Photocatalytic degradation of Orange II by titania addition to sol-gel glasses

Glasses on SiO2-CaO-ZnO-B2O3-K2O-Al2O3 oxide system modified by addition of titania (0, 3, 5, 12, and 20% w) have been prepared by sol-gel method. The obtained gels were aged, dried and fired at 600 A degrees C/1 h in order to stabilise the glass. The resulting fired powders were characterised by UV-Vis-NIR spectroscopy, scanning electron microscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD). Their photocatalytic capacity on the degradation of Orange II dye has been studied. The XRD and TEM studies indicate that system becomes amorphous with a nanostructured microstructure. From UV-Vis-NIR results the band gap calculated is around 3.5 eV for all modified glasses. Photoactivity of powders depends on amount of titania in glass composition and the specific surface area of prepared samples. The sample with highest surface area and lowest addition of titania (3% w sample) shows similar activity than commercial anatase used as reference.