Effect Of Hydrogen Peroxide Addition Research Articles

Effects of hydrogen peroxide on the low-temperature ignition delay times of ethylene/air/Ar mixtures in an RCM

Hydrogen peroxide with strong oxidative activity has received increasing attention in the field of ignition and combustion enhancement. To further seek out its potential benefits in ignition, the effects of hydrogen peroxide on the ignition delay times of ethylene were experimentally investigated using a rapid compression machine and numerically analyzed via the AramcoMech 3.0. The experiments with different levels of hydrogen peroxide (0 – 7000 ppm) were performed at Pc = 3.33 MPa, Tc = 817.9 – 921.0 K, φ = 0.5 – 1.5, and a dilution of 45 mol% Ar. Experimental results showed that adding hydrogen peroxide can effectively shorten the ignition delay times, and extend the low-temperature limitations. The improving effect was proceeded by three stages (0 – 1000 ppm, 1000 – 4000 ppm, and 4000 – 7000 ppm) of different decreasing rates. Kinetic analyses revealed that adding hydrogen peroxide promoted the production of OH radical to highlight the H-abstraction reaction of ethylene, further accelerating the oxidation of vinyl to vinyloxy and then to formaldehyde. Moreover, higher heat release rates were obtained with the addition of hydrogen peroxide for its exothermic character. By the kinetic effects of hydrogen peroxide addition, the ignition delay times of ethylene/air/Ar mixtures were significantly decreased. However, with the increase of additive fraction, the growth rate of both heat release rate and rate of production of OH radical were slowed down, lessening the enhancement effect on the ignition delay times.

Scalable preparation of high-quality graphene by electrochemical exfoliation: effect of hydrogen peroxide addition

Scalable preparation of high-quality graphene by electrochemical exfoliation: effect of hydrogen peroxide addition

NOx Mitigation and Ignition Promotion Effects of Hydrogen Peroxide Addition to H2–Air Mixtures

NOx Mitigation and Ignition Promotion Effects of Hydrogen Peroxide Addition to H2–Air Mixtures

New composite membranes based on PVDF fibers loaded with TiO2: Sm nanostructures and reinforced with graphene/graphene oxide for photocatalytic applications

New composite membranes based on PVDF fibers loaded with Sm doped TiO2 (TiO2:Sm) nanostructures and graphene-based nanoparticles obtained by the electrospinning technique are reported. The addition of the inorganic nanostructures induced photocatalytic properties, while the graphene-based nanoparticles (G - graphene or GO - graphene oxide) improved the mechanical properties. Advanced instrumental methods for material analysis (e.g., XRD, SEM, mechanical, and DVS) were employed to characterize the structure and surface properties. The membranes were used in photocatalytic assays for the degradation of methylene blue (MB) under visible light irradiation. To intensify the photocatalytic processes, the effect of hydrogen peroxide addition was also investigated. The results revealed that the PVDF-based membrane containing 15% TiO2:Sm and 2.5% GO showed an optimal photocatalytic activity due to its high porosity, relevant adsorption capacity, and improved mechanical properties. The response surface methodology was employed to optimize the experimental conditions of the photocatalytic process. The addition of H2O2 significantly increased the rate constant of photodegradation reaction (k = 6.624× 10−1 min−1), disclosing a half-life of the reaction of about 1 min. This short half-life time represents a remarkable outcome for a photocatalytic process conducted under visible light irradiation. Good recycling capacity was observed for the optimal (TiO2:Sm)[15%]/PVDF/GO[2.5%] composite membrane.

Computational analysis of the effect of hydrogen peroxide addition on premixed laminar hydrogen/air flames

In the current work, the effect of H2O2 addition on the flame structure, laminar flame speed and NOx emissions is investigated in the context of 1D laminar premixed H2/air flames at Tu = 300 and 600 K, p = 1 and 30 atm, ϕ = 0.5. Mathematical tools from the computational singular perturbation approach are used in order to identify the key chemical and transport mechanisms. The H2O2 addition causes a significant increase to the laminar flame speed (sL), heat release (Q) and NOx emissions. Indicatively, 10% H2O2 addition (per fuel volume) at Tu = 300 K, p = 1 atm results in 72% increase of sL, 100% increase of Q, and 140% increase of the mass fraction of NO. Depending the conditions the flame structure is altered through the chain carrying reaction 10f (H2O2 + H → H2O + OH) or the chain branching 9f (H2O2 (+M) → 2OH (+M)); the first is favored at low temperatures/pressures while the latter is favored at sufficiently high temperatures/pressures. Both reactions boost the radical pool generation, therefore contributing to the broadening of the reaction zone. The reaction with the largest contribution to Q that is mostly affected (decreased) by the addition of H2O2 is reaction 21 (H + O2 (+M) ↔ HO2 (+M)). Moreover, the H2O2 addition enhances the stability of the flame. Finally, the increased production of NO is mainly associated with the increased temperature that is reached with the addition of H2O2.

Improving efficiency for removal of ammoniacal nitrogen from wastewaters using hydrodynamic cavitation

The present study reports significant improvements in the removal of ammoniacal nitrogen from wastewater which is an important problem for many industries such as dyes and pigment, distilleries and fisheries. Pilot plant studies (capacity, 1 m3/h) on synthetic wastewater using 4-amino phenol as model nitrogen containing organic compound and two real industrial effluents of high ammoniacal nitrogen content were carried out using hydrodynamic cavitation. Two reactor geometries were evaluated for increased efficiency in removal-orifice and vortex diode. Effect of initial concentration (100–500 mg/L), effect of pressure drop (0.5–5 bar) and nature of cavitating device (linear and vortex flow for cavitation) were evaluated along with effect of salt content, effect of hydrogen peroxide addition and aeration. Initial concentration was found to have significant impact on the extent of removal: ~ 5 g/m3 removal for initial concentration of 100 mg/L and up to 12 g/m3 removal at high concentration of 500 mg/L. Interestingly, significant improvement of the order of magnitude (up to 8 times) in removal of ammoniacal nitrogen could be obtained by sparging air or oxygen in hydrodynamic cavitation and a very high removal of above 80% could be achieved. The removal of ammoniacal nitrogen by vortex diode was also found to be effective in the industrial wastewaters and results on two different effluent samples of distillery industry indicated up to 75% removal, though with longer time of treatment compared to that of synthetic wastewater. The developed methodology of hydrodynamic cavitation technology with aeration and vortex diode as a cavitating device was found to be highly effective for improving the efficiency of the conventional cavitation methods and hence can be highly useful in industrial wastewater treatment, specifically for the removal of ammoniacal nitrogen.

Addition of hydrogen peroxide to methylene blue conjugated to β-cyclodextrin in photodynamic antimicrobial chemotherapy in S. mutans biofilm.

This study evaluated the effect of hydrogen peroxide addition on β-cyclodextrin-conjugated methylene blue in antimicrobial photodynamic therapy(a-PDT) in S. mutans biofilm model using laser or light emitting diode (LED) (λ = 660 nm). A preliminary assay was performed to evaluate the cytotoxicity of hydrogen peroxide in oral fibroblasts by the colorimetric method (MTT). Afterwards, groups were divided into (n = 3, in triplicate): C (negative control), CX - chlorhexidine 0.2% (positive control), P (methylene blue/β-cyclodextrin), H (Hydrogen Peroxide at 40 μM), PH, L (Laser), LP, LH (Laser+Hydrogen Peroxide), LPH, LED, LEDP, LEDH, and LEDPH. The biofilm was formed in 24 h with BHI + 1% sucrose (w/v). Light irradiations were conducted with laser, 9 J, 323 J/cm2, 113 s or with LED, 8.1 J, 8.1 J/cm2 for 90 s. Microbial reduction was evaluated by counting the viable microorganisms of the biofilm after the respective treatments, in a selective culture medium, and laser confocal microscopy evaluation. LP, LH, LPH, LEDP, LEDH, and LEDPH groups statistically reduced the counts of S.mutans compared with the C group and the log reductions were of 1.87, 1.94, 2.19, 0.91, 0.92, and 1.33, respectively; the addition of hydrogen peroxide did not potentiate the microbial reductions (LPH and LEDPH) compared with the LP and LEDP groups. The association of hydrogen peroxide with the conjugated β-cyclodextrin nanoparticle as photosensitizer did not result in an enhanced effect of a-PDT; hydrogen peroxide behaved as a photosensitizer, since it reduced the number of S. mutans when associated with laser light.

Effects of hydrogen peroxide addition on two-stage ignition characteristics of n-heptane/air mixtures

Rising fuel cost and environmental concerns of greenhouse emissions have driven the development of advanced engine technology with optimal fuel strategy that can simultaneously yield high thermal efficiency and low emissions. Due to its strong reactivity and extra oxygen atom serving as an oxidizer, hydrogen peroxide (H2O2) has been used along with other hydrocarbons to promote overall combustion process. To explore the potential benefits of H2O2 in clean combustion technology, a numerical study with detailed chemistry is conducted to investigate the effects of H2O2 addition on the two-stage ignition characteristics of n-heptane/air mixtures at low-to-intermediate temperatures (below 1000 K), with due emphasis on how the negative temperature coefficient (NTC) behavior is affected. The results show that H2O2 addition shortens both the first-stage and total ignition delay times of n-heptane/air mixtures and suppresses the NTC behavior by reducing the upper turnover temperature. With increasing H2O2 addition, the lower turnover temperature, corresponding to the first-stage ignition delay minimum, is found to increase first and then decrease. Chemical kinetic analyses show that the addition of H2O2 promotes both first- and second-stage ignition reactivity by enhancing OH production through H2O2 decomposition. Furthermore, low-temperature chemistry controls the first-stage ignition, while H2O2 chemistry dominates the second-stage ignition.

Hydrogen Peroxide Enhances the Antibacterial Effect of Methylene Blue-based Photodynamic Therapy on Biofilm-forming Bacteria.

Recently, increased attention has been focused on endoscopic disinfection after outbreaks of drug-resistant infections associated with gastrointestinal endoscopy. The aims of this study were to investigate the bactericidal efficacy of methylene blue (MB)-based photodynamic therapy (PDT) on Pseudomonas aeruginosa (P. aeruginosa), which is the major cause of drug-resistant postendoscopy outbreak, and to assess the synergistic effects of hydrogen peroxide addition to MB-based PDT on biofilms. In planktonic state of P. aeruginosa, the maximum decrease was 3 log10 and 5.5 log10 at 20 and 30 J cm-2 , respectively, following MB-based PDT. However, the maximum reduction of colony forming unit (CFU) was decreased by 2.5 log10 and 3 log10 irradiation on biofilms. The biofilm formation was significantly inhibited upon irradiation with MB-based PDT. When the biofilm state of P. aeruginosa was treated with MB-based PDT with hydrogen peroxide, the CFU was significantly decreased by 6 log10 after 20 J cm-2 , by 7 log10 after 30 J cm-2 irradiation, suggesting significantly higher efficacy than MB-based PDT alone. The implementation of the combination of hydrogen peroxide with MB-based PDT through working channels might be appropriate for preventing early colonization and biofilm formation in the endoscope and postendoscopy outbreak.

The Effect of Hydrogen Peroxide Addition on the Citric Acid Leaching of Lead, Copper, and Zinc from Contaminated Soil with Heavy Metals

The Effect of Hydrogen Peroxide Addition on the Citric Acid Leaching of Lead, Copper, and Zinc from Contaminated Soil with Heavy Metals

Effects of hydrogen peroxide addition on combustion characteristics of n-decane/air mixtures

To curb the carbon footprint from the combustion of fossil fuels, hydrogen-enriched fuels have received much research attention in recent years. Hydrogen peroxide (H2O2) has unique combustion characteristics, as it can be used as a fuel or serve as an oxidizer when reacting with other fuels. Considering the dual nature of H2O2 and exploring its potential benefits in clean combustion technology, a numerical study is carried out to systematically investigate the effects of H2O2 addition on combustion properties of n-decane/air mixtures, including ignition delay times, laminar flame speeds, extinction residence times, and emissions of CO and NOx. The results show that H2O2 addition can greatly enhance the premixed combustion with shortened ignition delay times, increased laminar flame speeds, and extended extinction limits. While CO emissions increase with increasing H2O2 addition for stoichiometric and lean n-decane/air mixtures, NOx emissions first increase with increasing H2O2 addition and then decrease as air is completely replaced by H2O2. Sensitivity and reaction pathway analyzes are further conducted to identify the changes in controlling chemistry as a result of H2O2 addition. It is found that the production of OH radicals are greatly enhanced by H2O2 decomposition, and OH radicals play a dominant role in fuel oxidation process. The current simulation results suggest that reduced NOx emissions can be achieved with H2O2 addition at leaner combustion conditions without compromising the static combustion stability.

Effect of hydrogen peroxide addition to methane fueled homogeneous charge compression ignition engines through numerical simulations

The effect of the direct injection of hydrogen peroxide into a port-injected methane fueled homogeneous charge compression ignition engine was investigated numerically. The injection of aqueous hydrogen peroxide was implemented as a means of combustion phasing control. A single-cylinder homogeneous charge compression ignition engine (2.43 L Caterpillar) was modeled using the Cantera 2.0 flame code toolkit, the GRI-Mech 3.0 chemical reaction mechanism, and a single-zone slider-crank engine model. Start of injection timing and the amount of injected hydrogen peroxide were manipulated to achieve desired combustion phasing under a wide range of intake temperatures. As the concentration of hydrogen peroxide is increased, the combustion phasing is advanced up to 22° for the conditions investigated in this study. This advancing effect is most pronounced at small concentrations (<10 g H2O2/kg CH4) and early injection timings (start of injection < 25° before top dead center). The model suggests hydrogen peroxide can be introduced as a means of combustion phasing control while maintaining the low emissions and peak in-cylinder pressures inherent in homogeneous charge compression ignition engines.

Effect of Hydrogen Peroxide Addition on the Photochemical and Sonochemical Destruction of Pyridine in Wastewater

Effect of Hydrogen Peroxide Addition on the Photochemical and Sonochemical Destruction of Pyridine in Wastewater

Chemical effect of hydrogen peroxide addition on characteristics of methane–air combustion

The effects of hydrogen peroxide addition on the reaction pathway of premixed methane/air flames are numerically investigated using the PREMIX code with the GRI-Mech 3.0 chemical kinetic mechanisms and detailed transport properties. Hydrogen peroxide is used as the oxidizer substituent of air. Results show that the laminar burning velocity and adiabatic flame temperature of premixed methane–air flame are significantly increased with H2O2 addition. The addition of hydrogen peroxide increases not only all the reaction rates of intermediate species, but also the concentrations of intermediate species. The traditional reaction pathways of CH4/air flame are altered by the addition of hydrogen peroxide, due to the enhanced production of OH and HO2. The enhanced OH radicals promote HO2 productions through reaction (R89). The increased HO2 accelerates the progressive reaction of CH3 to form CH3O and then CH2O.

Repression of ergosterol level during oxidative stress by fission yeast F-box protein Pof14 independently of SCF

We describe a new member of the F-box family, Pof14, which forms a canonical, F-box dependent SCF (Skp1, Cullin, F-box protein) ubiquitin ligase complex. The Pof14 protein has intrinsic instability that is abolished by inactivation of its Skp1 interaction motif (the F-box), Skp1 or the proteasome, indicating that Pof14 stability is controlled by an autocatalytic mechanism. Pof14 interacts with the squalene synthase Erg9, a key enzyme in ergosterol metabolism, in a membrane-bound complex that does not contain the core SCF components. pof14 transcription is induced by hydrogen peroxide and requires the Pap1 transcription factor and the Sty1 MAP kinase. Pof14 binds to and decreases Erg9 activity in vitro and a pof14 deletion strain quickly loses viability in the presence of hydrogen peroxide due to its inability to repress ergosterol synthesis. A pof14 mutant lacking the F-box and an skp1-3 ts mutant behave as wild type in the presence of oxidant showing that Pof14 function is independent of SCF. This indicates that modulation of ergosterol level plays a key role in adaptation to oxidative stress.

Effect of Modified Fenton’s Reaction on Microbial Activity and Removal of PAHs in Creosote Oil Contaminated Soil

This study describes the removal of polycyclic aromatic hydrocarbons (PAHs) from creosote oil contaminated soil by modified Fenton's reaction in laboratory-scale column experiments and subsequent aerobic biodegradation of PAHs by indigenous bacteria during incubation of the soil. The effect of hydrogen peroxide addition for 4 and 10 days and saturation of soil with H(2)O(2) on was studied. In both experiments the H(2)O(2) dosage was 0.4 g H(2)O(2)/g soil. In completely H(2)O(2)-saturated soil the removal of PAHs (44% within 4 days) by modified Fenton reaction was uniform over the entire soil column. In non-uniformly saturated soil, PAH removal was higher in completely saturated soil (52% in 10 days) compared to partially saturated soil, with only 25% in 10 days. The effect of the modified Fenton's reaction on the microbial activity in the soil was assessed based on toxicity tests towards Vibrio fischeri, enumeration of viable and dead cells, microbial extracellular enzyme activity, and oxygen consumption and carbon dioxide production during soil incubation. During the laboratory-scale column experiments, the toxicity of column leachate towards Vibrio fischeri increased as a result of the modified Fenton's reaction. The activities of the microbial extracellular enzymes acetate- and acidic phosphomono-esterase were lower in the incubated modified Fenton's treated soil compared to extracellular enzyme activities in untreated soil. Abundance of viable cells was lower in incubated modified Fenton treated soil than in untreated soil. Incubation of soil in serum bottles at 20 degrees C resulted in consumption of oxygen and formation of carbon dioxide, indicating aerobic biodegradation of organic compounds. In untreated soil 20-30% of the PAHs were biodegraded during 2 months of incubation. Incubation of chemically treated soil slightly increased PAH-removal compared to PAH-removal in untreated soil.

Using Aluminum for Space Propulsion

The combination of aluminum and water was theoretically analyzed to assess its performance potential for space propulsion, in particular for microrocket applications and whenever a compact package is desirable. Heat of reaction, impulse density, and handling safety are features making this combination interesting for chemical thrusters, especially because thrust is higher than typical of satellite electric thrusters. Ideal specific impulse I s p , thrust coefficient, adiabatic flame temperature, and combustion products were calculated for chamber pressures 1-10 atm, nozzle area ratios 25-100, and mixture ratios O/F 0.4-8.0. I s p reaches up to 3500 m/s. Also, the effect of hydrogen peroxide addition to aluminum and water on performance was explored. This combination improves performance slightly at the expense of simplicity, making it less attractive for microrocket engines. Ignition delay times were conservatively estimated assuming that aluminum was coated with its oxide and ignition occurred after the melting of the aluminum oxide. For this purpose heating and kinetics times were evaluated, the first by a one-dimensional physical model, the second by a reduced scheme. Results indicate that the heating time of a 0.1-μm-diameter aluminum particle may be of order 0.4 μs, whereas overall kinetics takes 10 μs: thus, the Al/water combination looks practical in principle for microrocket chambers characterized by short residence times.

Pulp Potential Control in Flotation: The Effect of Hydrogen Peroxide Addition on the Extent of Xanthate Oxidation

The effect of increasing the redox potential by means of hydrogen peroxide additions upon the extent of oxidation of potassium ethyl xanthate (KEX: C2H5OCS2K) was investigated. The study was carried out at pH 7 in solutions of constant ionic strength (0.01 M NaNO3) using an initial surfactant concentration of 100 mg/L (6.176 × 10−4 M KEX). The Eh was varied in the range of 260 to 450 mV (vs SHE). The concentration of surfactant was determined by means of UV spectrometry at a wavelength of 280 nm. At shorter wavelengths it was observed that the absorbances of NaNO3 and H2O2 interfere with the measurement. It was determined that the main product of the oxidation of xanthate was perxanthate; no dixanthogen was detected regardless of the Eh of the solution.

Pulp Potential Control in Flotation: The Effect of Hydrogen Peroxide Addition on the Extent of Xanthate Oxidation

Pulp Potential Control in Flotation: The Effect of Hydrogen Peroxide Addition on the Extent of Xanthate Oxidation