Phosphoric acid ester cation-exchange resins. 2. Physicochemical characterization

Abstract

Water contents, ion-exchange selectivity coefficients, and specific electrical conductances of phosphate monoester (PME) and phosphate diester (PDE) cation-exchange resins are measured. The group 1 cation forms contain the most water (e.g., 39.2% for Na+-PME and 28.8% for Na+-PDE), while the hydrogen and polyvalent cation forms have the lowest water contents (e.g., 24.9% for Ca2+-PME and 17.9% for H+-PDE). The selectivity coefficients for eight cation-pair systems on the PME resin and three cation-pair systems on the PDE resin are determined. The resins exhibit high selectivities for the proton and polyvalent cations (e.g., log ffHNa = 0.98 for PME and log 7fMgNa = 1.42 for PDE). The specific electrical conductances for four ionic forms of each resin are measured, the Na+ forms exhibiting the highest values (e.g., 5.0 X '3 "1 cm"1 for Na+-PME) and the divalent forms having much lower values (e.g., 2.4 X "4 "1 cm"1 for Cu2+-PDE).