Photocatalytic effect with AEROSIL® fumed silica
How it works
AEROSIL® Titania grades effectively inhibit the growth of bacteria, viruses, algae and other microorganisms on surfaces or in liquids. In order to understand semiconductor photochemistry three modes of action need to be discussed:
Throughout the photomineralization process, organic compounds are fully mineralized. Reactions using AEROXIDE®, AEROPERL® or AERODISP® grades and UV-light include the complete decomposition of phenol, chlorophenols, nitroaromates, aromatic amines, agricultural effluents, and crude oil in water.
Radicals are formed on the titanium dioxide surface when it is irradiated with UV light. These radicals can also attack the cells of microorganisms, so that nanoscaled titanium dioxide can effectively be used to inhibit the growth of bacteria, viruses, algae, yeast, mold, and other microorganisms on surfaces or in liquids.
On surfaces coated with TiO2, UV excitation produces electron-hole pairs; these holes can oxidise bridging O2-species to oxygen; thus creating "oxygen vacancies". Following adsorption of water a hydroxylation takes place and the surface properties are changing to a considerably more hydrophilic behaviour.
"How it works" — at a glance...
Surfaces are coated with TiO2
UV irradiation activates the photocatalytic properties of nano-scaled titanium dioxide
Radicals are formed on the surface and attack the cells of micro organisms inhibiting the growth of bacteria, viruses, algae etc.
Decomposition of the organic compounds; carbon dioxide and water are the final products.
Additional effects: Surfaces coated with TiO2 show superhidrophilicity (water contact angle <5°)