Effect of operating parameters on photocatalytic reduction of chromium (VI) using rotating disc photocatalytic reactor (RDPR)

Abstract

A new photocatalytic reactor design for water treatment was characterized by the use of rotating disc photocatalytic reactor. In this study, Ti02 was immobilized on stainless steel disc by sol-gel method. Experiments in a reactor containing 20 rotating disc with uv light irradiation at the wavelength of 380 nm were performed. The effect of the initial pH of wastewater, wastewater flow rate (Qw), rotating disc speed (Vr) and amount of TiC2 coating surface are on photocatalytic reduction of chromium (VI) over Ti02/stainless steel disc have been determined. The studied photoreactor has been show'n to effectively reduce chromium (VI) concentration in a wide range and the rate of photocatalytic reduction increases with increase of flow rate, rotating speed and amount of TiC2 coating surface area at the system condition pH 3. It was found that the maximum rotating speed at 200 rpm and the highest flow rate 90 ml/s provide highest kinetic coefficient rate. At initial concentrations of chromium (VI) less than 150 ppm, the kinetic behavior was followed the zero order pattern and changed to pseu-do first order pattern at the initial concentration of chromium (VI) higher than 150 ppm. The intrinsic kinetic coefficients following the Langmiur-Hinshelwood were found as 0.3592 mg/L.min and 0.0482 L/mg. From this research, this type of reactor exhibited certain advantages, which are immobilization of the catalyst for industrial practical usage and high performance with the reaction in thin liquid film.