Dense photocatalytic activity

The effect of heat treatment and crystal structure of dense Ti02 coating on the photocatalytic decomposition of aqueous acetic acid was also reported [43]. The efficiency increases with the content of anatase phase and thickness up to 300 nm. Yu et al. [44] prepared dip coatings on fused quartz and/or soda-lime glass with a barrier layer of Si02 and studied the degradation of MO as a function of the number of layers, finding that activity increases when the thickness and temperature are increased. Films treated at 500 °C show maximum photocatalytic activity. 

Gehrke et al. [ 131 ] recently used a dip-coating process to deposit photocatalytic TiO nanoparticles (P25, Evonik) on a metallic filter material (micro-sieve). The fouling repellent and photocatalytic nanocoatings degraded the water impurities close to the micro-sieve surface before a dense cake layer was formed. This kind of surface activation is, however, restricted to chemically robust materials, excluding polymeric membranes that would be degraded by the induced oxidation process [125]. 

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