Effect Of Peroxide Concentration Research Articles

Physico Chemical Characteristic of Kappa Carrageenan Degraded Using Hydrogen Peroxide

<p>Abstract<br />Kappa carrageenan is polysaccharide that widely used in food, pharmaceutical, cosmetic, textile and printing industries as coagulate agent, stabilizer and gelling agent. Hydrogen peroxide (H2O2) is strong oxidator to degrade polysaccharide. Hydrogen peroxide has some advantades such as cheap, easy to get and savety environment. Degradation method using hydrogen peroxide is a technology based on establishment radical hydoxile reactive that attack the glycosidic of polysaccharides as a result reducing in molecular weight of polysaccharide. The aims of this study were to analyze the effect of hydrogen peroxide concentration, temperature and degradation time to molecular weight of refined kappa carrageenan. Structural changes on kappa carrageenan degradation were characterized by viscometer, SEM and FTIR. Hydrogen peroxide concentration, temperature and degradation time were significantly reducing molecular weight and changes in the structural function of refined kappa carrageenan. The lowest molecular weight of refined kappa carrageenan degraded was obtained from the treatment 3% of hydrogen peroxide at temperature 80°C and degradation time for 4 hours.<br /><br /></p>

Physico Chemical Characteristic of Kappa Carrageenan Degraded Using Hydrogen Peroxide

Kappa carrageenan is polysaccharide that widely used in food, pharmaceutical, cosmetic, textile and printing industries as coagulate agent, stabilizer and gelling agent. Hydrogen peroxide (H2 O2 ) is strong oxidator to degrade polysaccharide. Hydrogen peroxide has some advantades such as cheap, easy to get and savety environment. Degradation method using hydrogen peroxide is a technology based on establishment radical hydoxile reactive that attack the glycosidic of polysaccharides as a result reducing in molecular weight of polysaccharide. The aims of this study were to analyze the effect of hydrogen peroxide concentration, temperature and degradation time to molecular weight of refined kappa carrageenan. Structural changes on kappa carrageenan degradation were characterized by viscometer, SEM and FTIR. Hydrogen peroxide concentration, temperature and degradation time were significantly reducing molecular weight and changes in the structural function of refined kappa carrageenan. The lowest molecular weight of refined kappa carrageenan degraded was obtained from the treatment 3% of hydrogen peroxide at temperature 80°C and degradation time for 4 hours.

Effect of bleaching teeth with hydrogen peroxide on the morphology, hydrophilicity, and mechanical and tribological properties of the enamel

The tooth whitening process is intended to restore the original color of teeth. It consists of the application of oxidizing agents, including hydrogen peroxide. Although these products considerably improve the color of teeth, their effects on other properties of enamel are not fully understood. This work aimed to study the effects of hydrogen peroxide concentration on hydrophilicity, roughness, morphology, and mechanical and tribological properties of human tooth enamel. Human teeth were subjected to bleaching sessions with 6%, 15%, and 35% hydrogen peroxide to achieve a similar level of whitening. The enamel roughness and morphology were characterized by atomic force microscopy and scanning electron microscopy. Vickers microindentation hardness data were obtained. The hydrophilicity was determined using the captive bubble method. Reciprocating, ball-on-flat friction, and wear tests were conducted in artificial saliva using zirconia as the ball and polished enamel as the flat specimens. Although all three test solutions improved tooth color, they also changed the properties of the enamel. Morphological and roughness changes were observed, and there was a decrease in hardness and wear resistance. The wettability was nearly unaffected. It was found that the 15% hydrogen peroxide solution damaged the enamel the least. It was concluded that there is an ideal concentration of hydrogen peroxide for whitening treatments.

A Single-Blind Randomized Trial About the Effect of Hydrogen Peroxide Concentration on Light-Activated Bleaching.

To compare the bleaching efficacy and tooth sensitivity (TS) of two hydrogen peroxide (HP) concentrations (20% and 35%) used for in-office bleaching associated or not with a light-emitting diode (LED)/laser light activation. Seventy-seven patients with a right maxillary canine darker than A3 were selected for this single-blind randomized trial. The participants were distributed in four groups: bleaching with 35% HP, 35% HP + LED/laser, 20% HP, and 20% HP + LED/laser. The anterior teeth were bleached in two sessions, using a 35% or 20% HP gel with a one-week interval. Each session had three applications of 15 minutes. For the light-activated groups, the LED/laser energy (Whitening Laser Light Plus, DMC) was employed according to the manufacturer's instructions. The color change was evaluated by subjective and objective methods. Participants recorded TS with five-point verbal and visual analog scales. Color change in ΔE was evaluated by analysis of variance and Tukey tests (α=0.05) and in ΔSGU with Kruskall-Wallis and Dunn test. The absolute risk of TS and TS intensity were evaluated by Fisher exact test and Kruskall-Wallis test, respectively (α=0.05). All groups achieved the same level of whitening, except for the 20% HP group, which showed the lowest degree of whitening in the subjective analysis. The use of light did not increase the absolute risk or intensity of TS. No significant difference among groups was observed when color changes were assessed with the spectrophotometer. According to the value-oriented shade guide, the use of LED/laser light activation was able to increase the degree of whitening of the 20% HP group, but this association was not useful for the 35% HP gel. The spectrophotometer, however, did not detect significant differences among groups.

Effect of hydrogen peroxide concentration on surface properties of Ni–Cr alloys

The effect of concentration of hydrogen peroxide (H2O2) on the surface properties of Ni–Cr alloys was studied. Surface roughness and surface morphology of Ni–Cr alloys were evaluated by surface profiler and scanning electron microscopy after being immersed in different concentrations of H2O2 for 112 h. Surface corrosion products of Ni–Cr alloys were analyzed by photoelectron spectrograph after being immersed in 0% and 30% H2O2. The order of increasing surface roughness of Ni–Cr alloys after being immersed in different concentrations of H2O2 was 0<3.6%<10%<30%. As the concentration of hydrogen peroxide increased, the surface roughness of Ni–Cr alloys increased and the surface morphology showed different degrees of corrosion. According to the XPS results, the corrosion products formed on the outmost surface layer of the studied samples are Ni(OH)2 and BeO.

Effect of biochar artificial ageing on Cd and Cu sorption characteristics

The present investigation was carried out to optimize the artificial ageing process of biochar by the hydrogen peroxide method. For the optimization of three oxidation parameters (concentration of oxidizing agent, reaction time, temperature) the Box–Behnken Design under Response Surface Methodology was effectively applied. As a response, the sorption capacity of aged biochar for Cd and Cu was studied. The results demonstrate the crucial effect of hydrogen peroxide concentration on sorption capacity for both studied metals. For Cd sorption capacity a positive effect was detected whereas the sorption efficiency of aged biochar for Cu decreased with increasing concentration of the oxidizing agent. The effects of reaction time and temperature had lower statistical significances. Differences in sorption mechanism of Cd and Cu by biochar-based sorbent were detected. ANOVA analysis as well as 3D surface plots revealed that maximum sorption capacity of aged biochar-based sorbents for Cd was obtained at CH2O2=14.9997%, t=5.99998h, T=20.0°C and for Cu at CH2O2=5.05%, t=2.00h, T=59.5°C. The results confirm that RSM represents an excellent tool for predicting optimal parameters of chemical engineering processes like the hydrogen peroxide oxidation of biochar to optimize its sorbent behaviour. The application of BBD under RSM could reduce the number of required experiments from 39 to 17.

Remediation of a Diesel-Contaminated Soil Using a Fenton-Like Advanced Oxidation Process: Optimization by Response Surface Methodology

Magnetite, a naturally occurring mineral of iron oxide, and zero-valent iron (ZVI) were used to catalyze hydrogen peroxide and initiate a dark Fenton-like reaction of diesel-contaminated loamy sand in a batch system at circumneutral pH. The effects of hydrogen peroxide concentration and catalyst content on the removal efficiency of total petroleum hydrocarbons (TPHs) were studied. A central composite rotatable design was applied and the derived equation for magnetite and ZVI were linear and quadratic, respectively. In both equations, the factor of hydrogen peroxide concentration was more significant than catalyst content. At optimum conditions (4.27 wt% of catalyst content and 2.17 mol/L of hydrogen peroxide), 57% and 67% of TPH removal were achieved by magnetite and ZVI, respectively. The obtained results suggest the potential of ZVI and magnetite to catalyze a heterogeneous Fenton-like reaction at circumneutral pH. It seems that using ZVI, rather than magnetite, as a catalyst may result in slightly more TPH mineralization; however, since magnetite is a naturally occurring mineral, it may be able to compete economically with ZVI.

Optimization of extraction conditions of barley β-glucan by oxidation with hydrogen peroxide and heat treatment

In this study, response surface methodology was employed to optimize conditions for the extraction of barley β-glucan. A central composite experimental design was applied to investigate the effects of hydrogen peroxide concentration (X1: 0.2–0.8%), temperature (X2: 90–150 °C), and time (X3: 5–35 min) on the extraction of both total and soluble β-glucan. As a result, the highest total β-glucan content was 7.52% at a peroxide concentration of 0.451%, a temperature of 120 °C and an extraction time of 22 min, and this value was greatly influenced by X1 (P < 0.001). The highest soluble content was 6.31% at 0.444%, 105 °C, and 21 min. This extraction was affected by X1 (P < 0.001) and X2 (P < 0.001). With increasing X1 and X2 values, β-glucan content decreased and β-glucan purity increased. Our study showed that oxidation with hydrogen peroxide followed by heat treatment is an efficient and high-yielding method for the extraction of high-purity β-glucan from barley.

The effect of hydrogen peroxide on uranium oxide films on 316L stainless steel

For the first time the effect of hydrogen peroxide on the dissolution of electrodeposited uranium oxide films on 316L stainless steel planchets (acting as simulant uranium-contaminated metal surfaces) has been studied. Analysis of the H2O2-mediated film dissolution processes via open circuit potentiometry, alpha counting and SEM/EDX imaging has shown that in near-neutral solutions of pH 6.1 and at [H2O2]⩽100μmoldm−3 the electrodeposited uranium oxide layer is freely dissolving, the associated rate of film dissolution being significantly increased over leaching of similar films in pH 6.1 peroxide-free water. At H2O2 concentrations between 1mmoldm−3 and 0.1moldm−3, formation of an insoluble studtite product layer occurs at the surface of the uranium oxide film. In analogy to corrosion processes on common metal substrates such as steel, the studtite layer effectively passivates the underlying uranium oxide layer against subsequent dissolution. Finally, at [H2O2]>0.1moldm−3 the uranium oxide film, again in analogy to common corrosion processes, behaves as if in a transpassive state and begins to dissolve.This transition from passive to transpassive behaviour in the effect of peroxide concentration on UO2 films has not hitherto been observed or explored, either in terms of corrosion processes or otherwise. Through consideration of thermodynamic solubility product and complex formation constant data, we attribute the transition to the formation of soluble uranyl–peroxide complexes under mildly alkaline, high [H2O2] conditions – a conclusion that has implications for the design of both acid minimal, metal ion oxidant-free decontamination strategies with low secondary waste arisings, and single step processes for spent nuclear fuel dissolution such as the Carbonate-based Oxidative Leaching (COL) process.

Effect of hydrogen peroxide concentration on enamel color and microhardness.

The aim of this study was to investigate the effect of hydrogen peroxide gels with different concentrations (20%, 25%, 30%, and 35%) on enamel Knoop microhardness (KNH) as well as on changes in dental color (C). Cylindrical specimens of enamel/dentin (3-mm diameter and 2-mm thickness) were obtained from bovine incisors and randomly divided into six groups (n=20), according to the concentration of the whitening gel (20%, 25%, 30%, 35%, control, thickener). After polishing, initial values of KNH0 and color measurement, assessed by spectrophotometry using the CIE L*a*b* system, were taken from the enamel surface. The gels were applied on the enamel surface for 30 minutes, and immediate values of KNHi were taken. After seven days of being stored in artificial saliva, new measures of KNH7 and color (L7* a7* b7*, for calculating ΔE, ΔL, and Δb) were made. Data were submitted to statistical analysis of variance, followed by Tukey test (p<0.05). Differences in gel concentration and time did not influence the microhardness (p=0.54 and p=0.29, respectively). In relation to color changes, ΔE data showed that the 35% gel presented a higher color alteration than the 20% gel did (p=0.006). Bleaching with 35% hydrogen peroxide gel was more effective than with the 20% gel, without promoting significant adverse effects on enamel surface microhardness.

The effect of hydrogen peroxide concentration and solid loading on the fractionation of biomass in formic acid

This study investigated the fractionation of biomass using a decomposing mixture of hydrogen peroxide-formic acid as a pretreatment for the biorefining of Miscanthus×giganteus and of sugarcane bagasse. The main parameters investigated were the hydrogen peroxide concentration (2.5, 5.0 and 7.5wt%) and biomass loading (5.0 and 10.0wt%). At the highest hydrogen peroxide concentration used (7.5wt%), the energy released by the decomposition of the H2O2 could heat the reaction mixture up to 180°C in a short time (6–16min). As a result, highly delignified pulps, with lignin removal as high as 92wt%, were obtained. This delignification process also solubilised a significant amount of pentosan (82–98wt%) from the initial biomass feedstock, and the resulting pulp had a high cellulosic content (92wt%). The biomass loading only affected the reaction rate of hydrogen peroxide decomposition. Various analytical methods, including Fourier transform infrared spectroscopy, and thermogravimetric and elemental analyses, characterized the lignin obtained.

Treatment of Sulfonated Azo Dye Reactive Red 198 by UV/H2O2

UV/H2O2system was tested on the color removal of sulfonated azo dye Reactive Red 198 (RR), which is widely used in textile process. The effects of hydrogen peroxide concentration, temperature, pH, and the in-line addition of hydrogen peroxide on high color and chemical oxygen demand (COD) removals were investigated. The kinetic of dye decolorization was also determined. The results showed that 2% H2O2decreased the process efficiency, while 1% H2O2solution led to a better performance of the system. Despite the fact that the pH increase had small effect on color removal, it affects positively COD removals. The same behavior was found for temperature increase. A high temperature resulted in a slight decrease in color removal and a sharp decrease for COD removal. In addition the H2O2in-line provided a small improvement in both color and COD removals. UV/1% H2O2treatment was the most efficient, the good performance was linked to higher amount of hydroxyl radicals formed.

Performance of blast furnace waste for azo dye degradation through photo-Fenton-like processes

This study investigated the use of blast furnace dust (BFD) as a catalyst to degrade an azo dye (RR195) by photo-Fenton-like processes. This waste contains hematite, magnetite and maghemite as iron sources, and its dissolution provides more Fe3+ than Fe2+ for the Fenton reaction in solution. The effect of hydrogen peroxide concentration and catalyst dosage on the kinetics of hydrogen peroxide decomposition and dye decolorization was also studied. The photo-Fenton-like process was compared to Fenton-like (using BDF without irradiation), Fenton and photo-Fenton (using FeSO4 as iron source), UV/H2O2 and UV processes. The results indicated that BFD can be effectively used as a catalyst in the photocatalytic process because it was able to completely degrade H2O2 via an adjusted Langmuir–Hinshelwood model. Although the photo-Fenton-like reaction with BFD showed the same decolorization efficiency of RR195 as the homogeneous photo-Fenton process (using FeSO4), the catalyst considerably increased the reaction rates (more than five times) according pseudo-first-order kinetics. The results of the irradiated systems using BFD can be more efficient in dye decolorization due to greater hydroxyl radical production through Fe2+/Fe3+ cycling and by the occurrence of homogeneous and heterogeneous reactions. The practical use of the steel waste is promising, because it increases the reaction rates and its high density and magnetic proprieties enable an easy solid–liquid separation and reuse, making it a versatile material for environmental applications.

Shear and elongational flow properties of peroxide‐modified wood/low‐density polyethylene composite melts

AbstractAdding fillers to a polymer melt may result in a strain softening behavior in elongational flow in long‐chain branched materials, showing strain‐hardening behavior when compared with unfilled one. To improve the strain‐hardening properties in wood/LDPE composites, the effect of peroxide concentration on both the molecular architecture and molar mass distribution, and the rheological quantities in shear and elongation is studied. Addition of wood flour increases the viscosity according to a logarithmic mixing rule, as expected from the large particle size and the filler fractions used. The peroxide has multiple effects on the molar architecture of the polymer. First, a gel fraction of cross‐linked material is formed, the concentration of gel being dependent of the amount of peroxide used. Second, a higher molar mass component is detected, leading to higher value of Mw and to a broader molar mass distribution. Finally, the degree of long‐chain branching unexpectedly decreases with increasing peroxide content. The changes in molecular architecture are hardly influenced by addition of the wood flour. The peroxide treatment leads to an improved strain‐hardening behavior, detected by elongational viscosity and melt strength measurements. However, the addition of wood flour decreases the amount of strain hardening.POLYM. COMPOS., 33:2084–2094, 2012. © 2012 Society of Plastics Engineers

Effect of Hydrogen Peroxide Concentration on Corrosion Resistance of Cerium-Based Conversion Coatings on Mg AZ91D Alloy

The corrosion resistance of cerium-based conversion coatings (CeCCs) on Mg AZ91D alloy was investigated as a function of the hydrogen peroxide (H2O2) concentrations in the CeCC spray deposition solution. The corrosion performance of the coated panels was evaluated by ASTM B117 neutral salt spray testing and electrochemical analysis. Coating morphology and thickness were characterized by scanning electron microscopy (SEM) and Auger electron spectroscopy (AES), respectively. All of the panels coated with H2O2 in the solution had better corrosion resistance than the 0 vol.% H2O2 in solution. Magnesium alloy panels coated with 4 and 8 vol.% of H2O2 concentrations in the spray solution performed the best in salt spray tests. Mg AZ91D alloy panels coated with 4 vol.% H2O2 had the highest impedance (12,000 Ohm.cm2), while 0 vol.% peroxide had the lowest impedance (3000 Ohm.cm2), in agreement with salt spray performance.

Flocculation, Ozonation, and Fenton’s Process in the Treatment of Distillery Effluents

This paper reports the application of flocculation, Fenton’s process, and ozonation on the depuration of distillery wastewaters. The treatment processes were analyzed separately; nevertheless, integration schemes were also considered. The commercial flocculant 923PWG led to up to 84% of total suspended solids (TSS) removal even if a very low chemical oxygen demand (COD) abatement was observed (<2%). The effect of hydrogen peroxide concentration and [H2O2]/[Fe2+] molar ratio were tested on the Fenton’s process efficiency. Moreover, the H2O2 injection mode was still analyzed. Gathering up both COD degradation and biodegradability enhancement, it was possible to select the following operating conditions: [H2O2]=0.5 M and [H2O2]/[Fe2+]=10 (mol/mol), being the oxidant totally introduced at the beginning of the reaction. Ozonation showed poor results regarding organic matter removal; however, it seems to be an interesting methodology raising the effluent’s biochemical oxygen demand (BOD5)/COD ratio. In fact, in the strategies involving the integration of ozonation with Fenton’s process, it was possible to conclude that ozone oxidation did not improve COD degradation; nonetheless, it was essential to improve biodegradability, particularly when conducting ozonation (at pH=3) after Fenton’s process was revealed to be an interesting approach leading to an effluent amenable to further biodegradation.

Effect of Hydrogen Peroxide Concentration on Corrosion Resistance of Cerium-Based Conversion Coatings on Mg AZ91D Alloy

not Available.

Mesoporous silica iron-doped as stable and efficient heterogeneous catalyst for the degradation of C.I. Acid Orange 7 using sono–photo-Fenton process

Iron-containing mesostructured silica (Fe 2O 3/SBA-15) was prepared and used as heterogeneous catalyst in the integrated sono–photo-Fenton process. The effect of hydrogen peroxide concentration, initial pH, Fe 2O 3/SBA-15 loading, ultrasonic power, and initial solution concentration on the decolorization of C.I. Acid Orange 7 (AO7) by the integrated heterogeneous sono–photo-Fenton process was investigated in order to optimize process efficiency. The results showed that the decolorization efficiency increased with the increase of hydrogen peroxide concentration, ultrasonic power, Fe 2O 3/SBA-15 loading, but decreased with the increase of initial pH and initial dye concentration. Catalyst stability was evaluated by measuring iron leaching in solution. The particles size distribution of spent catalyst evidenced a remarkable size reduction during reaction, leading to more reactive surface and higher mass transfer rate. The main reaction intermediates were separated and identified using GC–MS and a possible degradation pathway was proposed.

Effect of hydrogen peroxide concentration on surface micro- roughness of silicon wafer after final polishing

The effect of hydrogen peroxide (H 2O 2) concentration in alkaline slurry on the surface micro-roughness of final polished silicon wafer was investigated. The root mean square roughness (RMS) reached minimum with H 2O 2 when the concentration is 0.05 wt%. Meanwhile, the contact angle of the polished surface was decreased to 21°. This decrease was attributed to enhanced chemical reaction in the CMP process. Electrochemical impedance was measured to explore the variation with addition of H 2O 2 in the reaction process of silicon erosion. Based on the measurements, a mechanism was suggested to explain the phenomenon in combine with the coefficient of friction force in the chemical mechanical polishing (CMP) process.

Bleaching and Dyeing of Superfine Wool Powder / Polypropylene Blend Film

Fibers based regenerated protein draw much attention for recycling discarded protein resources and can produce biodegradable and environmental friendly polymers. In this study, superfine wool powder is blended with polypropylene (PP) to produce wool powder/PP blend film through extrusion and hot-pressing. Hydrogen peroxide is used to bleach the black colored surface of the blend films. The effects of peroxide concentration, bleaching time and powder content on the final whiteness and mechanical properties of the blend films are investigated. The bleached films are dyed with acid red dyes and the dyed color is evaluated using a Computer Color Matching System. Color characters of dyed films, such as L*, a*, b*, ΔE*ab, C*ab and K/S values are measured and analyzed. The study not only reuses discarded wool resources into organic powder, widens the application of superfine wool powder on polymers, but also improves the dyeing properties of PP through the addition of protein content.