The full name of titanium anode is titanium-based metal oxide coated electrode (MMO), also known as insoluble anode. It is formed by coating a metal oxide coating with specific properties on a titanium substrate. Titanium itself has poor conductivity, but the metal oxide coating has low resistivity, good conductivity, stable chemical composition, stable crystal structure, stable electrode size, good corrosion resistance, long life, and good electrocatalytic performance, which is conducive to reducing the overpotential of oxygen and chlorine evolution reactions and saving electricity.
Classification
By function, it can be divided into chlorine evolution anode and oxygen evolution anode. Chlorine evolution anode is mainly used in chloride electrolyte system, and chlorine is released during electroplating; oxygen evolution anode is mainly used in sulfate, nitrate, hydrocyanate and other electrolyte systems, and oxygen is released during electroplating.
By application field, there are titanium anodes for chlor-alkali industry, titanium anodes for electroplating, etc. Compared with graphite electrodes, titanium anodes for chlor-alkali industry can increase current density, improve product quality and output. Titanium anodes for electroplating can replace conventional lead-based alloy anodes, and have the advantages of high electrochemical catalytic performance, energy saving, high stability, and no pollution to the plating solution.
Advantages
Long working life: In the diaphragm method of producing chlor-alkali industry, metal anodes are resistant to corrosion by chlorine and alkali, and the anode life can reach more than 6 years, which is much longer than the 8 months of graphite anodes.
High product purity: It can overcome the dissolution problem of graphite anodes and lead anodes, avoid contamination of electrolytes and cathode products, and improve the purity of metal products.
High current density: In the diaphragm method of producing chlor-alkali, the working current density of titanium anodes can reach 17A/dm², which is more than twice that of graphite anodes, which can effectively improve labor production efficiency.
Improved electrolytic cell structure: It makes it possible to operate chlorate electrolytic cells at high temperature and high current density, reducing power consumption and improving production performance.
Stable electrode size: The distance between electrodes does not change during the electrolysis process, which can ensure that the electrolysis operation is carried out under the condition of stable cell voltage, avoiding the short circuit problem after the lead anode is deformed, and improving current efficiency.
Low power consumption: The titanium anode has a low working voltage, and the DC power consumption can be reduced by 10% – 20%.
Manufacturing
The preparation of titanium anode usually includes the following key steps:
Titanium substrate treatment: Select high-purity titanium as the substrate, and use CNC machine tools for precision processing to ensure the geometric accuracy of the anode. Then, through fine surface grinding and cleaning, impurities and oil stains are removed to provide an ideal adhesion surface for subsequent coatings.
Coating preparation: Advanced means such as vacuum coating, plasma spraying or chemical deposition are used to tightly attach a carefully proportioned mixture of active electrochemical substances to the titanium substrate. For example, modern production processes use chemical coprecipitation combined with micro-arc oxidation to construct a sandwich structure composed of RuO₂ – IrO₂ – TiO₂ on the titanium substrate, with a total thickness controlled between 2 – 5μm.
Application
Chlor-alkali industry: It is a key component in chlor-alkali production, which can improve production efficiency, reduce energy consumption, and improve product quality.
Electroplating industry: widely used in nickel plating, gold plating, chromium plating, zinc plating, copper plating and other non-ferrous metal electroplating industries. It is used as an anode or auxiliary anode to make the coating uniform, the cell voltage low, the energy consumption low, and the production efficiency high.
Water treatment field: can be used for seawater desalination, wastewater treatment, disinfection of domestic water and food utensils, treatment of cooling circulating water in power plants, etc. For example, the ruthenium iridium titanium anode electrocatalytic oxidation system deployed by an environmental protection company can increase the degradation efficiency of PPCPs in wastewater to 99.7%.
Electrolytic organic synthesis: used as an electrode material in organic synthesis to promote the electrolysis reaction of organic compounds and realize the synthesis of specific organic products.
Battery production: helps to improve the performance and life of batteries, and is used in the research and development and production of some new batteries.
Use and Maintenance
Operation Specifications: The electrolyte should remain stable, especially without hydrogen ions and fluoride ions; a filter should be added before entering the electrolytic cell, and no metal particles larger than 0.1mm should be contained; the distance between the cathode and the anode should be adjusted reasonably, generally 5-25mm; pay attention to the current density during operation, and keep it within 2000A per square meter; when starting up and loading the current, it should be done step by step.
Daily Maintenance: During the use of the anode, pay attention to protecting the coating on the surface of the anode, avoid contact with the coating part, and prevent contamination or scratches by foreign objects. When shutting down, try not to soak it in the solution in the power-off mode, and add a small current of about 5A to protect the cathode plate. The working temperature of the electrolyte should not be too high, and the reasonable temperature is 25-40 degrees Celsius.
Development Trends
With the continuous innovation of technology, titanium anodes have made major breakthroughs in materials and coating technology. On the one hand, new coating materials continue to emerge, such as by doping nanocarbon materials, ZrO₂, CeO₂, etc., which significantly improve the electrolysis efficiency and reduce energy consumption. On the other hand, with the acceleration of the global layout of the hydrogen economy and the rise of third-generation semiconductor materials, ruthenium-iridium-coated titanium anodes are developing in the direction of ultra-thinness (<1μm) and functionalization. From the perspective of the entire life cycle, the environmental benefits of titanium anodes are significant, with a reduced carbon footprint and reduced heavy metal emissions, which is in line with the concept of green development. In the future, it will show great potential in emerging fields such as new energy and environmental protection. According to Grand View Research, the global market size will reach US$1.76 billion by 2030, with a compound annual growth rate of 9.8%.
