Classification and characteristics of titanium anodes
Titanium anode has good conductivity and corrosion resistance, low cost, much longer service life than lead anode, and can work stably for more than 4,000 hours. It is an inevitable trend in the development of electroplating zinc and tin production at home and abroad. Titanium electrodes are currently used in Japan, the United States, Germany, and China. They not only greatly save electroplating energy consumption, but also create conditions for the production of thick galvanized and tin steel plates because they can increase the electroplating current density.
Titanium anode is also called titanium-based metal oxide coated titanium anode (MMO), or KSA anode, which is a dimensionally and shape-stable anode. It uses titanium as the substrate, and brushes precious metal coating on the titanium substrate to make it have good electrocatalytic activity and conductivity. Generally, industrial pure titanium GR1 and GR2 are used.
Titanium anode classification:
1. It is distinguished according to the gas evolved from the anode during the electrochemical reaction. The chlorine-evolving anode that precipitates chlorine gas is called a chlorine-evolving anode, such as a ruthenium-coated titanium electrode. The one that precipitates oxidation is called an oxygen-evolving anode, such as an iridium-coated titanium electrode and a platinum-titanium mesh. /plate.
Chlorine evolution anode (ruthenium-based coated titanium electrode): The electrolyte contains high ammonia ion content, which is generally used in hydrochloric acid environment, electrolysis of seawater and electrolysis of salt water. The product forms include ruthenium-iridium-titanium anode and ruthenium-iridium-tin-titanium anode.
Oxygen evolution anode (iridium-coated titanium electrode): The electrolyte is generally a sulfuric acid environment. Product forms include iridium-tantalum anode, iridium-tantalum-tin-titanium anode and high-iridium titanium anode.
2. Platinum-coated anode: titanium as base material. The surface is coated with platinum, and the coating thickness is generally 0.5-5μm. The mesh size of the platinum titanium mesh is generally 12.5x4.5mm or 6 x 3.5mm.
The main features of ruthenium-iridium chlorine-evolving titanium anode for hydrogen-alkali industry:
1. The anode size is stable and the electrode spacing does not change during the electrolysis process, which ensures that the electrolysis operation is carried out under the condition of stable cell voltage.
2. Low working voltage, small power consumption, and can reduce power consumption by about 20%.
3. Titanium anodes have a long working life. In the chlorine production industry using the diaphragm method, coated titanium anodes are resistant to corrosion by chlorine and alkali.
4. It can overcome the dissolution problem of graphite anode and lead anode, avoid contamination of electrolyte and cathode products, and improve product quality.
5. Can increase current density. For example, in the production of chlor-alkali by the diaphragm method, the current density of the graphite electrode is 8A/dm2, and the titanium anode can be doubled to 17A/dm2. In this way, the output can be doubled in the case of the same electrolytic plant and electrolytic cells.
6. It has strong corrosion resistance and can work in many electrolytic media that are highly corrosive and have special requirements.
7. It can avoid the short circuit problem after the lead anode is deformed, thereby improving the current efficiency.
8. The base titanium material can be used repeatedly.
