Layered double hydroxides (LDHs), shown as the general formula of [M2+1−xM3+x(OH)2]x+(An−)x/n∙yH2O, are useful for various applications such as anion exchangers/adsorbents, catalysts and catalysts’ supports, and drug/gene carriers due to their structural, compositional and morphological characteristics and their variation. The x value (M3+/(M2+ + M3+) ratio) in layered double hydroxides (LDHs), corresponding to the layer charge density, is one of the important parameters for controlling the properties of LDHs. The x values in commonly available LDHs are limited (0.2 < x < 0.3). In order to obtain LDHs with x < 0.2, Mg2+ Ga3+–LDHs with interlayer iodide were examined. The linear correlation between lattice parameter a and x value in the products with x of 0.06–0.24 was seen, suggesting the successful substitution of Mg2+ in the brucite-like sheet with Ga3+. Carbonate and dodecyl sulfate types MgGa–LDH were prepared by ion exchange with carbonate anion and reconstruction in aqueous solution of sodium dodecyl sulfate. The products with x of 0.06 were dispersed in water and hexanol better than those with x of 0.24 for MgGa–LDHs containing carbonate and dodecyl sulfate, respectively, suggesting effects of the lower layer charge density on the dispersion.
Characteristics and mechanisms of sorption of organic contaminants onto sodium dodecyl sulfate modified Ca-Al layered double hydroxides
