On the mechanism of ion exchange in zirconium phosphates—XIX exchange of alkaline earth cations using acetate salts
- Additional Document Info
- View All
Zirconium phosphate was found to exchange alkaline earth cations in macro quantities from acetate solutions. Rates of exchange decrease with increasing crystallinity of the exchanger but increase appreciably with temperature. Magnesium ion exchange is very slow even at 100°C. Both Mg2+ and Ba2+ each form a single exchanged phase. Their respective compositions are close to ZrMg0.75-1.0H0.5-0(PO4)2·4H2O and ZrBa0.8-1.0H0.4-0 (PO4)2·2H2O. In contrast Ca2+ and Sr2+ each form phases with cation contents close to half-exchange, i.e. ZrCa0.5-0.65H1-0.7(PO4)2·3H2O and ZrSr0.45-0.55H1.1-0.9(PO4)2·3.5H2O. these phases are then converted to ZrCa0.85-1H0.3-0(PO4)2·4H2O and ZrSr0.65-1H0.7-0(PO4)2·2.5H2O, respectively at higher loadings. Apparently acetate ion is a sufficiently strong base to initiate exchange and then maintain pH values high enough to achieve high metal loadings. © 1978.
author list (cited authors)
Clearfield, A., & Hagiwara, H.