Performances of the photocatalytic reactors composed of glass supports coated with a transparent TiO₂ thin film and their application to CELSS

Abstract

Photocatalytic reactors are usually operated by suspending photocatalyst particles or packing with photocatalyst immobilized on any solid support, which provide heterogeneous reaction systems where reactions take place on the two-dimensional plane. Thus, these conventional reactors have unavoidable limitation to enhancement in the reaction rate because it is difficult to acquire a sufficient reaction field. On the other hand, titanium dioxide (TiO₂) can be dissolved in an aqueous solution of H₂O₂ to provide a transparent yellow solution, which enables to prepare a transparent TiO₂ thin film on the surface of a solid support. Based on this coating technique, two types of photocatalytic reactors were constructed; 1) consisting of a glass column packed with glass beads or short glass tubes and 2) a circular arrangement of 19 glass tubes linked in series and a fluorescent light positioned in the center. To investigate the performance of these two reactors, photocatalytic degradation of 2, 4-dinitrophenol was carried out in a batchwise recirculation system. Furthermore, the latter reactor was applied to oxidation of ethylene as an example of application to CELSS.