Showing papers on "Hydrogen peroxide published in 2013"
TL;DR: In this article, the effect of initial oxidant concentration on photo-assisted persulfate (PS), hydrogen peroxide (H 2 O 2 ) and peroxymonosulfates (PMS) oxidation processes were evaluated and compared for aqueous phenol degradation.
514 citations
TL;DR: In this article, the reactions of nanomolar concentrations of Cu(I) and Cu(II) with H 2 O 2 have been investigated in 2.0mM NaHCO 3 and 0.7m NaCl at pH 8.0.
475 citations
TL;DR: In this paper, a leaching process for the recovery of cobalt and lithium from spent lithium-ion batteries (LIBs) is developed, where three different organic acids, namely citric acid, malic acid and aspartic acid, are used as leaching reagents in the presence of hydrogen peroxide.
340 citations
TL;DR: This overview describes the main biological reactions of hydrogen peroxide and takes a kinetic approach to identifying likely targets in the cell and considers diffusion of hydrogenperoxide and constraints to its acting at localized sites.
Abstract: Hydrogen peroxide is generated in numerous biological processes and is implicated as the main transmitter of redox signals. Although a strong oxidant, high activation energy barriers make it unreactive with most biological molecules. It reacts directly with thiols, but for low-molecular-weight thiols and cysteine residues in most proteins, the reaction is slow. The most favored reactions of hydrogen peroxide are with transition metal centers, selenoproteins, and selected thiol proteins. These include proteins such as catalase, glutathione peroxidases, and peroxiredoxins, which, as well as providing antioxidant defense, are increasingly being considered as targets for signal transmission. This overview describes the main biological reactions of hydrogen peroxide and takes a kinetic approach to identifying likely targets in the cell. It also considers diffusion of hydrogen peroxide and constraints to its acting at localized sites.
338 citations
TL;DR: Differences in oxidative ability of the activated persulfate were related to different radicals generated during activation, and greater removal of high molecular weight PAHs was measured with Persulfate activation.
312 citations
TL;DR: It is reported here that Au NPs can catalyze the rapid decomposition of hydrogen peroxide and mimic SOD and catalase mimetics, and it is found that, mimicking SOD, AuNPs efficiently catalyzeThe decompositionof superoxide.
296 citations
TL;DR: In this paper, chemical and bactericidal effects induced by plasma in water upon electro-spraying through DC-driven positive transient spark discharge in air were investigated, and the degree of inactivation and oxidative damage of bacteria increased with the increasing acidity of the solution.
Abstract: Chemical and bactericidal effects induced by plasma in water upon electro-spraying through DC-driven positive transient spark discharge in air were investigated. Inactivation of E. coli was determined in dependence on pH (controlled by buffers) and correlated with chemical changes induced in water. Productions of hydrogen peroxide, nitrites, nitrates, peroxynitrites, and pH changes were determined, and the extent of oxidative stress induced in bacteria was evaluated. The degree of inactivation and oxidative damage of bacteria increased with the increasing acidity of the solution. Acidified nitrites interacting with hydrogen peroxide were determined as the most important bactericidal ROS/RNS agents in plasma-treated water. A possible role of peroxynitrites, ozone, and metal nanoparticles is discussed.
284 citations
TL;DR: It is shown that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale, showing that chemically interconnected enzymes can be drawn together.
Abstract: Using fluorescence correlation spectroscopy, we show that the diffusive movements of catalase enzyme molecules increase in the presence of the substrate, hydrogen peroxide, in a concentration-dependent manner. Employing a microfluidic device to generate a substrate concentration gradient, we show that both catalase and urease enzyme molecules spread toward areas of higher substrate concentration, a form of chemotaxis at the molecular scale. Using glucose oxidase and glucose to generate a hydrogen peroxide gradient, we induce the migration of catalase toward glucose oxidase, thereby showing that chemically interconnected enzymes can be drawn together.
262 citations
TL;DR: Supported gold–palladium nanoparticles are active for the oxidation of methane, giving a high selectivity for the formation of methyl hydroperoxide and methanol, using hydrogen peroxide as the oxidant.
Abstract: Supported gold–palladium nanoparticles are active for the oxidation of methane, giving a high selectivity for the formation of methyl hydroperoxide and methanol, using hydrogen peroxide as the oxidant (see picture). The optimal methanol selectivity is achieved by performing the reaction in the presence of hydrogen peroxide that has been generated in situ from hydrogen and oxygen.
225 citations
TL;DR: In this article, the removal of cylindrospermopsin (CYN) by UV-254nm-mediated advanced oxidation processes (AOPs) was evaluated, and the results indicated that the presence of transition metals in natural water sources could be an important factor in AOPs.
Abstract: With increasing worldwide incidence of toxic cyanobacterial blooms in bodies of water, cylindrospermopsin (CYN) has become a significant concern to public health and water management officials. In this study, the removal of CYN by UV-254 nm-mediated advanced oxidation processes (AOPs) was evaluated. Cylindrospermopsin, at an initial concentration of 1 μM, was significantly degraded, 75% at a UV fluence of 80 mJ cm−2, 100% at 20 mJ cm−2, and 100% at 40 mJ cm−2, by UV/H2O2, UV/S2O82−, and UV/HSO5− processes, respectively, at an initial oxidant dose of 1 mM. The calculated second-order rate constants of CYN with hydroxyl radicals, k OH/CYN, was 5.1 × 109 M−1 s−1 and with sulfate radicals, k SO 4 − / CYN , was 4.5 × 109 M−1 s−1. The observed pseudo-first-order reaction rate constant increased linearly with increasing initial oxidant concentration. The destruction of CYN by both radicals was inhibited by radical scavengers, such as natural organic matter (NOM) and alkalinity. The presence of transition metals in tap water samples appeared to enhance the treatment efficiency of CYN by UV/HSO5−. The ICP-MS analysis of the metals in the water samples, revealed copper residual of 40.6 ± 3.3 μg L−1 in tap water, and 13.6 and 8.1 μg L−1 in two natural water samples. Results of this study suggest that the presence of transition metals in natural water sources could be an important factor in AOPs. This study is a new and feasible approach to remove CYN as well as other organic contaminants from water resources.
224 citations
TL;DR: To augment the removal of pharmaceuticals different conventional and alternative wastewater treatment processes and their combinations were investigated and optimal conditions for removal were established regarding the duration of cavitation, amount of added hydrogen peroxide and initial pressure, all of which influence the efficiency of the process.
TL;DR: This work demonstrates that bicarbonate-activated H2O2 can be applied as a novel oxidant source in pollutant degradation using a supported cobalt catalyst, and it was found that singlet oxygen and the carbonate radical may play a key role in the degradation process.
Abstract: Developing novel technologies to cleanup wastewater has attracted attention for a long while in academic and industrial communities not only for environmental issues but also for recycling water sources. This work demonstrates that bicarbonate-activated H2O2 can be applied as a novel oxidant source in pollutant degradation. Using a supported cobalt catalyst, bicarbonate-activated H2O2 can efficiently degrade various dyes and phenol at ambient temperature. Because the reaction media remains weakly basic during degradation, the cobalt leaching from the solid catalyst has been efficiently avoided and the lifetime of the catalyst can be extended to above 180 h without significant activity loss in a fixed-bed test. Different scavengers, including ascorbic acid, t-butanol, sodium azide, benzoquinone, and tiron, have been tested to identify the active species, which may be involved in pollutant degradation, and it was found that singlet oxygen and the carbonate radical may play a key role in the degradation process.
TL;DR: In this paper, the authors reported an efficient, highly selective, and low temperature graphene-catalyzed reaction process for one-step oxidation of benzene to phenol with hydrogen peroxide as the oxidant.
Abstract: We report an efficient, highly selective, and low temperature graphene-catalyzed reaction process for one-step oxidation of benzene to phenol with hydrogen peroxide as the oxidant. The chemically converted graphene (CCG) from small graphite was used as the catalyst. The conversion of benzene reaches 18%, with phenol being the sole product. The catalyst was reusable and very stable. By XPS, C K-edge X-ray absorption spectra, benzene-TPD, and kinetic measurements, it was concluded that the moderate H2O2 activation rate, good benzene adsorption ability, and balanced kinetic control over the oxidation reaction are responsible for the outstanding catalytic performance of the metal-free catalyst.
TL;DR: In this paper, an advanced oxidation process based on dielectric barrier discharge at the gas water interface was used for the oxidative decomposition of dye contaminated wastewater, which achieved high degradation yield up to 67 g/kW h.
TL;DR: In this article, the effect of added salt on the propulsion of Janus platinum-polystyrene colloids in hydrogen peroxide solution is studied experimentally, and it is argued that the seemingly paradoxical experimental observations could be theoretically explained by using a generalised reaction scheme that involves charged intermediates and has the topology of two nested loops.
Abstract: The effect of added salt on the propulsion of Janus platinum-polystyrene colloids in hydrogen peroxide solution is studied experimentally. It is found that micromolar quantities of potassium and silver nitrate salts reduce the swimming velocity by similar amounts, while leading to significantly different effects on the overall rate of catalytic breakdown of hydrogen peroxide. It is argued that the seemingly paradoxical experimental observations could be theoretically explained by using a generalised reaction scheme that involves charged intermediates and has the topology of two nested loops.
TL;DR: In this article, a simple chemical method using hydrazine hydrate as the main reagent was firstly used to modify graphite felt as cathode for efficient electro-Fenton process.
TL;DR: In this article, the gamma irradiation-induced degradation of sulfamethazine (SMT) in aqueous solution in the presence of hydrogen peroxide (H2O2) was investigated.
TL;DR: Chlorine showed the strongest ability to impair the cell integrity with a majority (≥ 88%) of the cells compromised within the first minute and with the cell lysis rates ranging of 0.640-3.82 h(-1) during 1-60 min.
TL;DR: This review examines the contemporary concepts for how hydrogen peroxide is sensed and transduced into a biological response by introducing post-translational oxidative modifications on select proteins, focusing on CAMKII, PKA, and PKG, kinases whose redox regulation has notable impact on cardiovascular function.
Abstract: Significance: Oxidants were once principally considered perpetrators of injury and disease. However, this has become an antiquated view, with cumulative evidence showing that the oxidant hydrogen peroxide serves as a signaling molecule. Hydrogen peroxide carries vital information about the redox state of the cell and is crucial for homeostatic regulation during health and adaptation to stress. Recent Advances: In this review, we examine the contemporary concepts for how hydrogen peroxide is sensed and transduced into a biological response by introducing post-translational oxidative modifications on select proteins. Oxidant sensing and signaling by kinases are of particular importance as they integrate oxidant signals into phospho-regulated pathways. We focus on CAMKII, PKA, and PKG, kinases whose redox regulation has notable impact on cardiovascular function. Critical Issues: In addition, we examine the mechanism for regulating intracellular hydrogen peroxide, considering the net concentrations t...
TL;DR: A powerful strategy that is based on self-propelled micromotors, for a high-yielding accelerated oxidative decontamination of chemical threats using low peroxide levels and no external agitation is described.
Abstract: Rapid field conversion of chemical weapons into non-toxic products is one of the most challenging tasks in weapons of mass destruction (WMD) science. This is particularly the case for eliminating stockpiles of chemical warfare agents (CWAs) in remote storage field locations, where the use of large quantities of decontaminating reagents, long reaction times, and controlled mechanical agitation is impossible or undesired. New efficient “clean” technologies and (bio)chemical processes are thus sought for detoxifying stored agents, counteracting nerve-agent attacks, and decommissioning chemical weapons. Environmentally friendly solutions of hydrogen peroxide, combined with suitable activators (e.g., bicarbonate), have been shown to be extremely useful for decontaminating a broad spectrum of CWAs to yield nontoxic products. These peroxide-based systems, which rely on the in situ generation of OOH nucleophiles, have recently replaced chlorine-based bleaching processes, which produce undesirable products, and have thus led to effective decontamination of the chemical agents GB (Sarin, isopropyl methylphosphonofluoridate), VX ((S)-[2-(diisopropylamino)ethyl] O-ethyl methylphosphonothioate), GD (Soman, pinacolyl methylphosphonofluoridate), and HD (sulfur mustard). Yet, such an oxidative treatment commonly requires high peroxide concentrations (20–30%; approaching a stoichiometry of 1:50), along with prolonged operation and/or mechanical agitation. Such reaction conditions are not suitable or not desired for eliminating stockpiles of CWAs in remote field settings or hostile storage locations, as large quantities of the reagents may not be transportable on military aircrafts and require special packaging and handling. The efficient elimination of chemical-weapon stockpiles in field locations thus remains a major challenge to the chemistry and defense communities. Herein, we describe a powerful strategy that is based on self-propelled micromotors, for a high-yielding accelerated oxidative decontamination of chemical threats using low peroxide levels and no external agitation. Functionalized synthetic micromotors have recently demonstrated remarkable capabilities in terms of isolation and transport for diverse biomedical and environmental applications, but not in connection to increasing the yield and speed of chemical reactions. The new motor-based method relies on the use of peroxide-driven microtubular engines for the efficient selfmixing of a remediation solution, which dramatically accelerates the decontamination process. Fluid mixing is extremely important for enhancing the yield and speed of a wide range of chemical processes, including decontamination reactions, where quiescent conditions lead to low reaction efficiency and long operations. The observed mixing, which is induced by the peroxide-driven micromotor, is analogous to that reported for the motility of E. coli bacteria, where a large-scale collective motion has been shown to enhance diffusion processes. Enhanced diffusion of passive tracers has also been observed in the presence of catalytic nanowire motors. Although the new micromotor strategy presented herein was applied to the accelerated, high-yielding, and simplified decontamination of organophosphate (OP) nerve agents, the concept could have broad implications for enhancing the efficiency and speed of a wide range of chemical processes in the absence of external agitation. The concept of the micromotor/peroxide-based decontamination of chemical threats is illustrated in Figure 1. This new strategy relies on micromotors without mechanical stirring (Figure 1A). A known number of micromotors were placed in a nerve-agent-contaminated solution, along with hydrogen peroxide (used as the oxidizing agent as well as the micromotor fuel), the peroxide activator (NaHCO3 or NaOH), and the surfactant sodium cholate (NaCh), which was essential for bubble generation. The oxidative conversion of the OP nerve agent into para-nitrophenol (p-NP) was achieved under mild quiescent conditions that involve the in situ generation of OOH nucleophiles with no external stirring (Figure 1B). The decrease in concentration of the OP [*] Dr. J. Orozco, G. Cheng, D. Vilela, Dr. S. Sattayasamitsathit, Prof. R. Vazquez-Duhalt, Dr. G. Vald s-Ram rez, Dr. O. S. Pak, Prof. J. Wang Departments of Nanoengineering and Mechanical Engineering University of California San Diego La Jolla, CA 92093 (USA) E-mail: josephwang@ucsd.edu G. Cheng, Prof. C. Kan Tsinghua University, Beijing, 100084 (China) D. Vilela, Prof. A. Escarpa University of Alcal 28871 Alcal de Henares (Spain)
TL;DR: In this paper, a temperature-responsive magnetic ionic liquid (IL) N-butylpyridinium tetrachloroferrate ([BPy][FeCl 4 ]) catalyst was prepared.
TL;DR: In this article, a cadmium indium sulfide microsphere was used as an efficient photocatalyst in inactivation of Escherichia coli K-12 under visible light (VL) irradiation for the first time.
Abstract: New types of visible-light-driven photocatalysts with high activity for bacterial inactivation are needed to address the problems caused by outbreak of harmful microorganisms. In this study, cadmium indium sulfide (CdIn2S4) microsphere, which can be synthesized continuously by a facile ultrasonic spray pyrolysis method, was used as an efficient photocatalyst in inactivation of Escherichia coli K-12 under visible light (VL) irradiation for the first time. The as-prepared CdIn2S4 showed a micro-spherical morphology with diameter of 0.5–1.0 μm. It had an energy band gap of 2.02 eV and BET surface area of 34.8 m2/g. It was found that bacterial cells could also be effectively inactivated inside a partition system without the direct contact with the photocatalyst, which was attributed to the diffusible photon-generated hydrogen peroxide (H2O2) rather than hydroxyl radicals ( OH). Large amounts of H2O2 were produced from both conduction and valance bands with the involvement of superoxide ( O2−). The used CdIn2S4 could be easily recycled by the partition system without loss of activity. The destruction process of bacterial cells was from the cell wall to the intracellular components as confirmed by TEM study. In addition, the O2− and OH radicals were also detected in the CdIn2S4-VL system by ESR spin-trap with DMPO trapping technology.
TL;DR: To identify the reactive species in the Fenton system, the oxidation of a series of different compounds was studied for iron- and copper-catalyzed reactions at varying pH values, with evidence suggesting the production of hydroxyl radical or high-valent metal species.
TL;DR: A green approach for the synthesis of silver nanoparticles (Ag NPs) by using locust bean gum (LBG) polysaccharide and its application to detect hydrogen peroxide (H2O2) was reported in this paper.
Abstract: Green synthesis of nanoparticles and their applications in sensing area is of great interest to the research community. Herein we report a green approach for the synthesis of silver nanoparticles (Ag NPs) by using locust bean gum (LBG) polysaccharide and its application to detect hydrogen peroxide (H2O2). Ag NPs were synthesized by mixing optimized weight percent of LBG with a known quantity of silver nitrate (AgNO3) at 55–60 °C. Synthesized Ag NPs were characterized by UV–vis spectroscopy and atomic force microscopy (AFM). The size of synthesized Ag NPs was in the range of 18–51 nm depending upon the concentration of LBG and AgNO3. Further, a low cost and portable optical fiber based sensor using LBG stabilized Ag NPs was developed for monitoring the H2O2 concentration as low as 0.01 mM.
TL;DR: F foliar applied moringa leaf extract could ameliorate salinity-induced adverse effects by activation of antioxidant defense system and decrease in accumulation of Na+ and Cl− into shoots under moderate saline conditions.
Abstract: Amongst naturally occurring plant growth stimulants, moringa (Moringa oleifera Lam.) has attained enormous attention being rich in cytokinin, antioxidants and macro–micro nutrients in its leaves. In this study, potential of foliar applied moringa leaf extract (MLE; 30 times diluted), benzyl amino purine (BAP; 50 mg L−1) and hydrogen peroxide (H2O2; 120 μM) at tillering, jointing, booting and heading growth stages was evaluated to induce salt resistance in wheat. Water spray treatment was taken as control. Wheat cv. Sehar-2006 was grown under normal (4 dS m−1), medium (8 dS m−1) and high (12 dS m−1) soil saline conditions. Application of these stimulants decreased the shoot Na+ and Cl− contents, with simultaneous increase in shoot K+ contents. Maximum shoot K+ (48.62 %) contents were recorded with MLE application under high salinity. Activities of leaf antioxidants viz. superoxide dismutase, peroxidase and contents of total soluble phenolics were increased at medium salinity level; whereas ascorbate contents were also improved by MLE application at high salinity level. However, maximum increase in leaf total soluble protein (35.9 %) was observed with BAP application at medium salinity. The shoot length, shoot and root dry weights were decreased with increase in level of salt stress. Grain weight (18.5 %) and kernel yield (18.5 %) were also improved by MLE application under saline and normal conditions than other stimulators used. In conclusion, foliar applied moringa leaf extract could ameliorate salinity-induced adverse effects by activation of antioxidant defense system and decrease in accumulation of Na+ and Cl− into shoots under moderate saline conditions.
TL;DR: In this paper, the authors investigated the catalytic mechanisms of catalytic ozonation in the presence of ZSM-5 zeolites and γ-alumina in water using amplex red and 4-chloro-7-nitrobenzo-2-oxa-1,3-dizole (NBD-Cl) probe molecules.
Abstract: This study aims to investigate mechanisms of ozonation in the presence of ZSM-5 zeolites and γ-alumina in water. Four ZSM-5 zeolites with varying silica to alumina ratios and with both hydrogen and sodium counter ions were used in the study (Z1000H:SiO2/Al2O3 = 1000, Z900Na:SiO2/Al2O3 = 900, Z25H:SiO2/Al2O3 = 25 and Z25Na:SiO2/Al2O3 = 25). The formation of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) and superoxide ion radical (oO2−) was investigated during ozonation in the presence of ZSM-5 zeolites and alumina using amplex red and 4-chloro-7-nitrobenzo-2-oxa-1,3-dizole (NBD-Cl) as probe molecules. To the authors’ knowledge, this is the first report utilising NBD-Cl and amplex red to study mechanisms of catalytic ozonation. The results showed that alumina promotes much higher formation of ROS in aqueous solutions when compared to ozonation alone and ozonation in the presence of ZSM-5 zeolites. The process was found to be pH dependent. Furthermore, alumina showed its highest activity at a pH close to its point of zero charge. The presence of tertiary butyl alcohol (TBA) and phosphates in the reaction solution did not have a significant effect on ROS production in the presence of ZSM-5 zeolites. However, in the case of alumina, the presence of phosphates significantly lowered ROS formation. This indicates the critical importance of surface hydroxyl groups of alumina in ozone decomposition and ROS formation. In contrast to H2O2 formation, TBA did not have a significant effect on oO2− production in the case of alumina. This suggests that oO2− plays a significant role in the formation of hydroxyl radicals. Furthermore, both zeolites and alumina were found to catalyse the removal of NBD-Cl from aqueous solution. Therefore, it is suggested that alumina operates through a radical mechanism leading to the production of ROS. On the other hand, zeolites serve as reservoirs of ozone and adsorbents of organic compounds, which interact via direct ozonation pathways. The activity of zeolites depends on the silica to alumina ratios of the zeolite and is independent of the nature of the zeolite counter ions.
TL;DR: This protocol describes the synthesis of MitoPY1 and how to use this chemical tool to visualize mitochondrial H2O2 in live cells.
Abstract: Mitochondria peroxy yellow 1 (MitoPY1) is a small-molecule fluorescent probe that selectively tracks to the mitochondria of live biological specimens and responds to local fluxes of hydrogen peroxide (H2O2) by a turn-on fluorescence enhancement. This bifunctional dye uses a triphenylphosphonium targeting group and a boronate-based molecular switch to selectively respond to H2O2 over competing reactive oxygen species (ROS) within the mitochondria. MitoPY1 can be used to measure mitochondrial H2O2 levels in both cell culture and tissue models. In this protocol, we describe the synthesis of MitoPY1 and how to use this chemical tool to visualize mitochondrial H2O2 in live cells. The preparation of MitoPY1 is anticipated to take 7–10 d, and assays involving microscopy of cultured mammalian cells can be performed in 1–2 d.
TL;DR: This is the first report of a molecular iodine catalyzed cross-dehydrogenative coupling (CDC) reaction between two sp(3) C-H bonds.
TL;DR: In this article, Fenton oxidation with zero-valent iron (ZVI) and hydrogen peroxide was investigated to improve the degradation of the complex-mixture of organic compounds present in the wastewater.
Abstract: The pre-treatment of a pharmaceutical wastewater (PWW) by Fenton oxidation with zero-valent iron (ZVI) and hydrogen peroxide was investigated to improve the degradation of the complex-mixture of organic compounds present in the wastewater The influence of different crucial parameters such as the initial hydrogen peroxide concentration, the ZVI concentration and the capacity of the ZVI/H2O2 system to treat different organic loading have been evaluated The optimal conditions for degradation led to TOC reductions of up to 80% in only 1 h of treatment This degree of organic mineralization was reached by using moderate loadings of ZVI and hydrogen peroxide (ZVI/TOC weight and H2O2/TOC molar ratios of 12 and 32, respectively) Moreover, the use of waste-metallic iron shavings in terms of TOC removal compared to commercial ZVI powder may be a promising and cheaper development
TL;DR: In this paper, a modified gas diffusion electrode (MGDE) was applied to carbon black to generate hydrogen peroxide (H2O2) in the form of a microporous layer.