Study of ion exchange selectivity of organic ions by using 31P NMR spectroscopy

Ion exchange distribution of the phenyl phosphoric acid has been studied on various types of chloride form strong base resins as a function of pH at 25 degreesC, at 0.1 M ionic strength. Equilibrium measurements were supplemented by the study of pH dependence of the P-31 NMR spectra of the resin-phase phenylphosphate species. Equations were derived to describe the pH dependence of the overall distribution coefficient and the chemical shift of the resin-phase solute species. Experimental data were evaluated by using these model equations and the values of the individual distribution coefficients, ion exchange selectivity coefficients and the resin-phase P-31 chemical shifts of the mono- and divalent ions have been calculated. Comparison of distribution data of the individual species corroborated the significance of the role of hydrophobic interaction in the selectivity of organic ion exchange processes. A well-defined correlation between the ion exchange selectivity and the resin-phase P-31 NMR chemical shift data has been pointed out. (C) 2002 Published by Elsevier Science B.V.