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В статье приводится практический опыт внедрения машинного обучения на алюминиевом заводе. Показано, что алюминиевый завод является предприятием с большим (более двух тысяч идентичных производственных объектов – электролизеров) количеством объектов анализа, по каждому из которых существуют сотни различных технических параметров эксплуатации объект; взаимосвязи между параметрами эксплуатации определить классическими методами анализа затруднительно. Эти обстоятельства делают алюминиевое производство идеальным кандидатом для внедрения элементов искусственного интеллекта в производственный процесс. В ходе внедрения машинного обучения на алюминиевом заводе были проведены стадии пассивного и активного экспериментов, разработана методика определения эффективности проведенных мероприятий. Внедрение методов машинного обучения позволяет оптимизировать трудозатраты основного технологического персонала, при этом повысить эффективность производства., The article provides practical experience in implementing machine learning at an aluminum plant. It is shown that an aluminum smelter is an enterprise with a large (more than two thousand identical production facilities – pots) number of objects of analysis, for each of which there are hundreds of different technical parameters of the object's operation, it is difficult to determine the relationship between the operation parameters by classical methods of analysis. These circumstances make aluminum production an ideal candidate for the introduction of artificial intelligence elements in the production process. During the implementation of machine learning at an aluminum plant, the stages of passive and active experiments were carried out, a methodology was developed to determine the effectiveness of the measures taken. The introduction of machine learning methods allows optimizing the labor costs of the main technological personnel, while increasing production efficiency., Цифровая экономика, Выпуск 2 (23) 2023, Pages 90-96

Electrochemical devices based on nickel hydroxide electrodes are used in different areas. The main ones are chemical current sources, variable transparency “smart” windows, devices for carrying out electrocatalytic reactions, sensors for determining various substances. In this regard, methods of nickel hydroxide synthesis are of great interest, especially those that allow forming nickel hydroxide directly on the surface of electrodes. One of these methods is electrochemical deposition with cathodic current polarization. The available information on nickel hydroxide synthesis from nickel solutions was considered. It was shown that the available data mainly covered information on dilute solutions from 0.01 to 0.25mol/L Ni(NO3)2. In addition, no comparison was found in the literature for the efficiency of the cathodic formation of Ni(OH)2at different concentrations of nickel nitrate. To eliminate the lack of information, the dependence of the current efficiency on the concentration of nickel nitrate in the electrodeposition solution was determined at a constant cathode current density of 0.625mA/cm2. The resulting dependence decreased nonlinearly with increasing concentration. The nickel hydroxide deposit formed in this case had an X-ray amorphous structure, and it depended little on the Ni(NO3)2concentration. In addition, the current efficiency reached zero at concentrations of 1.5mol/L Ni(NO3)2and higher. However, with polyvinyl alcohol in the solution and at Ni(NO3)2concentrations of 1.5 and 2mol/L, electrochemically and electrochromically active Ni(OH)2films were deposited. The current efficiency calculated indirectly for 1.5 and 2mol/L Ni(NO3)2solutions was 3.2 and 2.3%, respectively. Thus, it was concluded that polyvinyl alcohol affected the mechanism of nickel hydroxide electrodeposition from aqueous solutions of nickel nitrate.

ObjectiveTo prevent the marine biofouling adhesion and corrosion of ship hulls and pipes, a system is designed which produces chlorine through seawater electrolysis using an ion-exchange membrane electrolytic bath. Thereby, the law and efficency of the electrolytic bath under different conditions is studied. MethodsFirst, the effects of brine temperature, brine concentration, current density and time of brine resided in the bath on the efficiency of the electrolysis process are investigated. Minitab software is then used to optimize the parameters of the electrolysis process using the specific energy consumption rate as the evaluation index. Finally, the seawater pretreatment process and electrolysis process are verified on site under real sea conditions. ResultsThe current density and residence time of the electrolysis parameters were reasonably controlled at 3 000 A/m2 and 46 s respectively，in this case, the current efficiency was higher than 80%, the cell voltage was lower than 6 V, and the surfaces of the anodes, cathodes and ion-exchange membranes after electrolysis were clean. ConclusionThe practical tests show that this system can produce chlorine for anti-fouling.

A review of the literature is devoted to the patterns of the electrodeposition of zinc-nickel alloys including the kinetics of cathodic reduction of zinc, nickel, and zinc-nickel alloys in ammonium chloride, sulphate, and glycinate deposition electrolytes. We studied the data on the effectiveness of the corrosion resistance of zinc-nickel coatings and summarised the principal patterns of selective dissolution of the Zn-Ni alloys. The role of the addition of glycine to an ammonium chloride deposition electrolyte was determined in the modification of the morphological and anticorrosive properties of the coatings.

A hard chromium plating technique was established using trivalent chromium chloride with a highly concentrated calcium chloride aqueous solution. The obtained films show dense and uniform microstructure, high hardness of 1000 HV and good wear resistance, which are comparable to those of conventional hexavalent chromium plated film. The hardness properties showed little thermal degradation, in contrast to the case of hexavalent chromium film. The carbon content was one magnitude lower than that of a conventional trivalent chromium bath containing carboxylic acids. The lack of thermal degradation of film hardness might derive from the inhibited particle growth resulting from the low carbon content and the high oxygen content. The current efficiency was 60-70%, much higher than those of hexavalent chromium plating and conventional trivalent chromium plating. Because trivalent chromium plating technique using a highly concentrated calcium chloride aqueous solution produces excellent film characteristics and productivity, this plating technique is anticipated as a technology underpinning the industrial production of hard chromium plating.

A characteristic of obtaining metal powders by direct current electrolysis is changes in the morphology of particles over the loose deposit layer thickness up to the formation of large spherulites. Deposits should be periodically removed from the cathode in order to obtain a powder with homogeneous composition. This paper justifies the choice of the parameter describing the change in loose deposit properties and proposes a method for determining the periodicity of its removal from the cathode. Loose zinc deposits were obtained at 25°C from zincate electrolyte containing 0.3 mol L–1 of ZnO and 4 mol L–1 of NaOH at a current setpoint exceeding six times the limiting diffusion current calculated using the smooth electrode. Electrode potential, deposit thickness and evolved hydrogen volume were measured directly in the process of electrolysis. Current redistribution between the metal reduction and hydrogen evolution leads to a change in the structure of loose deposit particles. It is shown that the differential current efficiency of zinc is the parameter describing the change in the loose zinc deposit density. Its value should not exceed 0.96, in order to ensure deposition of loose deposit with homogeneous properties. A further increase in current efficiency will lead to the formation of aggregates at the deposit growth front. It is proposed to determine the periodicity of loose deposit removal from the cathode using the empirical equation for the time dependency of differential current efficiency of zinc. The mathematical and statistical analysis of the data obtained in six replicates was carried out. The interval approach made it possible to significantly narrow the range of permissible differential current efficiency values and, as a consequence, to determine empirical equation coefficients with acceptable accuracy and calculate the growth time period of a deposit with homogeneous structure. The obtained approach can be used to estimate the time period of loose metal deposition accompanied by hydrogen evolution. © 2020, Allerton Press, Inc. This study was supported by the Government of the Russian Federation, regulation no. 211, state assignment no. 0836-2020-003.

A high current efficiency two-stage amplifier with inner feedforward path compensation (IFPC) technique is proposed in this paper. To improve the current utilization of the whole structure, the recycling folded cascode amplifier (RFC) is adopted as the first stage, and the inner feedforward path which is used to eliminate the non-dominant pole is composed of the input stage of RFC and the tail current transistor of the second stage amplifier. By using the IFPC technique, the proposed amplifier achieves an extended gain-bandwidth (GBW) and sufficient phase margin (PM) compared to that of the two-stage amplifier using single Miller compensation (SMC). Moreover, this compensation technique avoids extra power consumption since it does not require additional circuits. The proposed two-stage IFPC amplifier was fabricated in a $0.18~\mu \text{m}$ CMOS technology and the chip area of it is about $0.076mm^{2}$ . The simulated open loop AC response shows the DC gain, GBW, and PM are 130dB, 2.01MHz, and 58.3°, respectively. Measured results of transient response show when driving a 120pF load capacitance, the proposed amplifier achieves 368ns average 1% settling time, and about 1.56V/ $\mu \text{s}$ average slew rate (SR). Note that under the condition of 1.8V power supply, the power consumption is only $108\mu W$ , proving the proposed two-stage IFPC amplifier can achieve high current efficiency while maintaining stability.

The efficiency of boron-doped diamond electrodes (BDD) has been investigated by electrolysis of an aqueous solution containing sodium sulfate. A Synthesis StarterKit from Condias was used, which contained the BDD anode with an active surface area of 3.14 cm2, and electrosynthesis was performed in a batch mode reactor. In this report, the electrooxidation of sodium sulfate to sodium persulfate is well reported. The production of persulfate was studied at different cell voltages and electrolyte concentrations. The amount of persulfate produced was determined by the iodometric titration and itwas found that its concentration in the electrolyte was directly proportional to the persulfate concentration, i.e, a larger amount of persulfate could be obtained when the electrolyte was highly concentrated, up to 1 M. For each of the samples the amount of persulfate that theoretically is possible to produce was calculated and subsequently compared to the actual amount of persulfate that was formed, ie. current efficiencies. These current efficiencies were unexpectedly low for all experiments except for one data point. Hydrogen gas was also produced as a by-product at the cathode, but it couldn ot be collected in the present setup. The results and some possible improvements are discussed in the report. Effektiviteten av att använda bor-dopad diamant (BDD) för elektrosyntes med en vattenlösning innehållande natriumsulfat för att producera persulfat har undersökts. Den utrustningen som använde svar ett Syntes StarterKit från företaget Condias, denna innehöll en cell med BDD som anodmaterial vilken hade en aktiv area på 3,14 cm2. Produktionen av persulfat studerades vid olika cellspänningar och elektrolytkoncentrationer. Mängden av producerad persulfat bestämdes genom titrering. Detv isade sig att koncentrationen av elektrolyten var proportionell mot persulfatkoncentrationen, dvs. mer persulfat producerades vid högre elektrolytkoncentrationer. För varje prov beräknades även det teoretiska antalet mol persulfat som kan åstadkommas och jämfördes sedan med det faktiska antalet mol som producerades, detta gav strömeffektiviteten för den önskade reaktionen. Denna effektivitet var oväntat låg för alla prov förutom ett i experiment 4. Vätgas producerades som en biprodukt vid katoden, men på grund av begränsad tillgång till utrustning och tid kunde denna gas inte samlas uppför vidare analys. Resultaten och möjliga förbättringar diskuteras även i rapporten.

The process of electrodeposition of nickel coatings from electrolytes based on a deep eutectic solvent (DES) mixture of choline chloride and lactic acid with a molar ratio of 1:3 was studied. The physicochemical properties and characteristics of DES, namely, con­ductivity, FT-IR and NMR analysis were determined. FT-IR results confirmed that H-bonds occurring between two components in DES were the main force leading to the eutectic formation. Electrochemical techniques were used to characterize the deposition process and scanning electron microscopy was used to study the deposit morphology. Based on polarization measurements, it has been found that at NiCl2·6H2O content of 1.14 M and a temperature of 75 °C, the limiting current density of nickel electrodeposition was near 2 A dm-2. The polarization of the cathodic nickel deposition varied within -0.63 to 1.1 V at current density of 0.25 A dm-2 It has been shown that an increase of water content in the electrolyte does not significantly affect the current efficiency of the nickel electrodeposition process, which was in a range 85-93 %. However, the increase in water content contributes to the increase of heterogeneity and crystal grains size distribution of galvanic deposits. The established values of the Wagner number indicate the predominance of the primary current density distribution in the process of electrodeposition of nickel coatings. Galvanic coatings possess a highly developed nanostructured surface, exhibit increased capillary properties, and can be used as electrode materials for the process of electrolysis of water.

Electrolytically produced calcium is one of the most demanded materials in obtaining pure materials. At the same time, the existing technologies and devices for the electrolytic production of calcium were developed in the last century, and at present there are practically no works aimed at optimizing them. However, increasing the capacity and efficiency of existing devices for the production of calcium is in demand. To analyze possible ways to improve calcium production, a comprehensive understanding of the processes occurring at the electrodes and in the electrolyte during electrolytic production of calcium is required. This review briefly outlines the main points concerning the electrolytic production of calcium: from a brief history of the development of methods for the electrolytic production of calcium and established ideas about its physicochemical processes to information about new developments using the electrolysis of CaCl2-based melts. Review content: brief history of process development; base electrolyte for calcium production, including preparation of CaCl2 and influence of additions on it physicochemical properties; data on calcium solubility in CaCl2; information about alternative electrolytes for calcium production; short description of electrode processes in the CaCl2-based melts; proposed technologies and devices for the electrolytic production of calcium.

Проблематика. Останнім часом гостро постає проблема утилізації та регенерації концентрованих відпрацьованих технологічних розчинів, що містять іони кольорових металів, зокрема міді. Особливу складність переробки таких розчинів спричиняє наявність у них нітратів і хлоридів, які зумовлюють їх високу агресивність. Електроосадженню міді з такого типу розчинів присвячена дуже велика кількість праць. Проте технологічні засади регенерації нітратовмісних розчинів методом електроекстракції є малорозробленими. Мета дослідження. Розробка технологічних засад очищення забрудненого водного середовища та дослідження процесу регенерації концентрованих нітратовмісних розчинів методом електроекстракції міді зі встановленням впливу катодної густини струму і складу розчину на ефективність вилучення міді та якість катодних осадів. Методика реалізації. Методом вольтамперометрії встановлено вплив складу розчину на поляризацію та граничну густину струму осадження міді. На основі гравіметричних досліджень визначено вплив густини струму і міжелектродної відстані на катод­ний вихід за струмом міді та якість катодного осаду. Методом рентгенофлюоресцентного аналізу досліджено кількісний та якісний склад катодних осадів міді. Результати дослідження. Показано можливість отримання компактної міді за густин струму 15–25 А/дм2 при виході за струмом близько 100 % та вмісті міді в розчині 2 М. Встановлено, що за густин струму, менших 10 А/дм2, вихід за струмом міді перевищує 100 %, що пов’язано з випадінням основних солей міді у прикатодному шарі. На основі вольт-амперних вимірювань встановлено, що електроосадження міді з досліджуваних нітратно-хлоридно-сульфатних розчинів відбувається з дифузійними обмеженнями. Висновки.У результаті проведених досліджень встановлено основні технологічні параметри процесу електроекстракції міді з концентрованих нітратно-сульфатно-хлоридних розчинів. Отримані дані є необхідними для вирішення важливих екологічних проблем утилізації концентрованих металовмісних промислових відходів. Подальші дослідження будуть спрямовані на оптимізацію струмового режиму процесу електроекстракції міді та розробку напівпромислової установки для електроекстракції міді з нітратовмісних розчинів. Background. Recently, the problem of recycling and regeneration of concentrated waste technological solutions containing non-ferrous metal ions, in particular copper, has become acute. The particular complexity of processing such type of solutions is caused by the presence of nitrates and chlorides in their composition, causing their chemical aggressiveness. There is a great number of works devoted to electrodeposition of copper from nitrate-containing solutions. However, the background technology for the regeneration of nitrate-containing solutions by electrowinning method is poorly developed. Objective. The aim of the investigation is to develop background technology for the purification of contaminated aquatic environment and to study the process of regeneration of concentrated nitrate-containing solutions by the method of copper electrowinning with establishing the influence of the cathodic current density and solution composition on the efficiency of copper extraction and the quality of cathode deposits. Methods. The effect of the solution composition on the polarization and limiting current density of copper deposition was determined by voltammetry. The influence of current density and inter-electrode distance on the cathodic copper current efficiency and the quality of the cathode sediments were determined on the basis of gravimetric studies. The quantitative and qualitative composition of copper cathode deposits was investigated by X-ray fluorescence analysis. Results. The possibility of compact copper obtaining in the solution with copper content of 2 M at the current densities of 15–25 A/dm2 with the current efficiency of about 100 % was shown. It was established that for current densities less than 10 A/dm2 the copper current efficiency exceeds 100 %, which is due to the precipitation of basic copper salts in the cathode layer. On the basis of current-voltage measurements it was established that the electrodeposition of copper from the investigated nitrate-chloride-sulfate solutions occurs with diffusion limitations. Conclusions.As a result of the conducted research the main technological parameters of the copper electrowinning process from concentrated nitrate-sulfate-chloride solutions are established. The obtained data are not indispensable for solving the important environmental problems of removing the concentrated metal-containing industrial waste. Further investigations will focus on optimization of the current mode of copper electrowinning process and development of semi-industrial plant for copper electrowinning from nitrate-contain solutions. Проблематика. В последнее время остро стоит проблема утилизации и регенерации концентрированных отработанных технологических растворов, содержащих ионы цветных металлов, в частности, меди. Особую сложность переработки таких растворов вызывает наличие в них нитратов и хлоридов, которые обусловливают их высокую агрессивность. Относительно электроосаждения меди из такого типа растворов существует большое количество работ. Однако технологические основы регенерации нитрат-содержащих растворов методом электроэкстракции мало разработанны. Цель исследования. Целью исследований является разработка технологических основ очистки загрязненной водной среды и исследование процесса регенерации концентрированных нитратсодержащих растворов методом электроэкстракции меди с определением влияния катодной плотности тока и состава раствора на эффективность извлечения меди и качество катодных осадков. Методика реализации. Методом вольтамперометрии установлено влияние состава раствора на поляризацию и предельную плотность тока осаждения меди. На основе гравиметрических исследований определено влияние плотности тока и межэлектродного расстояния на катодный выход по току меди и качество катодного осадка. Методом рентгенофлюоресцентного анализа исследованы количественный и качественный состав катодных осадков меди. Результаты исследования. Показана возможность получения компактной меди в интервале плотностей тока 15 – 25 А/дм2 при выходе по току около 100% и содержании меди в растворе 2 М. Установлено, что при плотностях тока меньше 10 А/дм2 выход по току меди превышает 100%, что связано с осаждением основных солей меди в прикатодному слое. На основе вольтаперних измерений установлено, что электроосаждение меди из исследуемых нитратно-хлоридно-сульфатных растворов происходит с диффузионными ограничениями. Выводы. В результате проведенных исследований установлены основные технологические параметры процесса электроэкстракции меди из концентрированных нитратно-сульфатно-хлоридных растворов. Полученные данные является не обходным для решения важных экологических проблем утилизации концентрированных металлосодержащих промышленных отходов. Дальнейшие исследования будут направлены на оптимизацию токового режима процесса электроэкстракции меди и разработку полупромышленной установки для электроэкстракции меди из нитратсодержащих растворов.

Electrochemical devices based on nickel hydroxide electrodes are used in different areas. The main ones are chemical current sources, variable transparency “smart” windows, devices for carrying out electrocatalytic reactions, sensors for determining various substances. In this regard, methods of nickel hydroxide synthesis are of great interest, especially those that allow forming nickel hydroxide directly on the surface of electrodes. One of these methods is electrochemical deposition with cathodic current polarization. The available information on nickel hydroxide synthesis from nickel solutions was considered. It was shown that the available data mainly covered information on dilute solutions from 0.01 to 0.25 mol/L Ni(NO3)2. In addition, no comparison was found in the literature for the efficiency of the cathodic formation of Ni(OH)2 at different concentrations of nickel nitrate. To eliminate the lack of information, the dependence of the current efficiency on the concentration of nickel nitrate in the electrodeposition solution was determined at a constant cathode current density of 0.625 mA/cm2. The resulting dependence decreased nonlinearly with increasing concentration. The nickel hydroxide deposit formed in this case had an X-ray amorphous structure, and it depended little on the Ni(NO3)2 concentration. In addition, the current efficiency reached zero at concentrations of 1.5 mol/L Ni(NO3)2 and higher. However, with polyvinyl alcohol in the solution and at Ni(NO3)2 concentrations of 1.5 and 2 mol/L, electrochemically and electrochromically active Ni(OH)2 films were deposited. The current efficiency calculated indirectly for 1.5 and 2 mol/L Ni(NO3)2 solutions was 3.2 and 2.3 %, respectively. Thus, it was concluded that polyvinyl alcohol affected the mechanism of nickel hydroxide electrodeposition from aqueous solutions of nickel nitrate., Электрохимические устройства на основе электродов с гидроксидом никеля применяются в разных направлениях. Основные из них – химические источники тока, «умные» окна с изменяемой прозрачностью, устройства для проведения электрокаталитических реакций, сенсоры для определения различных веществ. В связи с этим вызывают большой интерес методы синтеза гидроксида никеля и особенно те, которые позволяют формировать гидроксид никеля непосредственно на поверхности электродов. Одним из таких методов является электрохимический метод нанесения при катодной поляризации током. Рассмотрены имеющиеся ведомости относительно синтеза гидроксида никеля из растворов никеля и показано, что имеющиеся данные охватывают в основном информацию относительно разбавленных растворов от 0.01 до 0.25 М Ni(NO3)2. Кроме того, в литературе не было обнаружено сравнения эффективности процесса катодного формирования Ni(OH)2 при разных концентрациях нитрата никеля. Для того что, устранить существующий недостаток информации, была определена зависимость значения выхода по току от концентрации нитрата никеля в растворе электроосаждения при постоянной катодной плотности тока – 0.625мА/см2. Полученная зависимость нелинейно снижалась при увеличении концентрации. Сформированные при этом осадки гидроксида никеля имели рентгеноаморфную структуру, и она мало зависела от концентрации Ni(NO3)2. Кроме того, значение выхода по току достигало нулевого значения при концентрациях 1.5 М Ni(NO3)2 выше. Тем не менее, при условии наличия в растворе поливинилового спирта и при концентрациях Ni(NO3)2 1.5М и 2М осаждались электрохимически и электрохромно активные пленки Ni(OH)2. Выход по току, рассчитанный не прямым путем для растворов 1.5М и 2М Ni(NO3)2 составлял 3.2 и 2.3% соответственно. Таким образом, был сделан вывод о том, что поливиниловый спирт влияет на механизм электроосаждения гидроксида никеля из водных растворов нитрата никеля, Електрохімічні пристрої на основі електродів з гідроксидом нікелю застосовуються в різних напрямках. Основні з них – хімічні джерела струму, «розумні» вікна із змінною прозорістю, пристрої для проведення електрокаталітичних реакцій, датчики для визначення різних речовин. У зв'язку з цим викликають великий інтерес методи синтезу гідроксиду нікелю і особливо ті, які дозволяють утворювати гідроксид нікелю безпосередньо на поверхні електродів. Одним із таких методів є електрохімічний метод нанесення при катодній поляризації струмом. Розглянуті відомості щодо синтезу гідроксиду нікелю з розчинів нікелю та показано, що наявні дані охоплюють в основному інформацію щодо розбавлених розчинів від 0.01 до 0.25 М Ni(NO3)2. Крім того, в літературі не було виявлено даних щодо порівняння ефективності процесу катодного утворення Ni(OH)2 при різних концентраціях нітрату нікелю. Для того, щоб усунути наявний брак інформації, була визначена залежність значень виходу за струмом від концентрації нітрату нікелю в розчині електроосаджування при постійній катодній густині струму – 0,625мА/см2. Отримана залежність нелінійно знижувалась при збільшенні концентрації. Сформовані при цьому осадки гідроксиду нікелю мають рентгеноаморфну структуру, і вона мало залежить від концентрації Ni(NO3)2. Крім того, значення виходу за струмом досягають нульових значень при концентрації 1.5 М Ni(NO3)2 та вище. Тем не менш, при наявності в розчині полівінілового спирту та концентрації Ni(NO3)2 1.5М і 2М осаджувались електрохімічно та електрохромно активні плівки Ni(OH)2. Вихід за струмом, розрахований не прямим шляхом для розчинів 1.5М і 2М Ni(NO3)2 склав 3.2 і 2.3% відповідно. Таким чином, був зроблений висновок про те, що полівініловий спирт впливає на механізм електроосадження гідроксиду нікелю з водних розчинів нітрату нікелю

The processing of solutions containing sodium salts of naphthenic acids (sodium naphthenate) is in high demand due to the high value of the latter. Such solutions usually include an excessive amount of alkali and a pH of around 13. Bipolar electrodialysis can convert sodium naphthenates into naphthenic acids; however, until pH 6.5, the naphthenic acids are not released from the solution. The primary process leading to a decrease in pH is the removal of excess alkali that implies that some part of electricity is wasted. In this work, we propose a technique for the surface modification of anion-exchange membranes with sulfonated polyetheretherketone, with the formation of bilayer membranes that are resistant to poisoning by the naphthenate anions. We investigated the electrochemical properties of the obtained membranes and their efficiency in a laboratory electrodialyzer. Modified membranes have better electrical conductivity, a high current efficiency for hydroxyl ions, and a low tendency to poisoning than the commercial membrane MA-41. We propose that the primary current carrier is the hydroxyl ion in both electromembrane systems with the MA-41 and MA-41M membranes. At the same time, for the modified MA-41M membrane, the concentration of hydroxyl ions in the anion-exchanger phase is higher than in the MA-41 membrane, which leads to almost five-fold higher values of the specific permeability coefficient. The MA-41M membranes are resistant to poisoning by naphthenic acids anions during at least six cycles of processing of the sodium naphthenate solution.

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m2. The most efficient green PhOLED with 10 wt% of Ir(ppy)3 {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m2, which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.

The electrodeposition of invar Fe-Ni alloy with low thermal expansion was performed at 100-5000 A·m–2 and 105 C·m–2 in agitated Watt’s solution containing NiSO4, NiCl2, FeSO4, C3H4O4, C7H4NNaO3S and H3BO3 at 50ºC. With increasing the concentration of malonic acid, the Ni content in deposits decreased at higher current density region than 2000 A·m–2, while it increased at lower current density region than 1000 A·m–2. The current efficiency for alloy deposition decreased with increasing the concentration of malonic acid. The deposits were composed of granular crystals whose size decreased with increasing the concentration of malonic acid. With an addition of saccharin, the Ni content in deposits significantly decreased, and the current efficiency for alloy deposition increased. With an addition of boric acid, the Ni content in deposits somewhat decreased, and the current efficiency for alloy deposition increased. The surface morphology of deposits changed with the current density and an addition of saccharin, and rarely changed with an addition of boric acid. It was found that the morphology depended on the Ni content in deposits. The deposits with Ni content of 29-38 mass% were composed of granular crystals approximately 300 nm in size, while the deposits with Ni content of 41-52 mass% showed the smooth surface consisted of fine crystals. The effects of additives on the Ni content in deposits and current efficiency can be explained by the change of partial polarization curve for Fe and Ni deposition and hydrogen evolution in Fe-Ni alloy deposition.

In the present paper, an Al rod as liquid cathode was added into the SmF3-LiF-Sm2O3 molten salt system and subsequently the Al-Sm alloy was prepared by the liquid cathode electrolysis method. The effects of electrolysis temperature, cathode current density and electrolyte composition on the current efficiency were studied. The results demonstrated that the maximum content of Sm in the Al-Sm interalloy could reach up to 32.8 wt.%, whereas the alloy was mainly composed of the Al substrate, Al4Sm and Al3Sm phases. The current efficiency increased first subsequently decreased as the electrolysis temperature and cathode current density increased. Simultaneously, the electrolyte composition had a high impact on the current efficiency. When the mass ratio of SmF3and LiF was 4, the current efficiency was 62.8 %.

To elucidate the effects of the electrolysis conditions on the formation of electrodeposited invar Fe–Ni alloys with low thermal expansion, Fe–Ni electrodeposition was performed at 10–5000 A·m−2 and 5 × 105 C·m−2 in an agitated solution containing NiSO4, NiCl2, FeSO4, H3BO3, C7H4NNaO3S, and C3H4O4 at 40°C–60°C. In the low-current-density region, the Ni content in the deposits significantly decreased with increasing current density, reached a minimum, and then increased after reaching the diffusion-limiting current density for Fe deposition. With the increasing concentration of FeSO4 in the solution, the Ni content in the deposits decreased in the lower-current-density region, reached a constant at a moderate current density, and then began to increase at higher current density. As a result, the current density range in which the Ni content in the deposits reached a minimum and remained constant became wider with increasing FeSO4 concentration. With the decreasing pH of the solution, since the partial polarization curve for H2 evolution and the total polarization curve shifted to a higher-current-density region, the curve of the Ni content in the deposits as a function of the current density shifted toward a higher current density. The change in the composition of the Fe–Ni alloy deposits because of the electrolysis conditions can be explained by the changes in the total polarization curve and the partial polarization curves for Fe and Ni deposition and H2 evolution.

The process of Al-Ce alloy prepared by electrodeposition was studied in molten LiF-KCl-CeF3 salt at 820 °C. Several process parameters such as back electromotive force and current efficiency were measured by continuous pulse oscillograph. The results showed that the back electromotive force increased with the increase of the current intensity. With the addition of 2 wt.%Ce2O2, the back electromotive force decreased by 0,26 V on average, and increasing temperature could make the back electromotive force decrease as well. The back electromotive force changing period with feeding measured was 50 min. Finally, at 820 °C, the largest current efficiency (68.8 %) was obtained by electrolyzing for 2 h at 4 A.

The aim of this work is to obtain nanocomposite layers having a cobalt matrix with zirconium oxide nanoparticles (mean diameter 30 nm) through the electrodeposition process. The plating electrolyte suspension is prepared by adding ZrO2 nanoparticles in a sulfate-chloride cobalt electrolyte at a concentration of 0 and 10 g·L−1. The electrodeposition is performed at room temperature, using three current densities of 23, 48 and 72 mA·cm−2 and three deposition times of 30, 60 and 90 min. The influence of current density, time and nanoparticles concentrations on the characteristics of the obtained nanostructured layers are also discussed. ZrO2 ceramic nanoparticles as a dispersed phase in the cobalt deposition electrolyte modify the mechanism of its electro-crystallization, so they participate in this process by increasing the rate of cobalt deposition, confirmed by the thickness of the nanocomposite layers obtained. The paper presents some of the comparative results obtained regarding the thickness of the layers, the current efficiency and the inclusion of the nanoparticles into nanocomposite layers depending on the current density and time of the electrodeposition process. The analysis of Co/nano-ZrO2 nanocomposite layers with the help of optical light microscopy and electronic microscopy in cross-section highlights the good degree of adhesion of the layers to the metallic substrate made of 304L stainless steel. The results of the study show that as the current density and time increase, the thickness of the composite layers increases. The efficiency of the process is improved compared to the electrodeposition of pure cobalt layers. The degree of inclusion of ZrO2 nanoparticles increases with time and decreases with increasing of imposed current density on the electrodeposition process. The distribution of the dispersed phase in the cobalt metallic matrix is uniform. The layers obtained in this study can be applied in aircraft technology, in the automotive industry, as well as in biomedical applications in order to improve the properties and to increase the corrosion or tribocorrosion resistance in a specific environment.

This paper studies the preparation of Copper powder from Copper Sulphate aqueoussolution(CuSO4.5H2O), sulfuric acid (H2SO4) and copper chloride (CuCl2.2H2O)by usingthe process of electro-deposition. Process of Powder deposition have been investigated forcopper powder, it is a fine layer on cathode electrode by using the value of different fromcurrent densities (0.12, 0.14, 0.16, and 0.18) A/cm2.as it is noticed the weight of the powderrises with there is of current density. Diffractions of X-ray (XRD) revealed high crystallinityand pure copper powder not contain impurity or oxides. Size of the Crystallite has beenmeasured by Scherrer's Formula about (38.44 -43.161) nm. Optical microscopes haverevealed the particles of copper have dendritic shapes. The size of Particles analyzermeasured the size of a particle which is about (2.4 – 8.7) ?m.

Publisher's version (útgefin grein), This study reports the direct production of an aluminium–manganese alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated for current efficiency measurements. The temperature was varied from 965–980 °C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The manganese content was up to 3.0 wt%. Manganese was added in the form of Mn2O3. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of manganese during electrolysis. It was possible to produce Al-Mn alloys of up to 21 wt. % Mn. Current efficiency for the electrodeposition of Al–Mn alloy was estimated to be in the range of 93%. Current efficiencies with respect to aluminium were estimated. The solidified surfaces of the metal deposits were mostly flat, but some were deformed., Norges Teknisk-Naturvitenskapelige Universitet

Lithium carbonate is an important chemical raw material that is widely used in many contexts. The preparation of lithium carbonate by acid roasting is limited due to the large amounts of low-value sodium sulfate waste salts that result. In this research, bipolar membrane electrodialysis (BMED) technology was developed to treat waste sodium sulfate containing lithium carbonate for conversion of low-value sodium sulfate into high-value sulfuric acid and sodium hydroxide. Both can be used as raw materials in upstream processes. In order to verify the feasibility of the method, the effects of the feed salt concentration, current density, flow rate, and volume ratio on the desalination performance were determined. The conversion rate of sodium sulfate was close to 100%. The energy consumption obtained under the best experimental conditions was 1.4 kWh·kg−1. The purity of the obtained sulfuric acid and sodium hydroxide products reached 98.32% and 98.23%, respectively. Calculated under the best process conditions, the total process cost of BMED was estimated to be USD 0.705 kg−1 Na2SO4, which is considered low and provides an indication of the potential economic and environmental benefits of using applying this technology.

Publisher's version (útgefin grein), This study reports the direct production of an aluminium-titanium alloy during aluminium electrolysis in fluoride-based melts. Experiments were conducted in a laboratory cell dedicated to current efficiency mea-surements. The temperature was varied from 960 to 980 ◦C at a cathodic current density (CCD) of 0.9 A/cm2 and a cryolite ratio (CR) of 2.2. The titanium content was up to 1.0 wt%. Titanium was added in the form of a TiO2 precursor. Bath samples were collected regularly and analyzed with ICP-MS to observe the decay of titanium during electrolysis. The current efficiency for electrodeposition of Al–Ti alloys was estimated to be at least around 90%. The surface of the solidified metal deposits was mostly flat, but some deposits were partially deformed., Norges Teknisk-Naturvitenskapelige Universitet

This study is focused on finding optimised conditions for electrodeposition of NiP and NiP/SiC coatings, which enhance the coatings' microhardness. Both the effect of particles and the effect of he...

This study determined the kinetics of the synthesis, the chemical composition, and morphology of zinc-nickel coatings electrolytically obtained from low-concentration (0.04 М ZnCl2, 0.08 M NiCl2) ammiacate and ammonia-glycinate chloride solutions. Transient electrochemical methods (cyclic voltammetry and linear sweep voltammetry) allowed us to determine that the cathodic deposition of Zn–Ni alloy costings, regardless of the presence of glycine in the ammonium chloride electrolyte, is limited by the stage of diffusion mass-transfer of ions, whose electrochemical reduction (the charge transfer stage) is irreversible. The introduction of relatively high concentrations of glycine (0.3 М) in the electrolyte allows obtaining smoother coatings, which is demonstrated by the results of scanning electron microscopy. At the same time, energy dispersive X-ray spectroscopy demonstrated that the atomic fraction of nickel in the potentiostatically deposited coating increases on average by 9.7%. It is possible that the alteration of the chemical composition results in a significant decrease (on average by ~15 %) in the current efficiency in electrolytes with glycine, since it catalyses the side reaction of hydrogen evolution.

As the production of stainless steel increases, environmental concerns due to an increasing demand of production capacity, require an efficient use of energy and materials. Efficient removal of otherwise slow‐to‐dissolve chromium oxide layer can be achieved with electrochemical pre‐pickling before final mixed acid pickling. Neutral electrolytic pickling can be used to rapidly dissolve chromium oxides but suffers from low current efficiency of both the reaction and the system. In order to study the effect of critical parameters for the current efficiency of the system, a pickling device was assembled. A system current efficiency factorial analysis of bipolar neutral electrolytic pickling was conducted for temperature, electrolyte concentration, cell potential, and electrode‐to‐sample distance. Lowering the concentration of electrolytes shows potential to increase current efficiency significantly as conductivity can be used to reduce electrode‐to‐electrode short‐circuiting, which is the biggest cause of decreased efficiency in neutral electrolytic pickling. Increasing the temperature has a positive effect on efficiency, despite increased conductivity, possibly from increasing reaction kinetics.

A series of experiments with different NaCl concentrations added to the PCB (printed circuit board) wastewater were prepared to investigate the chloride effect on the formation of aluminum floc and removal efficiency of Cu and Ni. The effects of pH, current density, and different concentration of NaCl were studied and the results are discussed. Results imply that chloride ions are favored to avoid the passivation of the aluminum anode in the EC (electro-coagulation) system. Chloride ions used as the electrolyte can facilitate the release of Al3+, which results in the current efficiency of over 100% in the EC system. For the PCB factory&rsquo, s wastewater, the EC system could remove Cu2+ and Ni2+ effectively (both Cu and Ni concentration of treated wastewater was less than 1.0 mg/L within three minutes). PCB wastewater&rsquo, s pH value could maintain stably about 9.0 in the EC system when the initial pH value was around 2.5. The estimated electricity consumption for treating PCB wastewater by the EC process was about 0.894 kWh for each meter of cubic wastewater.

The process of ternary Co-W(Mo)-Zr alloys deposition on a copper substrate from pyrophosphate-citrate electrolytes in a pulsed mode was investigated. The effect of temperature, the pH of the electrolyte, and the current density on the composition, surface morphology, and current efficiency of ternary electrolytic cobalt alloys with refractory metals was studied. The resulting coatings are characterized by a uniformly developed surface without cracks, which provides a sufficiently high and reproducible microhardness. It was found that the size of the globules on the alloy surface decreases with increasing the current density up to 10 A/dm2. It was found that an increase in temperature favorably affects the current efficiency and microhardness of Co-W-Zr coatings. The regimes of the electrosynthesis of coatings by cobalt-tungsten-zirconium alloys with a given level of the surface development and microhardness were substantiated.

Many complexities arise when applying conventional water treatment processes to small and remote systems. A significant challenge is the difficulty and impracticality of supplying chemicals needed for oxidation processes. A burgeoning, yet currently under-utilised, type of treatment are electrochemical technologies, which are receiving considerable research attention and innovation at present. In particular, through the advancement of high oxygen overpotential electrodes, the ability to synthesise highly oxidative chemical species under circumneutral pH conditions has become possible. In this study, the generation of highly oxidative iron-based species, specifically ferrate (Fe6+), has been explored utilising a boron-doped diamond (BDD) electrode and low concentrations of Fe2+ typically found in raw water, thereby eliminating the chemical supply chain required for conventional oxidation processes. Electrochemical ferrate generation experiments were performed in a batch-recycle configuration and were found to be mass transfer limited, whereby the rate-limiting step was the diffusion of Fe2+ to the electrode surface. This was evidenced by very little variation in ferrate generation at the three current densities tested, specifically 3.1 ± 0.2, 2.6 ± 0.2 and 3.3 ± 0.2 μM were generated at 10, 40 and 80 mA/cm2, respectively. Measured Fe6+ concentrations correlated well with those predicted by a mathematical process model, which assumed a completely mass transport limited process. While cyclic voltammetry confirmed ferrate generation by direct oxidation at the BDD surface, the contribution of hydroxyl radicals was indicated by the presence and absence of methanol, an OH scavenger, with ferrate generation decreased by greater than 50 % with methanol, compared to non-scavenged experiments. The results provide one of the first quantitative studies regarding the oxidation mechanisms of ferrate generation by electro-oxidation, and the first example of ferrate generation at circumneutral pH from Fe2+ at levels representative of raw water.

To improve sulfuric acid recovery from sodium sulfate wastewater, a lab-scale bipolar membrane electrodialysis (BMED) process was used for the treatment of simulated sodium sulfate wastewater. In order to increase the concentration of sulfuric acid (H2SO4) generated during the process, a certain concentration of ammonium sulfate solution was added into the feed compartment. To study the influencing factors of sulfuric acid yield, we prepared different concentrations of ammonium sulfate solution, different feed solution volumes, and different membrane configurations in this experiment. As it can be seen from the results, when adding 8% (NH4)2SO4 into 15% Na2SO4 under the experimental conditions where the current density was 50 mA/cm2, the concentration of H2SO4 increased from 0.89 to 1.215 mol/L, and the current efficiency and energy consumption could be up to 60.12% and 2.59 kWh/kg, respectively. Furthermore, with the increase of the volume of the feed compartment, the concentration of H2SO4 also increased. At the same time, the configuration also affects the final concentration of the sulfuric acid, in the BP-A-C-BP (&ldquo, BP&rdquo, means bipolar membrane, &ldquo, A&rdquo, means anion exchange membrane, and &ldquo, C&rdquo, means cation exchange membrane, &ldquo, BP-A-C-BP&rdquo, means that two bipolar membranes, an anion exchange membrane, and a cation exchange membrane are alternately arranged to form a repeating unit of the membrane stack) configuration, a higher H2SO4 concentration was generated and less energy was consumed. The results show that the addition of the double conjugate salt is an effective method to increase the concentration of acid produced in the BMED process.

The study was conducted in a one-stage rotating electrobiological disk contactor (REBDC) and a rotating electrochemical disk contactor (RECDC). Synthetic wastewater with characteristics similar to the wastewater from soil-less cultivation of tomatoes was used in the experiment. Current efficiency (CE) values, that express the denitrification performance of bio- and electrochemical reactors, were higher in the electrobiological contactor than in the electrochemical one. Combining biological processes with electrochemical processes in the electrobiological contactor resulted in almost 20% higher current efficiency in the contactor operated at a density of 0.63 A/m2 and hydraulic retention time (HRT) = 4 h. The study showed that, in both the electrochemical and the electrobiological contactor, current density increase and hydraulic retention time extension increased electric power consumption (E) during phosphorus compounds removal and simultaneously lowered current efficiency.

Електроосадження композиційних покриттів тугоплавкими металами та цирконієм з кобальтом дозволяєотримувати покриття з унікальним поєднанням фізико-хімічних властивостей, недосяжних при використанні іншихметодів нанесення. Варіюванням складу електроліту в гальваностатичному режимі не вдається отримати якіснікомпозиційні покриття с високим вмістом тугоплавких компонентів та виходом за струмом. Як альтернативузапропоновано використання імпульсного режиму електролізу, що дозволяє вдосконалити технологічний процес отриманнякомпозиційних покриттів. Підбір співвідношення тривалості імпульсу та паузи дозволяє уникати введення дорогих добавокі співосаджувати в сплав метали, які в гальваностатичному режимі отримати неможливо. Тому метою роботи буловстановлення параметрів електрохімічного нанесення композиційних покриттів кобальту з тугоплавкими металами іцирконієм з нетоксичних електролітів імпульсним електролізом. Використання імпульсного режиму при співвідношеннітривалості імпульсу 110-3-2010-3с и тривалості паузи 210-3-2010-3с та амплітуді катодної густини струму 2-10 А/дм2надає можливість одержати композиційні сплави на основі кобальту з підвищеним вмістом цирконію, молібдену івольфраму порівняно зі стаціонарним режимам. Підвищення робочих густин струму приводить до збільшення вмістутугоплавких металів в композиційних сплавах, що містять молібден, а також відбувається зменшення розміру зерен уповерхневому шарі сплаву Сo-Mo-WхОy. На підставі аналізу експериментальних досліджень встановлено вплив амплітудиструму і частоти імпульсів на вихід за струмом і склад композиційних покриттів Сo-Mo-WхОy, Co-W-ZrO2 і Co-Mo-ZrO2.Управління складом гальванічних сплавів Сo-Mo-WхОy, Co-Mo-ZrO2 і Co-W-ZrO2 в досить широкому діапазоні концентраційсплавотвірних компонентів досягається варіюванням параметрів імпульсного електролізу, що дозволяє адаптуватитехнологію нанесення до потреб сучасного ринку. Electrodeposition of refractory metals and zirconium in composite alloys with cobalt allows to obtain coatings with a unique combination of physicochemical properties that are unachievable while using other methods of covering. By varying the composition of the electrolyte in galvanostatic mode it is impossible to obtain high-quality composite coatings with a high content of refractory components and current efficiency. As an alternative, it was suggested the use of pulsed electrolysis mode that allows to improve the producing of composite coatings. The selection of the ratio of pulse duration and pause allows avoiding the introduction of expensive additives and co-depositing metals in the alloy, which is not possible in the galvanostatic mode. Therefore, the purpose of the work was to determine the parameters for electrochemical deposition of cobalt coatings with refractory metals and zirconium from non-toxic electrolytes by pulsed electrolysis. The use of pulse mode at a ratio of the pulse duration 110-3-2010-3 s and a pause duration of 210-3-2010-3 s and an amplitude of the cathodic current density of 2-10 A/dm2 allows to obtain cobalt-based composite alloys with an increased content of zirconium, molybdenum and tungsten as comparing with stationary modes. Increasing the operating current densities causes the increase of the refractory metals content in composite alloys that contain molybdenum, and also decreases the grain size of the Сo-Mo-WхОy alloy surface layer. Based on the analysis of the experimental studies, the dependencies of current amplitude and pulse frequency on the current efficiency and composition of Сo-Mo-WхОy, Co-W-ZrO2 and Co-Mo-ZrO2 alloy coating were determined. The control of the composition of Сo-Mo-WхОy, Co-W-ZrO2 and Co-Mo-ZrO2 galvanic alloys in a quite wide range of alloying components concentrations is being achieved by varying the parameters of the pulse electrolysis, which allows adapting of the deposition technology to the needs of the modern market.

Sustainability and circularity are currently two relevant drivers in the development and optimisation of industrial processes. This study assessed the use of electrodialysis (ED) to purify synthetic erythritol culture broth and for the recovery of the salts in solution, for minimising the generation of waste by representing an efficient alternative to remove ions, ensuring their recovery process contributing to reaching cleaner standards in erythritol production. Removal and recovery of ions was evaluated for synthetic erythritol culture broth at three different levels of complexity using a stepwise voltage in the experimental settings. ED was demonstrated to be a potential technology removing between 91.7–99.0% of ions from the synthetic culture broth, with 49–54% current efficiency. Besides this, further recovery of ions into the concentrated fraction was accomplished. The anions and cations were recovered in a second fraction reaching concentration factors between 1.5 to 2.5 times while observing low level of erythritol losses (

Проблематика. Останнім часом гостро постає проблема утилізації та регенерації концентрованих відпрацьованих технологічних розчинів, що містять іони кольорових металів, зокрема міді. Особливу складність переробки таких розчинів спричиняє наявність у них нітратів і хлоридів, які зумовлюють їх високу агресивність. Електроосадженню міді з такого типу розчинів присвячена дуже велика кількість праць. Проте технологічні засади регенерації нітратовмісних розчинів методом електроекстракції є малорозробленими.Мета дослідження. Розробка технологічних засад очищення забрудненого водного середовища та дослідження процесу регенерації концентрованих нітратовмісних розчинів методом електроекстракції міді зі встановленням впливу катодної густини струму і складу розчину на ефективність вилучення міді та якість катодних осадів.Методика реалізації. Методом вольтамперометрії встановлено вплив складу розчину на поляризацію та граничну густину струму осадження міді. На основі гравіметричних досліджень визначено вплив густини струму і міжелектродної відстані на катод­ний вихід за струмом міді та якість катодного осаду. Методом рентгенофлюоресцентного аналізу досліджено кількісний та якісний склад катодних осадів міді.Результати дослідження. Показано можливість отримання компактної міді за густин струму 15–25 А/дм2 при виході за струмом близько 100 % та вмісті міді в розчині 2 М. Встановлено, що за густин струму, менших 10 А/дм2, вихід за струмом міді перевищує 100 %, що пов’язано з випадінням основних солей міді у прикатодному шарі. На основі вольт-амперних вимірювань встановлено, що електроосадження міді з досліджуваних нітратно-хлоридно-сульфатних розчинів відбувається з дифузійними обмеженнями. Висновки.У результаті проведених досліджень встановлено основні технологічні параметри процесу електроекстракції міді з концентрованих нітратно-сульфатно-хлоридних розчинів. Отримані дані є необхідними для вирішення важливих екологічних проблем утилізації концентрованих металовмісних промислових відходів. Подальші дослідження будуть спрямовані на оптимізацію струмового режиму процесу електроекстракції міді та розробку напівпромислової установки для електроекстракції міді з нітратовмісних розчинів., Проблематика. В последнее время остро стоит проблема утилизации и регенерации концентрированных отработанных технологических растворов, содержащих ионы цветных металлов, в частности, меди. Особую сложность переработки таких растворов вызывает наличие в них нитратов и хлоридов, которые обусловливают их высокую агрессивность. Относительно электроосаждения меди из такого типа растворов существует большое количество работ. Однако технологические основы регенерации нитрат-содержащих растворов методом электроэкстракции мало разработанны.Цель исследования. Целью исследований является разработка технологических основ очистки загрязненной водной среды и исследование процесса регенерации концентрированных нитратсодержащих растворов методом электроэкстракции меди с определением влияния катодной плотности тока и состава раствора на эффективность извлечения меди и качество катодных осадков.Методика реализации. Методом вольтамперометрии установлено влияние состава раствора на поляризацию и предельную плотность тока осаждения меди. На основе гравиметрических исследований определено влияние плотности тока и межэлектродного расстояния на катодный выход по току меди и качество катодного осадка. Методом рентгенофлюоресцентного анализа исследованы количественный и качественный состав катодных осадков меди.Результаты исследования. Показана возможность получения компактной меди в интервале плотностей тока 15 – 25 А/дм2 при выходе по току около 100% и содержании меди в растворе 2 М. Установлено, что при плотностях тока меньше 10 А/дм2 выход по току меди превышает 100%, что связано с осаждением основных солей меди в прикатодному слое. На основе вольтаперних измерений установлено, что электроосаждение меди из исследуемых нитратно-хлоридно-сульфатных растворов происходит с диффузионными ограничениями.Выводы. В результате проведенных исследований установлены основные технологические параметры процесса электроэкстракции меди из концентрированных нитратно-сульфатно-хлоридных растворов. Полученные данные является не обходным для решения важных экологических проблем утилизации концентрированных металлосодержащих промышленных отходов. Дальнейшие исследования будут направлены на оптимизацию токового режима процесса электроэкстракции меди и разработку полупромышленной установки для электроэкстракции меди из нитратсодержащих растворов., Background. Recently, the problem of recycling and regeneration of concentrated waste technological solutions containing non-ferrous metal ions, in particular copper, has become acute. The particular complexity of processing such type of solutions is caused by the presence of nitrates and chlorides in their composition, causing their chemical aggressiveness. There is a great number of works devoted to electrodeposition of copper from nitrate-containing solutions. However, the background technology for the regeneration of nitrate-containing solutions by electrowinning method is poorly developed.Objective. The aim of the investigation is to develop background technology for the purification of contaminated aquatic environment and to study the process of regeneration of concentrated nitrate-containing solutions by the method of copper electrowinning with establishing the influence of the cathodic current density and solution composition on the efficiency of copper extraction and the quality of cathode deposits.Methods. The effect of the solution composition on the polarization and limiting current density of copper deposition was determined by voltammetry. The influence of current density and inter-electrode distance on the cathodic copper current efficiency and the quality of the cathode sediments were determined on the basis of gravimetric studies. The quantitative and qualitative composition of copper cathode deposits was investigated by X-ray fluorescence analysis.Results. The possibility of compact copper obtaining in the solution with copper content of 2 M at the current densities of 15–25 A/dm2 with the current efficiency of about 100 % was shown. It was established that for current densities less than 10 A/dm2 the copper current efficiency exceeds 100 %, which is due to the precipitation of basic copper salts in the cathode layer. On the basis of current-voltage measurements it was established that the electrodeposition of copper from the investigated nitrate-chloride-sulfate solutions occurs with diffusion limitations.Conclusions.As a result of the conducted research the main technological parameters of the copper electrowinning process from concentrated nitrate-sulfate-chloride solutions are established. The obtained data are not indispensable for solving the important environmental problems of removing the concentrated metal-containing industrial waste. Further investigations will focus on optimization of the current mode of copper electrowinning process and development of semi-industrial plant for copper electrowinning from nitrate-contain solutions.

Electrowinning is one of the methods for recovery of nickel metal from pregnant leach solutions. In industrial practice, the Ni content in electrolytes is usually above 80 g/L. However, many nickel solutions obtained from processing of secondary nickel resources are much less concentrated and this makes the electrowinning of such solutions difficult. In the present study, Nickel electrowinning from 30 g/L sulfate solutions has been investigated and the effect of the parameters such as current density (CD), temperature (T) and boric acid concentration (BA) on the current efficiency and nickel deposit quality has been determined using a central composite design methodology. The statistical analysis of experimental results revealed the significant factors and a proper model was obtained for each response variable. The results revealed two important negative interaction effects of T´BA and CD´BA which means that increasing temperature and current density could result in a higher current efficiency and satisfactory Ni deposit quality only at lower boric acid concentrations. By using overlaid contour plot method for multiple response optimization, the optimum condition for attaining current efficiencies of >95% and a smoothand compact Ni deposit quality was determined as CD = 2-2.5 A/dm2, T = 25-30 °C, and BA = 10 g/L.

The effect of chromium(VI) on the kinetics of disproportionation of hypochlorous acid and hypochlorite was established in the solution for the electrolytic production of chlorate. The hexavalent chromium species Cr2O7 2-, HCrO4 - and CrO4 2- present in the solution catalyze the disproportionation reaction. In both the absence and presence of chromium(VI), disproportionation is a third-order reaction with respect to HClO and ClO-P, and a first-order reaction with respect to the hexavalent chromium species. In the presence of chromium(VI) ions, four parallel reactions probably take place in the solution i.e. uncatalyzed disproportionation and three parallel reactions catalyzed by Cr2O7 2-, HCrO4 - and CrO4 2-ions. Most likely, the hexavalent chromium species do not change the sequence of elementary reactions in the disproportionation mechanism but only speed up the rate-determining step through interaction with its reactants. In the chlorate production process, as chromium(VI) concentration increases, the optimum pH which ensures the maximum rate of disproportionation is shifted to an acid environment. This is due to an increase in the concentration of the catalytically most active species HCrO4 - with increasing acidity of the solution. A mathematical model of the kinetics of the chromium(VI)-catalyzed disproportionation of hypochlorite and hypochlorous acid into chlorate was set up. Good agreement was obtained between theoretical and experimental data. © 2018 The Electrochemical Society. This is the peer-reviewed version of the paper: Spasojević, M., Marković, D., Trišović, T., Spasojević, M., 2018. Mathematical model of the catalytic effect of chromium(VI) on hypochlorite disproportionation in chlorate electrolysis. Journal of the Electrochemical Society 165, E8–E19. [https://doi.org/10.1149/2.0291802jes]

In the silver electrorefining process, the presence of gold as an impurity in anodes can affect process performance. In the present investigation, the effect of gold on anode passivation and the kinetics of dissolution at high current density were studied. Experiments were conducted using artificial silver anodes with gold contents of 2%, 5%, 10% and 20% (w/w) and acidic nitrate electrolytes containing 40 g/dm 3 and 60 g/dm 3 of Ag + . Results obtained from potentiodynamic measurements showed that in order to have higher current densities than 50 mA/cm 2 and higher energy efficient operation, the gold content in anode should be limited to ≤ 10% with 60 g/dm 3 of Ag + electrolyte. In contrast, the same current density operation for 40 g/dm 3 electrolyte will be applicable for anodes with ≤ 3.2% gold content with high energy inefficiency.

We examined the electro-optical characteristics of organic light emitting diodes according to the N,N'-diphenyl-N,N'-di(m-tolyl)-benzidine (TPD) thicknesses. The thicknesses of TPD were varied from 5 nm to 50 nm. The current density of the device with a TPD thickness of 5 nm was 8.94 times higher than that with a thickness of 50 nm at a driving voltage of 10 V. According to the conduction&ndash, current characteristics of conductors, the current densities improved with a decreasing TPD thickness. Different from the current density&ndash, voltage characteristics, the current efficiency&ndash, current density characteristics showed an improved efficiency with a 50 nm TPD thickness. The current efficiencies of a device with a 5 nm TPD thickness at a driving voltage of 10 V was 0.148 and at a 50 nm TPD thickness 0.993 cd/A, which was 6.7 times higher than the 5 nm TPD thickness. These results indicated that hole transport in Organic Light-Emitting Diode (OLED) devices were more efficient with thin 5 nm TPD than with thick 50 nm TPD, while electron transport was more efficient with thick 50 nm TPD, which caused conflicting results in the current efficiency-current density and current density-voltage characteristics according to TPD thicknesses.

Ammonium (NH4+) can be recovered from water for fertiliser production or even energy production purposes. Because NH4+ recovery is more effective at increased concentrations, electrodialysis (ED) can be used to concentrate NH4+ from side streams, such as sludge reject water, and simultaneously achieve high NH4+ removal efficiencies. However, the effect of osmosis and back-diffusion increases when the NH4+ concentration gradient between the diluate and the concentrate stream increases, resulting in a limitation of the concentration factor and an increase in energy consumption for NH4+ removal. In this study, we showed that operation at dynamic current density (DCD) reduced the effect of osmosis and back-diffusion, due to a 75% decrease of the operational run time, compared to operation at a fixed current density (FCD). The concentration factor increased from 4.5 for an FCD to 6.7 for DCD, while the energy consumption of 90% NH4+ removal from synthetic sludge reject water at DCD remained stable at 5.4 MJ·kg-N−1.

Предлагается способ определения формы обрабатываемой поверхности (анода) электрод-инструментом (катодом) при моделировании предельно-стационарного электрохимического формообразования. Задача сводится к решению краевой задачи для определения двух аналитических функций комплексного переменного. Первая функция производит конформное отображение области параметрического переменного на физическую плоскость. Для ее определения используется интеграл Шварца и сплайн-интерполяция. Для определения потенциала и функции тока осесимметричного поля используются интегральные преобразования второй аналитической функции. Аналитическая функция определяется в виде суммы двух слагаемых. Первое слагаемое учитывает особенности функции, так, чтобы вторая функция особенностей не имела. Вторая функция определяется с помощью интеграла Шварца. Производится интерполяция сплайн-функциями, при этом коэффициенты сплайнов являются производными этих функций, с помощью которых вычисляются составляющие вектора напряженности. Предельно-стационарная осесимметричная задача решается методом коллокаций. Показано, что в предельно-стационарном режиме на обрабатываемой поверхности образуются две зоны: зона растворения материала заготовки с постоянным значением модуля напряженности электрического поля и зона отсутствия растворения, где модуль напряженности меньше критического значения. Представлены результаты численного решения. Проведена оценка погрешности полученных результатов. Проведено сравнение с результатами решения плоской задачи, показавшее их качественное совпадение., The economy of modern Russia is characterized by a number of problems: unemployment and the unemployed population, new requirements on the part of employers for vocational education, the discrepancy between the employers ’personnel needs and the professional capabilities of university graduates. All this is a consequence of the disagreement of the most important areas of modern society - the labor market and education. The increasing complexity of tasks requiring solutions in practice leads to an increase in employers' requirements for the level of training of graduates, which underlies the existing imbalance in the labor market according to qualitative criteria. The article presents the results of neural network modeling of the interaction of subjects of labor markets and educational services. It is shown that to assess the quality of training of specialists according to the criterion of meeting the needs of the regional labor market, indicators of the efficiency of higher education institutions can be used. The rationale for the feasibility of using graduate employment indicators for solving the problems of evaluating and analyzing the effectiveness of higher educational institutions is given. Neural network models of classification, clustering and regression are built for a comprehensive analysis of the relationship between the subjects of the labor market and educational services. Revealed the presence of a strong relationship between the performance indicators of the university and the average salary of graduates in the first year after graduation., №4(23) (2019)

The volumetric growth, composition, and morphology of porous alumina films fabricated by reduced temperature 280 K galvanostatic anodizing of aluminum foil in 0.4, 1.0, and 2.0 M aqueous sulfuric acid with 0.5–10 mA·cm−2 current densities were investigated. It appeared that an increase in the solution concentration from 0.4 to 2 M has no significant effect on the anodizing rate, but leads to an increase in the porous alumina film growth. The volumetric growth coefficient increases from 1.26 to 1.67 with increasing current density from 0.5 to 10 mA·cm−2 and decreases with increasing solution concentration from 0.4 to 2.0 M. In addition, in the anodized samples, metallic aluminum phases are identified, and a tendency towards a decrease in the aluminum content with an increase in solution concentration is observed. Anodizing at 0.5 mA·cm−2 in 2.0 M sulfuric acid leads to formation of a non-typical nanostructured porous alumina film, consisting of ordered hemispheres containing radially diverging pores.

Sodium chlorate is one of the main oxidizing agents used in the wood industry due to their capability of use as an elemental chlorine-free (CEF) bleaching. A simple way to produce chlorates is by the electrolysis of an aqueous sodium chloride (NaCl) solution. In the present study activated carbon cloth electrodes (ACC) modified with fluorine and platinum nanoparticles (Pt–F/ACC and Pt/ACC) were used as one of the electrodes. Electrofluorination was used for fluorination of the anodes and polyol method was used for the synthesis of platinum nanoparticles. Chlorate production using a typical solution of 100 ​g/l of sodium chloride (NaCl) and 2 ​g/l sodium chromate (Na2Cr2O7) and an applied current of 0.540 ​A was studied. Prior to the electrolysis assays, the microstructural properties of the electrodes were characterized by scanning electron microscopy and surface modifications and bonding using infra-red (FTIR) spectroscopy. Electrochemical properties were determined using cyclic voltammetry (CV), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization techniques. Interaction between fluorine (F) and platinum (Pt) on the electrode leads to an improvement of the electrocatalytic properties for chlorine evolution as observed from the increase in the current efficiency from 37.5% at 78.5% after 150 ​min of continuous electrolysis using Pt–F/ACC anodes. The results suggest that modified activated carbon material is an attractive and economical alternative as electrodes for chlorate production.

In this work, the effect of current efficiency on the electrochemical micromachining by moving electrode is studied theoretically. The Laplace equation for the electric potential and the equation of workpiece surface evolution are used as the mathematical model of the process. A new scheme of solution of free boundary problem for steady-state electrochemical micromachining is proposed. According to the scheme, the initial approximation of the workpiece surface is prescribed. In the course of modeling, the workpiece surface moves in the normal direction at a rate proportional to the discrepancy of the steady-state condition. The effect of various dependences of current efficiency on the local current density is analyzed. As a result of simulation, the dependences of the shape and sizes of machined surface on the current efficiency and the machining parameters are obtained.

Electrolyzed water has significant disinfection effects, can comply with food safety regulations, and is environmental friendly. We investigated the effects of immersion depth of electrodes, stirring, electrode size, and electrode gap on the properties and chlorine generation efficiency of electrolyzing seawater and its storage stability. Results indicated that temperature and oxidation-reduction potential (ORP) of the seawater increased gradually, whereas electrical conductivity decreased steadily in electrolysis. During the electrolysis process, pH values and electric currents also decreased slightly within small ranges. Additional stirring or immersing the electrodes deep under the seawater significantly increased current density without affecting its electric efficiency and current efficiency. Decreasing electrode size or increasing electrode gap decreased chlorine production and electric current of the process without affecting its electric efficiency and current efficiency. Less than 35% of chlorine in the electrolyzed seawater was lost in a 3-week storage period. The decrement trend leveled off after the 1st week of storage. The electrolyzing system is a convenient and economical method for producing high-chlorine seawater, which will have high potential applications in agriculture, aquaculture, or food processing.

Removal of ammoniacal nitrogen from residual waters traditionally relies on energy-consuming biochemical processes, while more novel alternative strategies focus on the recovery of total ammoniacal nitrogen for the production of fertilisers or the generation of energy. The recovery of total ammoniacal nitrogen as gaseous ammonia is more effective at high ammonia concentrations in the liquid feed. Typically, chemicals are added to increase the solution pH, whilebipolar membrane electrodialysis can be used to convert salt solutions to acid and base solutions by using only electricity. In this study, we used bipolar membrane electrodialysis to remove ammonium from water and to simultaneously produce concentrated dissolved ammonia, without using chemicals. The energy consumption and current efficiency to transport ammonium from the diluate (the feed water) were assessed throughout sequencing batch experiments.The total ammoniacal nitrogen removal efficiency for bipolar membrane electrodialysis ranged between 85 and 91% and the energy consumption was stable at 19 MJ·kg-N−1, taking both electrochemical and pumping energy into account. The base pH increased from 7.8 to 9.8 and thetotal ammoniacal nitrogen concentration increased from 1.5 to 7.3 g L−1, corresponding to a final ammonia concentration of 4.5 g L−1 in the base. Leakage of hydroxide, diffusion of dissolved ammonia and ionic species from the base to the diluate all contributed to a loss in current efficiency. Due to the increase in operational run time and concentration gradients throughout the sequencing batch experiments, the current efficiency decreased from 69 to 54%. We showed thatbipolar membrane electrodialysis can effectively be used to simultaneously remove ammonium from water and produce concentrated dissolved ammonia while avoiding the use of chemicals. Moreover, the energy consumption was competitive with that of the combination of electrodialysis and the addition of chemicals (22 MJ·kg-N−1).

Chromium (Cr) plating using trivalent chromium has been investigated as a replacement for the highly-toxic hexavalent chromium bath. Herein, we report novel chromium plating baths using hydrate-melts. Hydrate-melts have been investigated in recent years as an electrolyte for aqueous Li-ion batteries with a wide electrochemical window, and can be used as an electroplating bath in which the reduction of protons, i.e., bath decomposition, is suppressed. By using a hydrate-melt for electroplating with trivalent chromium, the increase of local pH during electrolysis is suppressed and generation of the electrochemically-inert oligomer of chromium hydroxide can be avoided. Crystalline chromium electrodeposits were successfully obtained from the hydrate-melt-based aqueous baths, which had not been possible with the conventional trivalent chromium process requiring organic coordination agents. Moreover, a current efficiency greater than 80% was achieved. The hydrate-melt-based aqueous bath, with low material cost, is a promising candidate for industrial trivalent chromium plating.

Methylsulfonylmethane (MSM) is one of the main sources of sulfur for living bodies, but it is hard to obtain as a pure compound. Conventional electrodialysis (CED) is a mature technology that can be used for the separation and purification of biochemical products. In this study, the purification of MSM from mixtures containing salt was performed by CED. The effects of operating conditions such as operation voltage drop, feed MSM concentration, and electrolyte salt concentration on the separation performances were investigated. The results showed that the current efficiency reached 74.0%, and the energy consumption could be 12.3 Wh&middot, L&minus, 1. As for the recovery rate and desalination rate, the highest recovery rate could be 97.4%, and the desalination rate was 98.5%. Based on process energy consumption calculation, the total cost of the whole process was estimated at only 2.34 $&middot, t&minus, 1. Thus, CED is highly efficient and cost-effective for the separation and purification of MSM.

The Electrodeposition process has been used to prepare Nickel-Tungsten alloys on low carbon steel substrate by using ammonical citrate bath. The influence of deposition condition by variation of current density (0.04-0.2 A/cm2) and solution temperature (60-70 °C), on the microstructure was studied. The optical microscope and the scanning electron microscopy (SEM) were used to study the morphology of the deposit while the energy dispersive spectroscopy (EDS) was used to approximate the composition, in addition to X-Ray diffraction examination. The results show that the current efficiency has the major influence on the tungsten content in the alloys due to the formation of ternary complex which reflected into the properties of the deposit. Keywords

International audience; The performances of a new electrocoagulation reactor with bipolar horizontal iron electrodes were investigated. These electrodes were piled up in the reactor in order to maintain a low gap between them and to increase the electroflotation process. Electrodes were perforated to allow the passage of gas and effluents, and adjacent ones were separated by grids of polyamide or polytetrafluoroethylene. The performances of the reactor were investigated thanks to the weight lost of the electrodes. These performances increased with the number of holes in the electrodes, the current intensity, and the flow rate of the effluent, and mainly in the absence of a gap between the electrode edges and the walls of the reactor. More important, when the electrodes were not sealed with a system of tightness a decrease of the current efficiency was observed, leading to higher voltage and contributing to increase considerably the energy consumption. The use of eight-hole electrodes and a high flow rate reduced significantly the voltage and increased the current efficiency. Moreover in the absence of a gap between electrode edges and reactor walls, the current efficiency reached 100%; the voltage was stable and did not vary anymore and the energy consumption was minimized. The results showed that the sealing between electrode edges and the walls of the reactor was the most determinant factor in the optimization of the investigated reactor. © 2018 Elsevier Ltd. All rights reserved.