NOVEL REACTOR FOR PHOTOCATALYTIC KINETIC-STUDIES

In the past decade an increasing interest in photocatalytic kinetic st udies has been observed, particularly related to promising remediation processes for air and water pollution. Normally, the reacting system includes a suspended-solid semiconductor and one or two fluid phases. One of the major problems lies in the difficulties associated with the proper evaluation of the absorbed radiant energy due to the unavoidab le system heterogeneities that produce light scattering. A novel form of reactor, combined with a radiation distribution model, has been use d to evaluate the volumetric rate of energy absorption during the phot ocatalytic oxidation of trichloroethylene in water using a suspension of titanium dioxide. All the required information to solve the radiati ve transfer equation in a one-dimensional photocatalytic reactor is ob tained either from radiation theory or from specially designed experim ents. The proposed approach permits a correct description of the radia tion field inside the heterogeneous reactor and, consequently, a preci se accounting of the absorbed photons. The quantum yield concept is re visited to propose an appropriate and equivalent property for solid ph otocatalyzed systems. Afterward, the reactor and the model were used t o evaluate heterogeneous-system quantum efficiencies.