| This study was designed to develop materials to be used as a photocatalyst for the destruction of organic contaminants. Two types of TiO2-based material were studied: thin-film TiO2 immobilized on a flat substrate and granule with TiO2 immobilized in its pores. The materials provide superior engineering properties over powder TiO 2 traditionally used in slurry photocatalytic process. This improvement overcomes the two most common and serious problems associated with the powder TiO2: shadowing effect at high TiO2 concentration, and poor settleability of powder TiO2.; The immobilization of TiO2 on a solid carrier introduces several mechanisms not normally found in conventional TiO2 slurry process. These mechanisms have been identified to include at least film transfer, adsorption, diffusion, and photocatalytic reaction. Two mathematical models, called thin-film model and granule model, were developed to incorporate these mechanisms for the photodegradation of organic molecules in a batch reactor. A numerical technique, i.e., orthogonal collocation method (OCM), was employed to solve the models. The OCM used six internal collocation points and applied Legendre polynomial to approximate the profile of solid concentration. The models were then coded and compiled using FORTRAN for simulation.; The results of this study indicated that both thin-film and granular TiO2 photocatalyst are suitable for the destruction of organic contaminants. Mathematical models developed in this study successfully incorporated several key mechanisms governing the process such as liquid-film transfer, intraparticle diffusion, adsorption, UV attenuation, and photocatalytic degradation. The study revealed that adsorption plays a key role in these photocatalytic processes. Model simulations provided valuable insights into the effect of process mechanisms, as well as their interactions. The results also pointed to possible ways to improve the performance of a TiO2-based composite catalyst. |
