New La3+ doped TiO2 nanofibers for photocatalytic degradation of organic pollutants: Effects of thermal treatment and doping loadings

Abstract The pure TiO2 and lanthanum (La3+)-doped titanium dioxide (TiO2) nanofibers were synthesized by electrospinning method followed via calcination at different temperatures (from 400 °C to 700 °C). Structures of the nanofibers were characterized by X-ray diffraction, scanning electron microscopy, TEM images and diffuse reflectance spectroscopy. The size of the nanofiber diameters was determined to be 129 and 101 nm, for pure TiO2 and (0.1%)La3+:TiO2 materials, respectively. The prepared nanofibers possess a crystalline structure, and wide distribution of the band-gaps, in the 2.867–3.210 eV range. Effects of La3+-dopant content, calcination temperature, and different doses of photocatalysts on the photodegradation efficiency were studied. The optimal level of La3+ and the optimal temperature of calcination were 0.1% La3+ and 600 °C, respectively. The photocatalytic degradation of methylene blue (91%, with a rate constant of 2.179×10−2 min−1) and ciprofloxacin (CIP) (99.5%, with a rate constant of 1.981×10−2 min−1) pollutants was highest on the (0.1%)La3+:TiO2 annealed at 600 °C, after 300 min irradiation under visible light. This photocatalyst displayed sustainable efficiency for CIP degradation up to five consecutive uses.