H2O2 Aqueous Solution Research Articles

Uranium dissolution and uranyl peroxide formation by immersion of simulated fuel debris in aqueous H2O2 solution

ABSTRACT The fuel debris generated in the accident at the Tokyo Electric Power Company’s Fukushima Daiichi Nuclear Power Station has been subject to water and ionizing radiation for years and will be until retrieval. Therefore, we investigated the potential degradation of this fuel debris caused by H2O2, which is the oxidant of major impact from water radiolysis. We performed leaching experiments on different kinds of simulated debris comprising U, Fe, Cr, Ni, and Zr in an aqueous H2O2 solution. Chemical analysis of the leaching solution showed that U dissolution was induced by H2O2. Raman analysis after the leaching revealed that uranyl peroxides were formed on the surface of the simulated debris. The U dissolution and uranyl peroxide formation were observed in most of the simulated debris. These results demonstrate that uranyl peroxides are possible alteration products of fuel debris from H2O2 reaction. However, the sample in which the main U-containing phase was a U-Zr oxide solid solution showed much less U dissolution and no Raman signal of uranyl peroxides. Comparison of these results indicates that formation of an oxide solid solution of Zr with UO2 improves the stability of fuel debris against H2O2 reaction.

Synthesis, structure, and properties of catechol functionalized tripodal chelate and its radical complex of strontium

A new tripodal chelate ligand (NaH3L·1.5H2O) was synthesized via Mannich reaction from iminodiacetic acid and t-butyl-catechol in MeOH/H2O in the presence of polyformaldehyde and NaOH. Colorless NaH3L·1.5H2O react with Sr(OH)2 affords a deep-blue 2D-coordination polymer [Sr3L̇2·8H2O]·10.5H2O in aqueous solution. Crystal structure shows [Sr3L̇2·8H2O]·10.5H2O is a free radical 2D coordination polymer with g = 2.004 and guest accessible cavity 35.6% after removal water molecules in solid state. N2 adsorption indicates [Sr3L̇2·8H2O]·10.5H2O has specific surface area 5.4561 m2 g−1, average pore diameter is 18.48 nm, maximum N2 adsorption capacity is 18.05 cm3·g−1. [Sr3L̇2·8H2O]·10.5H2O is relatively stable in DMSO, with absorbance maximum at 259(7095), 305(6940) and 623 nm (4495 M−1 ·cm−1), but will decompose in the presence of HCl, citric acid and ascorbic acid. Stronger acid decomposes faster. Large excess H2O2 can also decompose [Sr3L̇2·8H2O]·10.5H2O. The decomposition reaction is first-order to concentration of H+/H2O2 and [Sr3L̇2·8H2O]·10.5H2O. The second-order rate constants at room temperature DMSO solution are 6.86 × 10−4 and 15.5 s−1·M−1 for H2O2 and H+ respectively.

ENHANCEMENT THE SEEDLING QUALITY OF OKRA THROUGH PRIMING WITH H2O2

The experiment was conducted to evaluate the physiological fluctuations in the seeds of okra seeds primed with the aqueous solutions of H2O2 and to find the suitable strength(s) of H2O2 as the priming material for their highest seedling quality. The experiment had eight treatments: T1 (control/no priming), T2 (hydro-priming in plain H2O) and other six aquatic solutions of H2O2: T3 (0.5%), T4 (1.0%), T5 (1.5%), T6 (2.0%), T7 (2.5%) and T8 (3.0%). The seeds were soaked for six hours in those seven media (T2 toT8). The seeds were dibbled in wooden seed flats filled-in with coarse sand. The experiment was laid-out in the RCBD with three replications. Data collected for the 13 traits were: % germination, % abnormal seedlings, shoot length, root length, seedling length, shoot dry matter, root dry matter, seedling dry matter, number of secondary roots (>1cm) per seedling, number of true leaves per seedling, relative growth rate, seedling vigor index, and root: shoot ratio (dry weight basis). Except the first two traits, the rest 11 were collected at three stages: 10, 20 and 30 days after dibbling (DAD). It was lucid that H2O2 was significantly (P≤0.05%) effective to improve most of the traits noted. But 1% concentration was utmost helpful for both okra and others were toxic and hindered the maximum parameters for all the three species. Nevertheless, further studies with different varieties of those three vegetables species with variable doses of H2O2, priming time and temperature could be explored before drawing valid conclusions.

PEDOT:PSS hydrogel gate electrodes for OTFT sensors

PEDOT:PSS hydrogel is used as soft, conductive gate electrodes for low-voltage hygroscopic insulator field effect transistors (HIFETs). HIFETs are sensitive to aqueous solutions of KCl, NaCl and H2O2, introduced through the hydrogel gate electrode.

Influence of the Local Structure on the Photocatalytic Properties of Zinc Spinel Ferrite Nanoparticles

The correlation between iron distribution in octahedral or tetrahedral sites in synthetic magnetite and zinc spinel ferrites and their catalytic properties were investigated in this work. The zinc-doped nanomagnetites were prepared by co-precipitation method and annealed at 420 °C. X-ray diffraction, UV-Vis, X-ray absorption and 57Fe Mössbauer spectroscopies were used to identify iron sites. The obtained results showed that ZnII replaces the relatively smaller FeIII cation in the tetrahedral sites, increasing the cubic lattice dimension, and this replacement remarkably enhances the catalytic effectiveness of the Zn-spinel ferrite towards the indigo carmine degradation compared to undoped magnetite. The indigo carmine degradation experiments were carried out using photo-Fenton method in which 50 mL of indigo carmine dye aqueous solutions (20 mg L−1, pH 3.0), 20 mg ZnxFe(3-x)O4, and 2.0 mL H2O2 (aqueous solution at 0.028 mol L−1) were placed under UV light at 25 °C. Under these experimental conditions the degradation rate of indigo carmine was superior to 98%.

Mechanistic explanation for differences between catalytic activities of dissolved and aerogel immobilized Cu(II) cyclen

The copper(II) complex of 1,4,7,10-tetraazacyclododecane [Cu(II)-cyclen] was covalently immobilized in mesoporous silica aerogel. This immobilization significantly alters the catalytic activity of Cu(II)-cyclen when referenced to the dissolved complex in the oxidation of phenol by H2O2 in aqueous solution. In order to understand this phenomenon, the functionalized aerogel was characterized by scanning electron microscopy (SEM), N2 porosimetry, small angle neutron scattering (SANS), infrared spectroscopy (IR) and electron paramagnetic resonance spectroscopy (EPR). Aerogel morphology is typical of mesoporous silica aerogels, and the coordination mode of Cu(II) in the immobilized complex is well-related but not identical to solution phase Cu(II)-cyclen. The mechanisms of the catalytic reactions involving dissolved and immobilized Cu(II)-cyclen were explored by fine kinetic experiments using capillary electrophoresis (CE) and on-line UV–vis spectrophotometry. Hydroquinone, pyrocatechol and the related benzoquinones were identified as the main intermediates in both reaction systems. A detailed kinetic model is postulated based on global data fitting, which clearly highlights the mechanistic differences in the two systems. Interestingly, the activation of the catalyst by H2O2 is more effective in the case of the aerogel, but the total conversion of phenol is slower due to hindered mass transport compared to using dissolved Cu(II)-cyclen.

Enzymatic Oxidative Cascade for Oxofunctionalization of Fatty Acids in One-Pot.

The biocatalytic conversion of fatty acids to α-ketoacids was accomplished by the action of two enzymes combined in a simultaneous one-pot two-step cascade. In the first step, P450 monooxygenase from Sphingomonas paucimobilis used hydrogen peroxide in the so-called peroxygenase mode for the regio- and enantioselective formation of α-hydroxyacids. In the next step, these hydroxyacid intermediates were further oxidized to the corresponding α-ketoacids by an α-hydroxyacid oxidase from Aerococcus viridans at the expense of molecular oxygen, thereby regenerating hydrogen peroxide used in the first step. Overall, the cascade was designed to employ catalytic quantities of hydrogen peroxide and proceeded at room temperature in dilute aqueous H2O2 solutions (≤0.01%). This setup could be applied to the conversion of a range of fatty acids (C6:0 to C10:0) and was scaled up to allow the production of 2-oxooctanoic acid in 91% isolated yield.

Transparent, highly stretchable, fully self-recoverable ionic hydrogel for flexible ultra-sensitive sensors

Up to now, a variety of hydrogels have been explored for strain sensors, but simultaneous accomplishment of high stretchability, rapid full self-recovery, favourable transparency and excellent sensing properties through employing inexpensive raw materials and simple synthesis approach remains challenging. Herein, AlCl3·6H2O aqueous solution, as a sort of solvent, was utilized to facilely manufacture high performance hydrogel ionic conductors with novel one-pot dual ionic cross-linking approach. The resulting model hydrogel sensors manifested favorable transparency (>84%), excellent stretchability (1400%), good mechanical strength (421.2 kPa), outstanding rapid self-recovery (nearly full recover) and good anti-fatigue. Furthermore, our ionic hydrogel sensors demonstrated brilliant stretching sensitivity (gage factor as high as 9.6), and it displayed stable sensing performance for repeatedly real-time monitoring of both large and subtle deformations. Hence, the hydrogel sensors successfully achieved critical features combination and could serve as wearable devices to sense various human motions.

ENHANCEMENT OF SWEET GOURD SEEDLING QUALITIES PRIMING WITH H2O2

A study with three independent experiments for the seeds of three vegetable species was set at the roof top of Sunway Dormitory near the Bus Terminal, Dinajpur, Bangladesh, during March to May, 2019. The aims were to evaluate the physiological fluctuations in the seeds of sweet gourd cv. Monitaraprimed with the aqueous solutions of H2O2 and to find the suitable concentration. Each experiment had eight treatments: T1 (control/no priming), T2 (hydro-priming in plain H2O) and other six aquatic solutions of H2O2: T3 (0.5), T4 (1.0), T5 (1.5), T6 (2.0), T7 (2.5) and T8 (3.0%). The seeds were soaked for six hours in those seven media (T2 toT8). The seeds were dibbled in wooden seed flats filled-in with coarse sand. The experiments were laid-out in the Randomized Complete Block Design with three replications. Data collected for the 13 traits viz. % germination, % abnormal seedlings, shoot length, root length, seedling length, shoot dry matter, root dry matter, seedling dry matter, number of secondary roots (>1cm) per seedling, number of true leaves per seedling, relative growth rate, seedling vigor index, and root : shoot ratio (dry weight basis). Except the first two traits, the rest 11 were collected at three stagesviz.10, 20 and 30 days after dibbling (DAD). It was lucid that H2O2 was significantly (P≤0.05%) effective to improve most of the traits noted. Treatment T4 (1% concentration) was utmost helpful for sweet gourd and >1.5%, others were toxic and hindered the maximum parameters for all the three species. Nevertheless, further studies with different varieties of those three vegetables species with variable doses of H2O2, priming time and temperature could be explored before drawing valid conclusions.

SO2F2-mediated oxidation of primary and tertiary amines with 30% aqueous H2O2 solution

A highly efficient and selective oxidation of primary and tertiary amines employing SO2F2/H2O2/base system was described. Anilines were converted to the corresponding azoxybenzenes, while primary benzylamines were transformed into nitriles and secondary benzylamines were rearranged to amides. For tertiary amine substrates quinolines, isoquinolines and pyridines, their oxidation products were the corresponding N-oxides. The reaction conditions are very mild and just involve SO2F2, amines, 30% aqueous H2O2 solution, and inorganic base at room temperature. One unique advantage is that this oxidation system is just composed of inexpensive inorganic compounds without the use of any metal and organic compounds.

Photoelectrochemical sensing and mechanism investigation of hydrogen peroxide using a pristine hematite nanoarrays

In this paper, a facile hydrothermal combined with subsequent two-step post-calcination method was used to fabricate hematite (α-Fe2O3) nanoarrays on fluorine-doped SnO2 glass (FTO). The morphology, crystalline phase, optical property and surface chemical states of the fabricated α-Fe2O3 photoelectrode were characterized by scanning electron microscopy, X-ray diffraction, ultraviolet visible spectroscopy and X-ray photoelectron spectroscopy correspondingly. The α-Fe2O3 photoelectrode exhibits excellent photoelectrochemical (PEC) response toward hydrogen peroxide (H2O2) in aqueous solutions, with a low detection limit of 20 μM (S/N = 3) and wide linear range (0.01–0.09, 0.3–4, and 6–16 mM). Additionally, the α-Fe2O3 photoelectrode shows satisfying reproducibility, stability, selectivity and good feasibility for real samples. Mechanism analysis indicates, comparing with H2O, H2O2 possesses much more fast reaction kinetics over α-Fe2O3 surface, thus the recombination of photogenerated charges are reduced, followed by much more photogenerated electrons are migrated to the counter electrode via external circuit. The insight on the enhanced photocurrent, which is corelative to the concentration of H2O2 in aqueous solution, will stimulate us to further optimize the surface structure of α-Fe2O3 to gain highly efficient α-Fe2O3 based sensors.

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

Precise Construction of Stable Bimetallic Metal–Organic Frameworks with Single-Site Ti(IV) Incorporation in Nodes for Efficient Photocatalytic Oxygen Evolution

A novel methylenemalononitrile-BODIPY-based fluorescent probe for highly selective detection of hydrogen peroxide in living cells

Hydrogen peroxide (H2O2) plays vital roles in oxidative stress and signal transduction in living organisms, and its abnormal levels could be linked to many diseases. Despite numerous efforts spent, it is still urgent and of high importance to develop better H2O2 probes with good selectivity, high sensitivity and low backgrounds. To this end, a novel boron dipyrromethene (BODIPY)-based fluorescent probe with an electron-withdrawing methylenemalononitrile at the meso position has been rationally designed, successfully synthesized and investigated for detection of H2O2 in aqueous solutions and living cells, which exhibited high selectivity and sensitivity, fluorescent “turn-on” phenomenon at 540 nm, and ratiometric changes from 506 to 540 nm. Upon exposure to H2O2, a strong fluorescent emission at 540 nm appeared and the corresponding quantum yields changed from 0.009 to 0.13. The detection limit towards H2O2 was calculated to be 31 nM by the linear fluorescence change at 540 nm in the H2O2-concentration ranging from 2 to 10 μM. This probe was applicable in a pH range from 6 to 10. Meanwhile, the sensing mechanism was also confirmed by the 1H NMR and mass spectrometry, suggesting that the above changes might be ascribed to the quick addition and oxidization of the double bond. Furthermore, confocal imaging results also showed great enhancement of intracellular fluorescence upon exposure to H2O2 and PMA in RAW264.7 cells, unambiguously confirming its great potentials as a fluorescent probe for highly sensitive detection of both exogenous and endogenous H2O2 in living cells.

All-in-one photocatalysis device for one-step high concentration H2O2 photoproduction

Achieving multi-functions integrating reaction, separation and concentration into one-step catalysis process is a great challenge. Photocatalytic H2O2 generation is the cleanest and cheapest way for its production. Herein, an all-in-one photocatalytic device for H2O2 generation was designed by catalysis layer with ZIF-8/C3N4 composite and carbon dots-based evaporation layer (CDE). With this device, H2O2 solution with high concentration is obtained, and no need for extra separation and concentration processes. Under 2 sun illumination (3 h), H2O2 evolution reaches 17.13 μmol and H2O2 solution concentration gets to 10.15 mmol L−1. Mole fraction of H2O2 solution obtained by all-in-one device is 1.86 times more concentrated than that of not concentrated H2O2 solution. Besides, multiples devices can work concurrently to realize large-scale production and gain large amounts of H2O2 solution with high concentration. Moreover, all-in-one devices can be reused at least ten cycles. The relation between the structure and performance of the photocatalysis device is further studied by COMSOL Multiphysics software and mathematical analysis. All-in-one photocatalytic device promotes H2O2 photoproduction closer to the practical application due to realizing continuous production of amounts of aqueous solution of H2O2 with high concentration in one-step.

Oxidative Conversion of Glucose to Formic Acid as a Renewable Hydrogen Source Using an Abundant Solid Base Catalyst.

Formic acid is one of the most desirable liquid hydrogen carriers. The selective production of formic acid from monosaccharides in water under mild reaction conditions using solid catalysts was investigated. Calcium oxide, an abundant solid base catalyst available from seashell or limestone by thermal decomposition, was found to be the most active of the simple oxides tested, with formic acid yields of 50 % and 66 % from glucose and xylose, respectively, in 1.4 % H2O2 aqueous solution at 343 K for 30 min. The main reaction pathway is a sequential formation of formic acid from glucose by C−C bond cleavage involving aldehyde groups in the acyclic form. The reaction also involves base‐catalyzed aldose‐ketose isomerization and retroaldol reaction, resulting in the formation of fructose and trioses including glyceraldehyde and dihydroxyacetone. These intermediates were further decomposed into formic acid or glycolic acid. The catalytic activity remained unchanged for further reuse by a simple post‐calcination.

A microtubule-localizing activity-based sensing fluorescent probe for imaging hydrogen peroxide in living cells

Hydrogen peroxide (H2O2) is a major reactive oxygen species (ROS) in living systems with broad roles spanning both oxidative stress and redox signaling. Indeed, owing to its potent redox activity, regulating local sites of H2O2 generation and trafficking is critical to determining downstream physiological and/or pathological consequences. We now report the design, synthesis, and biological evaluation of Microtubule Peroxy Yellow 1 (MT-PY1), an activity-based sensing fluorescent probe bearing a microtubule-targeting moiety for detection of H2O2 in living cells. MT-PY1 utilizes a boronate trigger to show a selective and robust turn-on response to H2O2 in aqueous solution and in living cells. Live-cell microscopy experiments establish that the probe co-localizes with microtubules and retains its localization after responding to changes in levels of H2O2, including detection of endogenous H2O2 fluxes produced upon growth factor stimulation. This work adds to the arsenal of activity-based sensing probes for biological analytes that enable selective molecular imaging with subcellular resolution.

Efficient Synthesis of Monomeric Fe Species in Zeolite ZSM‐5 for the Low‐Temperature Oxidation of Methane

AbstractDirect oxidation of methane into value‐added C1 oxygenated products, such as methanol, is essential and remains a significant challenge in the field of catalysis. In this work, we have prepared Fe/ZSM‐5 materials via three different methods and investigated the influence of various preparation methods on the composition and catalytic performance of Fe/ZSM‐5 for the low‐temperature oxidation of methane. Through a combination of scanning transmission electron microscopy, ultraviolet‐visible diffuse reflectance and 57Fe Mössbauer spectroscopy, we have found that the highest proportion of monomeric Fe species of 71 % could be achieved in the ZSM‐5 zeolite by the solid‐state ion‐exchange method, affording an excellent C1 oxygenates yield of 120 mol/molFe with a C1 oxygenates selectivity of 96 % at 50 °C for 30 min in the aqueous solution of H2O2.

Fabrication of mesostructured Y2O3:Eu3+ materials from metal–organic frameworks and their H2O2-sensitive turn-off luminescence

Mesostructured Y2O3:Eu3+ phosphor particles were fabricated by a pyrolytic conversion from a pertinent metal–organic framework (MOF), namely, MOF-76(Y):Eu with 1,3,5-benzenetricarboxylic acid ligands, aiming at luminescence sensing of H2O2. Large rod-like MOF-76(Y):Eu particles 301 ± 150 μm in average length were initially obtained by a reaction at 80 °C for 24 h. They were converted to rod-like Y2O3:Eu3+ particles 122 ± 34 μm in average length after heating at 500 °C. The Y2O3:Eu3+ particles actually consisted of primary nanoparticles 7.55 ± 1.43 nm in average size and had a mesoporous structure with a high specific surface area of 80.8 m2 g−1. The photoluminescence intensity of the Y2O3:Eu3+ particles decreased after treating with an aqueous H2O2 solution, which was recognized as H2O2-responsive turn-off luminescence. Three other kinds of Y2O3:Eu3+ particles, including those obtained from other MOF particles synthesized at room temperature, were also prepared and the effects of the microstructure on the degree of turn-off luminescence were examined. It was then observed that the H2O2-sensitivity was enhanced more effectively by using the MOF-derived Y2O3:Eu3+ particles having the higher specific surface area.

Oxygen atom transfer catalysis by dioxidomolybdenum(VI) complexes of pyridyl aminophenolate ligands

A series of new cationic dioxidomolybdenum(VI) complexes [MoO2(Ln)]PF6 (2–5) with the tripodal tetradentate pyridyl aminophenolate ligands HL2-HL5 have been synthesized and characterized. Ligands HL2-HL4 carry substituents in the 4-position of the phenolate ring, viz. Cl, Br and NO2, respectively, whereas the ligand HL5, N-(2-hydroxy-3,5-di-tert-butylbenzyl)-N,N-bis(2-pyridylmethyl)amine, is a derivative of 3,5-di-tert-butylsalicylaldehyde. X-ray crystal structures of complexes 2, 3 and 5 reveal that they have a distorted octahedral geometry with the bonding parameters around the metal centres being practically similar. Stoichiometric oxygen atom transfer (OAT) properties of 5 with PPh3 were investigated using UV–Vis, 31P NMR and mass spectrometry. In CH2Cl2 solution, a dimeric Mo(V) complex [(µ-O){MoO(L5)}2](PF6)26 was formed while in methanol solution an air-sensitive Mo(IV) complex [MoO(OCH3)(L5)] 7 was obtained. The solid-state structure of the µ-oxo bridged dimer 6 was determined by X-ray diffraction. Complex 7 is unstable under ambient conditions and capable of reducing DMSO, thus showing reactivity analogous to that of DMSO reductases. Similarly, the OAT reactions of complexes 2–4 also resulted in the formation of dimeric Mo(V) and unsaturated monomeric Mo(IV) complexes that are analogous to complexes 6 and 7. Catalytic OAT at 25 °C could also be observed, using complexes 1–5 as catalysts for oxidation of PPh3 in deuterated dimethylsulfoxide (DMSO‑d6), which functioned both as a solvent and oxidant. All complexes were also tested as catalysts for sulfoxidation of methyl-p-tolylsulfide and epoxidation of various alkene substrates with tert-butyl hydroperoxide (TBHP) as an oxidant. Complex 1 did not exhibit any sulfoxidation activity under the conditions used, while 2–5 catalyzed the sulfoxidation of methyl-p-tolylsulfide. Only complexes 2 and 3, with ligands containing halide substituents, exhibited good to moderate activity for epoxidation of all alkene substrates studied, and, in general, good activity for all molybdenum(VI) catalysts was only exhibited when cis-cyclooctene was used as a substrate. No complex catalysed epoxidation of cis-cyclooctene when an aqueous solution of H2O2 was used as potential oxidant.

Patterning of transition metal dichalcogenides catalyzed by surface plasmons with atomic precision

Summary Plasmon-induced charge transfer has drawn considerable interests and spurred rapid developments of photovoltaics and photocatalysis. Various plasmonic metal/transition metal dichalcogenide (TMD) heterostructures have been developed to promote charge separation. For plasmon-induced catalysis, the transformation of TMDs is rare, and the erosion of TMDs has not yet been reported. Here, we report the etching of two-dimensional TMDs by planar surface plasmon polaritons (SPPs). We found that SPPs can etch various TMDs into desired layers and lateral size through controlling the light power and incident direction. In aqueous media, the strong plasmonic coupling at Au/MoS2 interface generates holes in the valence band of MoS2 that can weaken its interlayer interaction. As a synergistic effect, the plasmonic hot electrons produce oxidizing H2O2 to dissolve MoS2 from the top layers. Our results provide a new perspective for understanding the plasmonic coupling at metal-TMD interfaces and a reliable route toward fabricating well-defined TMDs.