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.

SCARING INTEREST IN LEARNING CHEMISTRY BASED ON CAREER INTEREST THROUGH ECOLECTROCHEMISTRY: PRESENTING INCLUSIVE CHEMISTRY IN ONLINE CLASS

The online learning of organic chemistry series chemistry in class XII MIPA Catholic SMA Santu Petrus Pontianak in the first three months of the odd semester showed a decrease in interest in learning chemistry. This study was conducted to find chemistry lessons that match the career interests of students, especially the study topics in the physical chemistry learning series (voltaic cells and electrolytic cells). On the topic of voltaic cells, group projects are carried out by choosing their own types of assignments according to the interests and learning styles of students with activities of making chemical songs, simple practicum, limited webinars and advertisements for voltaic cell products. On the topic of electrolysis cells, a group project was carried out with the concept of combining economics/business into electrochemistry, called ecolectrochemistry. The voltaic cell project assessment uses five parameters: the accuracy of the voltaic cell concept, the relevance of the voltaic cell concept to the concept raised, creativity, fulfillment of task requirements, and collaboration. The ecolectrochemistry project assesses problem-solving skills using the IDEALS model, presentation assessment and assessment of creative and disciplined attitudes. The active and enthusiastic involvement of students is better than in the organic chemistry series. There is an increase in interest in learning chemistry from 27.38% to 65.48% and there is an increase in the average learning outcomes of the physical chemistry learning series compared to the organic chemistry learning series. These results indicate that learning designed according to students'.

Diffusion in Heterogenous Media and Sorption—Desorption Processes

We investigate particle diffusion in a heterogeneous medium limited by a surface where sorption–desorption processes are governed by a kinetic equation. We consider that the dynamics of the particles present in the medium are governed by a diffusion equation with a spatial dependence on the diffusion coefficient, i.e., K(x) = D|x|−η, with −1 < η and D = const, respectively. This system is analyzed in a semi-infinity region, i.e., the system is defined in the interval [0,∞) for an arbitrary initial condition. The solutions are obtained and display anomalous spreading, that is, the dynamics may be viewed as anomalous diffusion, which in turn is related, and hence, the model can be directly applied to several complex systems ranging from biological fluids to electrolytic cells.

Application of Electrospun Nanofibers for Fabrication of Versatile and Highly Efficient Electrochemical Devices: A Review

Electrochemical devices convert chemical reactions into electrical energy or, vice versa, electricity into a chemical reaction. While batteries, fuel cells, supercapacitors, solar cells, and sensors belong to the galvanic cells based on the first reaction, electrolytic cells are based on the reversed process and used to decompose chemical compounds by electrolysis. Especially fuel cells, using an electrochemical reaction of hydrogen with an oxidizing agent to produce electricity, and electrolytic cells, e.g., used to split water into hydrogen and oxygen, are of high interest in the ongoing search for production and storage of renewable energies. This review sheds light on recent developments in the area of electrospun electrochemical devices, new materials, techniques, and applications. Starting with a brief introduction into electrospinning, recent research dealing with electrolytic cells, batteries, fuel cells, supercapacitors, electrochemical solar cells, and electrochemical sensors is presented. The paper concentrates on the advantages of electrospun nanofiber mats for these applications which are mostly based on their high specific surface area and the possibility to tailor morphology and material properties during the spinning and post-treatment processes. It is shown that several research areas dealing with electrospun parts of electrochemical devices have already reached a broad state-of-the-art, while other research areas have large space for future investigations.

Revisiting Chlor-Alkali Electrolyzers: from Materials to Devices

As an energy-intensive industry, the chlor-alkali process has caused numerous environmental issues due to heavy electricity consumption and pollution. Chlor-alkali industry has been upgraded from mercury, diaphragm electrolytic cell, to ion exchange membrane (IEM) electrolytic cells. However, several challenges, such as the selectivity of the anodic reaction, sluggish kinetics of alkaline hydrogen evolution, degradation of membranes, the reasonable design of electrolytic cell structure, remain to be addressed. For these reasons, this paper mainly reviews the research progress of the chlor-alkali industry from materials to devices, including hydrogen evolution anode, chlorine evolution cathode, IEM, and electrolytic cell system. Finally, the research directions and prospects in the chlor-alkali industry are proposed for its further improvement.

On the question of using solid electrodes in the electrolysis of cryolite-alumina melts. Part 1.

This article is aimed at identifying issues associated with the use of solid cathodes in the electrolysis of cryolitealumina melts in order to determine conditions for their practical application. The contemporary technology of using solid anodes and cathodes is reviewed from its inception to the present time. The problems of stable electrolysis are discussed, such as effects of the electrode surface on the technological process. It is shown that all attempts undertaken over the recent 100 years to use solid electrodes, both reactive and inert, have been challenged with the emergence of electrolysis instability, formation of precipitates of varying intensity on the electrodes and impossibility of maintaining a prolonged process at current densities of above 0.4–0.5 A/cm2. Information is provided on the attempts to use purified electrolyte components with different ratios, metal-like and ceramic electrodes with a high purity and a smooth surface in order to approach real industrial conditions. However, to the best of our current knowledge, these experiments have not found commercial application. The authors believe that the most probable reason for the decreased current efficiency and passivation of solid electrodes consists in the chemical inhomogeneity and micro-defects of the bulk and surface structure of polycrystalline cathodes and anodes. It was the physical inhomogeneity of carbon electrodes that directed the development of the nascent electrolytic production of aluminium towards the use of electrolytic cells with a horizontal arrangement of electrodes and liquid aluminium as a cathode. This reason is assumed to limit the progress of electrolytic aluminium production based on the use of inert anodes and wettable cathodes in the designs of new generation electrolytic cells implying vertically arranged drained cathodes. The theoretical and experimental examination of this assumption will be presented in the following parts of the article.

Electrochemical CO2 reduction: water/catalyst interface versus polymer/catalyst interface

Due to the low solubility and diffusion coefficients of carbon dioxide in aqueous solution, the carbon dioxide electrolytic cells with aqueous electrolytes are difficult to achieve high conversion current density....

Electrochemical conversion pathways and existing morphology of arsenic(III) in anode-cathode separated electrolytic cells

To explore the electrochemical conversion of arsenic at different voltages and pH, an open separated electrolytic cell with a platinum anode and a graphite cathode was selected for this paper. The form and concentration of arsenic in the anodic cell and cathodic cell were detected. Experimental results proved that at 40.0 V, As(III) in an acid electrolyte in the cathodic cell was firstly mainly reduced to AsH3 with trace As(0) as intermediate. As the electrolysis time arrived at 27 min, pH in the cathodic cell jumped suddenly from acidity to alkalinity, accompanied by the majority of the remaining As(III) converting to As(V) for an instant. As time went on, As(III) and As(V) remained almost unchanged at the ratio of 1:3, and the reduction of As(III) became extremely weak in the alkaline environment. When pH in the cathodic tank was adjusted to keep it acid, As(III) was eventually converted to AsH3. Compared with high voltage, at a low voltage of 1.0 V the cathode failed to achieve the potential of As(III) reduction and As(III) was eventually oxidized to As(V) in the acid catholyte. Electrochemical oxidation of As(III) in the open cathodic cell was likely caused by in-situ generation of peroxide from electrochemical reduction of O2. Theoretical support for electrochemical oxidation of As(III) on a carbon cathode in neutral and weak alkaline media is provided in this study.