Photocatalytic degradation of dichlorvos solution using TiO2-supported ZSM-11 zeolite

Abstract

Heterogeneous catalysis involving semiconductors has been developed in the last 10-15 years due to its potential applications to environmental problems (Oancea and Oncescu, 2008). In recent years, advanced oxidation processes (AOPs) have been proposed as attractive alternatives for the treatment of contaminated ground-, surface-, and wastewater containing pesticides or non-biodegradable organic pollutants (Phanikrishna Sharma et al., 2008a). Among the most used processes are heterogeneous photocatalysis. The semiconductor TiO2 has been widely utilized as a photocatalyst for inducing a series of reductive and oxidative reactions on its surface (Chong et al., 2010). TiO2 is one of the most appropriate material due to its high activity in the photodegradation of organic compounds, low cost, low toxicity, and chemical stability (Yamaguchi et al., 2009, Fuchs et al., 2009). The anatase form of TiO2 is more active generally for the degradation of various organic pollutants than rutile (Mahalakshmi et al., 2009). The efficiency of TiO2 is influenced by many factors, such as crystalline structure, particle size, and preparation methods (Hsien et al., 2001). However, poor adsorption and low surface area properties lead to great limitations in exploiting anatase to the best of its photoefficiency. In addition, technical limitations for adopting this technology are separation of the catalyst, its reuse and its low quantum efficiency (Phanikrishna Sharma et al., 2008b). On the other hand, supporting TiO2 is commonly reported to be less photoactive due to the interaction of TiO2 with the support during the thermal treatments and limitations to mass transfer (Mohamed et al., 2005).