Mancuso A., Sacco O., Vaiano V., Sannino D., Venditto V., Pragliola S., Morante N., 2021, Visible Light Active Fe-N Codoped TiO2 Synthesized through Sol Gel Method: Influence of Operating Conditions on Photocatalytic Performances, Chemical Engineering Transactions, 86, 565-570.
Acid Orange 7 (AO7) is an azo dye present in the effluents coming from the textile industry. It is a coloring agent consisting of an azo group bonded to aromatic rings. This azo dye can react with other chemical substances producing aromatic amines which cause toxic and carcinogenic effects in the environment. For this reason, it is necessary to eliminate this compound from aqueous discharges. Recently, the scientific research has focused the attention on heterogeneous photocatalysis based on semiconductor oxides because it is a technology able to completely degrade many organic pollutants to carbon dioxide and water at ambient temperature under UV/visible light irradiation. In photocatalysis, the most used semiconductor is titanium dioxide (TiO2). TiO2 presents various crystalline phase and a wide band gap (3.2 eV for anatase), therefore, it can be activated only under UV light irradiation. In order to make TiO2 active under visible light, in this work TiO2 doped with metallic (Fe) and non-metallic element (N) was synthetized through sol-gel method. The photocatalytic tests on discoloration of AO7 aqueous solution were carried in a photoreactor surrounded by visible-LEDs strip. To determine the optimum conditions for the photodegradation, the influence of photocatalyst dosage (1.5 - 6 g L-1), initial AO7 concentration (5 - 20 mg L-1), initial pH of the solution (3-8) and the incident visible light intensity (3.25 to 13 mW cm-2) was investigated. It was observed that the Fe-N-TiO2 photocatalyst reached about 90% of AO7 discoloration and 83% of mineralization efficiency under the optimized working conditions, in a very short time (60 min) using a photocatalyst dosage of 3 g L-1 and AO7 initial concentration of 10 mg L-1.
