Floating TiO₂-Cork Nano-Photocatalysts for Water Purification Using Sunlight

In the present study, titanium dioxide (TiO₂) nano-photocatalysts were synthesized through microwave irradiation. In a typical microwave synthesis, TiO₂ nanomaterials were simultaneously produced in powder form and also directly covering cork substrates. The TiO₂ nanopowder was analyzed by X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM), revealing that the solvothermal microwave synthesis resulted only in the TiO₂ anatase phase. From Fourier-transform infrared spectroscopy (FTIR), cork’s organic species, along with bands of TiO₂, were detected. UV–VIS absorption spectrum revealed an absorption extension to the visible region, since a brown powdered TiO₂ product was obtained. Very fine nanoparticles were observed displaying a nearly spherical shape that agglomerates in larger particles. These larger particles fully covered the surface of the honeycomb cork cells, originating TiO₂ functionalized cork platforms. The TiO₂ functionalized substrates were further tested as floating photocatalysts and their photocatalytic activity was assessed from rhodamine B degradation under solar simulating light and natural sunlight. Reusability tests were also performed under natural sunlight. The strategy applied in this research work allowed the production of green and low-cost cork platforms based on TiO₂ photoactive materials with the ability to purify polluted water under natural sunlight.