What Does Inert Anode Mean?
An inert anode is an anode that is insoluble in the electrolyte under the conditions obtained in electrolysis. Inert anodes are non-consumable.
The use of inert anodes in the aluminum smelting process is a groundbreaking technology, capable of revolutionizing industry. Though it is not currently in practice, once introduced it may enable the elimination of any hazardous emissions.
Unlike carbon anodes, inert anodes are not corroded during the aluminum reduction process and do not release CO2, but rather pure oxygen.
Corrosionpedia Explains Inert Anode
An inert anode does not participate in reactions during electrolysis. For example, an anode of platinized titanium is used in cathodic protection which is long-lasting and requires an impressed direct current.
For many years industry has been looking at the possibility of using inert anodes made of ceramics, metals or cermets (composites of ceramics and metals). Using inert anodes avoids the formation of CO2, so that only pure oxygen is produced as a byproduct. Inert anode technology in the aluminum sector could contribute:
- Increased energy efficiency
- Reduction in operating costs
- Significant reductions of emissions such as CO2 and perfluorocarbons
- Process productivity increase
- Lower emissions
Anodic potentials and materials made of inert anodes have significant impact on corrosion. For example, the corrosion rate of tin oxide-based anodes showed normal corrosion at anodic potentials of 2.2 to 2.4 V with respect to aluminum. At potentials higher than ~2.5 V, the anodes showed catastrophic corrosion. Catastrophic corrosion can be ascribed to decomposition of the anode material by depletion of alumina at the anode surface provoked by low bulk concentration of alumina and/or high current density.