On the mechanism of ion exchange in zirconium phosphates—XIV The effect of crystallinity on NH4+/H+ exchange of α-zirconium phosphate
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The ion exchange behavior of zirconium phosphates possessing different degrees of crystallinity was examined for the NH4+/H+ system. In the most crystalline exchangers ammonium ion is initially taken into solid-solution without phase change. This initial uptake is followed by conversion of the solid solution to a fully exchanged ammonium ion phase Zr(NH4PO4)2·H2O. The composition range of the solid solution increases with decreasing crystallinity until, in the amorphous exchanger it covers the entire range of ammonium ion uptake. The exchange process is reversible for the amorphous exchanger with K = 7·4 × 10-5. However, with the more crystalline exchangers a half-exchanged phase, Zr(NH4)H(PO4)2·0·33H2O, is obtained when H+ replaces NH4+. These results differ significantly from other published data. © 1976.
author list (cited authors)
Clearfield, A., & Hunter, R. A.