Polyoxometalate-intercalated ZnAlFe-layered double hydroxides for adsorbing removal and photocatalytic degradation of cationic dye

New polyoxometalate (POM)-intercalated layered double hydroxides (LDH) were prepared by aqueous ion exchange of a ZnAlFe LDH precursor with the POM anions [P2W17](10-) and [CoW12](5-). The physicochemical properties of the as-prepared products were characterized by powder X-ray diffraction method and infrared spectroscopy. These two POM-LDH materials, having both the adsorption and photocatalytic capacities, could be used for the removal of cationic dye methylene blue (MB) from aqueous solutions. The intercalation of large cluster anion into ZnAlFe LDH could endow with not only the adsorption function to cationic dye but also the photocatalytic performance of ZnAlFe LDH materials. Therefore the POM-LDH shows much higher adsorption capacity than the pure LDH and the adsorbed MB could be degraded by photocatalysis. Furthermore, their sorption isotherms and photocalalytic performance were investigated theoretically and experimentally.