Hydrothermal synthesis of bare TiO2 nanowires and polystyrene (PS)-TiO2 nanowires used for selective photocatalytic oxidation of 3-pyridinemethanol in water and PS photodegradation in solid state

Abstract In the present work, nanowire (NW) structured TiO 2 nanoparticles were prepared using the hydrothermal method and characterized by X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), and BET specific surface area techniques. They were obtained in the anatase phase and presented a high surface area (ca. 300 m 2 /g). A commercial TiO 2 (anatase, Merck) was used for comparison. The TiO 2 catalysts were tested for photocatalytic oxidation of 3-pyridinemethanol to 3-pyridinemethanal and vitamin B 3 in water under UVA irradiation. The effects of acid treatment and subsequent calcination for TiO 2 catalysts after the hydrothermal synthesis were also investigated. The sample, subjected to acid treatment and calcined at 300 °C (NW-HCl-300), showed the highest photocatalytic activity and selectivity towards the products. Consequently, this sample and Merck TiO 2 were used to prepare polystyrene (PS)/TiO 2 composites using the hydrothermal method. They were characterized by XRD, SEM–EDX, Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), UV–Vis, Gel Permeation Chromatography (GPC), and contact angle measurements and tested for PS (present in the composite) photodegradation. The results indicated that NW-HCl-300 had a high surface area, and was highly hydroxylated, favouring a good distribution of PS in the composite. The composite presented high thermal stability, but under UVA irradiation the polymer underwent solid-state photocatalytic degradation due to the contact with TiO 2 . The composite photodegradation was investigated using gravimetric, GPC, FT-IR, UV–Vis, and SEM techniques.

Перевод пока недоступен