A NOVEL LAYERED ZIRCONIUM-PHOSPHATE ZR2O3(HPO4) - SYNTHESIS AND CHARACTERIZATION OF PROPERTIES

Several novel crystalline layered zirconium phosphates with compositio n Zr2O3(MPO(4)). nH(2)O (M=Na, K) were prepared by the partial hydroly tic decomposition of amorphous or crystalline alpha-zirconium phosphat es in alkaline media under mild hydrothermal conditions. The correspon ding Li-and Cs-forms of this phosphate were obtained by successive tre atment of Na- or K-forms with LiOH or CsOH solutions. Two hydrogen for ms of the novel zirconium phosphate (psi-ZrP)-Zr2O3(HPO4). 1.5H(2)O an d Zr2O3(HPO4). 0.5H(2)O were prepared by acid treatment of the salt fo rms. The intercalation of n-alkylamines into the psi-ZrP-H from the ga s phase was also studied. All the synthesized materials were character ized by elemental analysis, TGA, X-ray, IR and P-31 MAS NMR spectrosco py. The data indicate that the novel zirconium phosphate is a monohydr ogen phosphate. It was found also that psi-ZrP exhibits unexpectedly a nd extremely high hydrolytic stability in alkaline media; the phosphor us release in 1M NaOH being lower than 0.11-0.13 mmol PO4/g in compari son with the complete hydrolytic decomposition of other known layered zirconium phosphates in this medium. The ion exchange behavior of the novel psi-zirconium phosphate in its H-form, theoretical ion exchange capacity (IEC) of 2.86 meq/g, as well as Na- and K-forms towards alkal i, alkaline-earth, and some di- and tri-valent metal cations in differ ent model solutions was studied over a wide pH range (2-14) by the bat ch technique and an explanation of the experimental facts is proposed.