Photocatalytic reduction of nitrate over TiO2 and Ag-modified TiO2

Abstract EN

This research work presents the efficiency of the TiO2 and Ag–TiO2 thin films prepared by the sol–gel method and coated onto the surface of 304 stainless steel sheets used in the photocatalytic nitrate reduction processes.

The Ag–TiO2 thin films had the weight by weight (w / w) ratio of Ag+ / TiO2 of 0.1 % as Ag atom.

The XRD results showed that the crystalline phase structure of TiO2 on the Ag–TiO2 thin films was anatase.

The optical band gaps of the TiO2 and 0.1 % Ag–TiO2 thin films were respectively 3.27 and 2.70 eV, while the surface of the prepared catalysts was hydrophobic with the respective average water contact angles of 94.8° and 118.5° for the TiO2 and 0.1 % Ag–TiO2 thin films.

The net efficiencies of photocatalytic nitrate reduction of TiO2 and 0.1 % Ag–TiO2 were 41.4 % and 70.0 %, respectively.

The loading of Ag only influenced the nitrate removal efficiency without affecting the stoichiometric ratio of formate to nitrate.

The net stoichiometric ratio of formate to nitrate of all experiments was 2.8:1.0, which is close to the stoichiometric ratio of 2.5:1.0 of the nitrate reduction to nitrite and then to nitrogen gas.