For the first time two different nanoclay minerals were combined with nanophase anatase for the synthesis of three-phase nanocomposites with improved photocatalytic properties. The novel halloysite (H)+palygorskite (Pal)-TiO2 nanocomposites were prepared using palygorskite and halloysite from Greece. Three nanocomposites were synthesized using [Hal+Pal] to TiO2 mass ratios of [10+20]:70, [15+15]:70 and [20+10]:70, respectively by depositing anatase form of TiO2 on the clay surfaces using titanium isopropoxide as a precursor under hydrothermal treatment at 180°C. Phase composition, particle morphology and physical properties of these three-phase nanocomposites were characterized by XRD, ATR-FTIR, SEM, TEM, DR-UV-Vis, N2-adsorption/desorption isotherms. The photocatalytic activities of three-phase clay-titania nanocomposites in decomposing NOx gas and toluene vapor were determined. The three-phase clay-titania nanocomposites showed significantly higher photocatalytic activity in decomposing inorganic and organic pollutants compared to that of either palygorskite- or halloysite-TiO2 nanocomposites under both UV- and visible-light irradiation. These studies led to a new class of clay-based nanocomposite materials with advanced photocatalytic properties.
ASJC Scopus subject areas