Dried- and Annealed Gels

The porous structure of the gels has been characterized by N2-adsorption, scanning electron microscopy (SEM), atomic force microscopy (AFM), and emanation thermal analysis (ETA) [16, 20]. The porosity of films was evaluated by refractive index measurements. 

In order to evaluate the effect of the pore structure, measurements of the photocatalytic activity of anatase films were made for some samples using a flow-type reactor. A black light was used as source of light with an intensity about 10 MW (wave length 365 nm) at the film surface. The apparent surface area of films was 50 cm, and humid air with 50% relative humidity, containing 1 ppm NO, was passed through the reactor at a flow rate of 3.01 min. The NO c concentration was monitored with a chemiluminescent NO analyzer [35], 

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Some examples of the pore properties for the dried and annealed gels are summarized in Table 7.1. 

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