A Comparative Study between Photocatalytic activity of ZnO/bentonite Composites Prepared by Precipitation, Liquid-state Ion Exchange and Solid-state Ion Exchange Methods

Abstract

ZnO/bentonite photocatalyst was synthesized using different methods, including: precipitation, liquid-state ion exchange (LSIE) and solid-state Ion exchange (SSIE) methods. In most studies done so far, LSIE and precipitation method have been used to prepare composites. The SSIE is a new method. The purpose of this research is to produce nanocomposites with each of these methods and compare their photocatalytic activity. The physicochemical properties of the prepared photocatalysts were determined by scanning electron microscope (SEM), energy dispersive X-ray (EDX) and diffusive reflective spectroscopy (DRS) analysis. The Photocatalytic activity was evaluated by degradation of methyl orange (MO) with the prepared photocatalysts. SEM images showed that the ZnO particles were successfully distributed on the bentonite in the samples prepared by precipitation method. Nevertheless, after ion exchange-based methods, no particles were formed on the bentonite surface. This is because of very small size of ZnO particles which in the interlayer space of bentonite. The EDX and DRS analysis confirmed the formation of composites. The photodegradation of MO were 84, 85 and 87% for the composites prepared by LSIE, SSIE and precipitation methods, respectively. Ultimately, the photocatalytic composites prepared by the solid-state method are very bright due to their simple production, low price and short time due through direct heating of the reaction.