Synthesis of hectorite–TiO2 and kaolinite–TiO2 nanocomposites with photocatalytic activity for the degradation of model air pollutants

We studied the synthesis and photocatalytic activity of small-sized TiO2 supported on hectorite and kaolinite. Deposition of TiO2 on the clay mineral surface was conducted by using a sol–gel method with titanium isopropoxide as precursor. Anatase TiO2 particles formation was achieved by hydrothermal treatment at 180 °C. Material characterization was conducted using XRD, SEM, XPS, ICP-OES, BET and porosimetry analysis. fficiency in synthesizing clay–TiO2 composites depended strongly on the clay mineral structure. Incorporation of anatase in hectorite, an expandable clay mineral, was found to be very significant (> 36 wt.% Ti) and to be followed by important structural changes at the clay mineral surface. Instead, no major structural modifications of the clay were observed for kaolinite–TiO2, as compared with the untreated material. Photocatalytic performance of clay–TiO2 composites was evaluated with ATR-FTIR following the oxidation of adsorbed toluene and d-limonene, two model air pollutants. In either case, the photocatalytic removal efficiency of these hydrophobic substrates by the synthesized clay–TiO2 composites was comparable to that observed using pure commercial TiO2 (Degussa P25).