Development of new photo-catalytic reactors for waste water treatment

The efficiency of photocatalytic reactors using immobilized photocatalysts have been found to be lower than those using dispersed titanium compound particles (slurry). However, for practical applications, immobilized catalyst is preferred as it does not need an additional separation process to recover the photocatalyst. Zeolites, as catalyst supports, offer the advantage of having high absorptivity for organics in wastewater aiding at preconcentrating pollutants on their surface. More than 40 different types of zeolites and their modifications as a support were synthesized and tested. Different methods of loading TiO2 on zeolites and special techniques to characterize distribution of the photocatalyst were developed. Adsorbency of various organic materials commonly present in wastewater was also evaluated. Lab-scale experiments on the newly developed immobilized photocatalyst particles (100-900 microns) have already been conducted. The design and development of the appropriate photocatalytic reactor requires a study of the hydrodynamics of the reactor coupled with the intrinsic rate kinetics to achieve higher quantum yields and optimum photocatalyst requirements. An annular fluidized bed photocatalytic reactor operating in absorption and regeneration modes has been constructed for the purpose of kinetic studies. The reactor has been modelled and simulation results are presented in this study. Kinetic studies are being carried out to obtain reliable intrinsic rate data using the newly developed photocatalyst. The data so obtained will be used to verify the reactor model to facilitate its scale-up.