Preparation, Characterization and Intercalation Reactions of New Nano-Ordered Layered Materials, Zn-Al-Si LDH

Layered double hydroxides (LDHs) and anionic clay are nano-ordered layered compounds and are well known for their ability to intercalate anionic compounds. Most LDHs are prepared conventionally only with di- and tri-valent cations. Alumina-silicate structures are very familiar in the literature as cationic clay or zeolite structure, however, there is no data for alumina-silicate as anionic clay. In this study, a new series of Zn-Al-Si LDHs with various Zn/Al/Si ratios, consisting of di-, tri-, and tetra-valent cations, were prepared and characterized by energy-dispersive X-ray spectrometry (SEM/EDS), X-ray powder diffraction (XRD), infrared spectra (IR), thermal analyses (TG, DTG and DTA), and scanning electron microscopy (SEM). Characterization of the samples containing molar percentages of aluminum and silicon 20∼40 % revealed formation of well crystallized phases, layered structures and no excess phases. XRD results and thermal analyses indicated that the carbonate anions have two orientations inside the interlayer region. After intercalation reactions with organic acids, mono- and di-carboxylic acids, the interlayer spacing of Zn-Al-Si LDH increased and organic-inorganic nano-hybrid materials formed. SEM images showed that the morphology of Zn-Al-Si LDH before and after intercalation reactions is plate-like structure. The results presented in this work conclude that the formation of the layer double hydroxide is not limited to the reactions between di- and trivalent cations, although these are the only reactions reported by many researchers.