Sepiolite nanoplatform for the simultaneous assembly of magnetite and zinc oxide nanoparticles as photocatalyst for improving removal of organic pollutants

Novel ternary ZnO/Fe₃O₄-sepiolite nanostructured materials were developed in a two-step procedure based on the incorporation of ZnO nanoparticles on a substrate composed by magnetite nanoparticles previously assembled to the sepiolite fibrous silicate (Fe₃O₄-sepiolite). The structural and morphological characterization shows that both, ZnO and Fe₃O₄ nanoparticles, were homogeneously dispersed on the surface of sepiolite. Therefore, the resulting material is characterized as a multifunctional nanoplatform simultaneously providing magnetic and photoactive properties. ZnO/Fe₃O₄-sepiolite materials exhibit superparamagnetic properties at room temperature, which is one of the sought properties in view to facilitate their recovery from the reaction medium after application as heterogeneous catalysts. ZnO/Fe₃O₄-sepiolite materials were tested as photocatalysts using methylene blue dye in water as model of a pollutant molecule, showing full decolorization after 2h of UV irradiation. Moreover, the photocatalytic activity of this nanoplataform may be maintained after reuse in several consecutive cycles of treatment. Remarkably, the ZnO/magnetite-sepiolite nanostructured material displays a similar activity as ZnO/sepiolite materials, but shows the additional advantage of easier recovery by means of a magnet which facilitates its reuse.