Photocatalytic degradation of azo dye acid red G by KNb3O8 and the role of potassium in the photocatalysis

The layered photocatalyst KNb3O8 was prepared using a solid-state reaction method. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to characterize the photocatalyst. The photocatalytic degradation of acid red G over the photocatalyst under UV irradiation was studied. The influences of catalyst dosage, initial concentration of acid red G were determined as well. The kinetics of photocatalytic degradation of acid red G follows first-order kinetics. The H+-exchanged KNb3O8 was prepared and its photocatalytic activity is much lower than that of the KNb3O8. The roles of the layered structure of the KNb3O8 and the potassium ions between the layers in the photocatalytic reaction were discussed.