Ion—solvent interaction: viscosity of ternary electrolytes in dioxane-water mixtures at 35°

The viscosities of the chlorides, bromides and nitrates and perchlorates of Mg²⁺ and Ba²⁺, of the chlorides and nitrates of Ca²⁺ and Sr²⁺, and of the sulphates of Na⁺ and K⁺ at mass fraction of dioxane, 10, 20 and 30% have been measured at 35°. The values of the constant A and B of the viscosity equation indicate ion—ion and ion—solvent interaction respectively. The ion-solvent interaction is found to be of the order NO^?₃ > ClO^?₄ > Br^? > Cl^? and K⁺ > Na⁺.     

The effect of some soluble inorganic admixtures on the early hydration of portland cement

The effects of the soluble chlorides, bromides, nitrates, sulphates and acetates of Ca²⁺, Mg²⁺, Li⁺, Na⁺ and Zn²⁺ as well as the corresponding mineral acids on the early hydration of neat Portland cement pastes have been studied. Both the cations and anions are ranked according to their general effectiveness as accelerators of the hydration of the Ca₃SiO₅ phase: Ca²⁺>Mg²⁺>Li⁺>Na⁺>H₂O>Zn²⁺ and OH^? >Cl^?>Br^? >NO₃^?SO₄²～H₂O > CH₃CO₂^?.     

Effects of electrolytes on the reduction of 2,4‐dinitrotoluene by zero‐valent iron

BACKGROUND: Dinitrotoluenes (DNTs) are environmentally persistent, making the remediation of contaminated streams and groundwater difficult. Zero‐valent iron (Fe⁰) can be used as an electron source for the reduction of recalcitrant DNTs in waste‐water and thus enhance their biodegradability. However, little is known about the qualitative effects of major anions and cations present in waste‐water on the reduction of DNTs by Fe⁰. RESULTS: The presence of Na₂SO₄ and NaCl at levels between 0.25 and 2 mmol L^?1 was observed to enhance the reactivity of Fe⁰ towards 2,4‐DNT. The positive effect of K₂SO₄ is stronger than that of Na₂SO₄ at the same level (1 mmol L^?1). Varying (NH₄)₂SO₄ from 0.1 to 1.0 mmol L^?1 improved the efficiency of 2,4‐DNT degradation by Fe⁰. The effects of varying NaNO₃ and NaNO₂ from 0 mmol L^?1 to 4.7 mmol L^?1 and 0 mmol L^?1 to 5.8 mmol L^?1, respectively, were also investigated. Both NaNO₃ and NaNO₂ at low concentration improved the efficiency of 2,4‐DNT degradation by Fe⁰, however, at high concentration, inhibiting effects appeared. CONCLUSION: SO₄^2?, Cl^?, Na⁺, K⁺ and NH₄⁺ notably enhanced 2,4‐DNT reduction by Fe⁰ at the tested concentrations. The positive effect of K⁺, Cl^? was relatively stronger than that of Na⁺ and sulfate (SO₄^2?). However, the effect of NH₄⁺ was relatively weaker at concentrations greater than 1.0 mmol L^?1. The presence of low concentrations of NO₃^? and NO₂^? promoted 2,4‐DNT reduction by Fe⁰ and inhibited the reaction. The results suggest that 2,4‐DNT reduction by Fe⁰ can be controlled by the ions composition of the waste‐water. Copyright © 2010 Society of Chemical Industry     

Separation performance of a nanofiltration membrane influenced by species and concentration of ions

Nanofiltration (NF), which has been largely developed over the past decade, is a promising technology for the treatment of organic and inorganic pollutants in surface and ground waters. The ESNA 1 membrane from the Nitto Denko Corporation of Japan is made of aromatic polyamide, which provides salt rejection from 50% to 90%. In this paper permeation experiments of aqueous solutions of five chlorides (NH₄Cl, NaCl, KCl, MgCl₂ and CaCl₂), three nitrates (NaNO₃, Mg(NO₃)₂ and Ca(NO₃)₂), and three sulfates (NH₄)₂SO₄, Na₂SO₄ and MgSO₄) were carried out. The effects of species and concentration of salts on the separation performance of the ESNA 1 membrane were investigated. The experimental results showed that the rejection to most salts by the ESNA 1 membrane decreased with the growth of the concentration. Then, the reflection coefficient and solute permeability of ESNA 1 membrane were calculated by the Spiegler-Kedem equation from experimental data. The reflection coefficients of the ESNA 1 membrane to salts are all above 0.95. The salt permeabilities, except for magnesium and calcium salts, increased with the growth of concentration. The sequence of rejection to anions by the ESNA 1 membrane is R(SO²⁻₄) > R(Cl⁻) > R(NO⁻₃) at the same concentration which ranges from 10 mol/m³ to 100 mol/m³. The sequence of rejection to anions by the ESNA 1 membrane can be written as follows: R(Na⁺) > R(K⁺) > R(Mg²⁺) > R(Ca²⁺) at 10 mol/m³ concentration and R(Mg²⁺) > R(Ca²⁺) > R(Na⁺) > R(K⁺) at 100 mol/m³ concentration.     

Effect of soluble ash components on the viscosity of lignite-water mixtures

The removal of multivalent cations from lignite-water mixtures (LWM) was shown to lower mixture apparent viscosity by a factor of about 40, for example, at 100 s^?1 by reducing both the yield stress and plastic viscosity. The cations Ca⁺⁺, Mg⁺⁺, Al⁺⁺⁺, K⁺, and Na⁺, among others, were found to be present in the aqueous phase of the LWM in concentrations ranging from 546 ppm to 8 ppm. The primary anions present were CI^? and SO₄⁼. The degree to which the cations affected viscosity were of order trivalent > divalent > monovalent. The nature of the anion was found to be relatively unimportant. A process utilizing ion-exchange resins for removing multivalent cations to produce low viscosity lignite-water or coal-water mixtures is described.     

Scavenging Ratios in an Urban Area in the Spanish Basque Country

For a period of six years (1995–2000) the scavenging ratio, which is the ratio of a pollutant's concentration in water to its concentration in air, collected at an urban site in the Spanish Basque Country was studied. The aerosol is characterized by SO₄ ^2? and NO₃? with 1.79 and 1.61 μg m^?3, respectively. Greater fractions of SO₄ ^2?, NO₃?, and NH₄+ ions were present in the fine particle range, while greater fractions of other ions appeared in the coarse range. The most important species found in the precipitation is SO₄ ^2? with 3.0 mg l^?1. NO₃?, Ca²⁺, and Cl^? are the second most important ions. The volume-weighted mean concentration of H⁺ is 4.6 μg l^?1 (pH = 5.3). The concentration of all analyzed ions (except H⁺) decreases throughout the rain event, showing the washout phenomenon of the rainwater. The scavenging ratio for the anthropogenic ions NO₃?, SO₄ ^2?, NH₄+, and K⁺ is lower than the scavenging ratio for the marine-terrigenous ions, Cl^?, Na⁺, and Ca²⁺.     

Influence of Some Hofmeister Anions on the Krafft Temperature and Micelle Formation of Cetylpyridinium Bromide in Aqueous Solution

In this work, the effect of some Hofmeister anions on the Krafft temperature (T_K) and micelle formation of cetylpyridinium bromide (CPB) have been studied. The results show that more chaotropic anions increase, while the less chaotropic ones lower the T_K of the surfactant. More chaotropic I^? and SCN^? form contact ion pairs with the cetylpyridinium ion and reduce the electrostatic repulsion between the CPB molecules. As a result, these ions show salting‐out behavior, with a consequent increase in the T_K. In contrast, less chaotropic Cl^? and NO₃^? increase the activity of free water molecules and enhance hydration of CPB molecules, showing a decrease in the T_K. A rather unusual behavior was observed in the case of SO₄^2? and F^?. These strong kosmotropes shift from their usual position in the Hofmeister series and behave like moderate chaotropes, lowering the T_K of the surfactant. Because of the high charge density and the strong tendency for hydration these ions preferentially remain in the bulk. Rather than forming contact ion pairs, these ions stay away from the CPB molecules, decreasing the T_K of the surfactant. In term of decreasing the T_K, the ions follow the order NO₃^? > SO₄^2? > Cl^? > F^? > Br^? > SCN^? > I^?. The critical micelle concentration (CMC) of the surfactant decreases significantly in the presence of these ions due to the screening of the micelle surface charge by the excess counterions. The decreasing trend of the CMC in the presence of the salts follows the order SCN^? > I^? > SO₄^2? > NO₃^? > Br^? > Cl^? > F^?.     

How the Influence of Different Salts on Interfacial Properties of Surfactant–Oil–Water Systems at Optimum Formulation Matches the Hofmeister Series Ranking

In this work, we present the effects of salts on sodium dodecyl benzene sulfonate micellization and on the interfacial performance of a sodium dodecyl benzene sulfonate–heptane–brine system at optimum formulation, i.e., hydrophilic–lipophilic deviation (HLD) = 0. In order to do that, interfacial tension and dilational interfacial rheology properties of surfactant–heptane–water systems at optimum formulation are measured using an interfacial spinning drop tensiometer with an oscillating velocity, which can accurately measure interfacial rheology properties at both low and ultralow interfacial tensions. The brines used contain one of the following salts: MgCl₂, CaCl₂, NaCl, NH₄Cl, NaNO₃, CH₃COONa, or Na₂SO₄. We performed a one-dimensional salinity scan with each of these salts to achieve an optimum formulation. In relation to the Hofmeister series, we found that, at optimum formulation, systems with chaotropic ions (NH₄⁺, NO₃⁻) present interfaces with ultralow interfacial tensions, very low dilational modulus, and a low phase angle, whereas kosmotropic ions (Mg²⁺, Ca²⁺, SO₄⁻²) generate high interfacial tension and high rigidity monolayers. Intermediate ions in the Hofmeister series (Na⁺, CH₃COO⁻, Cl⁻) present interfaces with intermediate properties. Furthermore, according to the Hofmeister series, interfaces can be respectively ordered from higher to lower rigidity for surfactant counterions Mg²⁺ > Ca²⁺ > Na⁺ > NH₄⁺ and coions SO₄²⁻ > CH₃COO^– > Cl⁻ > NO₃⁻, which correspond to a salting-out (highest rigidity) and salting-in (lowest rigidity) effect. We observed that counterions have a more significant effect on surfactant–oil–water system properties than those that act as coions.     

Rapid Separation of Tl+ and Pb2+ from Various Binary Cation Mixtures Using Dicyclohexano-18-crown-6 Incorporated into Emulsion Membranes

Abstract

Relative transport rates of metal cation nitrates (Na⁺, K⁺, Rb⁺, Cs⁺, Ag⁺, Tl⁺, Ca²⁺, Sr²⁺, Ba²⁺, and Pb²⁺) in a water-toluene-water emulsion membrane system were measured. The toluene component contained the surfactant Span 80 and the crown ether dicyclohexano-18-crown-6. The aqueous receiving phase contained Li₄P2O₇. When each metal cation was individually present in the aqueous source phase, metal extraction was complete within 10 min with the order of extraction being Tl⁺ > Cs⁺ > Ag⁺ > Rb⁺ > K⁺ ≥m Na⁺ and Pb⁺ > Ca²⁺ > Sr²⁺ > Ba²⁺ for uni-and bivalent cations, respectively. Significant extraction was found for all cations except Na⁺, K⁺, and Ba²⁺. Some metal ions were concentrated nearly 10-fold in a 10-min period. Relative transport rates were determined when binary cation mixtures of either Tl⁺ or Pb²⁺ were present at equal concentrations with each of the remaining metal ions in the source phase. Tl⁺, when present with either Na⁺, Cs⁺, or Rb⁺, was selectively extracted from the source phase. Complete and nearly exclusive extraction of Pb²⁺ was observed in the presence of all cations including Tl⁺. The enrichment ratios of Pb²⁺ in the binary mixtures were approximately 10 while those of the second cation were less than 0.5 except for Sr²⁺ which was 0.86. Corresponding separation factors for Pb²⁺ ranged from 1000 to > 6000.     

Synthesis and properties of a cellulose exchanger with the crown ether diaminodibenzo-17-crown-5 as anchor group

A new cellulose exchanger was synthesized from “o-aminophenolcellulose” by diazotation and coupling with diaminodibenzo-17-crown-5. The distribution coefficients for Ca²⁺, Sr²⁺, Ba²⁺, Na⁺ and K⁺ were determined in water/methanol mixtures as a function of the water content. Separation of Ca²⁺, Na⁺ and K⁺ and fractionation of the calcium isotopes ⁴⁸Ca and ⁴⁰Ca were investigated. The enrichment factor ε = 4.9 · 10^?3 for ⁴⁸Ca²⁺ is appreciably higher than that found for cation exchange resins with ? SO₃H groups, but lower than that reported for certain cryptands.     

Hydrochemical and stable isotopic assessment of groundwater quality and its variations in rice-growing areas in East China

Agricultural activities are frequently associated with water contamination. Thus, the development of efficient strategies for groundwater protection in agricultural areas requires an assessment of the contaminants. Given this perspective, groundwater quality monitoring is carried out in a rice-growing area in Hangjiahu Plain, East China. Thirty-two piezometers are installed to measure physico-chemical parameters such as major ions, field-measured parameters (pH, electrical conductivity (EC), dissolved oxygen, and temperature), and δ¹⁵N isotopic ratios and their variations in space and time. The groundwater shows a variable chemical composition, e.g. EC ranged from 760 to 2,300 μS cm^?1. Most groundwater is weakly acidic, and is characterized as Ca²⁺ + Na⁺? HCO₃ ^? + SO₄ ^2? + Cl^? type. The results demonstrate NH₄ ⁺ coming from agricultural activities and SO₄ ^2? deriving from natural chemical inputs are the major contaminants in the groundwater at the study area. Correlations among NO₃ ^?, NH₄ ⁺ and K⁺ suggest that these ions come from the same source of fertilizer and indicate a significant degree of nitrification in the study area. The highly positive correlations among the variables of HCO₃ ^?, SO₄ ^2?, and Mg²⁺ indicated that these ions were derived from the same source of natural chemical inputs. Nitrate isotopic composition suggests that nitrate in groundwater originates from chemical fertilizers, manure, and soil organic matter.     

Novel PVA-based polymers showing an anti-Hofmeister Series property

A series of poly(vinyl alcohol)-trimellitate (PVA-T) polymers with different esterification degrees (ED: 82, 61, and 32 mol%) were prepared through the esterification of PVA and trimellitic anhydride (TA). Solubilities of these polymers and the swelling properties of PVA-T hydrogels, which were prepared by crosslinking with ethylene glycol diglycidyl ether (EGDGE), were investigated in various salt solutions comprising of SO₄²⁻, Cl⁻, SCN⁻ and Li⁺, Na⁺, K⁺, Cs⁺. The PVA-T polymers proved to have larger solubilities in salt solutions (1 M) than in pure water, and the ionic “salting-in” effect was significant in order of SO₄²⁻ > SCN⁻ > Cl⁻ for anions, and Li⁺ > Na⁺ > K⁺ > Cs⁺ for cations, regardless of their ED values. The PVA-T hydrogels also showed corresponding swelling properties; they significantly swelled in sulfate solutions of medium concentration (0.1-1 M), while in other salt solutions no appreciable swelling occurred. The marked salting-in effects exerted by sulfate anion, which is otherwise a typical “salting-out” agent, means that PVA-T polymers have an “anti-Hofmeister Series” (anti-HS) property. This is naturally ascribed to the trimellitic acid group because the degree of swelling in sulfate solutions was more significant for PVA-T with higher ED values; the combination of π-electron system and acidic protons seems to be essential to endow polymers with the anti-HS property.     

Interactions of Some Hofmeister Cations with Sodium Dodecyl Sulfate in Aqueous Solution

In this work, we have investigated the influence of some alkali metal ions on the Krafft temperature (T_K) and critical micelle concentration (CMC) of a classical ionic surfactant, sodium dodecyl sulfate (SDS), over a wide range of temperature. The alkali metal cations such as Li⁺, Na⁺, Cs⁺, and K⁺ are found to affect the solubility and hence the T_K of the surfactant. It was observed that kosmotropic Li⁺ lowers the T_K of the surfactant. Due to the common ion effect, the solubility of SDS decreases in the presence of Na⁺, resulting in an increase in the T_K. On the other hand, chaotropic K⁺ and Cs⁺, capable of forming contact ion pairs with the chaotropic dodecyl sulfate ion, lower the solubility and hence elevate the T_K. In terms of decreasing the T_K, the ions follow the trend: Li⁺ > Na⁺ > Cs⁺ > K⁺ except for 0.0025 M CsCl. The added cations screen the charge of the micelle surface and facilitate closer packing of the surfactant with a consequent decrease in the CMC. In terms of the effectiveness in lowering the CMC, the ions follow the order: Cs⁺ > K⁺ > Na⁺ > Li⁺. In the presence of added electrolytes, the γ_CMC values are found to be lower than the corresponding values in pure water. The thermodynamic parameters (Gibbs free energy, enthalpy, and entropy changes) of micellization were calculated to gain insights into the mechanism of the process.     

Determination of the charge of complex species that are reduced at the dme and of the coefficient of transfer, α, in the Cu(II)aq. M citrate (M: Li+, Na+ and K+) system

The minimum presented by the polarograms of the reduction of Cu(II) in Li⁺, Na⁺ and K⁺ citrate is analysed in order to determine the charge of the reacting species and the coefficient of transfer, α, of the process. The results obtained allow the participation of the complex anions (Cu₂Cit₂)^2? and (CuCit₂)^4? in dilute and concentrated citrate solutions to be established, respectively, as well as a cation—reacting anion interaction, increasing in the order K⁺ > Na⁺ > Li⁺. The value of the coefficient of transference α = 0.40 is in agreement with that found by other techniques.     

Solid-liquid equilibria in concentrated aqueous salt solutions—systems with a common ion

A thermodynamic correlation is presented for solid-liquid equilibria in concentrated aqueous salt systems containing a common ion. It is assumed that no solid solutions are formed, although the solid phase can be a pure salt, a multiple salt or a hydrate. Predictions of solid-liquid equilibria in multicomponent systems are made using parameters calculated from solid-liquid equilibrium data for the constituent binary and ternary systems.Parameters are given for the prediction of solid-liquid equilibria in the aqueous system containing Na⁺, K⁺, Mg⁺⁺, NO^?₃, Cl^?, SO^--₄ from 0–50°C. These parameters correlate the available solid-liquid equilibrium data for ternary systems with an error in liquid-phase composition of less than 2 grams salt/100 grams H₂O. Errors are similar in the estimation of solid-liquid equilibria in four-component systems such as NaNO₃-NaC1-Na₂SO₄-H₂O.     

Electrokinetic Properties of Vermiculite and Expanded Vermiculite: Effects of pH,Clay Concentration and Mono- and Multivalent Electrolytes

Abstract

In this study, the zeta potential values of vermiculite and expanded vermiculite were measured to determine the effect of pH, clay concentration, and various mono- and multivalent electrolytes including NaCl, KCl, NH₄Cl, NaNO₃, NaClO₄, Na₂SO₄, Na₂CO₃, Na₃PO₄·12H₂O, MgCl₂·6H₂O, CaCl₂·2H₂O, BaCl₂, SrCl₂·6H₂O, CuCl₂·2H₂O, CoCl₂·6H₂O, NiCl₂, AlCl₃, and CrCl₃·6H₂O on the electrokinetic properties of vermiculite samples. It was found that generally the measured zeta potential values of expanded vermiculite for the studied systems were slightly more negative than that of vermiculite. The pH profiles of vermiculite and expanded vermiculite at acidic, natural, and basic pH values were obtained to determine the effect of time on the pH values of clay suspensions. The zeta potential measurements showed that the surface charge of clay particles was negative in water. The isoelectric point of vermiculite and expanded vermiculite were determined as pH 2.30 and 2.57, respectively. Divalent cations (Mg²⁺, Ca²⁺, Sr²⁺, and Ba²⁺), heavy metal ions (Cu²⁺, Ni²⁺, and Co²⁺) and trivalent cations (Al³⁺ and Cr³⁺) were potential determining ions for vermiculite and expanded vermiculite particles. Moreover, divalent and trivalent cations caused the change of surface charge from negative to positive. On the other hand, monovalent cations (Na⁺, K⁺ and NH₄ ⁺), monovalent anions (Cl^?, NO₃ ^?, and ClO₄ ^?) and multivalent anions (SO₄ ^2?, CO₃ ^2?, and PO₄ ^3?) acted as indifferent ions for these clay particles.     

Effects of inorganic salts on the spectral behavior of poly(N‐vinyl‐2‐pyrrolidone) in aqueous solutions

Electronic spectral behavior of poly(N‐vinyl‐2‐pyrrolidone) (PVP) was determined in aqueous solutions including a variety of inorganic salts (phosphates, mono‐ and dihydrogen phosphates, sulfates, chlorides, nitrates, bisulfites, and persulfates) for several concentrations. The n → π* excitations are shifted to longer wavelengths depending on the nature and the concentration of salt. The resulting dependence of λ_max on the molar concentration can be expressed to show the increasing effect of anionic and cationic species in bathochromic shift. The increasing order of effectiveness of anions in shifting the λ_max is S₂O₈ ⁼ > S₂O₅ ⁼ > PO₄ ³⁻ > HPO₄ ²⁻ > SO₄ ²⁻ > H₂PO₄ ²⁻ > Cl⁻. The order for the cation is as Na⁺ ≈ K⁺ ≈ NH₄ ⁺ in the 0.1–0.6M concentration range and Na⁺ ≈ K⁺ > NH₄ ⁺ in > 0.6M aqueous solutions. The changes observed in λ_max by the salt were correlated with the changes occurring in the structure of water and the polymer–solvent interactions. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 1434–1439, 2000     

Effect of sodium and potassium sulphates on zinc electrowinning

In order to evaluate the intrinsic effect of high concentrations of sodium and potassium sulphates in zinc electrowinning solutions, measurements of coulombic efficiency were carried out under mass transfer-controlled conditions in synthetic solutions of very high purity. A solution composition of 1 mol dm^–3 ZnSO₄+1.5 mol dm^–3 H₂SO₄ was employed with and without additions of 0.5 mol dm^–3 Na₂SO₄ and/or 0.25 mol dm^–3 K₂SO₄. With temperature and current density similar to plant practice (37° C, 650 A m^–2) and electrode rotation rates of 10 and 45 s^–1, the coulombic efficiency for three successive batch tests (200 mg zinc) increased by an average of 1.2% (from an average of 96.0%) for additions of 0.5 mol dm^–3 Na₂SO₄+0.25 mol dm^–3 K₂SO₄. The results were evaluated in terms of available theories, solution purity and predicted changes in solution composition (zinc and hydrogen ion activities) and physical properties following additions of Na₂SO₄/K₂SO₄. It was concluded that in the plant situation the increase in coulombic efficiency would probably be offset by an increase in cell voltage of about 2%, the net effect on power efficiency being a decrease of about 1%. The zinc deposit morphology and preferred orientation were also studied. The addition of sodium and/or potassium sulphate to the solution resulted in rougher, darker zinc deposits, a slight grain refining effect, and a change from random to predominantly basal (002), (004) crystal orientation (at 45 s^–1).     

Affinity of Cation-Exchange Membranes Towards Metallic Cations: Application in Continuous Electropermutation

The objective of this work was to correlate the separation process of the metallic cations (M(II)) by electropermutation (EP) of multications solution with the affinity of ion-exchange materials (IEMs). The obtained results show that the affinity order is similar for all tested IEMs and is as follows: Pb(II)>Cd(II)>Zn(II)>Mg(II). Furthermore, the order of the transfer flux (J) of metallic cations obtained with different tested cation-exchange membranes (CEMs) is identical to that encountered for the affinity order. Further analysis of the results demonstrated that the affinity of IEMs and the transfer flux change in reverse order of hydration ionic radius (r) of metallic cations: r_Mg(II)>r_Zn(II)≥r_Cd(II)>r_Pb(II). During the EP, the order of metallic cations transfer is as established previously when using different electro-regeneration cations (H⁺, Na⁺, NH₄⁺) and different co-ions (NO₃^?, Cl^?_, SO₄^2?). However, the extent of the transfer flux as a function of the nature of electro-regeneration cation follows the order: J_M(II)(H⁺)>J_M(II)(NH₄⁺)>J_M(II)(Na⁺). The removal rates of metallic cations vary in the range 89?99%. This work shows that the orders of the IEMs affinity and the transfer are mainly determined by the properties of metallic cations such as the hydration ionic radius. Nevertheless, the importance of the fixation and the transfer of metallic cations depend on the IEMs’ nature.     

Poly[poly(oxypropylene) phosphate] macroionophores for transport and separation of cations in a hybrid: Cation‐exchange polymer and liquid membrane system

Poly[poly(oxypropylene) phosphate]s (PPOPP, M_n = 5800, 8100, 10,400), with different POP units (400, 1200, 2000), were synthesized and applied as cation‐selective macroionophores in a multimembrane hybrid system (MHS). The solution of PPOPP in dichloroethane formed the flowing liquid membrane (FLM) circulating between two polymer cation‐exchange membranes, and subsequently, between two polymer‐made pervaporation (PV) membranes. It was found that the PPOPP macroionophores activate the preferential transport of Zn²⁺ cations from aqueous solutions containing competing Cu²⁺, Ca²⁺, Mg²⁺, K⁺, and Na⁺ cations. The following separation orders were observed for PPOPPs with POP‐400 and POP‐1200: Zn²⁺ > Cu²⁺ ? Ca²⁺, Mg²⁺, K⁺, Na⁺, and for PPOPP with POP‐2000: Zn²⁺ > Cu²⁺,Ca²⁺ ? Mg²⁺, K⁺, Na⁺. Always, the particular cations are separated as: Zn²⁺ > Cu²⁺, Ca²⁺ > Mg²⁺, and K⁺ > Na⁺. The properties of PPOPPs were compared to respective transport and separation characteristics corresponding to those of respective poly(propylene glycol)s and poly(oxypropylene) bisphosphates. The results of investigation indicate that the bifunctional character of PPOPPs is caused by the presence of ionizable groups and probably pseudocyclic POP structures. By comparing the separation of cations in the simple MHS[FLM] system and the system supported by pervaporation unit [MHS[FLM‐PV] it was found that continuous dehydration of an organic FLM improves the system overall performance. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1436–1445, 2004