A rate equation for a gas-liquid bimolecular reaction at low gas concentrations

The film model was used to suggest an equation that could be used to describe kinetics when the rate of a chemical reaction is first-order in the dissolved gas and dissolved substance with which the dissolved gas reacts. The equation is applicable at arbitrary solute concentrations and allows the kinetics of gas-liquid processes to be analyzed without assumptions concerning kinetically or diffusion controlled conditions etc.     

Effect of the conditions of structure formation on the physicochemical properties of ozonated shungites

It was investigated the influence of ozone on the physicochemical properties of shungites (type 1) (75–98% C) from Nigozero and Chebolaksha deposits (Karelia) formed by hydrothermal (Nigozero) and high-temperature (Chebolaksha) processes. Ozonation was found to affect the specific surface and the total pore volume of shungites considerably. The pore size distribution pattern depends on the volume morphology (texture) of the sample. An increase in the temperature and pressure during the structure formation of shungite (Chebolaksha) led to a shift of the maximum on the distribution pattern towards the formation of mesopores. The size distribution of pores with the dominant contents of micro- and submesopores for both shungites correlated with the basic structural nanoelements of shungite carbon. The peculiarities of the ozonation of shungite nanocarbon found previously (the non-steady state vibrational kinetics of ozonation and the absence of carbon(II) oxide among the reaction products) were confirmed.     

Lignin transformations and reactivity upon ozonation in aqueous media

The reaction of ozone with lignin in aqueous acidic solutions is investigated. The Danckwerst model is used to describe the kinetics of gas/liquid processes occurring in a bubble reactor. The efficient ozonation rate of a soluble lignin analog, sodium lignosulfate, is determined. The main lines of the reaction between ozone and lignin are revealed on the basis of kinetic analysis results and IR and UV spectroscopy data.     

Dehydroxylation and formation of KU-1 silica glass surface defects during annealing

Formation of KU-1 silica glass surface defects under annealing is considered. Based on experimental data obtained by annealing of silica glass samples in the temperature range of 800–980°C, it is shown that internal stress forming due to dehydroxylation of the surface zone is the main cause of surface defects. To determine the depth of this zone for different annealing conditions, a formula is suggested. It shows that the internal stress is less than the critical one and the silica glass surface is not changed if the annealing temperature is 850°C or higher due to the fast relaxation rate. At a lower annealing temperature, the surface defects are formed in a few tens of hours during annealing.     

The dependence of the oxygen-exchange properties of Ce<Subscript>0.5</Subscript>Zr<Subscript>0.5</Subscript>O<Subscript>2</Subscript> on the method of synthesis

The oxygen-exchange properties of Ce_0.5Zr_0.5O₂ samples prepared by the traditional coprecipitation method with the use of a biotemplate (pine wood sawdust) were studied by the temperature-programmed reduction and oxidation methods. The use of the template and the presence of alkali and alkaline-earth metal cations in it provides a high mobility of oxygen and a high capacity with respect to oxygen in the biomorphic oxide. Impurities cause the segregation of Ce- and Zr-enriched phases under high-temperature treatment conditions, which worsens the redox properties of the biomorphic sample. Nevertheless, the ability of the biomorphic sample to play the role of an “oxygen buffer” remains high compared with the coprecipitated oxide subjected to similar treatments.     

Determination of uptake coefficient for ClO radicals on the surface of mineral salts

The uptake of ClO radicals on KBr, NaCl, and NaBr dry solid films was studied at 1 Torr pressure of helium over the temperature range 290-350 K using a flow tube technique with a modulated molecular beam mass spectrometer as the detection method. A Pyrex tube with the deposited salt sample was introduced into the flow reactor along its axis. The ClO uptake coefficient on the KBr surface did not depend on temperature within the experimental accuracy of ～20%. Chlorine oxide radicals were prepared using the reaction of Cl with ozone. It was found out that the ClO uptake coefficient strongly depended on ozone concentration. The uptake coefficients at T = 293 K and [O(3)] = 4.6 × 10(13) molecules cm(-3) were found to be (9.6 ± 5.7) × 10(-4), (3.7 ± 1.5) × 10(-4), and (12.3 ± 3.6) × 10(-4) for KBr, NaCl, and NaBr, respectively. Bromine-containing species were not observed during the interaction of ClO radicals with KBr film. The results obtained indicate that the ClO loss through heterogeneous interaction with salt surface is not sufficiently rapid to compete with gas-phase self-reaction in the atmosphere.     

The germanium(II) ate complex [Ph3PiPr][Ge(OCOMe)3]: the first structurally characterized compound containing a discrete [E14(II)O3](−) (E14(II) = Si,Ge, Sn or Pb) anion

An X‐ray diffraction study reveals an unusual structure of the new thermally stable germanium(II) ate complex [Ph₃PⁱPr][Ge(OAc)₃] (4) containing a discrete [Ge(OAc)₃]^(?) anion containing monodentate acetate ligands with a trigonal pyramidal germanium centre. Copyright © 2005 John Wiley & Sons, Ltd.     

XPS study of the electronic structure of heterometallic complexes [Fe2MO(O2CCH3)6(H2O)3] · 3H2O (M = Co,Ni)

Heterometallic compounds of general formula [Fe ₂ ^III M^IIO(O₂CR)₆(H₂O)₃] · 3H₂O (R = CH₃, M = Co, Ni; R = CCl₃, M = Co, Ni) have been studied by XPS. The compounds have been identified as high-spin complexes with metal atoms in oxidation states M(II) and M(III). Analysis of the XPS data revealed the tendency of the XPS pattern and magnetic parameters of molecules to change with a change in the electronic nature of metal atoms. The assignment is based on the degree of covalence of the M-O bond. In chloro-substituted heterocomplexes, electron density delocalization on the metal atoms with metal-to-ligand charge transfer through three bonds (M-O-C-C) is observed. The substitution in terminal groups leads to the change in the electron density distribution between the carboxylate and terminal groups.     

Mechanism of the formation of hydrogen tetroxide and peroxide via low-temperature interaction between hydrogen atoms and molecular oxygen

A mechanism and kinetic model for the synthesis of peroxide radical condensate via the low-temperature interaction of hydrogen atoms with O₂ molecules is proposed. The main components of the reaction, hydrogen tetroxide H₂O₄ and hydrogen peroxide H₂O₂, are formed in a low-temperature liquid layer formed near the cold surface during synthesis. Molecules of H₂O₄ and H₂O₂ are stabilized by transitioning to the solid phase. The dependences of the \(N_{O_2 } /N_{H_2 O_2 }\) ratio on the ratio of concentrations of H and O₂ in the gas phase, calculated on the basis of the model, are consistent with the experimental data.     

NiO and ZrO2-based catalysts in the reaction of complete methane oxidation

The reaction of complete methane oxidation over deposited catalysts (NiO/ZrO₂ and NiO/YSZ) and binary oxides NiO_ZrO₂ produced by co-precipitation, by the sol gel method, and using a bio-template (NiO content in the samples, 10.1 mol %) is investigated. It is shown that binary oxides cause methane oxidation at lower temperatures than their deposited analogue: the temperature of methane half-transformation is 470, 500, and 520°C for binary oxides, while T ₅₀ = 570°C for NiO/ZrO₂. Major factors affecting the activity of binary oxides in the methane oxidation reaction are determined: the dispersion of the active phase (NiO) and the availability of the second component with high mobility of the lattice oxygen.