| Summary: | Layered double hydroxides (LDHs) calcined, denoted as CLDHs, have been shown to recover their original layered structure in the presence of appropriate anions. In the light of this so-called "memory effect", the removal of Amido Black (AB), an anionic dye, from aqueous solution by calcined Zn-Al-NO₃ and Zn-Al-C0₃ LDHs was investigated in batch mode. The study looked at the influence of pH values, dye-adsorbent contact time, initial dye concentration, adsorbent dosage, particle size, and various temperatures on the decolorization rate of AB. The adsorption isotherms, described by Freundlich model are L-type. The characterization of the solids CLDHs, both before and after removal of AB, by X-ray diffraction, Scanning Electron Microscope and infrared spectroscopy shows that the AB adsorption on CLDHs is enhanced by reconstruction of a matrix hydrotalcite intercaled by the dye, and the intercalation of the organic ion was clearly evidenced by the net increase in the basal spacing from 7.6 A for Zn-Al-NO₃ and 7.59 for Zn-Al-CO₃.
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