Adsorption of indigo carmine dye by Mg-Al-CO3 calcined layered double hydroxides

Adsorption of Indigo Carmine (IC), an anionic dye, from aqueous solution by calcined Mg₂-Al-CO₃ LDH was investigated in batch mode. The adsorption of IC on CLDH is described by Freundlich isotherm model. Characterization of the CLDHs solids, both fresh and after removal of IC by X-ray diffraction and infrared spectroscopy shows that the IC adsorption on CLDH is enhanced by reconstruction of a matrix hydrotalcite intercalated by the dye. The intercalation of the IC in the layered host structure increase with increasing concentration of the dye in solution and the temperature of heating of LDH. The intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 0.762 nm for [Mg₂-Al-CO₃] to 2.132 nm for the organic derivative.