Functionalized 3D polyurethane foams with microwave-synthesized TiO2 nanostructures for solar light-driven degradation of tetracycline

Abstract

Pharmaceutical substances present in soils and water supplies pose a significant risk to the ecosystem. Solar light-driven photocatalysis with titanium dioxide (TiO₂) nanophotocatalysts has been widely explored for the degradation of these substances in aquatic resources. However, the lack of reported sustainable methods to produce TiO₂ nanophotocatalysts and the challenges associated with their use in powder form during photocatalytic experiments further limit their scale-up. Herein, we show an eco-friendly approach to synthesize TiO₂ nanopowders using a fast microwave method (10 min) and their further incorporation on polyurethane (PU) foams by a simple dip-coating process. Ethanol, isopropanol (IPA), and water were employed for the microwave synthesis of TiO₂ nanophotocatalysts, unveiling distinct structural and optical properties for the material synthesized in each solvent. When ethanol was used as a solvent, TiO₂ anatase nanocrystals were obtained, which exhibited high-index {012}/{102} facets with surface steps and bulk defects. These defects together with the superior specific surface area and higher capacity for surface oxygen adsorption contributed to a significant adsorption capacity (about 58% in 240 min) of tetracycline (TC) and overall TC removal of ∼90% after 30 min of simulated solar light exposure. Reusable TiO₂-PU foams achieved ∼80% of TC removal in 180 min of light exposure. This study showcases the successful surface modification of PU foams with TiO₂ nanostructures highlighting their potential for an efficient removal of tetracycline from water while ensuring ecological safety, as demonstrated by the ecotoxicity assays using the Artemia salina model.