What is a titanium anode?

Titanium anode is the anode intitanium.html> titanium-based metal oxide coating. Depending on the surface catalytic coating, it has oxygen evolution function and chlorine evolution function respectively. Generally speaking, electrode materials must have good 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 the best candidate to meet the above comprehensive requirements. The required metals are generally industrial pure titanium grades 1 and 2.

Product function
The functions of the metal oxide coating on the titanium anode are: low resistivity, good conductivity (titanium itself has poor conductivity), stable chemical composition of the noble metal coating, stable crystal structure, stable electrode size, and corrosion resistance Good, long life, good electrocatalytic performance, conducive to reducing the overpotential of oxygen evolution and chlorine evolution reactions, and saving electric energy.

advantage
1. The titanium anode has a long working life. In the chlor-alkali industry produced by the diaphragm method, the metal anode is resistant to corrosion by chlorine and alkali. The anode life has reached more than 6 years, while the graphite anode is only 8 months.

2. It can overcome the dissolution problem of graphite anode and lead anode, avoid contamination of electrolyte and cathode products, and thus improve the purity of metal products.

3. Can increase current density. In the production of chlor-alkali by the diaphragm method, the working current density of the graphite anode is 8A/dm2, and the titanium anode can be doubled to 17A/dm2. In this way, under the same conditions of the electrolytic plant and electrolytic cell, the output can be doubled, improving The single-tank production capacity effectively improves labor production efficiency. When performing electrolysis at high operating current densities, titanium anodes are more suitable.

4. Due to the use of metal anodes, high temperature and high current density operation of chlorate electrolyzers is possible. The use of metal anodes improves the structure of the electrolytic cell, reduces power consumption, accelerates the chemical reaction of hypochlorite to gas chlorate, thereby improving production performance.

5. With the adoption of DSA, the design concepts and operating conditions of mercury method and diaphragm method salt electrolyzers can be improved, and energy consumption can be reduced. The low overpotential characteristics of DSA make it easy to remove air bubbles on the surface between electrodes and in the electrodes, which is an important reason for the decrease in cell voltage of metal anode electrolyzers.

Because titanium anodes have many advantages, their development has brought great economic benefits to the chlor-alkali industry, so their use was soon promoted around the world. The world's chlor-alkali production capacity is about 41 million tons per year, and no less than 70% of it uses titanium anodes. Titanium anodes are known as a major technological revolution in the chlor-alkali industry. Subsequently, titanium anodes have also been widely used in many electrolysis industries.

6. The size of the anode is stable, and the distance between the electrodes does not change during the electrolysis process, which ensures that the electrolysis operation is carried out under the condition of stable cell voltage.

7. It can avoid the short circuit problem after the lead anode is deformed, thus improving the current efficiency.

8. Titanium anode is light in weight and can reduce labor intensity.

9. The switch is easy to make and can be made with high precision.

10. The working voltage is low, so the power consumption is small, which can save power consumption, and the DC power consumption can be reduced by 10%~20%. The main reasons for low working voltage of titanium anodes:
1) The overpotential of active-coated titanium anodes for both chlorine and oxygen is relatively low. When producing chlor-alkali by electrolysis of brine, the titanium anode has a low overpotential for chlorine, which is 140mV lower than the graphite anode at 1A/cm2;
2) It can reduce the "bubble shielding effect". The bubbles generated on the surface of the metal anode are relatively small and break away quickly. This greatly reduces the aeration between the electrodes, the ohmic drop between the two electrodes is about 700mV, and the bubble diameter is about 3mm;
3) Reduce the resistance of the anode structure;
4) The distance between poles is shortened.

In the 1960s, the world's salt electrolysis industry consumed about 150 billion kilowatt-hours of electricity annually. Using metal anodes could save about 300 million kilowatt-hours of electricity every year.

11. In chlor-alkali production, the use of titanium anodes results in high product quality, high purity of chlorine, no CO2, and high alkali concentration, which can save heating steam and energy consumption.

12. It has strong corrosion resistance and can work in many electrolytic media that are highly corrosive and have special requirements.

13. The base metal titanium can be used repeatedly.

14. With the emergence of metal anodes, the latest ion membrane electrolysis technology that has recently emerged in the chlor-alkali industry can be designed and industrialized.

Classification
Soluble anodes and insoluble anodes

The soluble anode plays the role of supplementing metal ions and conducting electricity during the electrolysis process, while the insoluble anode only plays the role of conduction. The earliest insoluble anodes were graphite and lead-based anodes. In the 1970s, titanium anodes began to be used in the electrolysis and electroplating industries as a new technology. Insoluble anodes can be divided into two categories: chlorine evolving anodes and oxygen evolving anodes. Chlorine-evolving anodes are mainly used in chloride electrolyte systems. During the electroplating process, chlorine gas is released from the anode, so it is called chlorine-evolving anodes. Oxygen-evolving anodes are mainly used in electrolyte systems such as sulfate, nitrate, and hydrocyanate. Electroplating During the process, oxygen is released from the anode, so it is called an oxygen-evolving anode. Lead alloy anode, oxygen evolution anode, and titanium anode have oxygen evolution, chlorine evolution, or both functions depending on the catalytic coating on their surface.

Titanium anode for chlor-alkali industry

Compared with graphite electrodes, the diaphragm method is used to produce caustic soda. The working voltage of graphite anodes is 8A/DM2 and the coated anode can be doubled to 17A/DM2. In this way, the products can be doubled under the same electrolysis environment, and the quality of the products produced is high, and the purity of chlorine gas is high.

Titanium anode for electroplating

The insoluble anode for electroplating is a titanium substrate (mesh, plate, strip, tube, etc.) coated with a noble metal oxide coating with high electrochemical catalytic performance. The coating contains a highly stable valve metal oxide. The new insoluble titanium anode has high electrochemical catalytic energy, and the oxygen evolution overpotential is about 0.5 V lower than that of the lead alloy insoluble anode. It has significant energy saving, high stability, does not pollute the plating solution, is light in weight, and is easy to replace. The oxygen evolution overpotential of the new insoluble titanium anode is also lower than that of the platinum-coated insoluble anode, but its lifespan is more than doubled. It is widely used as an anode or auxiliary anode in various electroplating. It can replace the conventional lead-based alloy anode. Under the same conditions, it can reduce the cell voltage and save power consumption; insoluble titanium anode has good stability during the electroplating process. (chemistry, electrochemistry), long service life. This anode is widely used in nickel plating, gold plating, chromium plating, zinc plating, copper plating and other electroplating non-ferrous metal industries.

Lead and lead alloy anodes

Lead alloy anodes are oxygen evolution anodes. The electrolyte for the oxygen evolution reaction is sulfuric acid and sulfate. They are mainly used in electrolytic metallurgy. This anode has the disadvantage that its geometric dimensions change during the electrolysis process. , during the electrolysis process, the lead anode matrix is first converted into lead sulfate and then into lead oxide. Lead sulfate is an intermediate layer that is an insulator and acts as a chemical barrier to protect the inner lead matrix in a sulfuric acid environment. Lead oxide is a practical electrode in the outer layer, and oxygen evolution reaction occurs on it. The oxygen evolution potential of lead oxide is very high, and it rises rapidly with the increase of current density. This characteristic of lead alloy anode is caused by the oxidation of its outer layer material. The inherent characteristics of lead - lead oxide is determined by the fact that it is a poor conductor of electricity. In addition, during the electrolysis process, the electrochemical performance of the lead oxide anode structure continues to decay, and the generation of internal stress causes the oxides to fall off layer by layer. In addition, the generation of lead peroxide also causes the oxides to continuously dissolve, and the sulfuric acid as the intermediate layer Lead is converted into lead oxide again, becoming a new outer layer of oxide electrocatalytic active material, and the inner layer of lead matrix is oxidized again, forming a new intermediate protective layer of lead sulfate. Therefore, during the electrolysis process, lead and its alloy elements continue to dissolve into the electrolyte and precipitate, causing solution pollution (chemical precipitation in the solution) and cathode product pollution (electrodeposition of contaminants on the cathode surface). The purity of the electrolyzed copper cannot be very high. Good ones are guaranteed).

Coated titanium anode

Coated titanium anode, commonly known as DSA (Dimensionally Stable Anode), also known as DSE (Dimensionally Stable Electrode), is a new type of insoluble anode material developed in the late 1960s. DSA coated titanium anodes are mainly used in the two major sectors of electrochemistry and electrometallurgy.

The application fields of DSA coated titanium anodes include: chlor-alkali industry, chlorate production, hypochlorite production, perchlorate production, persulfate electrolysis, electrolytic organic synthesis, electrolytic extraction of non-ferrous metals, electrolytic silver catalyst production, Manufacturing of copper foil by electrolysis, mercury recovery by electrolytic oxidation, water electrolysis, preparation of chlorine dioxide, hospital sewage treatment, treatment of cyanide-containing wastewater from electroplating plants, disinfection of domestic water and food utensils, treatment of cooling circulating water in power plants, wool spinning Treatment of factory dyeing and finishing wastewater, treatment of industrial water, production of acid-base ionized water by electrolysis, galvanizing, rhodium plating, palladium plating, gold plating, lead plating on copper sheets, desalination of seawater by electrodialysis, production of tetramethyl hydroxide by electrodialysis Ammonium, molten salt electrolysis, battery production, cathodic protection, production of negative electrode foil, anodization of aluminum foil, etc. It is widely used in chemical industry, metallurgy, water treatment, environmental protection, electroplating, electrolytic organic synthesis and other fields.