Factors determining ion-exchange selectivity. 2. The electrostatic effect as determined from gas-solid reactions Academic Article uri icon


  • The magnitude of the electrostatic effect in ion exchange was determined by measuring the free energy of the reaction Zr(MPO4)2(s) + xHCl(g) ⇄ ZrM2-xHx(PO4)2(s) + xMCl(s) where M = Li+, Na+, K+. The free energies so determined were extrapolated to 25°C and converted to free energies of the reactions Zr(MPO4)2(s) + H+(g) ⇄ ZrMH(PO4)2 + M+(g) and ZrMH(PO4)2(s) + H+(g) ⇄ Zr(HPO4)2 + M+(g) by means of a thermodynamic cycle. The selectivity was in the order H+ > Li+ > Na+ > K+ as predicted by Eisenman's theory. The sequence is largely determined by the differences in free energies of vaporization and ionization of the alkali metals. © 1983 American Chemical Society.

author list (cited authors)

  • Clearfield, A., Day, G. A., & Pack, S. P.

citation count

  • 2

publication date

  • November 1983