Treatment with organic compounds such as oleic acid, oleylamine and organosilane endow titania nanonoparticles with specific properties like hydrophilicity or hydrophobicity, reduced mean size, improved dispersibility in polar and non-polar solvents, improved photocatalytic efficiency even under visible light irradiation.
TiO2 nanoparticles modified with hydrophilic organosilane compound (3-(2-aminoethylamino)propyltrimethoxysilane) depict the best photocatalytic activity for NO oxidation and NOx removal.
TiO2 nanoparticles grafted simultaneously with hydrophilic 3-(2-aminoethylamino) propyltrimethoxysilane and hydrophobic octadecyltriethoxysilane showed excellent photoactivity concerning De-NOx process in relation to bare photocatalyst. The incorporation of the TiO2 nanoparticles modified with the two mentioned modifiers in paints with low resin content, gave the best result in comparison with other modifiers as well as improved photocatalytic properties of the paint in comparison with the incorporation of bare photocatalyst.
In order to obtain anisotropic and controllable hydrophobic properties biphase toluene/water emulsion processing was used. When amphiphilically modified nanoparticles with hydrophilic polyethylene glycol and hydrophobic oleylamine were incorporated in cement matrix, they depict excellent photocatalytic activity. The attached hydrophobic groups facilitate the accumulation of TiO2 at the cement surface and its exposure to irradiation and air pollutants, while the attached hydrophilic OH groups of polyethylene glycol enhance the De-NOx ability.
Photonic efficiencies of photocatalytic paint with TiO2 nanoparticles modified with hydrophilic and hydrophobic modifiers (left), Photonic efficiency of photocatalytic cement with TiO2 modified with hydrophilic and hydrophobic modifiers in biphase solvent (right).