ZnO nanorods decorated calcined Mg-Al layered double hydroxides as photocatalysts with a high adsorptive capacity

The nanocomposites of magnesium-aluminium-carbonate-layered double hydroxides (Mg-AlCO3-LDHs) and ZnO nanorods were prepared via a homogeneous precipitation process. The presence of ZnO nanorods made the calcined Mg-Al-CO3-LDHs, the strong adsorptive adsorbents for anions, have a photocatalytic activity. Both Mg-Al-CO3-LDHs and the nanocomposites with various ZnO/Mg-Al-CO3-LDHs mass ratios from 0.5:1 to 3:1 were characterized by X-ray diffraction, transmission electron microscope and UV-vis diffuse reflectance spectra. The nanocomposites quickly adsorbed the anionic dyes such as acid red G (ARG) without the light illumination. and the adsorbed dyes on the recovered nanocomposites were then degraded in a separated photocatalytic reactor. The adsorption ability of the nanocomposites and their photocatalytic activities for the removal of ARG were evaluated by the Fourier transform infrared spectra and UV-vis extinction spectra. The sample at 3:1 ZnO/Mg-Al-CO3-LDHs mass ratio was shown to have higher photocatalytic efficiencies. (C) 2009 Elsevier B.V. All rights reserved.