Smart pathways for the photocatalytic degradation of sulfamethoxazole drug using F-Pd co-doped TiO2 nanocomposites

We report the doping of TiO2 with fluorine (F) and palladium (Pd) to synthesize F-Pd co-doped TiO2 nanocomposites via a microwave-assisted hydrothermal synthesis method as a smart pathway to achieve efficient photocatalytic degradation of sulfamethoxazole (SMX) using both a solar simulator and direct sunlight irradiation. SMX is an emerging persistent drug that might have toxic effects on aquatic organisms because of its antibiotic-resistance. The F-Pd co-doped TiO2 nanocomposites produced in this work have an outstanding extension effect on the photocatalytic activity of TiO2 to the visible and near infrared regions; thus, showing efficient photocatalytic degradation of SMX and floatation of fluorinated products. TEM images shows that the particles of the F-Pd co-doped TiO2 nanocomposites have average particle sizes ranging between 5 - 25 nm. The band gap of the F-Pd co-doped TiO2 shifted down to 0.54 eV which is a significant shift from the band gap of TiO2 i.e., 3.26 eV. Thus, the photodegradation of 94.4 % of SMX was achieved within 20 min and 98.8 % after 70 min under direct sunlight irradiation. In addition, more than 42.5 % of SMX was degraded by F-Pd co-doped TiO2 nanocomposites with 3 % and above of Pd after just 5 min of adsorption in the dark. By doping TiO2 with F and Pd, three processes were thus achieved: 1) photocatalytic degradation, 2) fluorination of the degraded products and 3) floatation as fluoropolymer. These three processes, therefore, present one of the smart pathways to provide an efficient water treatment system for wastewater.