Anodic oxidation Titanium dioxide 6 Coatings 5 Amines 4 Fourier transform infrared spectroscopy 4 Heterogeneous photocatalysis 4 Hexavalent chromium 4 Oxidation 4 Room temperature 4 Scanning electron microscopy 4 Spectroscopic analysis 4 Thermogravimetric analysis 4 UV-vis spectroscopy 4 Ultraviolet spectroscopy 4 Nanotubes 3 Photocatalysis 3 TiO2 nanotubes 3 Acid treatments 2 Acidic aqueous solution 2 Adaptive devices 2 Adsorption 2 Alumina 2 Aluminum 2 Aluminum coatings 2 Aluminum oxide 2 Amination 2 Amine 2 Amine functionalization 2 Amine groups 2 Ammonium compounds 2