Intrinsic Kinetic Study for Photocatalytic Degradation of Diclofenac under UV and Visible Light

This study employs a semibatch, swirl-flow, monolithic type photocatalytic reactor to determine intrinsic kinetic parameters for the photocatalytic degradation of a common anti-inflammatory drug, diclofenac (DCF), in an immobilized system under both UV and visible radiation. The goal of this work was (a) to find a better reactor configuration that provides improved residence time distribution of fluid, (b) to obtain a suitable support system (such as fiberglass sheet) for the immobilization of various photocatalysts (Degussa P25 TiO2 and modified TiO2 (doped and dye-sensitized), (c) to compare degradation rates with Degussa P25 when doped and dye-sensitized photocatalysts is used particularly under visible radiation, and finally (d) to determine true kinetic parameters after correcting for external mass transfer resistance that exists when catalysts is immobilized as a function of various operating parameters such as flow rate, catalyst loading, pH, light intensity, initial concentration, and photocatalyst type. The objective of this study lies in obtaining true kinetic data independent of reactor types and, therefore, can be used for process scale-up and high-rate water treatment. It was observed experimentally that a better degradation rate can be achieved with dye-sensitized catalysts activated under visible light.