Abstract
Titanium dioxide (TiO2) doped with neodymium (Nd), one rare earth element, has been synthesized by a sol-gel method for the photocatalytic degradation of rhodamine-B under visible light. The prepared samples are characterized by X-ray diffractometer, Raman spectroscopy, UV-Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller measurement. The results indicate that the prepared samples have anatase and brookite phases. Additionally, Nd as Nd3+may enter into the lattice ofTiO2and the presence of Nd3+substantially enhances the photocatalytic activity ofTiO2under visible light. In order to further explore the mechanism of photocatalytic degradation of organic pollutant, photoluminescence spectrometer and scavenger addition method have been employed. It is found that hydroxide radicals produced by Nd-dopedTiO2under visible light are one of reactive species for Rh-B degradation and photogenerated electrons are mainly responsible for the formation of the reactive species.
Highlights
Dye wastewater discharged into nature mainly by dyestuff, textile industry, and some artificial way causes severe ecological problems
X-ray photoelectron spectra (XPS) measurements were performed in a PHI Quantum 2000 XPS system with a monochromatic Al Kα source and charge neutralizer to analyze surface chemicals and evaluate the amount and states of Nd atoms in the prepared samples
The degree of crystallinity and crystal structure of the prepared TiO2 and Nd-doped TiO2 samples were examined by XRD
Summary
Dye wastewater discharged into nature mainly by dyestuff, textile industry, and some artificial way causes severe ecological problems. The overall efficiency achieved so far with TiO2based systems is not sufficiently high to enable practical applications This low efficiency is mainly due to the fast recombination of charge carriers produced by irradiated TiO2 and the low quantum yield in the generation of reactive species for organic degradation [7, 8]. TiO2 with anatase and brookite phases as a photocatalyst has been rarely studied because brookite TiO2 has no activity for organic pollutant degradation and it needs higher temperature to prepare. There are quite a few publications about metal-doped TiO2, the mechanism for the improvement of photocatalytic activity has not been clear so far. The photocatalytic mechanism of Nd-doped TiO2 was investigated in detail by photoluminescence spectrometer (PL) [17] and scavenger addition method [18]
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