Effect of operational parameters on photocatalytic reduction of chromium (VI) using fixed bed photocatalytic reactor (FBPR)

Abstract

A fixed bed photoreactor is one type of newly developed photochemical reactor for immobilized photocatalyst in photocatalysis process. In this research, Tio2 was used as photocatalyst and the studied operational parameters included initial pH of wastewaters, wastewaters flow rate(Qw), wastewater level (Hw), coating surface area (A) and initial concentration of chromium (VI). Effects of each operational parameter on treatment ability of fixed bed photoreactor were measured in terms of residual fraction of chromium (VI) in aqueous solution. From this research, the optimum pH was found pH 3. It was found that the photocatalytic activity of chromium (VI) increased with the increasing of wastewater flow rate and water level. The optimum flow rate was found as 80 mL/sec at 4 cm water level. The deposition and tranformation of chromium (VI)was enhanced by the increasing of TiO2 coating surface area. The kinetic study of the photocatalysis process using a fixed bed photoreactor was followed zero order patterns when initial concentration of chromium was lower than 100 mg/L. The kinetic pattern was changed to pseudo first order model at high initial concentration of chromium (>100 mg/L). The kinetic coefficients consist of the adsorption equilibrium constants (K) and degradation rate constants (k) followed Langmuir-Hinshelwood equation using this reactor were calculated as 0.3486 mg/L.min and 0.2620 L/min, respectively.