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 co-precipitation method and tested as photocatalysts for 2,4-dichlorophenoxyacetic acid (2,4-D) degradation. High specific surface areas (138–70 m2/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.