Classification Of Titanium Anodes

Soluble anode and insoluble anode

Soluble anode plays the role of supplementing metal ions and conducting electricity in the electrolysis process, while insoluble anode only plays the role of conducting electricity. The earliest insoluble anodes were graphite and lead 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 anodes and oxygen anodes. Chlorine anodes are mainly used in chloride electrolyte systems. Chlorine gas is released from the anode during the electroplating process, so they are called chlorine anodes; oxygen anodes are mainly used in sulfate, nitrate, hydrocyanate and other electrolyte systems. Oxygen is released from the anode during the electroplating process, so they are called oxygen anodes. Lead alloy anodes are oxygen-evolving anodes, and titanium anodes have oxygen evolution, chlorine evolution or both functions according to their surface catalytic coatings.

Titanium anodes for chlor-alkali industry
Compared with graphite electrodes, the working voltage of graphite anodes is 8A/DM2 in the production of caustic soda by the diaphragm method, and the coated anode can be doubled to 17A/DM2. In this way, the product can be doubled under the same electrolytic environment, and the quality of the product is high and the purity of chlorine is high.

Titanium anode for electroplating
The insoluble anode for electroplating is a precious metal oxide coating with high electrochemical catalytic performance coated on a titanium substrate (mesh, plate, strip, tube, etc.), and the coating contains a valve metal oxide with high stability. 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, no pollution to the plating solution, light weight, and easy replacement. The oxygen evolution overpotential of the new insoluble titanium anode is also lower than that of the platinum-plated insoluble anode, but the life span is increased by more than 1 times. It is widely used as an anode or auxiliary anode in various electroplating processes, and can replace conventional lead-based alloy anodes. Under the same conditions, it can reduce the cell voltage and save energy consumption; the insoluble titanium anode has good stability (chemical, electrochemical) during the electroplating process and has a long service life. This anode is widely used in the electroplating of non-ferrous metals such as nickel plating, gold plating, chrome plating, zinc plating, and copper plating.

Lead and lead alloy anode
Lead alloy anode is an oxygen evolution anode. The electrolyte for oxygen evolution reaction is sulfuric acid and sulfate, which is mainly used in electrolytic metallurgy. This anode has the defect that the geometric dimensions will 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, which is an insulator and acts as a chemical barrier to protect the inner lead matrix in a sulfuric acid environment. Lead oxide is an electrode in the actual sense on the outer layer, where oxygen evolution reaction occurs. The oxygen evolution potential of lead oxide is very high and rises rapidly with the increase of current density. This characteristic of the lead alloy anode is determined by the inherent characteristics of its outer layer material lead oxide - lead oxide 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 its internal stress causes the oxide to fall off layer by layer. In addition, the generation of lead peroxide also causes the oxide to dissolve continuously. The lead sulfate as the intermediate layer is converted into lead oxide again, becoming a new outer oxide electrocatalytic active substance, 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 alloy elements continue to dissolve into the electrolyte and precipitate, causing solution pollution (chemical precipitation in the solution) and cathode product pollution (electrodeposition of pollutants on the cathode surface, and the purity of copper electrolyzed cannot be well 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 anode is mainly used in two major departments: electrochemistry and electrometallurgy.
The application fields of DSA coated titanium anode include: chlor-alkali industry, chlorate production, hypochlorite production, perchlorate production, persulfate electrolysis, electrolytic organic synthesis, electrolytic extraction of non-ferrous metals, production of electrolytic silver catalyst, electrolytic copper foil, electrolytic oxidation recovery of mercury, water electrolysis, preparation of chlorine dioxide, hospital sewage treatment, electroplating plant cyanide wastewater treatment, domestic water and food utensils disinfection, power plant cooling circulating water treatment, wool spinning plant dyeing and finishing wastewater treatment, industrial water treatment, electrolytic preparation of acid and alkali ion water, copper plate zinc plating, rhodium plating, palladium plating, gold plating, lead plating, electrodialysis desalination of seawater, electrodialysis preparation of tetramethylammonium hydroxide, molten salt electrolysis, battery production, cathodic protection, production of negative foil, anodization of aluminum foil, etc. The application is widely involved in chemical industry, metallurgy, water treatment, environmental protection, electroplating, electrolytic organic synthesis and other fields.