Synthesis and Characterization of Layered Double Hydroxides with a High Aspect Ratio

A new route for synthesis of Mg/Al layered double hydroxide (Mg6Al2(OH)16(CO3)•4H2O) has been introduced, which can be considered as a modified calcination-rehydration method. Under the hydrothermal conditions, LDHs with a high aspect ratio were synthesized and characterized by inductively coupled plasma-atom emission spectrometer (ICP-AES), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal measurement (TG-DTG) and scanning electron microscopy (SEM). XRD patterns display the crystalline enhanced with the increase of hydrothermal temperature and aging time. TG-DTG curves show the more stable LDHs were synthesized at higher temperature. SEM images indicate the lateral size of the synthesized LDHs locates at ca. 1 - 6 μm and the thickness at ca. 35 - 60 nm. And the particle size depends strongly on the treatment temperature and aging time. A buffer solution consisted of HCO3- and CO32- keeps the pH of reaction system in a certain range and offers a low supersaturated reaction circumstance. This is of high importance for the formation of LDHs with a high aspect ratio