Evaluation of the physical properties and photodegradation ability of titania nanocrystalline impregnated onto modified kaolin

In this study, a microporous layer photocatalyst of titania nanocrystallites heterocoagulated with structurally modified kaolin (TiO2-K) was synthesised via a modified sol-gel method. Physical properties (particle size, morphology, stability and settleability) and photodegradation capacity of the TiO2-K catalyst subject to its synthesis, regeneration and use for water treatment were studied. The modified kaolin, as a support for the titania nanocrystallites had a delaminated sandwich silica structure that minimises chemical intercalation within the nanocomposite structure. Microscopic examination revealed that the TiO2 nanocrystallites were uniformly deposited on the kaolin external surface, resulting in a high degree of photon activation. Compared to the commercial TiO2 P25, the TiO2-K demonstrated a superior photocatalytic degradation capacity to remove an anionic Congo red dye. Its removal efficiency and photo-reaction performance were improved when the TiO2-K was regenerated by a thermal treatment. The TiO2-K particles can be easily separated from the water system for further reuse. This unique nanocomposite photocatalyst shows promising technical advantages for a continuous industrial process of water treatment. © 2010 Elsevier Inc.Vipasiri Vimonses, Meng Nan Chong and Bo Ji