Preparation of MgGa Layered Double Hydroxides and Possible Compositional Variation

Layered double hydroxides (LDHs), shown as the general formula of [M²⁺_1-xM³⁺_x(OH)₂]^x+(A^n-)_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.