Preparation of a well-ordered layered nanocomposite from zinc-aluminum-chloride layered double hydroxide and hydrogenophosphate by ion exchange

The ion exchange of hydrogenophosphate ion in Zn-Al-chloride layered double hydroxides was investigated. The chloride precursors prepared by coprecipi tation at pH 10 preserved their lamellar structure following ion exchange. It was found that the aging time is important in controlling the crystalliz ation of the phosphate-exchanged compounds; long aging times of more than 8 h lead to poorly crystallized phases. The grafting of the anion onto hydro xylated sheets by moderate thermal treatment was confirmed by a combination of several techniques, including powder X-ray diffraction (XRD), infrared (IR) spectroscopy, and thermal analyses. (C) 1999 Elsevier Science Ltd.