Enhanced photocatalytic degradation of a cationic dye using slurry of anatase titania in a falling film reactor

Abstract Dyes are hazardous when it comes to dispense of the production process wastewater to the environment. The presence of trace amounts of dyes in water bodies threatens the lives of aquatic creatures and upsets the balance of the ecosystem. Moreover, the diffusion to the drinking water bodies can result in catastrophic incidents. Heterogeneous photocatalysis has shown great potential for the treatment of dyeing wastewater. Careful selection of the three main components of a photocatalytic system: irradiation source, photocatalyst and reactor configuration determines its effectiveness. In the current study, a mercury UVC lamp, along with a slurry of anatase Titania were used in a batch recirculating falling film reactor. Methylene blue was used as a model cationic dye. Photocatalyst characterization was carried out using BET, XRD and TEM analyses. Effects of the solution flow rate, initial solution pH, photocatalyst dose and initial dye concentration were studied. It was found that these factors greatly influence both the reaction rate and the removal extent. Moreover, the kinetics of the photocatalytic reaction were studied using Langmuir-Hinshelwood and Modified Freundlich kinetic models. The photocatalytic degradation of the Methylene Blue using the falling film reactor showed an outstanding performance where 98% removal was achieved.