Photocatalysis of organic pollutants by catalyst supported on adsorbents

Abstract

Over the last 20 years, the scientific and engineering interest in the semiconductor photocatalysis has grown tremendously due to its many advantages for water and air treatment. This process is based on hydroxyl radical chemistry and couples low energy light with inexpensive semiconductors (usually titanium dioxide) as the photocatalyst. This process is a viable alternative for overcoming many drawbacks in traditional treatment technologies.TiO2 has several advantages such as the ability of using solar energy, operation at ambient temperature, and good photochemical and mechanical r??sistance. However, there are certain limitations of using pure TiO2:(i) Due to small size (about 4-30nm) it agglomerates rapidly loosing its effective surface area as well as catalytic activity,(ii) It is non-porous exhibiting low adsorption capacity and (iii) It is poor adsorbent especially to non-polar organic compounds due to its polar surface.In this work, TiO2 photocatalysts supported on various adsorbents were developed and evaluated. Different adsorbents as catalyst support were selected based on the surface area and pore size distribution. These adsorbents such as mesoporous (MCM-41), microporous (I?-zeolite) and pillared structure (montmorillonite) were chosen and different loadings (10-80 %) of TiO2 were loaded on the adsorbent surface using sol-gel method. The surface area of the loaded catalyst was determined by BET analyzer.In this study , annular fluidized bed photoreactor was used to investigate the kinetics of photocatalytic degradation of methyl ethyl ketone(MEK) and trichloroethylene(TCE)The objective of this work is to compare the performances of three TiO2 supported catalyst in degrading organic pollutants (MEK and TCE) with different operating conditions. In addition, the performances of these catalysts were compared with those of bare TiO2 prepared by sol-gel method and commercially available Degussa P25.