I. Dekany et al., HYDROPHOBIC LAYERED DOUBLE HYDROXIDES (LDHS) - SELECTIVE ADSORBENTS FOR LIQUID-MIXTURES, Colloid and polymer science, 275(7), 1997, pp. 681-688
The external and internal surface area of the calcium aluminum double
hydroxide [Ca2Al(OH)(6)] NO3.2H(2)O were hydrophobized by the anionic
surfactants sodium dodecylsulfate and sodium dodecylbenzene sulfonate.
The adsorption behavior towards liquid mixtures (benzene/n-heptane an
d n-propanol/toluene) was studied by determining the surface excess ad
sorption isotherms, the heats of immersion in these liquids, and the b
asal spacing, i.e. the expansion of the interlayer space. Both hydroph
obic layered double hydroxides (LDHs) adsorbed n-heptane, benzene, tol
uene, and n-propanol between the layers with considerable increase of
the basal spacing. Interlamellar swelling of the hydrophobizised LDHs
in n-heptane was fundamentally different to the behavior of hydrophobi
zed 2:1 clay minerals (smectites, vermiculites). The surface excess is
otherms for benzene/heptane mixtures were U-shaped and indicate prefer
ential adsorption of benzene. Dodecylbenzene sulfonate double hydroxid
e preferentially adsorbed propanol from n-propanol/toluene mixtures bu
t the dodecylsulfate derivative adsorbed both compounds.