The role of primary (the particles’ size) and secondary (the particles’ content in the material) size effects of metal–ion-exchanger composites in the oxygen electrochemical reduction is elucidated. To this purpose, metal–ion-exchanger particulate composites with different grain size and the metal (Cu) particles’ content are prepared as spherical grains, based on macroporous sulfonic cation-exchange matrix (Lewatit K 2620). X-ray diffraction analysis showed the deposited metal basic particles to be nanosized. A special feature of the metal particles is that during the repeated cycles of their chemical deposition into the ion-exchange matrix pores both the capacity ε , and the particles’ radius r_0 increased. On this reason, the primary and secondary size effects appeared being interconnected in a common nanosized complex f = ε/ . -0emr_0. With the increasing of the capacity the complex increased up to certain limiting value, which is connected with percolation transition from separate metal clusters to collective associates. Correspondingly, the reduced oxygen specific amount also reached its constant value. The oxygen electroreduction process reached quasi-steady-state regime.

The process of electrochemical deoxygenation of water in an open flow system using a high-capacity Cu(0)-containing nanocomposite based on a Lewatit K 2620(Na + ) ion-exchange matrix is theoretically substantiated and implemented. Functioning is ensured by the simultaneous reduction of oxygen by means of polarization by an external current and due to the oxidation of copper nanoparticles with the formation of solid-phase products. It is shown that in a multistage electrochemical block filled with a granular nanocomposite layer, the process reaches a steady state over time, the rate of which is controlled by the value of the polarizing current. A seven-stage electrochemical unit is capable of continuously deoxygenating water by 95–96%. An additional chemical block increases the level of water deoxygenation to 99.9% or more. Theoretical calculation shows that for a rather long period (~10 4 h) the residual oxygen content can be ~1–3 μg/L (ppb).

The behavior of copper ion-exchange composites with metal particles of various sizes and contents in the electroreduction of oxygen dissolved in water have been studied. The primary size effect is significant for samples with low metal capacity: the smaller the metal particle size, the higher the process rate. At the same time, for samples with high metal capacity, the process occurs at approximately the same rate on copper particles obtained using different reducing agents due to the comparable size. A secondary size effect is observed due to the collective interaction of metal particles. The size effect was taken into account along with the effect of the content of metal particles using the proposed nanosized complex, which represents the ratio of capacity and size. At the level of electronic conductivity percolation, the nanosized complex reaches the limiting value corresponding to the highest degree of development of the reaction surface, which makes it possible to increase the current to the maximum current capacity. The reduction of oxygen occurs along several routes: electroreduction on copper particles, mainly on the surface of nanocomposite grains; and autocatalytic chemical reaction with electroregenerated metal nanoparticles in the nanocomposite grains. The electroreduction of oxygen generally reaches an intense steady-state mode.

New metal-polymer nanocomposites for deep water deoxygenation have been obtained and studied. A macro- and monoporous sulphocation exchanger with a nanometer pore size was used as the polymer matrix, and the metal was nanodispersed copper deposited in the pores of the matrix. A specific feature of the studied nanocomposites is their sodium ionic form, which eliminates the possibility of the formation of soluble copper oxidation products. The established linear dependence of the copper capacity on the number of cycles of ion-exchange saturation - chemical deposition shows that the process of metal deposition into the pores of the matrix does not have significant obstacles during 10 cycles and contributes to the production of high-capacity samples. The high efficiency and duration of the life cycle of high-capacity copper ion exchanger nanocomposites have been shown. Experimental studies of water deoxygenation in column-type apparatus with a nanocomposite nozzle were confirmed by a theoretical analysis of the process dynamics. Experimental data and theoretical calculations showed the deep level of water deoxygenation had practically unchanged values of pH and electrical conductivity. Residual oxygen can be controlled and does not exceed 3 μg/l (ppb). The hygienic and economic substantiation of the expediency of using the obtained nanocomposites is provided. The necessity of using modern nanocomposite metal-polymer materials for deep water deoxygenation circulating in technological systems was analysed. When using this innovation, the metal components of the distribution facilities will be protected from corrosion and, therefore, the hygienic requirements for the water quality of centralised drinking water supply systems will be ensured. Deep chemical water deoxygenation using copper ion-exchange polymer nanocomposites in sodium form allows solving the problem of the corrosion resistance of metals, ensuring that water meets hygienic requirements on a large scale. The competitive advantage of the considered water deoxygenation system in comparison with the known systems is the rejection of the use of precious metals-catalysts (palladium, platinum), pure hydrogen, and complex design solutions. The proposed new nanocomposite installation for water deoxygenation is characterised by its ease of use and can be built into a filter system for water purification. SWOT analysis of the advantages and disadvantages of the proposed method of water deoxygenation showed that its main advantages are the high oxygen capacity of the nanocomposite, low residual oxygen content (3 ppb (μg/l)) in the water, and ease of operation of the deoxygenator. Calculations of the economic efficiency of the nanocomposite have been carried out. The breakeven point is reached when producing only ~100 l of nanocomposite and a volume of sales ~1,600,000 roubles, above which a profit can be obtained. The payback period for an investment of ~15,000,000 roubles is rather short and will not exceed 2 years.

Предложена электродинамическая модель редокс-сорбции кислорода из воды на зернистых слоях металл-ионообменных нанокомпозитов. Особенностью является одновременное описание процесса восстановления кислорода по электрохимическому и химическому маршрутам. В связи с неоднородным окислением наночастиц металла кислородом проведен учет меняющегося по высоте и во времени омического сопротивления зернистого слоя нанокомпозита. Проверена адекватность модели на примере медьсодержащего нанокомпозита.

An electrodynamic model of the redox sorption of oxygen from water on metal-ion-exchange nanocomposites’ (NCs) granular layers is proposed. It features a simultaneous description of the oxygen reduction process along the electrochemical and chemical routes. Due to the inhomogeneous oxidation of metal nanoparticles by oxygen, the granular layer of the NC ohmic resistance, which varies in height and time, is taken into account. The adequacy of the model was tested on a copper-containing NC.

Technical carbon CH210 was processed by chemical reduction of the diazo derivative of anthraquinone for surface modification. The presence of anthraquinone groups on the carbon surface was confirmed by attenuated total internal reflection (ATR) IR spectroscopy. Carbon with the anthraquinone-modified surface was deposited on a glassy carbon support using a polymer binder. The behavior of the thus obtained catalyst in oxygen electroreduction in an alkaline medium was studied by the rotating disk electrode method. The kinetic characteristics of the reaction were determined: half-wave potential, limiting current, number of electrons, Tafel slope, exchange current, and charge transfer coefficient. Hydrogen peroxide is formed on the surface of the carbon–polymer composite at higher positive potentials than on technical carbon and glassy carbon electrodes. Therefore, the proposed material can be used as an effective electrocatalyst for this reaction.

The electroreduction of oxygen on thin-film metal–polymer nanocomposites that differ in the metal (Ag, Cu, Pd), content, particle size of the metal component, and ionic form of the Lewatit K2620 matrix (H + , Na + ) was studied. The limiting oxygen diffusion current and effective number of electrons involved in oxygen electroreduction were determined. The limiting current and the number of electrons increased with the content of metal nanoparticles and transition to larger nanoparticles. The oxygen electroreduction occurs by the four-electron mechanism, whereby the hydrogen peroxide intermediate product does not accumulate, and oxygen is reduced directly to water molecules. The electrochemical reduction of the metal oxidation products and hydrogen evolution can be observed depending on the ionic form of the matrix.

The electrochemical reduction of oxygen dissolved in water is studied using a thin granular layer of nanocomposites of copper–sulfonic acid cation exchanger in different ionic forms (H + , Na + ). It is established there is considerable acceleration of oxygen absorption in the initial period under the simultaneous impact of electrical polarization and chemical activity of nanocomposites, especially in the H + -form. The rate of the process later slows and reaches a constant value regardless of the ionic form of the nanocomposite and without changing the pH or electrical conductivity of water. Products of the oxidation of metal nanoparticles form as insular nuclei distributed over the volume of nanocomposite granules; some grains are oxidized with the formation of sharp boundaries of oxide layers. A stationary mode of oxygen absorption is established due to the constant generation of hydrogen ions required for the reaction on anodes and the regeneration of copper nanoparticles on cathodes. It is concluded that these patterns are based on conjugate processes of ion transfer, electrochemical and chemical oxygen reduction, and the oxidation and reduction of copper nanoparticles.

Kinetic features are studied of the chemisorption and reduction of molecular oxygen from water by metal–ion exchanger nanocomposites that differ in the nature of the dispersed metal and state of oxidation. In the Pd < Ag < Cu series, the increasing chemical activity of metal nanoparticles raises the degree of oxygen sorption due to its chemisorption and subsequent reduction, while the role of the molecular chemisorption stage increases in the Cu < Ag < Pd series. Metal particles or their oxides are shown to act as adsorption sites on the surface and in the pores of the ion-exchanger matrix; the equilibrium sorption coefficient for oxygen dissolved in water ranges from 20 to 50, depending on the nature and oxidation state of the metal component.

The specific energy parameters of nanostructured electrode materials of electrochemical capacitors obtained by the method of multistage calendering are studied in this work. The dependence of electrical conductivity; the specific capacity of an electrical double layer of electrodes; and the internal resistance of electrochemical capacitors on the nature, quantity, and spatial localization (in the volume of the active layer and/or at the active layer–current collector interface) of conductive dopants (carbon black and grown in vacuum carbon fibers) are examined.

Методом химического осаждения синтезированы новые нанокомпозиты медь-сульфокатионообменная матрица Lewatit SP-112 H и Lewatit K 2620. Полученные материалы отличаются изопористой структурой и монодисперсным распределением частиц меди по размеру. В химическом отношении синтезированные нанокомпозиты показывают более высокие скорости поглощения кислорода при однократном осаждении меди и практически одинаковые параметры при пятикратном осаждении, а также характеризуются большей воспроизводимостью кинетических данных по сравнению с аналогом КУ-23, что позволяет отнести их к высокоэффективным нанокомпозитным материалам для глубокого удаления молекулярного кислорода из воды

The redox sorption of molecular oxygen from water by a thin granular layer of a copper-ion exchanger nanocomposite in the currentless mode and under cathodic polarization is studied. The speed of propagation of the boundaries of the chemical reaction of stepwise oxidation of copper nanoparticles under the conditions of polarization slows considerably. At the same time, the amount of electrochemically regenerated copper from the resulting oxides that is capable of interacting with oxygen again grows. The stationarity of the redox sorption of oxygen is due to the equality of the rates of oxidation and reduction of the metallic component of the composite.

В работе изучены удельные энергетические параметры наноструктурных электродных материалов электрохимических конденсаторов, полученных методом многоступенчатого каландрирования. Исследована зависимость электрической проводимости, удельной емкости двойного электрического слоя электродов, внутреннего сопротивления электрохимических конденсаторов от природы, количества и пространственной локализации (в объеме активного слоя и/или на границе раздела активный слой / токовый коллектор) электропроводящих допантов (технический углерод и выращенные в вакууме углеродные волокна).