On the photocatalytic properties of elongated TiO2 nanoparticles for phenol degradation and Cr(VI) reduction.

Elongated TiO(2) nanoparticles with high aspect ratio have specific advantages in separation processes. In this study, TiO(2) nanofiber was prepared via a hydrothermal reaction, and TiO(2) nanoparticles with varied structural properties were obtained using hydrothermal and calcination post-treatments. Photocatalytic phenol degradation and Cr(VI) reduction over these catalysts was investigated. Results showed that hydrothermally prepared TiO(2) nanofiber consisted of titanate with high aspect ratio. Calcining the as-prepared TiO(2) nanofiber at 400 and 600 degrees C led to the crystalline phase transformation from titanate to TiO(2)-B and to the presence of mixed crystalline phases composed of TiO(2)-B and anatase. In contrast, hydrothermal post-treatment results in the generation of pure anatase TiO(2) nanoparticles. For photocatalytic phenol degradation, calcining the as-prepared TiO(2) nanofiber resulted in an enhanced catalytic activity, whereas TiO(2) nanoparticles obtained by calcination post-treatment showed lower catalytic activities for photocatalytic Cr(VI) reduction compared to as-prepared TiO(2) nanofiber. TiO(2) nanofiber modified using the hydrothermal post-treatment, however, exhibited the highest catalytic activity among TiO(2) nanoparticles examined for both photocatalytic phenol degradation and Cr(VI) reduction. Furthermore, TiO(2) nanoparticles obtained by hydrothermal post-treatment showed the best sedimentation efficiency, highlighting its prominent potential as a readily separable and recoverable photocatalyst. 2009 Elsevier B.V. All rights reserved.