Thermal analysis of calcite equilibrated with aqueous solutions of magnesium, strontium, barium and zinc chlorides

The Interactions between calcite particles and aqueous solutions containing MgCl₂, SrCl₂, BaCl₂ and ZnCl₂ in various concentrations were Investigated by thermal analysis of the solid fraction (TGA and DTG). In these systems calcite powder had been equilibrated with the solution for twenty days while the suspension had been shaken before the thenal treatment. Topochemical substitution of Ca by Mg or Zn was detected from the shift of the decarboxylation DTG peak to lower temperatures. This shift is correlated with the amount of sorbed Mg or Zn. Such a correlation was not observed with Sr or Ba and it was concluded that in these systems topochemical substitution played only a minor role during the interactions between calcite and these cations.