High photocatalytic activity of mixed anatase-rutile phases on commercial TiO sub(2) nanoparticles

Titanium dioxide (TiO sub(2)) is well-known as an active photocatalyst for degradation of various organic pollutants. Over the years, a wide range of TiO sub(2) nanoparticles with different phase compositions, crystallinities, and surface areas have been developed. Due to the different methods and conditions used to synthesize these commercial TiO sub(2) nanoparticles, the properties and photocatalytic performance would also be different from each other. In this study, the photocatalytic removal of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5- trichlorophenoxyacetic acid (2,4,5-T) was investigated on commercial Evonik P25, Evonik P90, Hombikat UV100 and Hombikat N100 TiO sub(2) nanoparticles. Upon photocatalytic tests, it was found that overall, the photocatalytic activities of the P25 and the P90 were higher than the N100 and the UV100 for the removal of both 2,4-D and 2,4,5-T. The high activities of the P25 and the P90 could be attributed to their phase compositions, which are made up of a mixture of anatase and rutile phases of TiO sub(2). Whereas, the UV100 and the N100 are made up of 100% anatase phase of TiO sub(2). The synergistic effect of the anatase/rutile mixture was reported to slow down the recombination rate of photogenerated electron-hole pairs. Consequently, the photocatalytic activity was increased on these TiO sub(2) nanoparticles.