Photocatalytic activity of ceramic tiles coated with titania supported on kaolinite

Abstract

Titania is an established photocatalytic material. The dispersion of titania nanoparticles on kaolinite particles as carrier and support precursor, TiO2-kao, has been studied to avoid losses in photocatalytic efficiency once fired by single-fired porcelain tile route. The photocatalyst was prepared using the hydrolytic sol-gel route. A commercial titania, P25, was used as a reference TiO2. The samples were fast fired at 800, 1015, 1100, and 1185 °C. Degradation of methylene blue was used to assess the photocatalytic performance. TiO2-kao and P25 applied to unglazed plates fired at 800 °C yielded ∼65% degradation, ∼50% due to photocatalysis, and ∼15% due to photolysis. P25 samples retained ∼10% of their photoactivity after firing at 1185 °C, TiO2-kao retained 80%. TiO2-kao on glazed tiles fired at 1185 °C retained 30% photoactivity. The photocatalytic losses in the glazed sample were due to the reduction in contact area caused by particle encapsulation in the glass layer.

Keywords

• Anatase
• Rutile
• Kaolinite
• Metakaolin
• Photocatalysis
• Ceramic tiles