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Corrosion, Wear, and Degradation of Materials
Published in Mahmoud M. Farag, Materials and Process Selection for Engineering Design, 2020
When two metals are placed in a galvanic cell, one of them assumes the role of the anode, and the other assumes the role of the cathode based on their relative tendency to ionize. For example, iron becomes the anode when placed with copper in a galvanic cell because of its stronger tendency to ionize. However, iron becomes the cathode when placed with zinc in the galvanic cell because of the stronger tendency of zinc to ionize. Table 3.1 ranks some common metals and alloys in order of their tendency to ionize in seawater. This galvanic series is a useful guide to design engineers in predicting the relative behavior of electrically connected metals and alloys in marine applications. Figure 3.2 shows examples of galvanic corrosion, in which dissimilar metals are unwisely placed in contact in the presence of an electrolyte.
Monitoring and Analysis
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
All galvanic cells consist of an electrolyte and two electrodes (see Figure 2.3.8). Electrolyte oxygen content is brought into equilibrium with that of the sample. The electrodes are polarized by an applied voltage that causes electrochemical reactions when oxygen contacts the electrodes. In this reaction, the cathode reduces oxygen into hydroxide, thus releasing four electrons for each molecule of oxygen. These electrons cause a current flow through the electrolyte, with magnitude in proportion to the electrolyte oxygen concentration.
Electrochemical Methods
Published in Jerome Greyson, Carbon, Nitrogen, and Sulfur Pollutants and Their Determination in Air and Water, 2020
Oxidation/reduction or redox reactions, as applied in electrochemical analysis, are carried out in cells which consist, essentially, of two conducting electrodes immersed either in a single solution or in two different solutions that are in electrical contact with one another. Depending upon the chemical nature of the electrodes and the consituents of the solution or solutions, the redox reactions in the cell may occur spontaneously. As such, the cell may serve as a source of electrochemical energy and is called a galvanic cell. Contrariwise, it may be necessary to apply electrical energy to the cell to induce the redox reactions; such a cell is called electrolytic. A battery is an example of a galvanic cell while an electroplating process is an example of an electrolytic cell.
Application of UV-synthesized anion exchange membranes to improve nickel removal through galvanic deposition process
Published in Journal of Dispersion Science and Technology, 2023
Masoud Delsouz Chahardeh, Ali Bozorg
Schematic of the galvanic cell established between stainless steel cathode and aluminum anode used in this study has been demonstrated in Figure 1. The batch cell was made of two 220 mL Plexiglas compartments connected together through an AEM placed in between. The whole unit was sandwiched by eight nuts and bolts. The cathode container was stirred by a magnetic stirrer and a digital multimeter (DT9205A, China) connected to the electrodes was used to record the electrical potential variation throughout the experiments. To compare the performance of the present electrogenerative cell with that of the electrolytic cell, similar setup but with applying electrical potential was used to assess the quantity and quality of the deposited nickel on the steel electrode. DC Power Supply (PS-305D, Dazheng, China) was used to apply 5 volts electrical potential during 6 hours in electrolytic cell.
Synthesis and modelling of the mechanical properties of Ag, Au and Cu nanowires
Published in Science and Technology of Advanced Materials, 2019
Nurul Akmal Che Lah, Sonia Trigueros
The electrochemical redox reaction in the absence of dilute electrolyte using galvanic-cell supports is also possible for the formation of Ag nanowires. The galvanic support usually used to reduce the resistance of the solution. The Ag layer coated on the plate surface indicated the reaction took place on the galvanic support. As the concentration of the electrolyte reduced and getting low, the diffuse area of the double layer becomes significant with the layer formation thickness increase up to a micron depth. This induced the electro-migration of the ions towards the tip of the diffuse island layer in the direction of current flow. Therefore, nanowires develop around the sharp tip. As the electric field gradient increased, a massive accumulation of Ag ions deposition occurred near the tip than the ones close to the smooth or boundary area, which further contribute to the formation of nanowires. The larger the magnitude of the electric current field, the higher the density of incoming Ag ions within that region and subsequently, the tip of the layer becomes thicker. Lengthier Ag nanobelt could be grown in hard AAM nanochannel templates with dimensions depending on the AAM template [124,125]. Also, the biomass-derived monolithic activated carbon (MAC) template has been used for high yield and lengthier Ag nanowires through this method [126]. MAC is also known for its role as growth initiator surface, which commonly used for the formation of both nanowires and nanobelts within the system.
Characterization of enzyme immobilized carbon electrode using covalent-entrapment with polypyrrole
Published in Journal of the Chinese Institute of Engineers, 2018
Rauzah Munauwarah, Adama A. Bojang, Ho Shing Wu
In the EBFCs, galvanic cell analysis was performed using the NI 9215 system to acquire voltage, current, and power density. In this study, data were collected every 10 s to prevent a dramatic drop or sharp peak on the graph. According to the half-cell analysis, the samples for the bioanode that generated the optimal performance were GOx–PPy–mediator–CNB and GOx–mediator–CNT, which immobilized on the hydrophilic electrode. Lac–mediator and Lac–mediator–CNT were the optimal samples for the biocathode when using the hydrophilic electrode. Thus, the galvanic cell analysis for the optimal electrode was investigated, as shown in Figure 12. During the analysis, at 12 h, the maximum power density for the first combination (GOx–PPy–mediator–CNB vs. Lac–mediator) surpassed 130 μW/cm2, and at 8 h, it gradually decreased. That for the second combination only reached 118 μW/cm2, and the activity was retained at 5 h.