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.