Structural analyses of RuO2-TiO2/Ti and IrO2-RuO2-TiO2/Ti anodes used in industrial chlor-alkali membrane processes

The morphology and composition of RuO2-TiO2/Ti and IrO2-RuO2-TiO2/Ti anodes, which have been used for the production of chlorine for more than 10 years, were analyzed by various methods; such as high-resolution scanning electron microscopy, high-resolution Auger electron spectroscopy, electron probe X-ray emission microanalysis and X-ray diffraction analysis. Drastic changes in the surface morphology, including partial exfoliation of a small amount of the oxide layer and a reduction in the content of ruthenium species through dissolution, were observed for the RuO2-TiO2/Ti anode. For the IrO2-RuO2-TiO2/Ti anode, on the other hand, there were moderate changes in the surface morphology and moderate dissolution of iridium and ruthenium species.