The disappearance of photocatalytic properties of titanium dioxide nanoparticles formed on PET fabrics treated in a simultaneous hydrothermal-dyeing process

In this paper, the influences of dyestuff Disperse Blue 79 and corresponding dyeing auxiliaries on the microstructure and the photocatalytic activities of titanium dioxide nanoparticles formed on polyethylene terephthalate (PET) fabric modified with tetrabutyl titanate in a simultaneous hydrothermal-dyeing process are studied. In contrast to the apparent photocatalytic activities of the crystalline titanium dioxide particles formed in the solely hydrothermal process using tetrabutyl titanate, the titanium dioxide nanoparticles formed in the simultaneous hydrothermal-dyeing process is non-crystalline and is covered with a layer of organic substances. It is thus concluded that the microstructure of the as-synthesized titanium oxide nanoparticles is greatly influenced by the presence of dyestuff and its corresponding dyeing auxiliaries. It is also found that these resultant non-crystalline titanium oxide nanoparticles in the simultaneous hydrothermal-dyeing process do not show any photocatalytic activity; the disappearance of the photocatalytic activity of the resultant titanium oxide nanoparticles in the simultaneous hydrothermal-dyeing process might be due to both their non-crystalline microstructure and their surface coating of organic substances.