Photocatalytic oxidation of ceftiofur sodium under UV–visible irradiation using plasmonic porous Ag-TiO₂ nanospheres

In this study, 250 nm sized porous anatase TiO₂ nanospheres (TiO₂ NSPs) composed of ∼ 10 nm sized anatase TiO₂ nanoparticles are obtained through a green synthetic route and their surfaces have been decorated with 3–4 nm sized plasmonic silver nanoparticles (AgNPs). Photoluminescence studies confirm that the AgNPs presence on TiO₂ NSPs surface effectively inhibits the radiative charge recombination and thus facilitates charge separation process at the Ag-TiO₂ NSPs interface, causing an enhanced photocatalytic activity. About 92% of the ceftiofur sodium (CFS) antibiotic taken initially is oxidized by Ag-TiO₂ NSPs upon 90 min white light irradiation, while Ag loaded Degussa P25 TiO₂ nanoparticles effects only 71% CFS oxidation. The synergistic effect given by plasmonic AgNPs and the continuous framework of anatase TiO₂ NPs contributes to inhibit the electron-hole recombination in the Ag-TiO₂ NSPs. Oxidation products of CFS in different water sources and their eco-toxicity effects identified through LC-MS and microtox-bioassays, respectively, indicate that the obtained oxidation products are non-toxic compared to pure CFS. Therefore, porous Ag-TiO₂ NSPs could be successfully applied in photocatalytic oxidation technologies, exploiting sunlight for the effective removal of pharmaceutical pollutants from wastewater.