TY - JOUR

T1 - Modeling of divalent/monovalent ion selectivity of ion-exchanger-based solvent polymeric membranes doped with coexchanger

AU - Mikhelson, K. N.

AU - Lewenstam, A.

PY - 2000/10/15

Y1 - 2000/10/15

N2 - It is shown that the addition of a coexchanger does not always improve the selectivity of an ion-selective electrode. As a model case, the selectivity toward divalent primary ions I2+ in the presence of monovalent interference J+ is numerically simulated for membranes based onion-exchanger R- and doped with a coexchanger (ionic additive) S+. It is, for the first time, demonstrated that the addition of a coexchanger, together with a high mobility of ion-exchanger sites, may be either beneficial or harmful to selectivity. Accordingly, two distinctive representatives of systems, i.e., membrane/solution are discussed. The theory is illustrated with experimental data obtained from PVC membranes based on calcium bis(2ethylhexyl)-phosphate plasticized with tris(2ethylhexyl)phosphate and doped with tetradecylammonium. Electrodes with these membranes exhibit both types of selectivity behavior. Interference from lithium with a calcium response may be sufficiently decreased by the addition of tetradecylammonium, while the interference from potassium and cesium was increased in the doped membranes.

AB - It is shown that the addition of a coexchanger does not always improve the selectivity of an ion-selective electrode. As a model case, the selectivity toward divalent primary ions I2+ in the presence of monovalent interference J+ is numerically simulated for membranes based onion-exchanger R- and doped with a coexchanger (ionic additive) S+. It is, for the first time, demonstrated that the addition of a coexchanger, together with a high mobility of ion-exchanger sites, may be either beneficial or harmful to selectivity. Accordingly, two distinctive representatives of systems, i.e., membrane/solution are discussed. The theory is illustrated with experimental data obtained from PVC membranes based on calcium bis(2ethylhexyl)-phosphate plasticized with tris(2ethylhexyl)phosphate and doped with tetradecylammonium. Electrodes with these membranes exhibit both types of selectivity behavior. Interference from lithium with a calcium response may be sufficiently decreased by the addition of tetradecylammonium, while the interference from potassium and cesium was increased in the doped membranes.

UR - http://www.scopus.com/inward/record.url?scp=0034667909&partnerID=8YFLogxK

U2 - 10.1021/ac991317o

DO - 10.1021/ac991317o

M3 - Article

AN - SCOPUS:0034667909

VL - 72

SP - 4965

EP - 4972

JO - Industrial And Engineering Chemistry Analytical Edition

JF - Industrial And Engineering Chemistry Analytical Edition

SN - 0003-2700

IS - 20

ER -