Preparation and investigation of thermolysis of L-aspartic acid-intercalated layered double hydroxide

L-Aspartic acid (L-Asp) has been intercalated into magnesium-aluminum layered double hydroxides by coprecipitation. The structure and composition of the intercalated material have been studied by X-ray diffraction, inductively coupled plasma emission spectroscopy, and elemental analysis. A schematic model of the intercalated structure has been proposed. Furthermore, the thermal decomposition of the hybrid material has been characterized by in situ powder X-ray diffraction, in situ Fourier transform infrared spectroscopy, thermogravimetry, differential thermal analysis, C-13 solid-state magic-angle spinning nuclear magnetic resonance, temperature-programmed decomposition, and gas chromatography-mass spectrometry. The thermolysis Of L-Asp LDH is quite different from that of the pristine L-Asp studied as a reference sample and is characterized by three steps: the first from room temperature to 150 degreesC is attributed to the loss of both adsorbed and interlayer water, accompanied by the destruction of the hydrogen bonding network and a decrease in basal spacing; the second step (250-350 degreesC) involves the polymerization and deamination Of L-Asp ions in the interlayer of LDH and dehydroxylation of the brucite-like layers; the third step in the temperature region of 350-450 degreesC corresponds to dehydroxylation of the brucite-like layers as well as further decomposition of interlayer materials.