Photocatalytic degradation of 1,2-dichlorobenzene using immobilized TiO2/SnO2/WO3 photocatalyst under visible light: Application of response surface methodology

Abstract

Photodegradation of 1,2-dichlorobenzene over illuminated trimetallic oxide consisting of rutile TiO2 in major portion together with WO3 and SnO2 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 TiO2 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 (R2 = 0.9992, Adj. R2 = 0.9982 and Pred. R2 = 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.