Detailed Explanation Of Titanium Anode
1. What is a titanium anode?
Titanium anode is the anode in the titanium-based metal oxide coating. According to the different catalytic coatings on the surface, it has the function of oxygen evolution and chlorine evolution. Generally, electrode materials should have good electrical conductivity, small change in pole pitch, strong corrosion resistance, good mechanical strength and processing performance, long life, low cost, and good electrocatalytic performance for electrode reactions. Titanium is currently the most satisfactory. The metal required for comprehensive requirements, generally industrial pure titanium TA1\TA2
The role of the metal oxide coating on the titanium anode is: low resistivity, good conductivity (the conductivity of titanium itself is not good), stable chemical composition of the precious metal coating, stable crystal structure, stable electrode size, and corrosion resistance Good, long life, with good electrocatalytic performance, which is beneficial to reduce the overpotential of oxygen evolution and chlorine evolution reactions and save electric energy.
2. The anodes in the metallurgical industry are divided into soluble anodes and insoluble anodes.
The soluble anode plays the role of supplementing metal ions and conduction during the electrolysis process, while the insoluble anode only plays the role of conduction. The earliest insoluble anodes were graphite and lead anodes. Titanium anodes began to be used in electrolysis and electroplating industries as a new technology in the 1970s. At present, insoluble anodes can be divided into two categories: chlorine evolution anodes and oxygen evolution anodes. Chlorine evolution anode is mainly used in chloride electrolyte system. Chlorine gas is released from the anode during the electroplating process, so it is called chlorine evolution anode; oxygen evolution anode is mainly used in electrolyte systems such as sulfate, nitrate, and hydrocyanate. Oxygen is released from the anode during the process, so it is called oxygen evolution anode. Lead alloy anode oxygen evolution anode, titanium anode has the function of oxygen evolution, chlorine evolution or both according to the different catalytic coating on the surface.
3. Lead and lead alloy anodes
The lead alloy anode is an oxygen evolution anode. The electrolyte for the oxygen evolution reaction is sulfuric acid and sulfate, which is mainly used for electrolytic metallurgy. This kind of anode has the defect that the geometrical size will change during the electrolysis process. In the electrolysis process, the lead anode matrix is first converted into lead sulfate and then into lead oxide. Lead sulfate is an intermediate layer. It is an insulator and acts as a chemical barrier. It can protect the inner lead matrix in a sulfuric acid environment. Lead oxide is an electrode in the actual sense on the outer layer. Oxygen evolution reaction occurs on the lead oxide. The oxygen evolution potential of lead oxide is very high, and it rises rapidly with the increase of current density. This feature of lead alloy anode is that its outer layer is oxidized. The inherent characteristics of lead-lead oxide is determined by the poor conductor of electricity. In addition, during the electrolysis process, the electrochemical performance of the lead oxide anode structure is constantly attenuated, and the generation of internal stress causes the oxide layer to fall off. In addition, the formation of lead peroxide also causes the oxide to continue to dissolve, as the intermediate layer of sulfuric acid Lead is converted into lead oxide again, which becomes a new outer layer oxide electrocatalytic active material, and the inner lead matrix is oxidized again to form a new lead sulfate intermediate protective layer. Therefore, during the electrolysis process, lead and its alloying elements continue to dissolve into the electrolyte and precipitate to cause solution pollution and cathode product pollution.
4. Titanium anode
Titanium anodes do not have the disadvantage of mechanical dimensional attenuation compared to graphite anodes and lead alloy anodes, so they are also called dimensional stability anodes. Titanium anodes have the following advantages: stable geometric dimensions; diversity of geometric shapes; excellent stability of electrochemical and chemical properties; excellent electrocatalytic activity; low anode potential and insensitive to changes in circuit density; energy saving and prolonged electrolysis The service life of the liquid; maintenance-free; long life (very important); high-quality cathode products (no impurities or very few impurities, uniform microstructure, such as electrolytic copper, zinc, nickel). The titanium anode is a double-layer composite structure composed of a metal substrate and a coating on the substrate. The titanium substrate acts as a conductor, and the coating functions as an electrochemical catalyst for the oxygen evolution/chlorine evolution reaction. The oxygen/chlorine evolution potential of this coating is low, and the oxygen/chlorine evolution potential hardly changes with the current density. Titanium-based conductor is a permanent material with a long coating life. It can be used to obtain almost completely pure cathode products without pollution and energy saving.
