Sonocatalytic Degradation of Rhodamine B in the Presence of TiO2Nanoparticles by Loading WO3

Abstract

In the present work, <TEX>$WO_3$</TEX> and <TEX>$WO_3-TiO_2$</TEX> were prepared by the chemical deposition method. Structural variations, surface state and elemental compositions were investigated for preparation of <TEX>$WO_3-TiO_2$</TEX> sonocatalyst. X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and transmission electron microscopy (TEM) were employed for characterization of these new photocatalysts. A rhodamine B (Rh.B) solution under ultrasonic irradiation was used to determine the catalytic activity. Excellent catalytic degradation of an Rh.B solution was observed using the <TEX>$WO_3-TiO_2$</TEX> composites under ultrasonic irradiation. Sonocatalytic degradation is a novel technology of treating wastewater. During the ultrasonic treatment of aqueous solutions sonoluminescence, cavitaties and "hot spot" occurred, leading to the dissociation of water molecules. In case of a <TEX>$WO_3$</TEX> coupled system, a semiconductor coupled with two components has a beneficial role in improving charge separation and enhancing <TEX>$TiO_2$</TEX> response to ultrasonic radiations. In case of the addition of <TEX>$WO_3$</TEX> as new matter, the excited electrons from the <TEX>$WO_3$</TEX> particles are quickly transferred to <TEX>$TiO_2$</TEX> particle, as the conduction band of <TEX>$WO_3$</TEX> is 0.74 eV which is -0.5 eV more than that of <TEX>$TiO_2$</TEX>. This transfer of charge should enhance the oxidation of the adsorbed organic substrate. The result shows that the photocatalytic performance of <TEX>$TiO_2$</TEX> nanoparticles was improved by loading <TEX>$WO_3$</TEX>.