Photodegradation of 2,4-dichlorophenoxyacetic acid using ZnAlFe layered double hydroxides as photocatalysts

ZnAlFe layered double hydroxides (LDHs) with different Zn:Al:Fe ratio were obtained by the coprecipitation method and tested as photocatalysts for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation. High specific surface areas (138-70 m(2)/g) as well as semiconductor properties (band gap values of 2.59-2.00 eV) were obtained in the samples calcined at 673 K. When calcined samples were put in contact with as solution containing 300 ppm of 2,4-D, the reconstruction of the LDHs (memory effect) and an unexpected high capacity of 2,4-D adsorption were observed. The photodegradation in aqueous phase after saturation of the LDHs with 2,4-D showed that the confined (adsorbed) 2,4-D can be successfully degraded with ZnAlFe LDH photocatalysts. (C) 2009 Elsevier B.V. All rights reserved.