Search

Photodegradation of 1,2-dichlorobenzene over illuminated trimetallic oxide consisting of rutile TiO 2 in major portion together with WO 3 and SnO 2 was studied with respect to the effect of physicochemical properties of the catalyst. The photocatalytic activity enhancement by the presence of surface defects due to calcination temperature was investigated with the information obtained from XRD, DRUV, PL, FESEM and XPS. Calcination of TiO 2 at 950 °C resulted in highest activity. Decrease in percentage of degradation of 1,2-dichlorobenzene was noted when it was immobilized on PVC film and chitosan beads. The effect of calcination temperature, catalyst loading and pH was investigated for slurry and after immobilization. Further optimization study was carried out with the aid of response surface methodology utilizing Box–Behnken design. High correlation was obtained for the experimental and the predicted value ( R 2 = 0.9992, Adj. R 2 = 0.9982 and Pred. R 2 = 0.9971). Optimization result showed that the maximum percentage of degradation was achieved at calcination temperature of 961.2 °C, with catalyst loading of 0.22 g and pH 7.2. The presence of two intermediates was identified during the reaction using GC–MS. On top of that the photocatalyst could also be reused for several times.

The dose dependence of magnetism in Co-implanted TiO2 rutile was investigated using the magneto-optic Kerr effect method at room temperature. The (100)- and (001)-oriented single-crystalline rutile TiO2 plates were used as substrates and implanted by Co ions with a varying dose range of 0.25-1.50×1017 ions/cm2. We observed paramagnetic behaviour for the low dose doped samples, but obtain clear hysteretic-like behaviour for intermediate and high dose doped samples. For the intermediate implantation doses of Co, ferromagnetic behaviour can be explained by the F-center (oxygen vacancies) exchange mechanism, while for the highest implantation dose, in addition to Co substitution on Ti sites, formation of Co nanoclusters may take place within the TiO2 irradiated region. © 2006 Elsevier Ltd. All rights reserved.