Improvement of the structural, morphology, and optical properties of TiO2 for solar treatment of industrial wastewater

Abstract

Hydrothermal preparation of pure anatase TiO2 with hybrid nano and micro-morphologies directly from titania sol under acidic condition in the absence of any additives or templates has rarely been reported. The present work has found that the post-hydrothermal treatment at 200°C for different times (6, 12, 24, and 36 h) of titania sol under an acidic environment affected strongly on the structural, morphology, and optical properties of TiO2. A single-crystalline anatase phase with high surface area was obtained. The TEM results showed that shape of TiO2 nanoparticles could be manipulated by post-hydrothermal treatment. The increasing of hydrothermal time (pH 2.5) significantly altered the morphology of TiO2 from pure aggregated nanospherical shape (6 h) into branched micro-flowers as a major shape in addition to nanorod, nanocube, and nanosphere shapes (24 h). Shape-controlled TiO2 nanoparticles showed a red shift in UV–Vis light reflectance spectra as compared to TiO2 nanoparticles obtainedwithout any hydrothermal treatment. The photoluminescence measurements confirm that hydrothermal treatment significantly decrease the electron–hole recombination chance in the obtained TiO2. The fluorescent probe method was used for evaluation of the photo-oxidative activity of different TiO2 nanomaterials. The highly active TiO2 nanoparticle (hydrothermally treated for 24 h) was applied for industrial wastewater treatment using solar radiation as a renewable energy source.