Sonochemical synthesis of Au– nanoparticles for the sonophotocatalytic degradation of organic pollutants in aqueous environment

Au– TiO 2 photocatalysts were sonochemically prepared by three different procedures and their photocatalytic and sonophotocatalytic efficiencies were evaluated by studying the degradation of a representative organic pollutant, nonylphenol ethoxylate (NPE) surfactant in aqueous solutions. In the first procedure, Au– TiO 2 nanoparticles were prepared by depositing sonochemically synthesized gold nanoparticles on Degussa P25 TiO 2 by stirring in the absence of an ultrasonic field. In the second procedure, Au nanoparticles were sonochemically synthesized and simultaneously deposited on Degussa P25 TiO 2 particles. In the third procedure, Au– TiO 2 nanoparticles were sonochemically synthesized by the simultaneous irradiation of an aqueous solution containing AuCl 4 - and titanium tetraisopropoxide. The prepared nanoparticles were characterized by UV–vis spectroscopy and transmission electron microscopy (TEM). The catalytic activities of these nanomaterials were compared for the degradation of a polydisperse nonylphenol ethoxylate, Teric GN9 by photocatalysis and sonophotocatalysis under visible light/high frequency ultrasound irradiation. The catalysts did not show a synergetic effect towards the sonophotocatalytic degradation of Teric GN9. This might be due to the interference of the degradation products generated during the simultaneous irradiation by light and ultrasound.