Photocatalytic degradation activity of titanium dioxide sol–gel coatings on stainless steel wire meshes

Stainless steel wire meshes have been functionalised with multiple titanium dioxide (TiO2) coatings deposited by the sol–gel technique, using titanium isopropoxide as precursor and titanium dioxide nanopowders dispersed in the colloidal solution. After the thermal conversion of the amorphous fraction of the coating into anatase, the functionalised stainless steel wire meshes were tested for the UV photodegradation of aqueous solutions of methylene blue, solid stearic acid and nitrogen oxides in air. The addition of TiO2 nanopowders in the colloidal deposition solution enhanced the photocatalytic performance of the deposited TiO2 layers in all the tested conditions. Moreover, increasing the number of coatings (from 1 to 4) improves the photocatalytic efficiency. The catalyst did not show reduced photoreactivity after four repeated cycles in water decontamination from methylene blue, and after up to 10 repeated cycles in nitrogen oxides photodegradation. Complete regeneration of the catalyst could be achieved by rinsing it with warm deionised water and was observed in the case of experiments for NOx abatement.