Halloysite and sepiolite –TiO₂ nanocomposites: Synthesis characterization and photocatalytic activity in three aquatic wastes

Two different nanoclay minerals were combined with nanophase anatase TiO₂ for the synthesis of clay-based nanocomposites for improved photocatalytic properties. A new Halloysite (Hal) + Sepiolite (S) - TiO₂ ternary nanocomposite was prepared using halloysite from Utah, USA and a recently discovered sepiolite from Greece. Three nanocomposites were synthesized with Hal-TiO₂, S-TiO₂ and [Hal+S] to TiO₂. As a result, TiO₂ particles (anatase) were homogeneously deposited and dispersed on the clay surfaces. Phase composition, particle morphology and physical properties of these nanocomposites were characterized by XRD, ATR-FTIR, FE-SEM, DRS-UV–Vis and N₂-sorption/desorption isotherms at 77 K. The photocatalytic activity of the clay mineral-TiO₂ nanocomposites was examined in the decomposition of paracetamol and tetracycline antibiotics as well as dye Rhodamine-B. The nanocomposites exhibited higher photocatalytic activity under UV irradiation for the decomposition of the targeted pollutants than the benchmark in the field, i.e. TiO₂- P25 photocatalyst.