Síntese e caracterização de nanocompósitos de TiO2@UiO-66 para fotocatálise do cetoprofeno

Abstract

Drugs and other emerging contaminants (ECs) persist in aquatic environments due to the limited efficiency of conventional wastewater treatments. In view of this limitation, advanced strategies have been developed, among which Advanced Oxidative Processes (AOPs) stand out, which act through the generation of highly reactive species, such as hydroxyl radicals (HO•), capable of degrading recalcitrant organic compounds. Within the POAs, heterogeneous photocatalysis (CF) using semiconductors and metalorganic structures (MOFs) is particularly promising, due to the high oxidation capacity and potential application under solar radiation, as reported in the literature. This study investigated the synthesis, characterization and application of TiO2 and UiO-66-based composites, prepared with different proportions, in the CF of ketoprofen, a non-steroidal anti-inflammatory drug widely detected in effluents. The TiO2 nanoparticles were synthesized by the sol-gel method and calcined at 450 °C for 4 h, while the UiO-66 was obtained by solvothermal synthesis at 120 °C for 24 h. Three composites were prepared containing 7.68%, 12.32% and 20.00% of UiO-66 to evaluate possible synergistic interactions with TiO2. SEM and TEM micrographs revealed irregular TiO2 nanoparticles (13.69 nm) and cubic particles of UiO-66 (18.00 nm). TEM images showed TiO2 deposited on top of UiO-66 in all composites. Selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns confirmed the formation of the anatase phase of TiO2 and the structure of UiO-66. Bands at 1546 and 1354 cm-1 in the FTIR were attributed to the vibrations of the carboxyl groups in the benzene rings of UiO-66. The Mott-Schottky analyses confirmed the n-type character of the composites and improvements in the electronic bands. The zeta potential revealed zero load points of 5.98 (TiO2), 5.82 (UiO-66) and 5.12 (TiO2@UiO-66 (7.68%)), indicating a more acidic surface in the composite. The photocatalytic efficiency was evaluated by Box-Behnken experimental design, varying pH, irradiation time and UiO-66 ratio. The composite TiO2@UiO-66 (7.68%) showed better performance, achieving more than 98% of ketoprofen degradation in 30 minutes under pH 3. By means of Artemia sp tests for the synthesized materials and for the best composite, which is without toxicity. Thus, TiO2@UiO-66 composites showed promise as a sustainable alternative for wastewater treatment under laboratory conditions.