Sorption of 2,4-dichlorophenol on modified hydrotalcites

The adsorption of anionic surfactants (sodium dodecyl sulfate (SDS) and sodium bis[2-ethylhexil]sulfosuccinate (AOT)) on hydrotalcite (HT) and the adsorption of 2,4-dichlorophenol (DCP) on HT and its modified forms from aqueous solutions was studied. The modification was carried out by calcinations (heat treatment) and hydrophobization using different anionic surfactants. The anionic surfactant isotherms were of the H-type. It was assumed that first the ion exchange mechanism takes place until approximately the anion exchange capacity of HT is reached and hereafter, the hydrophobic mechanism occurs forming surfactant bilayers. While the DCP adsorption was very poor on HT, significant uptake of DCP took place on calcined HT which was attributed to the simultaneously occurring rehydration and adsorption during the reconstruction of the layered structure. On anionic surfactant-HT complexes ("organo-hydrotalcites") DCP was considerably adsolubilized in the anionic surfactant layers intercalated in HT. The AOT-HT complex appeared the more effective adsorbents for DCP. (C) 2003 Elsevier B.V. All rights reserved.