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Removal of the Herbicide 2,4-Dichlorophenoxyacetate from Water to Calcined Layered Double Hydroxides
L. El Gaini, E. Sebbar, Y. Boughaleb, M. Bakasse, M. Lakraimi and A. Meghea

Layered double hydroxides (LDHs) are anionic clays with high anion exchange capacities. Calcination of LDHs increases significantly their anion-exchange capacities. In the present study, calcined products (CLDHs) were obtained by heating Mg/Al-LDHs at the temperatures: 300, 400, 500, 600 and 700C. The adsorption of the organic pesticide 2,4-dichlorophenoxyacetate (2,4-D) by CLDHs was performed at different pH values, the pesticide-adsorbent contact time and initial pesticide concentration. The adsorption is described by Langmuir-type isotherm and Freundlich-type isotherm. Characterization of the CLDHs solids, both fresh and after removal of 2,4-D by X-ray diffraction and infrared spectroscopy shows that the adsorption is also enhanced by reconstruction of a matrix hydrotalcite intercaled by the 2,4-D at high concentration.

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