Effects of hydrothermal temperature on formation and decoloration characteristics of anatase TiO2 nanoparticles

This paper describes the effects of temperature on the complex intermediate processes from the precursor to the fully-crystallized anatase TiO2 nanoparticles in hydrothermal synthesis. The anatase TiO2 nanoparticles were synthesized in a wide temperature range below 230A degrees C. The composition, morphology, and methylene blue (MB) decoloration characteristics of the obtained products were investigated by X-ray diffraction, Fourier transform infrared spectroscope, X-ray photoelectron spectroscope, and scanning and transmission electron microscope. The dehydrating polycondensation of Ti(IV)-hydrates and the decomposition of (NH4)(2)Ti3O7 intermediates with the temperature increase lead to the direct formation of anatase TiO2 nanoparticles under the hydrothermal environments. The strong MB decoloration of the hydrothermal products obtained at the low (a (c) 3/4130A degrees C) and high (a (c) 1/2180A degrees C) temperatures are attributed to the adsorption of Ti(IV)-hydrates and the photocatalysis of anatase TiO2 nanoparticles, respectively.