A novel layered zirconium phosphate Zr2O3(HPO4). Synthesis and characterization of properties.
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Several novel crystalline layered zirconium phosphates with composition Zr2O3(MPO4)nH2O (M=Na, K) were prepared by the partial hydrolytic decomposition of amorphous or crystalline -zirconium phosphates in alkaline media under mild hydrothermal conditions. The corresponding Li-and Cs-forms of this phosphate were obtained by successive treatment of Na- or K-forms with LiOH or CsOH solutions. Two hydrogen forms of the novel zirconium phosphate (-ZrP) - Zr2O3(HPO4)1.5H2O and Zr2O3(HPO4)0.5H2O were prepared by acid treatment of the salt forms. The intercalation of n-alkylamines into the -ZrP-H from the gas phase was also studied. All the synthesized materials were characterized by elemental analysis, TGA. X-ray. IR and 31P MAS NMR spectroscopy. The data indicate that the novel zirconium phosphate is a monohydrogen phosphate. It was found also that -ZrP exhibits unexpectedly and extremely high hydrolytic stability in alkaline media; the phosphorus release in 1M NaOH being lower than 0.11-0.13 mmol PO4/g in comparison with the complete hydrolytic decomposition of other known layered zirconium phosphates in this medium. The ion exchange behavior of the novel -zirconium phosphate in its H-form, theoretical ion exchange capacity (IEC) of 2.86 meq/g, as well as Na- and K-forms towards alkali, alkaline-earth, and some di- and tri-valent metal cations in different model solutions was studied over a wide pH range (2-14) by the batch technique and an explanation of the experimental facts is proposed.
