Visible-Light-Induced Photocatalytic\nDegradation of Azodyes in Aqueous\nAgI/TiO₂ Dispersion

Abstract

AgI/TiO₂ was prepared by the deposition−precipitation\nmethod and was found to be a novel visible light driven\nphotocatalyst. The catalyst showed high efficiency for the\ndegradation of the nonbiodegradable azodyes reactive\nred K-2G, reactive brilliant red X-3B, reactive red K-2BP,\nand reactive yellow KD-3G under visible light irradiation (λ\n> 420 nm). The catalyst's activity was maintained\neffectively after successive cyclic experiments under\nvisible irradiation without the destruction of AgI. On the\nbasis of the characterization of X-ray diffraction, X-ray\nphotoelectron spectroscopy, and Auger electron spectroscopy, the structure of AgI loaded on TiO₂ did not\nsignificantly change before and after reaction. K-2G was\ncompletely decolorized and partly mineralized. The\nmain intermediates are the small organic acids besides\nCO₂ and cyanuric acid, which is photostable. The ^•OH is the\nmain active oxygen species in the photocatalytic reaction\nby the studies of electron spin resonance and the\neffect of radical scavengers.