TiO2/MgAl layered double hydroxides mechanical mixtures as efficient photocatalysts in phenol degradation

MgAl layered double hydroxides (MgAl LDH) were synthesized by the sol-gel method using ultrasound irradiation in the crystallization step. The interlayer anions were nitrate and acetylacetonate-ethoxide. The solids were characterized by XRD, N-2-physisorption and TEM. TiO2/MgAl LDH mixtures were prepared by mixing the MgAl LDH (as prepared) or the calcined sample with TiO2 (Aldrich, 99.9% anatase) in different weight ratios. Photocatalytic activities of the TiO2/MgAl LDH mixtures were evaluated through the degradation of phenol as model pollutant. TiO2/MgAl LDH mixture (1:1) was more photocatalytically active for the degradation of phenol than pure TiO2. The synergy effect was attributed to a higher production of (OH)-O-center dot radicals, which were formed from the structural hydroxides. Also, the hydrotalcite phase enhanced the phenol adsorption and transfer to the TiO2 sites where the phenol was photocatalytically degradated. (C) 2011 Elsevier Ltd. All rights reserved.