Titanium-based lead dioxide Anode

1. Structural Design: Multi-layer Compositeness is Key

The titanium-based lead dioxide anode is not a simple coating, but rather a "sandwich" structure:

• Titanium matrix: Provides mechanical strength support.
• Intermediate bonding layer: To prevent the titanium surface from oxidizing during electrolysis and forming an insulating TiO₂ passivation film that leads to failure, a pre-coated intermediate layer such as tin-sulfide oxide, platinum group metal oxide, or tantalum will be applied. This is the core for the long lifespan of the electrode.
• Surface active layer (PbO₂): The actual functional layer, divided into α-PbO₂ and β-PbO₂, is usually used in combination to optimize performance.

2. Core performance

• High catalytic and strong oxidation capabilities: A high oxygen evolution potential (approximately 1.75V), which enables the preferential oxidation and degradation of organic substances during electrolysis rather than the release of oxygen.
• Excellent corrosion resistance: Extremely stable in oxidizing media such as strong acids (such as sulfuric acid and nitric acid).
• Good conductivity and stability: PbO₂ itself has good conductivity, and with the titanium substrate, the electrode resistance is low, and the cell voltage can be 5%-8% lower than that of traditional anodes. As an insoluble anode, the size is stable.
• Economy: The material cost is much lower than that of platinum and other precious metal anodes.

3. Main Limitations

• Degradation due to passivation failure: After the intermediate layer is damaged, the oxidation of the titanium substrate will cause the coating to peel off.
• Potential lead leaching: In extreme conditions or when the coating quality is poor, there is a risk of trace leaching of lead ions, which limits its application in certain high-purity product fields.
• Complex preparation process: Multi-layer preparation (such as pre-treatment, deposition of the intermediate layer, electro-deposition of PbO₂) requires high standards and significant quality variations.

How to choose and use

• Preferred scenarios: For treating complex and non-biodegradable organic wastewater, or when conducting electrolysis operations in a strongly acidic medium.
• Key evaluation indicators: Pay attention to the data from the accelerated life test; understand the specific material of the intermediate layer (such as tin-selenium oxide, tantalum, etc.) and the process.
• Usage precautions: · Avoid long-term use in a strongly alkaline environment (PbO₂ will dissolve). · Ensure that the electrolyte does not contain fluoride ions (which will severely corrode the titanium substrate). · When reactivating new electrodes or after a long period of inactivity, it is recommended to perform polarization treatment at a low current first.

 Horizontal Comparison and Advancement

Compared with the several electrodes discussed previously, the titanium-based lead dioxide anode has a clearly defined position:

• Comparison with stainless steel/nickel anodes: They are mainly used as cathodes or soluble anodes in alkaline or weakly corrosive environments, while titanium-based lead dioxide is an insoluble anode for highly corrosive and oxidizing environments, with completely different functions.
• Comparison with other titanium-based anodes (such as iridium-tantalum coated DSA): The latter is superior in chlorine evolution reactions (such as in the chlorine alkali industry) and has an extremely long lifespan, but in high oxygen evolution potential and strong oxidizing organic wastewater treatment, titanium-based lead dioxide has a greater cost advantage.