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Sorption of hydrochloric and perchloric acids and their sodium salts was studied by Cl− and ClO4− forms of ion exchanger Dowex 1×8 in the concentration range of the external electrolyte 0.25–4 mol/l. Sorption of water and the total amount of the solution were also studied. Sorption of the acid appeared markedly higher than that of the respective salts. A mathematical modeling and computer simulation of the processes were performed. The overall sorption was represented as a superposition of the Donnan membrane distribution and formation associates type RAn · (AnKt)i · (H2O)n in the homogeneous resin phase. The model expresses non-ideality of the resin phase in explicit form as formation of the above associates characterized by the constants of their formation. A good agreement between the experimental and calculated sorption in the whole concentration range was obtained in the assumption of two associates with i=1, 2 and n=1–3. The same factors control sorption of the acids and the salts and the difference in their behavior has a quantitative character. The main introduction into the overall sorption of the salts makes the Donnan distribution up to concentration of the external electrolyte 4 M, while the main part of the absorbed acids is contained in the associates.

A method for determination of the acidity parameters of ion exchangers with arbitrary functionality from potentiometric titration data was developed. Titration of ion exchanger RH (ROH) with alkali KtOH or acid HAn is considered as superposition of ion exchange H + –Kt + (OH − –An − ) and the reaction of neutralization. The method is based on the assumption of linear dependence of logarithm of the equilibrium coefficient of the ion exchange as a function of the neutralization degree. The acidity parameters are two constants of this dependence. They are thermodynamic equilibrium constant of ion exchange, p K and the difference between logarithm of the equilibrium coefficient at the complete and zeroth neutralization of the ion exchanger, Δp k . Specially developed computer program allows reconstruction of the potentiometric titration curve from the sets of the acidity parameters of each type of the functional groups in the resin. The theory was tested on a number of ion exchangers with different functionalities: sulfonic and carboxylic acid cation exchangers, polyfunctional weak base anion exchangers of different structures. The ion exchange capacity of each type of groups can be determined with precision higher than 0.1 meq/g. The p K i values of the groups present in macroamounts are determined with precision at least ±0.2 p K units.