Synthesis and thermal properties of ZnAl layered double hydroxide by urea hydrolysis

The synthetic zinc aluminum layered double hydroxide (LDH) with Zn/Al molar ratios of 0.25-8 was synthesized by the urea method. The structure, composition and morphological properties were investigated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). Pure layered double hydroxide phase was obtained when the Zn/Al ratios are 0.5, 1 and 2. The lower (0.25 and 0.33) and higher (3, 4, 6 and 8) initial Zn/Al molar ratios resulted in the formation of ZnAl-CO3-LDH with AlOOH and Zn-4(CO3)(OH)(6)center dot nH(2)O, respectively. The thermal properties of these LDHs were studied by the thermogravimetric and differential thermal analysis (TG-DTA). The XRD patterns of the calcined products at 900 degrees C showed that the LDHs prepared at different Zn/Al molar ratios can be used as good precursors for preparing mixed oxide or spinel. (C) 2013 Elsevier B.V. All rights reserved.