Electrocatalytic oxidation of aromatic pollutants (aniline, Methyl Orange, Eriochrome blue SE) is studied on lead dioxide, boron doped diamond, and ruthenium- and titanium-oxide-based anodes (DSA, dimensionally stable anode). The catalytic properties of the tested materials are studied using cyclic voltammetry and galvanostatic electrolysis. The activity of electrodes toward the electrochemical conversion of organics is shown to increase in the sequence of DSA < lead dioxide < boron doped diamond. The oxidation rate decreases in the order of Eriochrome blue SE > Methyl Orange > aniline for all electrodes. The oxidation process of the compounds corresponds to the pseudo-first-order reaction kinetics. The apparent rate constant grows at an increase in the applied current density and decrease in the initial pollutant concentration. The formation of both •OH and $${\text{SO}}_{4}^{{2\centerdot {\kern 1pt} - }}$$ radicals is confirmed by the free radical quenching studies; their contribution to the Eriochrome blue SE dye destruction process is evaluated.

The efficiency of new brands of technical carbon CH210 and C40 in the electrogeneration of Н2О2 from О2 in gas-diffusion electrodes (GDE) on their basis is studied in acidic solutions of the 0.5 М K2SO4 : 0.1 M H2SO4 (3 : 1) electrolyte. The textural characteristics of original materials and their mixtures with polytetrafluoroethylene used as the hydrophobizer are determined by low-temperature nitrogen adsorption as well as their electric double layer capacitance. For a comparison, similar studies are also carried out with technical carbon Vulcan XC-72. The rate constants for hydrogen peroxide decomposition on these materials in acidic solutions are determined. The data on the kinetics of hydrogen peroxide accumulation at the overall current density of 1500 А/m2 are as follows: the 6 h electrolysis produces the solution with Н2О2 concentration exceeding 2.5 М with the current efficiency higher than 70.0%. It is concluded that in this case, the surface area is not the determining factor. The technical carbons СН210 and С40 are comparable as regards their efficiency with the well-known technical carbon Vulcan XC-72 and can be used as electrocatalysts in GDE for electrosynthesis of Н2О2 from О2.

The results and prospects of the in situ (in the cell volume) and ex situ (outside the cell) use of aqueous solutions of hydrogen peroxide electrogenerated from oxygen in gas-diffusion electrodes (GDE) of carbon black are discussed. It is shown that using GDE based on technological A-437E carbon (acetylene black) and mesostructured carbon CMK-3 allows the Н2О2 solution with the concentration higher than 3 M to be obtained. It is found that electrosynthesized hydrogen peroxide may be used in situ with the high efficiency both in the indirect electrosynthesis of important organic and inorganic target products and in the destruction of organic and inorganic pollutants present in waste waters of different origin. Under the ex situ conditions, it is possible to synthesize the more concentrated solutions of Н2О2, organic peroxoacids, and inorganic peroxosolvates and also to carry out mineralization of exometabolites in autonomous life-support systems. These results may be helpful in selecting the most appropriate versions of using hydrogen peroxide solutions electrogenerated from oxygen for solving particular problems.

The efficiency of new brands of technical carbon CH210 and C40 in the electrogeneration of H(2)O(2)from O(2)in gas-diffusion electrodes (GDE) on their basis is studied in acidic solutions of the 0.5 \M K2SO4: 0.1 M H2SO4(3 : 1) electrolyte. The textural characteristics of original materials and their mixtures with polytetrafluoroethylene used as the hydrophobizer are determined by low-temperature nitrogen adsorption as well as their electric double layer capacitance. For a comparison, similar studies are also carried out with technical carbon Vulcan XC-72. The rate constants for hydrogen peroxide decomposition on these materials in acidic solutions are determined. The data on the kinetics of hydrogen peroxide accumulation at the overall current density of 1500 A/m(2)are as follows: the 6 h electrolysis produces the solution with H(2)O(2)concentration exceeding 2.5 \M with the current efficiency higher than 70.0%. It is concluded that in this case, the surface area is not the determining factor. The technical carbons CH210 and C40 are comparable as regards their efficiency with the well-known technical carbon Vulcan XC-72 and can be used as electrocatalysts in GDE for electrosynthesis of H(2)O(2)from O-2.

Electrochemical oxidation for degradation of industrial dye Methyl Orange in aqueous sulfate solutions with various electrocatalytic materials: boron-doped diamond electrode and electrode based on titanium and ruthenium oxides. The influence exerted by the main working parameters of electrolysis (current density, concentration of Methyl Orange, pH) on the discoloration efficiency and on the chemical oxygen demand (COD) was examined. It was shown that an increase in the current density and a decrease in the pollutant concentration improve the process efficiency. However, this leads to an increase in the specific electric energy consumption per unit mass of COD. It was found that the boron-doped diamond electrode is a more efficient electrocatalytic material, compared with electrode based on titanium and ruthenium oxides. At low concentrations of Methyl Orange (<50 mg L–1), there exists the possibility in principle of using the electrode based on titanium and ruthenium oxides not only for discoloration, but also for making lower the COD level.

Mesostructured carbon CMK-3 (Carbon Mesostructured by KAIST) synthesized by the template method is studied as the electrocatalyst for electrosynthesis of Н 2 О 2 from О 2 in a gas-diffusion electrode (GDE) in alkaline and acidic solutions. The texture characteristics of the original material and its mixture with hydrophobizer (polytetrafluoroethylene) are studied by the method of low-temperature nitrogen adsorption. The rate constants for hydrogen peroxide decomposition on these materials in alkaline and acidic solutions are calculated. Kinetic parameters of oxygen reduction in alkaline and acidic solutions are determined as well as the capacitance of gas-diffusion electrodes based on mesocarbon. The selectivity of the electrocatalyst is estimated by finding the current fracture γ consumed in oxygen reduction to hydrogen peroxide. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis of Н 2 О 2 from О 2 are obtained. The acidic solution of hydrogen peroxide with the concentration more than 3 M is obtained with the current efficiency higher than 80%.

Mesostructured carbon CMK-3 (Carbon Mesostructured by KAIST) synthesized by the template method is studied as the electrocatalyst for electrosynthesis of Н2О2 from О2 in a gas-diffusion electrode (GDE) in alkaline and acidic solutions. The texture characteristics of the original material and its mixture with hydrophobizer (polytetrafluoroethylene) are studied by the method of low-temperature nitrogen adsorption. The rate constants for hydrogen peroxide decomposition on these materials in alkaline and acidic solutions are calculated. Kinetic parameters of oxygen reduction in alkaline and acidic solutions are determined as well as the capacitance of gas-diffusion electrodes based on mesocarbon. The selectivity of the electrocatalyst is estimated by finding the current fracture γ consumed in oxygen reduction to hydrogen peroxide. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis of Н2О2 from О2 are obtained. The acidic solution of hydrogen peroxide with the concentration more than 3 M is obtained with the current efficiency higher than 80%.

Furnace black СН600 was studied as a catalyst for electrosynthesis of Н 2 О 2 from О 2 in a gas diffusion electrode in alkaline and acidic solutions. The texture properties of the starting black СН600 and gas diffusion electrodes (GDEs) based on it were determined by the low-temperature nitrogen adsorption (LTNA) method. The rate constants of Н 2 О 2 decomposition on black and its mixtures with fluoroplast-4D in acidic and alkaline solutions of electrolyte were calculated. The process selectivity γ (the current fraction spent on the two-electron reduction of oxygen), kinetic parameters of oxygen reduction, and double-layer capacity of the СН600-based GDE were determined. Data on the kinetics of hydrogen peroxide accumulation during electrosynthesis from oxygen in СН600-based GDE in acidic and alkaline solutions were obtained.

Mesoporous carbon prepared by template synthesis using SBA-15 mesostructured silicate material was tested as an electrocatalyst for electrochemical synthesis of Н 2 О 2 from О 2 in a two-layer gas-diffusion electrode. Preparative syntheses of Н 2 О 2 in 0.06 to 2.0 M aqueous solutions of various electrolytes (pH 2–8) were performed at current densities in the interval 0.05–0.19 A cm –2 . Solutions with an Н 2 О 2 concentration of 1–2.8 M were prepared with 46–70% current efficiency. Thus, the material tested shows promise as an electrocatalyst of two-electron reduction of oxygen to Н 2 О 2 .

Kinetics and selectivity of oxidation of dyes (Methyl Orange and Chrome Dark Blue) on a lead dioxide (Pb/PbO2) anode at various current densities, substrate concentrations, and pH values with the use of various active oxygen species was studied. It was shown that the electrochemical oxidation of dyes on the Pb/PbO2 anode occurs rather effectively under the chosen conditions. The mineralization efficiency in 5 h was 51 to 89.5 and 93 to 100% for, respectively, Methyl Orange and Chrome Dark Blue, depending on the electrolysis conditions.

Kinetics and selectivity of the aniline oxidation on a boron-doped diamond electrode and lead dioxide anode (Pb/PbO 2 ) in an acid electrolyte were studied under various generation conditions of active oxygen species. The resulting kinetic dependences can be described by a pseudo-first-order equation. The apparent rate constants of the process were determined for two electrolysis modes: direct anodic oxidation and oxidation with addition of hydrogen peroxide. UV spectroscopy was used to determine that the aniline destruction process occurs via formation of a number of intermediate products (benzoquinone, carboxylic acids). It was shown that the aniline destruction process can occur with a rather high efficiency (~80–90%) on the electrode types under study.

New graphitized carbon materials: technical carbon N220, С140, and СН85 (Omsktekhuglerod) were studied as catalysts of electrosynthesis of alkaline solutions of hydrogen peroxide from oxygen in gasdiffusion electrodes (GDEs). The kinetic parameters of oxygen reduction in alkaline solution and the capacity of gas-diffusion electrodes based on technical carbon N220, С140, and СН85 were determined. Data on the kinetics of hydrogen peroxide accumulation were obtained at different current densities. The fraction of current γ spent on the reduction of oxygen to hydrogen peroxide was determined. The rate constants of hydrogen peroxide decomposition under the given conditions were calculated.

The model reagents substrates, 1-butanol and 1-nonanol are used to study the general kinetic regularities of indirect electrocatalytic oxidation of aliphatic alcohols on conventional (Pb/PbO2) and catalytically active (oxide–hydroxide–nickel) electrodes to the corresponding carboxylic acids (butyric and pelargonic) at the participation of active oxygen forms (AOF) generated in situ from O2, H2O2, and H2O. It is found that the kinetics of the alcohol oxidation reaction correspond to the pseudo first order when the studied AOF generation schemes are used. The effect of the nature of electrode materials on the kinetic regularities of oxidation of aliphatic alcohols to the corresponding carboxylic acids is established for the aspects pointing to the presence of different active forms of bound oxygen determining the possible reaction routes. On the basis of the obtained results, the main possible oxidation routes with the participation of active oxygen generated in situ are considered.

The indirect electrocatalytic oxidation of glycerin on the platinum electrode in the acidic electrolyte involving active oxygen forms is studied. The dependence of selectivity of glycerin oxidation on the current density and concentration of substrate are investigated. It is found that the oxidation proceeds via the stage of formation of glycerin aldehyde, which can be obtained as the target product with a current efficiency of 72% and the substance yield of 26%. Formic acid is the main by-product of oxidation (0.17–0.29 M), glycolic and oxalic acids are contained in trace amounts. An additional presence of active oxygen forms in the studied electrolytes reduces the yield of glycerin aldehyde as a result of its further deeper oxidation to carboxylic acids.