Adsorption and photodegradation of methylene blue using a bulk Ti material with porous titania layer prepared by chemical oxidation

•Porous titania network was produced on the Ti bulk disk via H2O2 oxidation method.•After 90 min oxidation, a thicker titania layer (≈4 μm) with mixed amorphous–anatase phase was formed.•The point of zero charge (PZC) of the prepared titania layer was estimated at pH 2.2.•The prepared titania layer exhibited better methylene blue adsorption than P25 TiO2 nanoparticles.•Rougher surface could achieve higher dye photodegradation efficiency.

In this study, a chemical oxidation method was adopted to prepare a porous titania network on Ti bulk for dye adsorption and photodegradation. The prepared titania layer was characterized by SEM, AFM, ATR-FTIR, XRD, and zeta potential. Using a longer oxidation time (90 min), a thicker titania layer (≈4 μm) with pHpzc (pH of the point of zero charge) of ca. 2.2 and larger fraction of anatase phase could be formed. The prepared titania layer exhibited a better adsorption capability for MB (methylene blue) at various pH values than the commercial P25 TiO2 nanoparticles (pHpzc = 6.0–6.8). Moreover, the effect of surface roughness on dye photodegradation was investigated. With UV irradiation, it took 6 h to completely decompose MB using the titania layer prepared from the polished surface, whereas only half time was required by that abraded via #240 sandpaper. An improved dye photodegradation efficiency was achieved by a rougher surface for providing a larger surface area.