Al, As, Cd, Co, Cu, Cr, Fe, Ba, Ca, Mg, Ni, Pb, and Zn) in all extracts were determined by inductively coupled plasma atomic emission spectrometry. Pattern recognition method was carried out in order to provide better understanding of the nature of distribution of elements according to their origins. Results indicate possible leaching of As, Ca, Cd, Cu, Zn, and Pb. Among these elements As, Cd, and Pb are toxicologically the most important but they were not present in the first two phases with the exception of As. The leaching could be destructive and cause negative effects on plants, water pollution, and damage to some life forms.