Mechanism of ion exchange in zirconium phosphates. 28. Calorimetric determination of heats of rubidium(1+)-hydrogen ion exchange on .alpha.-zirconium phosphate

%Calorimetric Determinations of Ba2+ and La3+ in the Ion-Exchange Process Involving Pure and Modified α-Titanium Phosphates

“…Another example involves the exchanger zirconium phosphate with the cations rubidium, potassium, and lithium. The exchange enthalpic values were −13.46, −10.46, and −9.62 kJ mol -1 , respectively. , By comparison of our results with those data, some difficulties are inherent due to the fact that distinct exchangers and techniques were to obtain the thermodynamic data. In the previous study the enthalpy values were calculated from a series of isotherms at various temperatures, which procedure differs considerably from our calorimetric methodology.…”

“…A significant amount of investigations are devoted to ion-exchange reactions, with the great majority focused on structural features of these exchangers, probable in exploring the excellent chemical and thermal stabilities and also the facility in developing favorable ion-exchange properties. , Thus, the ion-exchange behavior of those materials has been applied with the complete series of alkaline metals and calcium, barium, and strontium with the matrixes of titanium and zirconium hydrogen phosphate in α or γ crystalline structures. − However, some thermodynamic data for the ion-exhange reactions are reported for α- or γ-titanium and α- or γ-zirconium phosphates in investigations involving alkaline metals 6-8,11,12 and transition metals Co(II) and Ni(II) with γ-titanium hydrogen phosphate, for which the corresponding ionic isotherms at distinct temperatures were obtained. The same exchange process was followed through calorimetric determinations with crystalline α-titanium phosphate and crystalline or amorphous zirconium phosphate. ,− While the exchange behavior of α-titanium hydrogen phosphate has been investigated, only few studies are found with other kinds of this modified matrix. However, those exchangers containing sodium and n -butylammonium intercalated forms were recently explored. , …”

Mechanism of ion exchange in zirconium phosphates. 31. Thermodynamics of alkali metal ion exchange on amorphous zirconium phosphate

“…Figure 6 shows standard heats, 0, for alkali metal ion exchange on amorphous ZrP determined in our previous calorimetric studies. 6,7,[9][10][11] The differential heats of exchange, , which give heats of exchange at constant metal load, i.e., heats for the following reaction (R)Xm + M+(aq) -(R)Xm + H+(aq) (8) were obtained from the relation = y2d(AHx°)/dX (9) The factor 1/2 arises because the °values are expressed as kilocalories per mole of exchanger while the values are given as kilocalories per mole of M+. The differential heats are given in Figure 7.…”