Synthesis and Catalytic Activity of TiO2 Nanoparticles for Photochemical Oxidation of Concentrated Chlorophenols under Direct Solar Radiation

The titanium dioxide (TiO2) nanoparticles catalyst was synthesized via sol-gel method using the titanium tetra-isopropoxide as starting material. The effects of calcination temperatures on the crystalline structure, surface area and photocatalytic activity of TiO2 nanoparticles were investigated. The anatase to rutile percentage decreases when temperatures greater than 500°C and evaluated from XRD intensity of (101) and (110) peak, respectively. Photocatalytic activity of TiO2 nanoparticles was tested by the degradation of chlorophenols namely, 2-chlorophenol (2-CP), 2, 4-dichlorophenol (2,4-DCP) and 2, 4,6-trichlorophenol (2,4,6T-CP) within range from 50 to 150 mgl-1 initial concentrations under direct solar radiation. The results of photodegradation, 99, 98 and 92 % was obtained for 50 mgl-1 of 2-CP, 2,4-DCP and 2,4,6-TCP receptively after 90 min irradiation time at pH of 6. At the same time, the efficiency value was decreased with initial concentration more than 50 mgl-1. The chemical oxygen demand (COD) removal follows the photodegradation in behavior was observed. The kinetic studies indicate that the reaction was following to first order and decrease of rate constant (Kapp) with initial concentration more than 50 mgl-1.