Preparation and intercalation chemistry of magnesium-iron(Ⅲ) layered double hydroxides containing exchangeable interlayer chloride and nitrate ions

摘要

Layered double hydroxides (LDHs) with Mg~(2+) and Fe~(3+) cations in the brucite-like layers and having chloride or nitrate ions in the interlayer region have been prepared and characterized by powder X-ray diffraction (PXRD), elemental analysis and thermal analysis. Thermal decomposition of the LDH-nitrate occurs in two steps, with loss of water followed by simultaneous dehydroxylation of the layers and loss of NO_x/O_2 arising from the nitrate anions. Thermal decomposition of the LDH-chloride involves an additional step, with chloride ions becoming grafted to the layers, prior to loss of HCl. The interlayer anions may be readily replaced by sulfate, thiosulfate, tartrate and vinylbenzenesulfonate ions suggesting that these materials may be useful precursors to Mg-Fe(Ⅲ) LDHs intercalated with a variety of inorganic and organic anions.