(680c) TiO2 Particle Property Investigation Featuring Moving Bed Adsorption and Photo-Assisted Degradation of Azo Dyes

The use of photon-driven chemical decomposition of organic pollutants such as benzene is a potentially viable solution for water polishing applications. Various attempts at advanced oxidation process (AOP) have yielded inherent operation and design limitations. To overcome these mass transfer, cross sectional area, and light scattering limitations a novel water treatment process has been developed relying on the characteristics of a circulating fluidized bed (CFB) system. This system allows for adsorption of a target contaminant onto the surface of a photocatalyst composite particle in a moving packed annular bed and photocatalytic degradation/regeneration of laden particles within a photon chamber in a continuous fashion.

The goal of this work is to independently study the adsorption and photocatalytic capabilities of photocatalyst-composite particles by effectively decoupling these two processes within the system. This study will give insight into the bottlenecks and limitations of photocatalyzed reactions by assisting in optimal design of these particles with a high quantum yield and efficient use of photons.

Azo dyes such as Procion Red and orange-II are used as model contaminants. TiO2 coated silica particles (.5mm, 1mm, and 2mm) are used as photocatalyst composite particles. An initial dye concentration of 500 ppm is used for all experiments. Photon chamber consists of a 2? OD quartz tube surrounded by six 50W UV bulbs (350 nm) in which the particles sediment through in lean phase fashion. Particles are removed prior to entering the UV chamber and upon exiting the UV chamber for analysis. Concentration of the contaminated water is monitored within the annular bed by a Beckman UV-Vis spectrophotometer.