COATING OF TiO2 RUTILE NANOPARTICLES IN A SUSPENSION WITH HYDRATED SiO2 AND Al2O3

摘要

The invention refers to a rapid, adaptable, manageable and reproducible approach to a synthesis of coated TiO2 nanoparticles with hydrated silicon and aluminium oxides with the use of harmless chemicals. The proposed method is based on a preparation of a well dispersed system of TiO2 nanoparticles and a controlled hydrolysis of Si02 from an alkaline precursor Na2Si03 in the presence of the mineral acid H2S04 or a hydrolysis of Al203 from an alkaline precursor of NaAlO2 in the presence of the mineral acid H2S04. The analyses have proved that the longer the coating times, the higher the SiO2 quantity and consequently the thickness of the coating. Controlled synthesis conditions were used to coat individual TiO2 nanoparticles. The mechanism of inorganic coating of TiO2 nanoparticles can be categorised as precipitation of hydrated oxides in the form of a thin layer onto already present particles (heterogeneous nucleation). The advantage of the method is its simplicity and the fact that a stable suspension of TiO2 nanoparticles is present in the whole method from the beginning to the end, which provides for healthy work conditions of industrial workers and users and also prevents negative effects on the environment (emission of nanoparticles).