Energy modeling of electrochemical anodization process of titanium dioxide nanotubes

Titanium dioxide nanotubes have some unique properties and have found a wide range of potential applications. Electrochemical anodization is a popular method for synthesis of TiO₂ nanotubes. While the TiO₂ nanotube morphologies are mainly controlled by the supplied electrical power and anodization time, energy inputs into the electrochemical anodization process also affect the sustainability performance of the technology in future industrial applications. This paper presents a mathematical modeling approach for understanding the direct energy consumptions in the electrochemical anodization process in which the process is divided into five stages including cleaning/drying, oxide layer formation, chemical diffusion, physical diffusion, and calcinations. Mathematical models based on thermodynamics and kinetics are developed for each of the above stages and validated using both experimental and literature data. The results demonstrate that about 67% of the energy input in the electrochemical anodization process is required by the physical diffusion. These models and analyses results could help understand the internal energy flow pattern within the electrochemical anodization process and aid sustainable development of the technology for future large-scale industrial applications.