M. Lakraimi

Dye-interleaved nanocomposite: Indigo carmine and methyl orange in the lamella of zinc-aluminium-layered double hydroxide

Layered organic-inorganic hybrid nanocomposite, containing an organic dye in an inorganic interlayer was prepared using indigo carmine (IC) and methyl orange (OM) as a guest in Zn2-Al layered double hydroxide (LDH) inorganic host by a ion exchange , with [Zn2-Al-Cl] LDH in aqueous solution. The affinity of the LDH with the dyes was studied as a function of contact time, initial pH of the solutions and initial dye concentration. It was found that 8h is enough time for the equilibrium state to be reached in IC and OM adsorption. IC and OM retention was independent of the initial pH. The adsorption isotherm of IC and OM, described by the Langmuir model, is of L-type. Powder X-ray diffractogram shows that the basal spacing of the Zn2-Al layered double hydroxide with Chloride as intergallery anion [Zn2-Al-Cl] expanded from 0.78 nm to 2.22 nm for the Zn2-Al layered double hydroxide-IC layered organic-inorganic hybrid nanocomposite [Zn2-Al-IC] and 2.4 nm for the Zn2-Al layered double hydroxide-OM layered organic-inorganic hybrid nanocomposite [Zn2-Al-OM].

Uptake of anionic dye from aqueous solution by zinc-aluminium-chloride layered double hydroxides

Fifteen percent of the total world production of dyes is lost during the dyeing process and released in the textile effluents. Removal of textile dyes from wastewater is one of the several major environmental concern because they are difficult to be removed by the conventional wastewater treatment systems (biological, physical and chemical methods) since they are designed to be resistant to degradation or fading by oxidizing agents and light. Adsorption, however, is an effective method for dye removal. In this way we studied the application of layered double hydroxides (LDHs) or hydrotalcite-like compounds as adsorbents to remove a hazardous anionic dye “Indigo Carmine (IC)” from aqueous solutions. LDHs with Zn and Al in the layers and chloride in the interlayer, was prepared following the coprecipitation method at constant pH. The affinity of this material with IC was studied as a function of contact time, initial pH of the solutions and initial dye concentration. It was found that 8 h is enough time for the equilibrium state to be reached in IC adsorption. IC removal was independent of the initial pH. The adsorption isotherm, described by the Langmuir model, is of L-type. The results, demonstrate that the IC adsorption on LDHs occurs by both adsorption on external surface and interlayer ion exchange. A mechanism for removal of IC anion has been confirmed by X-ray diffraction and IR spectroscopy.

Adsorption of indigo carmine dye by Mg-Al-CO 3 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.