The temperature dependence of the solubility product of copper (II) oxalate CuC(2)O(4)was determined in the range 20-45 degrees C from the results of precipitation potentiometric titration of aqueous Cu(2+)solution with oxalate solution. The titration was performed with a copper indicator electrode. Based on the obtained values of the solubility product, the formation enthalpy and entropy of solid copper oxalate have been found.

Abstract Treatment of plant biomass with ozone is a promising delignification method. It was shown that lignin removal from the cell wall during ozonation was limited by topochemical reactions and toke place in the secondary rather in the primary cell wall. The separation of cellulose microfibrils, the loss of cell wall stiffness and complete removal of intercellular substance during the delignification process were visualized by SEM. The dependence of the average diameter of the cellulose microfibril aggregates in the cell wall of ozonized straw on ozone consumption was studied. Lignin removal caused an increase of size of cellulose microfibrils aggregates. It was demonstrated that there was an optimal degree of delignification, at which cellulose became more accessible to enzymes in the subsequent bioconversion processes. The data on the ozone consumption, residual lignin content, and sugars yield in the enzymatic hydrolysis of ozonized wheat straw were obtained. It was also found that the optimum delignification degree for sugars yield was ≈10% of residual lignin content and optimum ozone consumption was 2 mol·О3/mol C9PPU (phenylpropane structural unit) of lignin in raw straw.

Present work is devoted to the spark plasma sintering (SPS) of multiwalled carbon nanotubes (MWCNTs), which was found to be an effective route to their compactisation. The products, obtained under different values of pressure (from 10 up to 22 MPa) and temperature (from 1000 up to 1800 degrees C), have been investigated by thermal analysis, SEM, HRTEM, Raman spectroscopy, X-Rays diffraction and low temperature nitrogen sorptometry as well as physical properties characterisation. It was found that the increase of temperature and pressure during SPS increased the density of the sintered samples and decreased their surface area. It is accompanied by appearance of the mesopores. Raman spectroscopy, TG and X-ray data show that the defectiveness of the CNTs decreased during SPS. Using a focused beam of the transmission electron microscope in-situ experimental simulation of the CNT consolidation and their crosslinking was successfully performed for the first time.

The aim of the research is to choose the most efficient adsorbent for two-stage ozone-sorption purification of groundwater containing both trichloroethylene (TCE) and tetrachloroethylene (PCE) between three carbon sorbents produced in Russia (AUT-M, CAUSORB-221, and AG-3). Sorption isotherms of TCE and PCE on AUT-M and CAUSORB-221 at 296 K were fitted by the Freundlich equation. The better TCE and PCE sorption ability of AUT-M in comparison with CAUSORB - 221 and AG-3 was demonstrated. The optimum parameters for ozonation and sorption stages of groundwater purification from TCE and PCE are elucidated using laboratory and pilot-plant scales. Prolonged test of this technology for purification of ground demonstrated that the higher achievable efficiency of destruction with ozone is 94% for TCE and 38% for PCE. Ozonation-sorption treatment of groundwater allows one to achieve TCE and PCE removal efficiency of 96-97% and 92-94% correspondingly. The most efficient carbon sorbent is microporous carbon fiber AUT-M. Using this sorbent, TCE and PCE concentrations in treated water decrease below the MPC level (5 mu g/L) adopted in Russia. It is concluded that the combination of ozonation with sorption of residual contaminants by carbon sorbents is a promising way for the purification of waters containing chlorinated contaminants.

General patterns of ozone pretreatment for subsequent fermentation into sugars are found, based on samples of different types of plant biomass. It is shown that the reactivity of plant substrates pretreated with ozone is determined by the amount of consumed ozone, and the rate of ozone consumption depends on the content of water in a sample. Optimum values of moisture (~2FSP) and ozone consumption (2–3 mol O 3 /C 9 PPU lignin) are found.

The transformation of pinewood under the action of ozone is investigated via synchronous thermal analysis in combination with the mass spectral (MS) analysis of incondensable products of pyrolysis. TG/DTG and MS data are analyzed from the viewpoint of the conversion of wood lignin (LG), hemicelluloses (HCs), and cellulose (CL) in the composition of products of LG oxidation using different amounts of absorbed ozone. Results from TG/DTG analysis indicate the destruction of hemicelluloses during pinewood ozonation. The lower temperature of the thermal destruction of cellulose material (CM) produced from ozonized wood correlates with the lower LG content, the depolimerization of CL, and the formation of products of oxidation in biomass ozonation. Data from TG/DTG and MS analyses suggest that when wood is treated with ozone, aromatic lignin structures are not only destroyed but polymerized as well.

The stability of 20[Formula: see text]wt.% Co/CNT catalyst was tested in the Fischer–Tropsch synthesis and the structural transformations both in the catalyst and support were analyzed. The catalyst showed high conversion and stable selectivity during three weeks of the test, which was attributed to the optimal and stable cobalt particle size of [Formula: see text]13–14[Formula: see text]nm promoted by the support pre-oxidation. XPS, Raman, and nitrogen adsorption data revealed that the carefully chosen catalyst annealing and reduction conditions ensured the preservation of the support structure.

Dedicated the memory of Akademician Valery Vasilievich Lunin, a friend, colleague, teacher, founder and leader of the research into application of supercritical fluids in chemistry. This review analyzes the rapidly developing applications of supercritical fluids, mainly supercritical carbon dioxide, in catalysis, chemistry of high-molecular-weight compounds, and medicinal chemistry in Russia and abroad. It considers the methods of catalyst preparation based on impregnation of inorganic and organic supports with metal-containing compounds, immobilization of organometallic and metal complex reagents in matrices of oxide and polymer supports, and deposition processes employing supercritical fluids. An analysis is presented of the prospects for applying CO 2 and some organic compounds, such as aliphatic alcohols, in sub- and supercritical states as reactants and (or) solvents for catalytic reactions of hydrocarbon isomerization and cracking, hydrogenation, dehydrogenation, oxidation, etc., including the asymmetric reactions. The review discusses processes of synthesizing and modifying polymer materials for various purposes, including aerogels, foams, and composites impregnated with photochromes, in a supercritical fluid medium. Special attention is paid to supercritical one-pot processes, which make the techniques of obtaining new materials simpler, less expensive, and more efficient. The work investigates the effect of supercritical CO 2 on the morphology, gas separation characteristics, and dielectric properties of polymers. One of the promising applications of supercritical fluids in medicine is the use in transplantology and pharmacology, for example, for the preparation of drug polymorphs with higher bioavailability. The review also provides an overview of the recent data on the use of EPR spectroscopy for studying the properties of supercritical fluids, including those exhibited in the vicinity of the critical point and identifying the intermediates of chemical reactions in such media.

Впервые метод электронного парамагнитного резонанса (ЭПР) использован для количественного описания процесса высвобождения парамагнитного биологически активного вещества из полимерного биодеградируемого матрикса. В качестве парамагнитного соединения выбран стандартный спиновый зонд TEMPONE, в качестве полимера - D,L-полилактид, вспененный в среде сверхкритического диоксида углерода (СК-CO). Показано, что высвобождение TEMPONE из пористого D,L-полилактида в фосфатный буфер с pH 7,4 происходит постепенно, без периодов выброса и стагнации, что свидетельствует о принципиальной возможности применения используемой технологии импрегнации и вспенивания полимера для создания материалов медицинского назначения. For the first time, the EPR-method was used to quantitatively describe the process of releasing a paramagnetic biologically active substance from a polymer biodegradable matrix. A standard TEMPONE spin probe was chosen as the paramagnetic compound, and D, L-polylactide foamed in supercritical carbon dioxide was used as the polymer. It is shown that the release of TEMPONE from porous D, L-polylactide into phosphate buffer with pH 7,4 occurs gradually, without periods of burst and stagnation, which indicates that it is possible in principle to use the used technology of impregnation and foaming of the polymer to create materials for medicalpurposes.

Porous oxide materials are widely used in environmental catalysis owing to their outstanding properties such as high specific surface area, enhanced mass transport and diffusion, and accessibility of active sites. Oxides of metals with variable oxidation state such as ceria and double oxides based on ceria also provide high oxygen storage capacity which is important in a huge number of oxidation processes. The outstanding progress in the development of hierarchically organized porous oxide catalysts relates to the use of template synthetic methods. Single and mixed oxides with enhanced porous structure can serve both as supports for the catalysts of different nature and active components for catalytic oxidation of volatile organic compounds, soot particles and other environmentally dangerous components of exhaust gases, in hydrocarbons reforming, water gas shift reaction and photocatalytic transformations. This review highlights the recent progress in synthetic strategies using different types of templates (artificial and biological, hard and soft), including combined ones, in the preparation of single and mixed oxide catalysts based on ceria, and provides examples of their application in the main areas of environmental catalysis.

Lithium and complex lithium greases were modified by few-layer graphene nanoflakes. Tribological tests demonstrate improvement of the lubricating characteristics, e.g. increase of the welding load and decrease of the wear scar diameter after the modification. XPS method showed occurrence tribochemical reaction between lithium 12-hydroxystearate molecules and graphene nanoflakes surface during exploitation of the grease. It was shown that graphene nanoflakes are corrosion-inactive in lubricating compositions and compatible with modern additive packages.

N-doped nanocarbons are promising materials for metal-free and supported catalysts. Three types of N-doped carbon nanotubes (N-CNTs) were synthesized by chemical vapor deposition (CVD), by oxidation of the CVD produced N-CNTs with nitric acid, and by post-doping of oxidized undoped CNTs with ammonia. Cobalt catalysts with 20[Formula: see text]wt.% loading supported on N-CNTs were tested in the Fischer–Tropsch synthesis. Oxidized N-CNTs containing pyridone groups demonstrated the best stabilization of cobalt nanoparticles. The catalyst on this support showed the highest selectivity towards [Formula: see text] hydrocarbons. The performance of the catalyst supported on CVD N-CNTs was the worst because of the large variation in cobalt particle size and low reduction degree. The catalysts supported on post-doped CNTs demonstrated the best activity, but high methane selectivity because of the low Co particle size ([Formula: see text][Formula: see text]nm).

The effectiveness of ozone pretreatment of pine wood for subsequent fermentation in sugars is studied. Kinetic curves for the ozone consumption by the samples with different water contents were obtained, and the optimum wood moisture values are determined during ozonation (50–70 wt %). It is found that the yield of reducing sugars in the enzymatic reaction grows in proportion to the amount of absorbed ozone and reaches a maximum at an ozone consumption of around 3 mmol/g of biomass, which corresponds to 2 mol-equivalent of O 3 /C 9 PPU lignin contained in the initial material. Upon prolonged ozonation, the yield of sugars falls.

The template pyrolysis synthesis, as a bottom-up approach, and oxidation, as a top-down approach, were combined to produce pristine and nitrogen doped carbon dots. Varying the precursor type, synthesis temperature and oxidation time the color of carbon dots was tuned from green to orange because of the bandgap changes and formation of interband states. TEM, Raman, and XPS data revealed the graphene core of carbon dots with the shell of carboxyl and hydroxyl functionalities. The bulk and surface N-doping of the carbon dots affected their photoluminescence in a different way because of the opposite effect on the p-electron system: the core modification led to a blue shift, while the surface amination resulted in a red shift. A blue shift was also observed for the undoped dots with increasing the synthesis temperature, while more prolonged oxidation led to a red shift. Excitation with different wavelengths revealed the inhomogeneity of photoluminescence sites in nitrogen-doped carbon dots.