Selectivity in preparative separations of inorganic electrolytes by size-exclusion chromatography on hypercrosslinked polystyrene and microporous carbons

Preparative-scale separation of concentrated solutions of simplest mineral electrolytes by size-exclusion chromatography was performed on three samples of commercially available microporous hypercrosslinked polystyrene sorbents “Macronet Hypersol” and two experimental samples of activated carbons. Selectivity of separation of a pair of electrolytes was found to be determined by the largest ions in each pair. Fortunately, selectivity rises at higher concentrations of electrolytes, which was explained by exclusion of smaller species from the concentrated solution, i.e., mobile phase, into small pores of the column packing that are inaccessible to large species. The separation of concentrated mixtures revealed another remarkable advantage of the new process – self-concentrating of each of two separated components in the corresponding fractions. Self-concentration is more pronounced for the minor component that occupied less space in the initial mixture. The new method may prove productive in processing pickle bath solutions.