Enhanced photocatalytic degradation of Diclofenac with Agl/CeO2: A comparison with Mn, Cu and Ag-doped CeO2

Diclofenac, an emerging pollutant, has long half-life and can lead to antibiotic resistance, destruction of aquatic ecosystem, etc. We studied the photocatalytic destruction of diclofenac using ceria synthesized through combustion synthesis and sol gel methods. The combustion synthesis method gives a catalyst with a higher surface area, though with a lower photoactivity. Sol gel ceria was then doped with metal ions: Mn, Cu, Ag to give metal-semiconductor and with AgI to give n-p semiconductor-semiconductor heterojunction photocatalysts. Mn/CeO2, Cu/CeO2 and Ag/CeO2 showed lower photoactivity, while AgI/CeO2 showed better activity over the native CeO2. Over 97% removal of diclofenac was obtained in less than 120 min using 125 W UV light. A 2.6-fold increase in the quantum efficiency was obtained on doping CeO2 with AgI. The enhanced activity of AgI-doped CeO2 is attributed to improved charge separation of electron-hole pairs generated on irradiation with UV light.