Photocatalytic degradation of microcystin-LR using TiO nanotubes under irradiation with UV and natural sunlight.

In order to investigate the catalytic performance of anodic TiO nanotubes and their practical application in the treatment of refractory microcystins (MCs) in natural-water samples, TiO nanotubes of diameter of 50-80 nm were fabricated by anodization in CHO·2HO containing NHF. Under irradiation with natural sunlight, MC-LR was totally degraded after 1 d using the anodic TiO nanotubes. In contrast, the removal efficiency without TiO nanotubes was as low as 47.7% within 20 d. In addition, a mixture of anatase and rutile TiO gave higher photocatalytic activity than the single phase did. The pH also influenced the adsorption capacity of the TiO nanotubes. The order of MC-LR degradation efficiencies at different pH values was 3.5 > 8.0 > 10.0. After five repeated experiments on the degradation of MC-LR for 7 h, the degradation efficiency was still stable. [ABSTRACT FROM AUTHOR]