A wide range of active pharmaceutical ingredients (API) is found in various water streams. These synthetic non-biodegradable organics create trouble in conventional wastewater treatment due to toxicity. There is a strong need to develop substitute technology such as visible light driven photocatalysis with a reusable photocatalyst to completely oxidize these substances into carbon dioxide and water. Sol-gel method was used for synthesis of Fe doped TiO₂ and Ag-Fe codoped TiO₂ nanoparticles with 0.5 wt% Fe and Ti/Ag molar ratio 30 (Ag-Fe CT 30). The morphology and structure of nanoparticles were studied using various analytical techniques. Ag-Fe CT 30 photocatalyst has exhibited excellent photocatalytic activity compared to commercial TiO₂, undoped TiO₂ and Fe doped TiO₂ nanophotocatalysts under solar and UV irradiation for removal of an antifungal drug intermediate, Difloro triazole acetophenone (DFTA) from water. COD reduction efficiency was highest with Ag-Fe CT 30 under solar and UV irradiation proves the potential of Ag-Fe CT 30 photocatalyst to absorb both UV as well as visible radiations. Ag-Fe CT 30 has shown good stability for 4 runs without much decline in the efficacy. This study provides insights on the solar application of a reusable Ag-Fe CT 30 photocatalyst for the treatment of high strength COD wastewater. Kinetics of COD reduction by photocatalysis has been determined.
 

Highlights

• TiO₂, Fe doped TiO₂ and Ag-Fe codoped TiO₂ nanoparticles have been successfully synthesized using the sol-gel method and characterized using various analytical methods.
• Photocatalytic activity of different photocatalysts for mineralization of DFTA is compared under solar and UV irradiation for COD removal (with initial COD of 75,000 mg/L) has been carried out.
• Kinetics for Ag-Fe codoped TiO₂ photocatalysis has been determined.
• The photocatalysts can be easily separated from the water after application and show good stability up to 4 runs indicated from six recycled tests.