The Application System for Titanium Anodes: Selection, Conditions, and Maintenance

The Application System for Titanium Anodes: Selection, Conditions, and Maintenance

The exceptional performance of titanium anodes is not intrinsic; their high efficiency and long service life depend on a rigorous application system encompassing precise selection, strict prerequisites, and standardized operation and maintenance.

Selection must precisely match the process. Titanium anodes are custom components; there is no universal model. The core basis for selection is the electrolysis process route and operating conditions. For mainstream membrane cell chlor-alkali production, ruthenium-titanium based coatings are the standard choice due to their excellent chlorine evolution activity and economy. However, when the process involves a more oxygen-rich environment-such as in

membrane cells using oxygen-depolarized cathode technology, or during chlorate electrolysis-the anode must withstand higher oxygen partial pressure and potential. In these cases, the oxidation-resistant iridium-tantalum based coating becomes essential. Incorrect coating selection will directly lead to rapid coating failure and voltage spikes.

High-quality brine purification is an absolute prerequisite. Titanium anodes have extremely stringent requirements for the purity of the feed brine. Alkaline earth metal ions like calcium, magnesium, strontium, and barium in the brine, if not removed to parts-per-billion (ppb) levels through chemical treatment ("two-alkali method") and chelating resin adsorption, can migrate under the electric field and deposit within the coating micropores and the ion-exchange membrane. This forms an insulating layer, leading to abnormal voltage increases and permanent damage. Impurities like sulfate and iodide ions can also cause coating poisoning or structural damage. Therefore, a stable and reliable secondary brine purification system is the "lifeline" for titanium anode performance.

Standardized operation and failure management are crucial. There are two major operational taboos: First, strict prevention of "reverse current," meaning measures must be taken to prevent external current from flowing backwards into the anode when the electrolyzer is shut down, as this causes permanent deactivation of the coating's active components through electrochemical reduction. Second, strict prevention of "dry running," meaning the anode must be immersed in the electrolyte when powered; exposure to air causes rapid oxidative damage. Normal performance degradation manifests as a slow, linear increase in cell voltage over time. An abnormal failure is indicated by a sharp, non-linear voltage increase within a short period, typically pointing to excessive brine impurities, local coating detachment, or substrate passivation, requiring immediate process investigation. For anodes with normal coating wear but an intact substrate, most of the performance can be restored through professional recoating processes (removing the old coating and reapplying a new one), which is an effective method for controlling long-term operating costs.