Preparation and Characterisation of TiO₂ Nanoparticle and Titanate Nanotube Obtained from Ti-Salt Flocculated Sludge with Drinking Water and Seawater

This study aimed to prepare and characterise titanium dioxide (TiO₂) nanoparticles and titanate nanotubes produced from Ti-sat flocculated sludge with drinking water (DW) and seawater (SW). The Ti-salt flocculated sludge from DW and SW was incinerated at 600 °C to produce TiO₂ nanoparticles. XRD results showed that the anatase TiO₂ structure was predominant for TiO₂ from DW (TiO₂-DW) and TiO₂ from SW (TiO₂-SW), which were mainly doped with carbon atoms. Titanate nanotubes (tiNT) were obtained when TiO₂-DW and TiO₂-SW were hydrothermally treated with NaOH solution. Structure phase, shape, crystallisation and photocatalytic activity of tiNT were affected by the incineration temperature and the amount of sodium present in different tiNT. The tiNT doped with thiourea incinerated at 600 °C presented anatase phase, showing a high increase of the degree of crystallisation with nanotube-like structures. The photocatalytic activity of these photocatalysts was evaluated using photooxidation of gaseous acetaldehyde. Thiourea doped tiNT-DW and tiNT-SW showed similar photocatalytic activity compared to commercially available TiO₂-P25 under UV light and indicated a photocatalytic activity under visible light.