In Situ Real-Time Quantitative Determination in Electrochemical Nuclear Magnetic Resonance Spectroscopy

For the purpose of acquiring highly sensitive and differential spectra in in situ electrochemical nuclear magnetic resonance (EC-NMR) spectroscopy, uniform distributions of amplitudes and phases of radio frequency (RF) fields in the sample are needed for consistent flip angles of all nuclei under scrutiny. However, intrinsic electromagnetic incompatibility exists between such requirements with electric properties of the conductive material in an electrolytic cell, including metallic electrodes and ionic electrolytes. This proposed work presents the adverse repercussions of gradually varying electrolyte conductivity, which is strongly associated with the change of ion concentrations in a real-time electrochemical reaction, on spatial distributions of RF field amplitude and phase in the detective zone of an NMR probe coil. To compensate for such a non-linear trend of the spatial dependent distribution, we eliminate different excitation effects of the RF field on the build-in external standard and the electrolyte both situated in nearly the same detection area, as well as promote the greater accuracy of quantitative determination of reactant concentrations. The reliability and effectiveness of the improved in situ EC-qNMR (quantitative NMR) method are confirmed by the real-time monitoring of the electrochemical advanced oxidation process for phenol, in which instant concentrations of reactants and products are detected simultaneously to verify the degradation reaction scheme of phenol.

ELECTROCATALYTIC OXIDATION OF STARCH IN TWO-CHAMBER CELL WITH REGENERATION OF OXIDANT IN SITU ON ELECTRODES FROM Pb/PbO2 AND GRAPHITE

Electrocatalytic oxidation of potato starch was investigated potassium iodate in a two-chamber electrolytic cell with in situ regeneration of the oxidant on Pb/PbO2 and graphite electrodes, depending on the current density, electrolyte pH and electrolysis time. To analyze the samples of the starting and oxidized starch, the methods of photometry, X-ray diffraction, gel permeation chromatography, and IR spectroscopy were used. The optimal conditions for starch dialdehyde production were determined: current density 50 mA/cm2, electrolyte pH 7, electrolysis time 80 min. and a temperature of 25 °С. The weight average molecular weights (Mw) of AIBN samples were determined, which are several orders of magnitude lower (104) than the average molecular weight of native starch (108).

A two-stage classifier switchable aluminum electrolysis fault diagnosis method

Traditional aluminum electrolysis fault diagnosis methods have problems such as low accuracy, small forecast advance, and high CPU usage, which make their popularity low in enterprises. Aiming at the above problems, a fault diagnosis method with switchable two-level classifiers is designed. The input data are first judged by the first-level algorithm. If it is determined that there is no fault, the result will be output directly. If it is determined that there is a fault in the electrolytic cell, the data will be transferred to the second-level network for specific fault diagnosis. The first level is based on the Random Forest algorithm with simple structure and good two-class classification effect and is optimized by the improved cuckoo algorithm. The second level is based on an improved DBN-DNN (Deep Belief Neural Network–Deep Neural Network) algorithm, and the training method is given. Experimental results show that this method can switch between different algorithms according to different situations, save computing resources, realize that a computer can monitor multiple electrolytic cells, and reduce investment costs. In addition, the accuracy and forecast advance have been significantly improved, which has promoted the popularization of fault diagnosis systems in aluminum electrolysis enterprises.

The Effect of Brush Plate Structure and Operating Parameters on the Energy Consumption of Electrolytic Cells

The nickel powder brush plate is a core component of the direct contact between the cleaning machine and cathode plate of an electrolyzer, and its movement in the electrolytic cell will affect the energy consumption of the electrolyzer. In order to optimize the structure of the brush plate, a cleaning trolley brush plate was taken as the research object, a mathematical model of its electrolyzer was established, and the reliability was subsequently verified. The influence of the structural and operating parameters of the brush plate on the energy consumption of the electrolytic cell was studied. The research results show that additional energy consumption is the lowest in the process of cleaning a return grooved brush plate. Brush plates with a large slotting area have less impact on the energy consumption of the electrolyzer. The slotting method, where the anodes are arranged directly opposite each other and relatively concentrated, can be adapted to render a more uniform current density distribution on the anode surface, with lower energy consumption and less variation in voltage and current. With the increasing number of slots from one to three, the current density distribution on the anode surface became more uniform, with a reduction in the variation range of the slot voltage and current in the branch where the cathode plate was cleaned and a decreased energy consumption. With the linear increase in brush cleaning speed, the impact time of the brush plate on the electrolyzer decreased nonlinearly, and as the extent of this decrease gradually diminished, the additional energy consumption showed the same trend. These research results were then used as a basis for optimizing the existing commonly used empirical C-brush plates. Following optimization, the current density distribution on the anode surface was found to be more uniform, the variation amplitude of tank voltage was reduced by 34%, the current drop amplitude of the branch circuit where the brushed cathode plate was located was reduced by 39%, the impact time on the current field of the electrolytic tank was reduced by 40%, and the additional energy consumption was reduced by 50.9%. These results can be served as a reference for further theoretical research related to brush plates.

Preparation of electrochemically deposited nickel—cobalt nanocomposite coating and research on its corrosion resistance

Alloying as a way of improving material properties has really gained a lot of global attention over the past few years. Alloying majorly improves physicochemical, electrochemical, thermal, and mechanical and corrosion resistance of a parent material. In this work, electrodeposition using a sulphamate electrolytic cell under varied concentrations of the secondary phase of cobalt. Characterization of the alloy was achieved using scanning electron microscopy (SEM), optical microscopy (OM), and X-ray diffraction (XRD) techniques. Corrosion resistance was investigated using potentiometric and impedance tests, reported, and well explained.

Electrical conductivity of Self-assembling Peptide-semiconducting dye Conjugate nanofibre networks

Conjugates comprising a semiconducting dye (Thiophene-diketopyrrolopyrrole, TDPP-dye) attached to a self-assembling peptide (HEFISTAH) assemble into long nanofibers. Well-ordered Langmuir-Blodgett films of these materials can be prepared. Networks of these nanofibres can be deposited to bridge electrodes. Although similar systems have been proposed as organic semiconductors, in this case, no electronic conductivity was observed. Instead, the fibres behaved as ionic (probably proton) conductors as a consequence of adsorbed water. A strong dependence of electrical conductivity on relative humidity and fibre network density was demonstrated. The system of nanofibers bridging gold electrodes behaved as an electrolytic cell, with oxygen reduction as a limiting electrode reaction.

Electrochemical Dyeing of Cotton Fiber for Environmental Protection

For environment-friendly dyeing, electrochemical dyeing method was researched. The low consumption of additives during dyeing is beneficial to environmental protection,and the electric field of electrochemical dyeing reduces the salt. Moreover, the K/S value of the fabric increases significantly at the same dye concentration. The alkaline electrolyte in the electrolytic cell may enhance the self-corrosion of the electrode during the electrochemical dyeing process. The results show that the electrochemical dyeing can reduce the amount of additives during the dyeing process.

HIGH EFFECTIVE RESOURCE-SAVING TECHNOLOGY OF REFINING VEGETABLE OILS

Показано, что эффективность комплексной рафинации зависит от организации и качества первичной очистки растительных масел непосредственно после их извлечения. Предложено использовать в качестве растительного адсорбента тонкодисперсный порошок из зерен фасоли, полученный их измельчением в роторно-валковом дезинтеграторе при давлении от 50 до 60 МПа. Для эксперимента использовали нерафинированное подсолнечное прессовое масло. Обработку масла полученным органическим порошком из зерен фасоли проводили следующим образом. Масло из форпресса при температуре от 95 до 100°С смешивали в роторно-валковом дезинтеграторе с адсорбентом в количестве 0,2% от массы масла, выдерживали в экспозиторе при температуре 90°С в течение 30 мин, а затем фильтровали. Установлено, что новый адсорбент обеспечивает повышение качества масла и полностью исключает присутствие в нем нежировых примесей и хлорогеновой кислоты. Исследована возможность использования электроактивированной воды в виде католита или анолита в качестве гидратирующего реагента при гидратации растительных масел. Для получения электроактивированной воды использовали водопроводную воду с рН 7,1 и окислительно-восстановительным потенциалом Eh +1,64 мВ. Электроактивированную воду получали в периодически действующем электролизере, варьируя продолжительность электролиза от 1 до 30 мин. Проведена пробная гидратация подсолнечного масла по традиционной технологии при температуре 60°С с последовательным введением католита и анолита с общим соотношением 1 : 1 в количестве 1% к массе масла. Установлено, что гидратация активированной водой подсолнечного масла, прошедшего очистку растительным адсорбентом, обеспечивает полное удаление фосфолипидов и значительное уменьшение массовой доли красящих веществ, снижение кислотного и перекисного чисел. Разработанные технологические решения позволяют готовить растительные масла к дистилляционной рафинации при более мягких температурных режимах масла и острого перегретого пара. It is shown that the efficiency of the complex of refining depends on the organization and quality of the primary refining of vegetable oils directly after their retrieval. Is offered use as a plant adsorbent a fine powder of grain beans obtained by their grinding in a rotary roller disintegrator at a pressure of from 50 to 60 MPa. For the experiment, crude sunflower press oil was used. Oil treatment of the obtained organic powder from the grain beans was performed in the following way. The oil from forpress at a temperature of from 95 to 100°C were mixed in a rotary roller disintegrator with the adsorbent in the amount of 0,2% by weight of oil, kept in exposure at 90°C for 30 min and then filtered. It is determined that the new adsorbent improves the quality of oil and completely eliminates the presence in him of non-lipid impurities and chlorogenic acid. In the next step the possibility of using electroactivated water in the catholyte or anolyte as a hydrating agent in the hydration of vegetable oils studied. Tap water with pH 7,1 and redox potential Eh +1,64 mV were used to obtain electroactivated water. Electroactivated water was obtained in the periodically current electrolytic cell, varying the duration of electrolysis from 1 to 30 min. Trial hydration of sunflower oil by traditional technology at 60°With sequential introduction of anolyte and catholyte with a common ratio of 1 : 1 in the amount of 1% by weight of oil carried out. It is established that hydration of sunflower oil by activated water, the last clean plant adsorbent, allows a complete removal of phospholipids and a significant decrease of the mass fraction of pigments, reduction of acid and peroxide numbers. Developed technological solutions allow to cook vegetable oils by distillation refining with milder temperatures oil and sharp superheated steam.

Implementation of digital automated control systems at electrolytic copper refining plants in Vietnam

The work aims to develop digital control and management systems of copper electrolytic refining processes when addressing energy efficiency issues. Thermal imaging scanners can be used to monitor the process state of an electrolytic cell. In this regard, the experience in the automation and control systems of OJSC Novgorod Metallurgical Plant was considered. Mathematical research methods and a stochastic model developed in the MatLab software were used. This model was applied at the Lao Cai copper-smelting plant (Vietnam). The proposed algorithm is based on the temperature variation in electrolyte depending on the heating of cathode and anode sections during short circuits due to dendritic growth, as well as process disturbance time. The algorithm was developed using the Visual BasicScript programming languages. The temperature rise in short circuit areas was recorded using a thermal imaging scanner immediately after the colour change of the cathode surface. It was shown that the duration of a short circuit depends on the amount of sludge deposited in an electrolytic cell. The sludge formed following the destruction of intergrown dendrites contains precious metals. The developed measures, along with those of digitisation, are necessary for effective management, taking into account the functional and kinetic characteristics of the copper refining process. The proposed solutions and control algorithms will allow remote access systems with augmented reality elements when creating a digital twin. This will reduce the specific power consumption by 20 –25% while decreasing the number of electrode short circuits. Controlling the composition and level of electrolyte and sludge will reduce material losses and maintain the concentration of noble metals in the electrolyte. To improve the control quality of automation during the electrolytic production of cathode copper, a number of technical measures were proposed that provide additional points of control to expand the process database. Furthermore, the proportion of manual periodic measurements of process parameters is reduced.