ADSORPTION OF SODIUM DODECYL-SULFATE ON LAYERED DOUBLE HYDROXIDES

Layered double hydroxides (LDH), or the so-called anionic clays, are h ydrotalcite-like compounds which can be represented by the general for mula [M1-x2+Mx3+(OH)(2)](x+) X-x/m(m-) . nH(2)O. They can be used as a dsorbents, catalysts and catalyst supports and they present many other industrial applications such as polymer stabilisers and anion exchang ers. On the other hand, the surfactants have been widely applied in in dustrial and household uses, so they constitute an important class of materials of commercial interest. The study of the adsorption of surfa ctants on these clays is thus very important due to the potential appl ication of these adsorbents in many industrial processes. The adsorpti on of dodecyl sulfate on a magnesium aluminium layered double hydroxid e was studied. The results obtained agree well with those found in the literature for the adsorption of this surfactant on other solids. We could observe that the adsorption follows the two-step model, confirme d by zeta potential measurements. We also observed that the amount of adsorbed surfactant increases with temperature. (C) 1998 Elsevier Scie nce B.V. All rights reserved.