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In this study, a series of novel composite membranes were synthesized utilizing polyethersulfone (PES), sulfonated polyethersulfone (SPES) as base polymer and titanium tungstomolybdate (TWM) as an inorganic ion exchange resin. The membranes were fabricated through the solution casting technique. The composite membranes exhibited enhanced thermal and chemical stability, as well as improved oxidative stability. All the composite membranes demonstrated higher hydrophilicity, with the SPES-TWM composite membranes displaying the lowest contact angle of 65°. The composite membranes also displayed favorable water uptake (up to 26% for SPES-TWM) and lower methanol uptake (maximum 12% for SPES-TWM) and better mechanical stability (maximum of 40 MPa for SPES-TWM). The SPES-TWM composite membranes exhibited the maximum ion exchange capacity of 1.32 meq.g−1. The transport number of 0.95 was obtained for SPES-TWM, which is comparable to the Nafion-117 membrane. The proton conductivity of both membranes increased as the temperature increased. The maximum proton conductivity of 6.3 mScm−1 was observed for SPES-TWM at 60 °C. • Composite membranes based on PES and SPES with nano TWM were prepared. • Composite membranes exhibited thermal stability up to 220 °C, mechanical stability of 44 MPa and good oxidative stability. • SPES-TWM membrane exhibited an IEC of 1.32 meqg−1 and proton conductivity of 6.3 mScm−1 at 60 °C. • SPES-TWM membrane exhibited higher diffusivity and permselectivity than PES-TWM membrane. • PES-TWM membrane displayed methanol permeation of 5.28 × 10−7 cm2s−1. [ABSTRACT FROM AUTHOR]

A perovskite-structured proton conductor, CaHf 0.9 In 0.1 O 2.95 , was synthesized via solid-state reaction, and proton conductivity and transport number of its grain interior were determined by using the defect equilibria model. The results reveal that the total conductivity of grain interior and the entire sample (grains and grain boundaries) of CaHf 0.9 In 0.1 O 2.95 , respectively, reaches 7.26 × 10−4 S∙cm−1 and 3.03 × 10−4 S∙cm−1 in a humid atmosphere at 800 °C. Moreover, it was observed that the conductivities of the grain interior exhibited higher values than those of the entire sample within the temperature range of 400–800 °C. The activation energy of the entire sample was higher than that of the grain interior; and for the charge carriers of CaHf 0.9 In 0.1 O 2.95 , the activation energy of oxygen vacancies and holes was higher than that of the proton. At 400–800 °C, transport properties of CaHf 0.9 In 0.1 O 2.95 were dominated by proton conduction under the atmosphere containing oxygen and water vapor, where the transport numbers of proton in the grain interior and the entire sample were estimated to be 0.541 and 0.497, respectively, at a temperature of 800 °C. Thus, the proton transport number of grain interior was found to be higher than that of the entire sample. Therefore, the grain interior of CaHf 0.9 In 0.1 O 2.95 can provide better proton conduction than grain boundary. In summary, these results exhibit that CaHf 0.9 In 0.1 O 2.95 possesses certain application prospects in electrochemical sensors. [ABSTRACT FROM AUTHOR]

Doped CaZrO 3 oxides exhibit high proton transport number and have been used in electrochemical hydrogen sensor to measure hydrogen content in aluminum melt. Ionic radius of Hf4+ is close to that of Zr4+; thus, it is speculated that doped CaHfO 3 oxides may also possess high proton transport number. In this study, CaHf 1− x In x O 3− δ (x = 0, 0.05, 0.1, 0.15, 0.2, 0.25) perovskite oxides were fabricated via solid-state reaction method. Phase composition and microstructure were characterized by X-ray diffraction and field emission scanning electron microscopy. Conductivities and transport properties of CaHf 1− x In x O 3− δ were investigated via defect equilibria model. The result indicated that conductivities and transport properties of CaHf 1− x In x O 3− δ after In doping could be improved. Moreover, conductivities increased with increasing In doping content until the stoichiometric ratio of Indium element was 0.1. CaHf 0.9 In 0.1 O 2.95 showed the highest total conductivities of 5.58 × 10−8 to 7.04 × 10−3 S ⋅ cm−1 at 400–800 °C. Transport properties showed that CaHf 1− x In x O 3− δ (x = 0.1, 0.15, 0.2, 0.25) oxides were dominated by protonic conduction under 21% O 2 and 2.5% H 2 O atmosphere at 400–650 °C, and the proton transport numbers of CaHf 1− x In x O 3− δ decreased with the increase in temperature in the range of 400–800 °C. CaHf 0.9 In 0.1 O 2.95 (x = 0.1) displayed a maximum proton transport number of 0.50 at 800 °C. These findings show potential application prospects of CaHf 1− x In x O 3− δ in electrochemical hydrogen sensor. [ABSTRACT FROM AUTHOR]

The electrical properties of the proton-conducting electrolyte BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ were studied using the 4-probe direct current (DC) method depending on temperature and oxygen partial pressure in the atmospheres, humidified with H 2 O and D 2 O. Ionic and electron hole contributions to the electrical conductivity were determined, and the transport numbers of charge carriers were calculated. It is shown that in air conditions BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ is a mixed ion-electron hole conductor. The contribution of electron hole conductivity decreases with the decrease of temperature and oxygen partial pressure. A significant isotope H/D effect in the electrical conductivity is observed for all investigated conditions expressed in the decrease in conductivity in D 2 O-containing atmospheres with the increase of activation energy values. Replacing H 2 O with D 2 O leads to decrease in the ion transport numbers and ionic conductivity values, while the electron hole conductivity remains almost the same. [Display omitted] • Under air conditions BCZYYb is a mixed ion-electron hole conductor. • A significant isotope H/D effect in the electrical conductivity of BCZYYb is observed. • Ionic conductivity of BCZYYb decreases in D 2 O-containing atmospheres. • The kinetic H/D effect dominates under the studied conditions. [ABSTRACT FROM AUTHOR]

KTaO 3 and KTa 0.9 M 0.1 O 3-α (M = Ti, Hf, Zr) were prepared by solid state reaction at 1330 °C for 2 h and characterized by x-ray diffraction. The AC impedance technique was used to analyze the sintered solid electrolytes in 1%H 2 /Ar and dry air atmosphere. Among KTa 0.9 M 0.1 O 3-α (M = Ti, Hf, Zr), KTa 0.9 Zr 0.1 O 3-α displays the highest conductivity in 1%H 2 /Ar atmosphere. The carriers transport numbers of solid electrolytes were measured by concentration cell method. The results show KTa 0.9 Zr 0.1 O 3-α is a pure proton conductor below 525 °C. Stability tests show that KTa 0.9 Zr 0.1 O 3-α has good chemical stability against CO 2 and H 2 O. [ABSTRACT FROM AUTHOR]

Understanding the transport phenomena in electrolyte mixtures involved in electrochemical processes is of utmost importance for the modelling and improvement of battery technology, fuel cells, ion-exchange membrane processes, and much more. In this work, we derive relations and present methods for the analysis of electric potential measurements of concentration cells and ion-exchange membrane permselectivity with ternary mixtures of KCl, H 2 O and ethanol (EtOH). Measurements of electric potentials across the Selemion CMVN (cation-exchange) and AMVN (anion-exchange) membranes in this ternary mixture suggest that the presence of EtOH affects the membrane permselectivity, but that the transference of EtOH is zero; i.e. , t a = 0. Instead, the decrease in membrane permselectivity can be explained by a varying water transference coefficient, t w. In the absence of EtOH we find t w ≈ 4 in both membranes, and that the decrease in t w is proportional to the average thermodynamic activity of EtOH in mixtures adjacent to the membranes. The membranes were also found to be charge selective, as quantified by the ionic transport numbers; i.e. , t K + = 1 for the Selemion CMVN and t K + = 0 for the Selemion AMVN. The presented method can readily be extended and leveraged to determine transference coefficients in other electrochemical systems. • New measurements of ion-exchange membrane electric potentials in KCl/H 2 O/EtOH. • Permselectivity is explained via non-eq. thermodyn. and transport numbers. • Permselectivity measurements indicate no transference of EtOH. • The membrane permselectivity varies due to co-transport of water with ions. • The co-transport of water decreases with increased EtOH concentration. [ABSTRACT FROM AUTHOR]

• Ion transport is simulated in a membrane electrochemical system towards NH 3 recovery. • NH 4 + dominates ion transport across the cation exchange membrane. • Na+ in anode solution slightly competes with NH 4 + transport. • Na+ in cathode solution benefits NH 4 + transport due to Donnan dialysis. Recovering ammonia nitrogen from wastewater is a sustainable strategy that simultaneously addresses both nitrogen removal and fertilizer production. Membrane electrochemical system (MES), which utilizes electrochemical redox reactions to transport ammonium ions through cation exchange membranes, has been considered as an effective technology for ammonia recovery from wastewater. In this study, we develop a mathematical model to systematically investigate the impact of co-existing ions on the transport of ammonium (NH 4 +) ions in MES. Our analysis elucidates the importance of pH values on both the NH 4 + transport and inert ion (Na+) transport. We further comprehensively assess the system performance by varying the concentration of Na+ in the system. We find that while the inert cation in the initial anode compartment competes with NH 4 + transport, NH 4 + dominates the cation transport in most cases. The transport number of Na+ surpasses NH 4 + only if the fraction of Na+ to total cation is extremely high (>88.5%). Importantly, introducing Na+ ions into the cathode compartment significantly enhances the ammonia transport due to the Donnan dialysis. The analysis of selective ion transport provides valuable insights into optimizing both selectivity and efficiency in ammonia recovery from wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • RE 3 GaO 6 (RE = Nd, Dy, Er) was experimentally verified as a mixed conductor of electron and oxide ion under an O 2 gas flow. • The conductivity of Dy 2.85 Ca 0.15 GaO 6–δ at 973 K was 2.1 × 10–4 S/cm, with the transport numbers of oxide ion being 21 %. • The main migration path of O2– in Dy 2.85 Ca 0.15 GaO 6–δ was via the vacancies at the O2 sites. First-principles calculations were conducted, which proposed that members of the RE 3 GaO 6 (RE = rare earth) system were oxide ion conductors. This study experimentally verified oxide ion conduction in Dy 3 GaO 6 , Er 3 GaO 6 , and Nd 3 GaO 6. The sintered bodies were synthesized by a solid-state reaction method, and their properties were characterized. The samples with dopants were observed to be mixed electron and oxide ion conductors. Dy 2.85 Ca 0.15 GaO 6-δ exhibited oxide ion conductivities of 2.1 × 10−4 S/cm at 973 K, with an oxide ion transport number of 21 % under O 2 gas flow. Additionally, the Rietveld refinement suggested that oxide ion migration might occur via the oxide ion vacancy between the O2 sites. Overall, the oxide ion conductivities of RE 3 GaO 6 increased in the following order: Nd > Dy > Er, which was in good agreement with that predicted by using the first-principles calculations. The discrepancy between the experimentally measured and predicted conductivities was caused by the solid-solution limit at the RE site for the dopants. [ABSTRACT FROM AUTHOR]

• Bismuth-based oxides, AE(TM) 2 Bi 2 O 9 , identified by materials informatics, are experimentally verified as good oxide ion conductors (e.g., 3.3 × 10−3 S/cm at 973 K for SrTa 2 Bi 2 O 9 , with transport numbers of >95 %). • First-principles calculations show a microscopic mechanism of the transport properties in terms of the weak bonding of oxygen with Ta or Nb, represented by the charge transfer between Ta/Nb and oxygen. Bismuth-based oxides (AE(TM) 2 Bi 2 O 9 , AE: Ca, Sr, Ba; TM: Nb, Ta), including SrTa 2 Bi 2 O 9 , SrNb 2 Bi 2 O 9 , BaNb 2 Bi 2 O 9 , and CaTa 2 Bi 2 O 9 were synthesized via a conventional solid-state reaction, and their ionic transport properties were investigated. All the materials are verified oxide ion conductors and identified in recent reports using materials informatics. The materials exhibited good oxide ion conductivities, for example, 3.3 × 10−3 S/cm at 973 K for SrTa 2 Bi 2 O 9 with transport numbers > 95 %. The materials have relatively high oxide ion conductivity without doping, which does not increase conductivity. First-principles calculations show a microscopic mechanism of oxide ion transport that is characterized by the weak bonding of oxygen with Ta or Nb. [ABSTRACT FROM AUTHOR]

A polyvinyl alcohol supported zirconium tungstate (ZrW/PVA) composite ion exchange membrane has been synthesized by the sol-gel technique. The membrane was prepared by blending zirconium tungstate sol into polyvinyl alcohol gel which was cross-linked with glutaraldehyde (GA). The prepared membrane was analyzed by FT-IR, optical microscopy, SEM, XRD & EDS. The membrane was found to be devoid of any cracks and defects. Electrochemical properties which include transport number, ion exchange capacity (IEC), and proton conductivity were also measured. An IEC count of 0.92 meq.g−1 and transport number of 0.88, thus obtained, were indicators of good electrochemical properties that shows its potential to be used in the direct methanol fuel cell. Moreover, water uptake, methanol uptake and chemical resistivity in the acidic and basic medium of the prepared membrane have also been assessed. Synthesized membrane showed high water holding capacity as compared to Nafion-117. The water uptake of ZrW/PVA composite membrane was found to be 114% which is much higher than that of Nafion-117 (29.2%) 18. The final weight loss of the ZrW/PVA composite membrane in acidic medium was 10%. Oxidative stability of the membrane was evaluated by using Fenton's reagent. The weight loss in the reagent after 24 h was 17% without disruption. • ZrW/PVA composite ion exchange membrane was successfully developed. • An IEC count of 0.92 meq.g−1 and a transport number of 0.88 was obtained. • The water uptake of ZrW/PVA composite membrane was found to be 114%. • Final weight loss in acidic medium was 10% & in the basic medium was 26%. • Oxidative stability under Fenton's reagent revealed 17% loss in weight. [ABSTRACT FROM AUTHOR]

SrCe 0.9 Y 0.1 O 3-δ -Ce 0.9 Y 0.1 O 2-δ (SCY-YDC, 1:1 mole ratio), as a novel composite electrolyte, was successfully synthesized and characterized. X-ray diffraction patterns showed that SCY-YDC composite electrolyte is a mixture of SCY and YDC. Besides, no impurity phase emerged after sintering at 1550 °C for 10 h. AC impedance spectroscopy was used to determine the electrical properties of SCY-YDC at 500–800 °C in various atmospheres. Partial conductivities of oxygen vacancies, protons, and electrons (p-type) were calculated using the defect structure model. Results showed that SCY-YDC is a mixed (hole, proton, and oxygen-ion) conductor. Moreover, the contribution of holes is minor at 650–800 °C in high pressure (1 atm) or low pressure (10−4 atm) O 2 atmospheres. Dominant carrier switched from protons to oxygen ions as temperature increased at vapor pressure in air of 0.038 atm. Total conductivity for SCY-YDC is 6.19 × 10−3 S cm−1 at 800 °C under pO 2 = 1 atm and pH 2 O = 6 × 10−3 atm, which is higher than that of SCY (2.47 × 10−3 S cm−1). Results also showed that SCY-YDC composite material exhibits higher ionic conductivity and lower electron-hole conductivity than SCY. Electron-hole transference number for SCY-YDC is 0.049 at 800 °C in pO 2 = 0.21 atm and pH 2 O = 0.038 atm. Ultraviolet–visible spectrophotometry results provided evidence that SCY-YDC can suppress electron conduction. [ABSTRACT FROM AUTHOR]

We analyse electromotive force measurements of concentration cells using non-equilibrium thermodynamics, and determine the transference coefficients of ion-exchange membranes in aqueous KCl solutions. By taking advantage of the analytical expression for the permselectivity, we extract transport coefficients with high accuracy. The transport number of K+ and the transference coefficient of water in the Selemion CMVN cation-exchange membrane are found to be 100 t K + = 99. 59 ± 0. 56 and t w = 3. 69 ± 0. 40 respectively, while for the Selemion AMVN anion-exchange membrane they are 100 t Cl − = 100. 21 ± 0. 37 and t w = − 3. 75 ± 0. 27. These results suggest that the membranes are perfectly selective to the target ion, and that each ion carries 3-4 water molecules through the membrane, which reduces the membrane permselectivity. In these concentration cells, the electrical potential contribution of the membrane alone was more easily isolated with bare Ag/AgCl electrodes without reference solutions and liquid junction plugs. Additionally, we find a large contribution to the measured concentration cell voltage from concentration gradients across the porous plug of the reference electrode, which cannot be explained by Henderson's equation alone. For most of the concentration range, the transport number of the porous plug is determined to be 100 t K + = 49. 43 ± 0. 78 with negligible water transport, similar to literature values for bulk electrolyte. In dilute electrolyte solutions with concentrations below 0.1 mol kg−1, the plug shows anomalous behaviour consistent with an increase in K+ selectivity and water co-transport. [Display omitted] • Membrane potentials of Selemion CMVN and AMVN in KCl solutions were measured. • Permselectivity modelled as function of salt and water transference numbers. • Permselectivity varies due to the co-transport of water with ions. • Water co-transport reduces available work from a reverse electrodialysis cell. • Junctions of reference electrodes have large contributions to measured voltages. [ABSTRACT FROM AUTHOR]

A series of Ba 3 Sr 1+ x Ta 2− x O 9− δ (x = 0,0.1,0.2,0.3,0.4) double perovskite proton conductors were fabricated at 1400 °C for 10 h and further sintered at 1650 °C for 10 h via a solid-state reaction process. Their phase composition, microstructure characterization and valence were investigated by XRD, FESEM and XPS techniques. Conductivities of these proton conductors were measured under the atmosphere of various water vapor and oxygen pressures by the electrochemical impedance spectra technique. It was found that the grain boundary thicknesses of Ba 3 Sr 1+ x Ta 2− x O 9− δ were significantly higher than other perovskite proton conductors. The total conductivities of Ba 3 Sr 1+ x Ta 2− x O 9− δ increased with the increase of both temperature and stoichiometric proportion of Sr, and Ba 3 Sr 1.4 Ta 1.6 O 8.4 exhibited the highest conductivity of about 4.4 × 10−3 S cm−1 at 750 °C. Additionally, the transport numbers of proton, oxide ion and hole were measured using defect equilibria model. The results indicated that Ba 3 Sr 1+ x Ta 2− x O 9− δ oxides were almost pure proton conductors at 400–550 °C and mixed proton - oxide ion - hole conductors at 550–850 °C, and Ba 3 Sr 1.3 Ta 1.7 O 8.55 exhibited the highest protonic transport number. The performance of the hydrogen sensor using Ba 3 Sr 1.3 Ta 1.7 O 8.55 was also measured in various hydrogen partial pressure, a good linear relationship between EMF and p H 2 was observed at 400–800 °C, and the response time was around 10s. • The structure of Ba 3 Sr 1+ x Ta 2− x O 9− δ moved from P 6 3 / mmc into F m 3 ¯ m with increasing x. • Ba 3 Sr 1.4 Ta 1.6 O 8.4 displayed a higher conductivity than BCN18. • The protonic transport number of Ba 3 Sr 1.3 Ta 1.7 O 8.55 is 0.88 at 600 °C. • The hydrogen partial pressure can be measured accurately at 400–800 °C. [ABSTRACT FROM AUTHOR]

Abstract In this study, the NiO additive was employed as a sintering aid to prepare dense BaZr 0.9 Y 0.1 O 3-δ (BZY10) ceramics for proton ceramic fuel cell (PCFC) and electrolysis cell (PCEC) applications. It was found that the NiO additive contributed to facilitating the grain growth and enhancing the proton conductivity of BZY10 ceramics. However, the subsequent studies on the transport number reveal a detrimental effect of NiO additive on increasing the electronic leakage of BZY10 ceramics under humid oxidizing atmosphere. This is expected to cause the misdiagnosis of the electrocatalytic activity of PCFC cathodes and a lower Faraday efficiency of PCECs. Considering the utilization of BZY10 ceramics as the proton conducting electrolyte, it is preferred to obtain a high density (∼95%) and applicable proton conductivity at the minimum NiO usage. This strategy was achieved by sintering the nanocrystalline BZY10 powders with 0.2 wt% NiO additive at 1500 °C for 6 h in air, of which the usage is 80% lower than that in the well-known solid state reactive sintering approach. Highlights • 0.2 wt% NiO additive facilitates densification of BZY10 proton conducting ceramics. • Compared to BZY10 ceramic, 0.2 wt%NiO addition induces even grain size distribution. • BZY10 + 0.2 wt%NiO ceramics give a proton conductivity of 0.0024 S cm−1 at 400 °C in H 2 • 0.2 wt% NiO addition increases electronic leakage of BZY10 in oxidizing atmosphere. [ABSTRACT FROM AUTHOR]

Abstract A detailed analysis of the electrical properties of the proton-conducting BaCe 0.8 Y 0.2 O 3-δ phase (BCY20) and the effects of Br doping has been undertaken. Members of the system of nominal stoichiometry BaCe 0.8 Y 0.2 O 2.9-(x/2)±δ Br x (x = 0, 0.05, 0.1 and 0.2) were synthesised by a citrate-nitrate process and high-temperature annealing up to 1500 °C. X-ray diffraction revealed the formation of single-phase material with a monoclinically distorted perovskite structure (space group I2/m) with greater distortion for Br-synthesised phase. Significant contrasts in electrical behaviour and stability between BCY20 and Br-synthesised series members were also found. However, chemical analysis by total X-ray fluorescence spectroscopy indicated that only trace amounts of Br remain after synthesis, indicating that Br addition influences stoichiometry but not directly the physicochemical properties. Higher conductivity is observed for the Br-synthesised compositions in wet and dry oxidising conditions in the temperature range 300–900 °C, reaching a value of 5.8 S m−1 at 800 °C for the x = 0.2 member in wet O 2 (pH 2 O ∼ 0.022 atm). Determination of partial-conductivity components indicated that, in humid conditions and low temperature, the conductivity of 20% Br-synthesised material is principally protonic (t H = 0.91 at 600 °C and pO 2 = 0.2 atm) and superior to that of BCY20. Mixed oxide-ionic-electronic conductivity dominates at high pO 2 (1 atm) and oxide-ionic conductivity at low pO 2 (∼10−4 atm) in the temperature range 600–900 °C for both BCY and Br-doped samples. Stability was found to be poorer in CO 2 for the Br-synthesised phases as determined by thermogravimetry and prolonged conductivity measurements. Graphical abstract Br addition on synthesis of BCY samples improves the ionic transport numbers in both wet and dry conditions. Image 1 [ABSTRACT FROM AUTHOR]

KNbO 3 and KNb 0.9 M 0.1 O 3-α (M = Ti, Hf, Zr, Sc, In, Yb) were prepared by solid state reaction at 920 °C for 4 h and characterized by X-ray diffraction. The electrical properties of solid electrolytes were measured by AC impedance in wet air, wet Ar and dry Ar. The order of conductivity in different atmospheres is σ (wet air)> σ (wet Ar)> σ (dry Ar). Among KNb 0.9 M 0.1 O 3-α (M = Ti, Hf, Zr, Sc, In, Yb), KNb 0.9 In 0.1 O 3-α displays the highest conductivity. The carriers transport numbers of each material were measured by concentration cell method. The results show KNb 0.9 In 0.1 O 3-α is almost a pure proton conductor below 625 °C. KNb 0.9 In 0.1 O 3-α has excellent chemical stability against CO 2 and H 2 O, but in the process of use should avoid rapid heating and cooling. • KNbO 3 , a new type of proton conductor, was prepared by solid-phase synthesis method. High density solid electrolytes were obtained by sintering at 950°C for 4h. Compared with traditional proton conductor, the sintering temperature is greatly reduced and the sintering time is shortened. • The effects of different doping elements on the electrical properties of KNbO 3 proton conductors were studied for the first time. In this study, we consider that the radius and valence of the doped elements together affect the conductivity of the solid electrolytes. • The tolerance of the material to CO 2 and H 2 O and the thermal cycle stability were tested. The material has excellent chemical stability against CO 2 and H 2 O, but rapid heating and cooling should be avoided in the process of use. [ABSTRACT FROM AUTHOR]

Electrodialytic (ED) transport of carboxylic acids from their ternary mixtures (acetic, malic and citric) of different compositions were investigated through anion exchange membrane (AEM). Solution pH played crucial role in selectivity and ion transport (expressed by limiting current density, LCD). These observations were analysed based on flow hydrodynamics, ion specific properties and ionic interaction with AEM influencing water uptake and membrane resistance. Fractional hydrolysis of weak acids generated complex mixture of multiple anions of varying charges which strongly influenced LCD. Theoretically estimated LCD (from effective diffusivity, D eff and Sh number based effective mass transfer coefficient, k eff ) could closely match experimental LCD (±4–8% deviation). The nature of solute species, concentration and their interaction with AEM strongly influenced ion transport. Estimation of D eff , transport number, ion exchange equilibrium and membrane resistance could satisfactorily explain the observed LCD. At low pH, LCD was proportional to available free ions while, at pH > 5.2 component specific properties/interactions dominated. Water uptake indicated variation in micro-structure and ion selectivity with different compositions of ternary mixture. This was attributed to shrinkage/swelling of membrane due to ion-membrane interactions. Stronger hydrophobic interaction of acetic acid caused shrinkage of micro-structure resulted in low water uptake but got reversed at higher pH. [ABSTRACT FROM AUTHOR]

Three distinct operational conditions, namely, ohmic, limiting current, and electroconvection region, respectively, can be created by applying different electric fields during ED operations. The fundamental of cation transport under ohmic and limiting current is well understood, however, the mechanism on cation transport under electroconvection is unclear. In order to clarify the feasibility of operating ED under electroconvection for the treatment of industrial wastewater (copper ion as the target pollutant), the methods of current-voltage profiling (C-V curve) and electrochemical impedance spectroscopy (EIS) were used to study the transport characteristics of Cu2+ through a cationic exchange membrane (CEM). The relevant operational parameters obtained above under electroconvection conditions were applied to a continuous ED system as to investigate the removal efficiency of Cu2+ -containing wastewater. Results indicated that ED system operated under electroconvection conditions was able to achieve high Cu2+ removal efficiency (around 74% in 4-min treatment) at high electricity efficiency as the theoretical calculation (based on Cu2+ transport number close to 1.0). The pH of copper wastewater in the ED system decreased slightly from 4.7 to 4.0 under electroconvection operation. The interface at the membrane-water was perturbed by the electroconvection operation, which facilitated ions transport across the membrane. An equivalent circuit composed of the Rs, Cm and Rm (parallel circuit representing the CEM), and constant phase element described well the Cu2+ transport behavior in the membrane-solution system according to the p value is greater than 1.0. [ABSTRACT FROM AUTHOR]

Herein, we report the galvanostatic modification of a commercial cation exchange membrane CMX by polypyrrole (Ppy). The presence of Ppy in the cation exchange membrane (CEM) was confirmed by cyclic voltammetry, stereo microscopy, fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive X-ray. Ppy was present both on the membrane surface and inside the pores. The quantity of Ppy in CEM, compactness of Ppy, and the charges on Ppy (negative or positive) were controlled effectively by changing the electrosynthesis conditions. The permeability and water content of the modified membranes obtained under different conditions were investigated. The transport properties of the modified CEMs were evaluated qualitatively using polarization curves and quantitatively by chronopotentiometry. NaCl and MgCl 2 solutions ranging in concentrations from 5 mM to 0.1 M were used for testing the selectivity. The presence of Ppy in the membranes decreased the transport number of Na and Mg, and the reduction in transport number was more significant for Mg. [ABSTRACT FROM AUTHOR]

The paper deals with relationships between the individual transmembrane fluxes of binary electrolyte solution components and the experimentally measurable quantities describing rates of transfer processes, namely, the electric current, the transmembrane volume flow and the rates of concentration changes in the solutions adjacent to the membrane. Also, we collected and rigorously defined the kinetic coefficients describing the membrane selective and electrokinetic properties. A set of useful relationships between these coefficients is derived. An important specificity of the proposed analysis is that it does not use the Irreversible Thermodynamic approach by analyzing no thermodynamic forces that generate the fluxes under consideration. Instead, all the regularities are derived on the basis of conservation and linearity reasons. The terminology "Kinematics of Fluxes" is proposed for such an analysis on the basis of the analogy with Mechanics where Kinematics deals with regularities of motion by considering no mechanic forces. The only thermodynamic steps of the analysis relate to the discussion on the partial molar volumes of electrolyte and ions that are the equilibrium thermodynamic parameters of the adjacent solutions. These parameters are important for interrelating the transmembrane fluxes of the solution components and the transmembrane volume flow. The paper contains short literature reviews concerned with the partial molar volumes of electrolyte and ions: the methods of measurement, the obtained results and their theoretical interpretations. It is concluded from the reviews that the classical theories should be corrected to make them applicable for sufficiently concentrated solutions, 1 M or higher. The proposed correction is taken into account in the kinematic analysis. [Display omitted] • Membrane phenomena are addressed in terms of transmembrane fluxes. • Contribution of ions to the transmembrane volume flow is analyzed. • The impact of electrostriction on the transmembrane volume flow is discussed. • Kinetic coefficients describing membrane selective properties are collected. • Fundamental relationships between these kinetic coefficients are derived. [ABSTRACT FROM AUTHOR]

[Display omitted] • A simple analytical method was developed to determine D , t + , and Λ. • A proposed model reproduced the time course of the measured current. • D and t + determined by this method showed the same trend as the reported values. • Λ calculated using D and t + showed the same trend as the measured impedance values. • It is important to exclude non-Faradaic processes for accurate analysis. A simple method for simultaneously determining the effective diffusion coefficient of salt (D), transport number (t +), and molar conductivity (Λ) of binary liquid electrolytes using chronoamperometry in a symmetrical parallel-plate lithium cell is proposed. The curve was fitted assuming a mass-transport-limited process to avoid the effect of the nonfaradaic current in chronoamperometry. The fitting function was based on the diffusion model. The D , t + , and Λ values obtained over a wide concentration range (0.005–1.0 M lithium perchlorate in propylene carbonate) show the same trend as those reported in the literature. Furthermore, the molar conductivity of the electrolyte determined using the proposed method also shows the same trend as that measured using the AC impedance method. [ABSTRACT FROM AUTHOR]

• Electrical conductivity of binary solutions of [SBP][BF 4 ], [TEA][OTf] and [TEA][BF 4 ] salts in acetonitrile. • Arrhenius and Vogel-Fulcher-Tammann activation energies of conductivity. • Densities and isobaric thermal expansion coefficients at 293.15 – 348.15 K. • NMR diffusion coefficients, transport numbers and dissociation degree of cations and anions. • Phase transitions, melting temperatures, cold crystallization of pure salts and their binary solutions. The electrical conductivity of binary solutions of tetraethylammonium trifluoromethanesulfonate ([TEA][OTf]), tetraethylammonium tetrafluoroborate ([TEA][BF 4 ]) and spiro-(1,1′)-bipyrrolidinium tetrafluoroborate ([SBP][BF 4 ]) in acetonitrile was measured at atmospheric pressure in the temperature range of 293.15–348.15 K for different salt mole fractions. The highest electrical conductivities of the acetonitrile solutions of [TEA][BF 4 ], [SBP][BF 4 ] and [TEA][OTf] were 96 ± 7, 94.5 ± 0.5 and 71.6 ± 0.5 mS·cm−1, respectively, at 348.15 K. The activation energy of the conductivity for nonassociating electrolytes was calculated using the Arrhenius equation, and the activation energy of the ionic conductivity of glass-forming liquids was calculated using the Vogel-Fulcher-Tamman equation. The cation and anion diffusion coefficients in the [TEA][OTf], [TEA][BF 4 ] and [SBP][BF 4 ] solutions in acetonitrile were determined by the robust pulsed-gradient stimulated echo sequence technique. Experimental density data were used to calculate the isobaric thermal expansion coefficients in the temperature range of 293.15–348.15 K. The thermophysical properties (the temperatures and heats of the phase transitions and the melting temperatures) of the pure salts and their binary solutions in acetonitrile were determined by differential scanning calorimetry. [ABSTRACT FROM AUTHOR]

In this work, a systematic work was performed to investigate the electrochemical transport properties of acceptor-doped BaZrO 3 by measuring electromotive force on various gas concentration cells. For the measurements in the wet oxidizing atmosphere, where significant hole conduction occurs, the transport numbers of the ionic conduction were corrected by taking the effect of electrode polarization into consideration. The results revealed that regardless of whether Sc, Y, In, Ho, Er, Tm or Yb was doped, proton conduction predominated in the reducing atmosphere with the transport number close to unit. However, the contribution of ionic conduction weakens, and the contribution of hole conduction enhances, when the samples are exposed to the moist oxidizing atmosphere. In addition, introducing Ba-deficiency results in degraded electrochemical conductivity, but the transport number in either the moist reducing or the moist oxidizing atmosphere does not change obviously. [ABSTRACT FROM AUTHOR]

Electrodialysis (ED) of solutions containing ternary combination of electrolytes (NaCl, KCl, CaCl 2 , MgCl 2 , FeCl 3 ) was carried out. Besides linear velocity of the fluid flowing through the ED cell, physical properties of cations and their interaction with the gel phase of membrane significantly influenced ion transport. The role of concentration polarization was evaluated from limiting current density (LCD) measurement. Theoretically estimated LCD values based on effective diffusivity of each ions and mass transfer coefficients (Sherwood number, Sh correlation) satisfactorily (error ± 5–7%) predicted experimental data. Measurement of transport number, adsorption equilibrium, water uptake and membrane resistance were carried out for each composition to understand the role of cations — membrane equilibrium in ion transport. Cations with higher charges showed reduced transport number, higher adsorption and higher resistance over cation exchange membrane (CEM). Water uptake measurement of equilibrated CEM showed negligible difference when cations of similar charges were interchanged while a meager 1.5% variation was noted when cations of different charges were interchanged. [ABSTRACT FROM AUTHOR]

PVC incorporated ZT/ZM composite materials have been synthesized via qualitative sol–gel method of material synthesis. Both the composite materials have the combination of inorganic ion-exchanger of different metal salt as well as same organic polymers, which is used to design a new class of organic–inorganic composite ion exchange membrane with much better chemical and mechanical properties, good ion-exchange capacity, higher thermal stability, reproducibility, selectivity etc. The physicochemical, electrochemical, mechanical and thermal properties of both the membranes were characterized by SEM, XRD, FTIR and simultaneous TGA–DTA studies were carried out to understand the ion exchange behavior of materials. The above analysis demonstrated the functional groups, material nature, thermal stability, surface structure, porosity, elemental percentages, ion transportation etc. The electrochemical properties have been studied by TMS theoretical approach which easily determined the important parameters of membranes like transport number, mobility ratio, charge density, charge effectiveness etc. The observed ionic potential and graphical fixed-charge density of both the membranes follows KCl < NaCl < LiCl and KCl > NaCl > LiCl order respectively. [ABSTRACT FROM AUTHOR]

The counter-ion transport-number of membrane affects columbic efficiency of electrochemical cells, many of which encounter varying salt concentration or temperature at different times of operation. Effect of NaCl concentration and temperature on the counter-ion transport number of commercial cation (Selemion CMV and Neosepta CMX) and anion (Selemion AMV and Neosepta AMX) exchange membranes was determined using chronopotentiometry. The transport number of the membranes didn't change with increasing NaCl concentration from 0.017 M to 0.1 M. Variation of transport number with temperature was determined from chronopotentiometric data using the Sand equation as well as a novel procedure. Values obtained from the Sand equation showed an anomalous trend, but the values obtained from the second procedure followed a consistent trend. The counter-ion transport number decreased significantly on increasing temperature by 20 °C and the decline was higher for the cation exchange membranes. [ABSTRACT FROM AUTHOR]

Molecular Dynamics simulations of the BAB type triblock copolymer lithium poly[(4-styrenesulfonyl) (trifluoromethylenesulfonyl) imide)]-block-poly(ethylene oxide)-block-lithium poly[(4-stryrenesylfonyl) (trifluoromethanesulfonyl) imide] (P(STFSILi)-b-PEO-b-P(STFSILi)) were carried out for different simulation temperatures and B-block lengths. By covalently binding the anion to the polymer backbone, it is immobilised and the cation transference number thereby raised significantly. It was found that the Li-ion diffusion decreases exponentially with growth of the B-block length. The poly(ethylene oxide) matrix dissolves Li-ions already during the equilibration stage of the simulation, and no Li-ion diffusion pathways were identified along the STFSI branches, which significantly influence the transport properties of the material. [ABSTRACT FROM AUTHOR]

• ED regeneration experiments of KCOOH liquid desiccant were conducted. • Effects of operating conditions on the ED regeneration performance were analyzed. • Overall transport number of KCOOH was higher than that of other liquid desiccants. • Regression equations for key parameters of the ED regeneration were obtained. In this work, the ED regeneration experiments were conducted using KCOOH (potassium formate) liquid desiccant, which is attracting attention due to its non-corrosiveness and low toxicity. Varying solution concentration, solution temperature, and current density, effect of the operating conditions on overall transport number, overall hydration number, overall osmotic coefficient, and area-specific resistance (ASR) was analyzed. In particular, effect of the solution temperature on the ASR, which was frequently ignored in previous research, was evaluated. As the solution temperature increased from 21 °C to 30 °C, the ASR decreased 21% and 17% at different concentration conditions. Additionally, the overall transport number of the KCOOH was compared with experimental data of different liquid desiccants in other research. The result showed that at low solution vapor pressure condition, KCOOH recorded the largest overall transport number so that it has a potential to be an energy-efficient working fluid for ED regeneration system. Furthermore, the analysis results and the regression equations can be utilized in developing a system modelling of the liquid desiccant regeneration using ED with KCOOH desiccant in future research. [ABSTRACT FROM AUTHOR]

• Interactions of anions with three different FAB-PK-130, BM-1, BM-2 membranes. • Selective AA/MA/CA recovery from ternary mixture using electrodialysis. • BM-2 microstructure resulted higher selectivity for AA− compared to other anions. • Order of ion selectivity remained at pH ∼ 7.5 is as follows: AA1− > MA2− > CA3−. • Current efficiency of 63.7% was noted with BM-2 for AA− ions at 6.0 mA·cm−2. Selective transport of carboxylic acids (acetic, AA; malic, MA; and citric, CA) from their equimolar (0.1 mol·L-1) ternary mixture was investigated through electrodialysis (ED) using three different anion exchange membranes [(i) Fumatech, FAB-PK-130, and two indigenous membranes made by solution blend of polyvinylidene fluoride (PVDF): copolymer of polymethyl methacrylate- co -polychloromethyl styrene (PMMA- co -PCMSt) at (ii) 50:50 wt% (BM-1), and (iii) 30:70 wt% (BM-2) followed by aminating them using tetramethyl 1,6 diamino hexane]. Recovery ratio (RR) for AA/MA and AA/CA mixtures were 1.97 and 2.71 respectively, indicating higher selectivity for AA through BM-2 and the same was explained based on highest ion exchange capacity (2.10 meq·g−1) and ion conductivity (2.3 mS·cm−1) data. Selective transport of AA was further endorsed by ED performance separately done with AA, MA and CA (0.1 mol·L-1 each) and equimolar binary (AA/MA) mixture at pH 7.5. Increasing trend in AA recovery: FAB-PK-130 < BM-1 < BM-2 at pH 7.5 was further supported by physical properties of the electrolyte (transport number from binary/ternary mixture) and membrane (water uptake, fractional adsorption, and ion conductivity) separately with each membrane. Highest current efficiency of 63.7% (energy consumption 5.13 kWh·kg−1) could be achieved with AA during ED analysis of ternary mixture through BM-2. [ABSTRACT FROM AUTHOR]

Electrodialysis are increasingly used in hybrid membrane technologies for the recovery and separation of weak polybasic acids from municipal and industrial wastewater and other solutions. It is known that the rate of generation of H+ and OH− ions at ion-exchange membrane boundaries during the treatment of such solutions is greater than that in the case of strong electrolytes, such as NaCl. One of the mechanisms of this generation, water splitting involving catalytic participation of functional groups, is relatively well understood. However, the second possible mechanism, where H+ ions are generated during acid dissociation at the depleted solution/anion-exchange membrane interface, is not sufficiently clear. Current-voltage characteristics (CVCs) of a Neosepta AMX anion-exchange membrane in 0.02 M NaH 2 PO 4 , NaH 2 Cit, KHT, and NaCl solutions are recorded. The effective transport number of H+ ion in the depleted boundary solution is measured to quantify the rate of the H+ ion generation. While the "water splitting" mechanism takes place in any kind of electrolytes, the "acid dissociation" mechanism is characteristic only for weak polybasic acids and other ampholytes, the electric charge of which depends on the pH. With that, the first mechanism occurs only at overlimiting currents, and the second occurs both in the underlimiting and overlimiting current modes. The dissociation of acid species at an AEM interface is caused by Donnan exclusion of protons as co-ions from the membrane. The rate of this reaction increases in the order KHT < NaH 2 PO 4 2.6 i lim Lev, there is a competition between both mechanisms of H+ ion generation. The obtained results give new insight into the understanding of the kinetics of H+/OH− ion generation and the impact of this process on the efficiency of electrodialysis of solutions containing polybasic acid species. [Display omitted] • Two mechanisms of H+/OH− ion generation occur in electrodialysis of weak acid salts. • "Water splitting" mechanism (1) is similar to that for the case of strong electrolytes. • "Acid dissociation" mechanism (2) occurs only in the case of polybasic acid salts. • Mechanism (2) is due to the Donnan exclusion of protons as co-ions from AEM. • Mechanism (1) requires a threshold potential difference, mechanism (2) is thresholdless; it dominates up to 3 i lim (the case of NaH2Cit). [ABSTRACT FROM AUTHOR]

Abstract: Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries since magnesium compounds are highly abundant in the earth and are environmental friendly. In this work, we have prepared polymethylmethacrylate (PMMA) based gel polymer electrolyte (GPE) films containing two different magnesium salts, which is magnesium triflate, Mg(CF3SO3)2 and magnesium perchlorate, Mg(ClO4)2 using solution casting technique. The ionic conductivity of both gel polymer electrolyte systems was evaluated using a.c impedance spectroscopy. Results show that at room temperature, GPE-Mg(CF3SO3)2 system exhibits the highest conductivity value at 1.27×10−3 S cm−1 for the film containing 20wt.% of Mg(CF3SO3)2 salt, while the highest conductivity value for the GPE-Mg(ClO4)2 system is 3.13×10−3 S cm−1 for the film containing 15wt.% of Mg(ClO4)2 salt. The conductivity-temperature studies of both GPE systems follow the Arrhenius behavior. The activation energies for ionic conduction were determined to be in the range of 0.18–0.26eV. The transport numbers of magnesium ions in both GPE systems were evaluated using the combination of a.c impedance spectroscopy and d.c polarization techniques. The results obtained indicate that the charge carriers in the GPE films for both systems are predominantly due to ions. [Copyright &y& Elsevier]

Highlights: [•] Study on charge transport properties of heavy metals. [•] The composite membrane was found to stable in all media. [•] The order of charge effectiveness HgCl2 2 2. [•] Separation capability of membranes for heavy metals. [Copyright &y& Elsevier]

Highlights: [•] Application of PAZMP membrane to fabricate Ni(II) ion selective electrode. [•] Preparation and characterization have also been done of ion exchange membrane. [•] Determination of liner potential response with concentration range of 1×10−7 M–1×10−1 M. [•] Chronopotentiometric studies of membrane were evaluated by Nernst-Planck equation. [•] Some physical parameters such as D 0, E a and ΔS° were calculated. [ABSTRACT FROM AUTHOR]

Abstract: Single-ion activity coefficients reported in literature for 10 ternary common-ion liquid-junction systems with KCl(aq) in the reference solutions and MX(aq) electrolytes in the test solutions at 25°C are reproduced in the present work numerically over wide MX molality ranges by functions of mean activity coefficients and transport numbers of ions in the liquid junction, the MX being BaCl2, CaCl2, CsCl, HCl, KF, K2SO4, LiCl, MgCl2, NaCl and SrCl2. The activity coefficients of solutes in the ternary systems are represented in the calculations by Scatchard's Neutral Electrolyte Model, and the transport numbers by a molality-based version of Van Rysselberghe's rule. An analysis is given of factors affecting the magnitudes of the functions, among them composition profiles in the liquid junction, formulation of Van Rysselberghe's rule, concentration dependence of ion mobilities, and non-ideality of electrolyte mixing. Most importantly, it is found that the exact functions can be approximated reasonably closely by a product of the mean activity coefficients in binary MX and KCl solutions, both at molality of the test solution, raised to powers that can be understood as related to effective transport numbers of the respective non-common ions in the liquid junction. Advantage is taken of the simple formulas to interpret the observed concentration dependences of single-ion activity coefficients in terms of the mean activity coefficients and effective transport numbers. [Copyright &y& Elsevier]

• Ca has the highest solubility in La2Ce2O7 among alkaline earth elements. • Proton concentration increases with increasing doping level. • Doping alkaline earth elements enhances mobility and conductivity of electrons. La 2 Ce 2 O 7 is known to be a disordered fluorite, i.e., 50% La-doped CeO 2 , exhibiting oxide ion conduction with contributions from protons in wet atmospheres and minority electrons under reducing conditions. Here, we report the effect of additional doping by partial substitution of La3+ with divalent alkaline earth cations A 2+ (A = Ca, Sr, Ba) on the hydration behavior and electrical conductivity of La 2 Ce 2 O 7. A single-phase cubic fluorite structure was obtained for La 2 Ce 2 O 7 , (La 1- x Ca x) 2 Ce 2 O 7-δ (x = 0–0.3), (La 1- x Sr x) 2 Ce 2 O 7-δ (x = 0–0.2), and (La 1- x Ba x) 2 Ce 2 O 7-δ (x = 0–0.05). Substitution by A 2+ enhanced the degree of hydration, which may be attributed to increased concentration of hydratable oxygen vacancies and coordination of oxide ions by A 2+ in addition to La3+, while the basicity of the different A 2+ seemed unimportant. The doping increased ionic conductivity slightly, while the n-type electronic conductivity under reducing atmospheres increased considerably. XPS analyses indicated that the concentration and binding energy of Ce 3d electrons decreased with increasing doping level of Ca, implying an enhanced mobility of electrons which may be attributed to an observed decrease in lattice parameter. [ABSTRACT FROM AUTHOR]

Abstract: Calcium–barium phosphate (CBP) composite membrane with 25% polystyrene was prepared by co-precipitation method. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transformed infrared (FTIR), and Thermogravimetric analysis (TGA) were used to characterize the membrane. The membrane was found to be crystalline in nature with consistent arrangement of particles and no indication of visible cracks. The electrical potentials measured across the composite membrane in contact with univalent electrolytes (KCl, NaCl and LiCl), have been found to increase with decrease in concentrations. Thus the membrane was found to be cation-selective. Transport properties of developed membranes may be utilized for the efficient desalination of saline water and more importantly demineralization process. The antibacterial study of this composite membrane shows good results for killing the disease causing bacteria along with waste water treatment. [Copyright &y& Elsevier]

Abstract: An ion exchange membrane was synthesized by impregnating sub-micron sized silica-immobilized phosphotungstic acid (Si-PWA) particles on a porous (poly vinylidene fluoride) (PVDF) film. Surface morphology, crystalline nature and thermal stability of the membrane were studied. The membrane was found to have a defect free surface, which contained both crystalline and amorphous phases and was stable up to 350°C. Electrochemical properties (transport number) of membranes of two different PWA/TEOS (tetraethoxyorthosilicate) ratios were compared and the one with a higher ratio gave better properties. Ion exchange capacity (IEC) of 0.82meq/g and counter-ion transport number of 0.91 indicated good electrochemical properties of the membrane synthesized with sol of PWA/TEOS ratio of 1.5. [Copyright &y& Elsevier]

Highlights: [•] PODA is very good absorbent of organic solvents and oils. [•] The oil sorbent PODA switches to hydrosorbent on addition of Au nanoparticles. [•] PODA/Au nanocomposites showed high ionic property and conductivity than PODA. [•] The PODA/Au hydrogels show high pH and salt sensitive swelling behavior. [•] A probable mechanism to account for the observation is also discussed. [Copyright &y& Elsevier]

Abstract: Transport and binding capabilities in aqueous solutions of 3,3-, 6,6-, and 6,9-ionene fluorides and bromides at 25°C were explored through the experimentally determined values for transport numbers of counterions and polyion constituents, along with the data for electrical conductivity in these solutions. Within the association theory, the fractions of free counterions and the effective linear charge densities of polyions were calculated. Experimental data were compared with the predictions of the Manning theory of polyelectrolyte solutions. It was determined that binding of the counterions to the polyion critically depends (i) on charge density of the polyion and (ii) on the chemical nature of the counterion in question. The effects of the charge density are the strongest in solutions of ionene bromides. Differences in the behavior of solutions of ionene fluorides and bromides are the consequence of different hydration capabilities of these ions. The effective linear charge density was found to be much lower than the one predicted from structural parameters of ionenes. The study addresses questions important to the biomedical field, in particular that of binding of ligands to charged macromolecules. [Copyright &y& Elsevier]

Abstract: The aim of this study was to investigate the preparation of novel membrane and the characterization of their properties. A new class of polyvinyl chloride (PVC) based polyvinyl alcohol Ce(IV) phosphate composite membrane was successfully prepared by solution casting method. The structural formation was confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and morphological studies. The thermal property was investigated by thermogravimetry analysis (TGA) method. The order of surface charge density for various electrolytes was found to be LiCl

Abstract: Membrane potential and membrane conductance measurements have been carried out using Dowex-50Kynar membrane, sodium chloride and urea as a hydrotrope, mixture of varying composition to examine the hydrotrope effect on electrochemical character of the membrane. A significant change on membrane electrochemical character is observed in the presence of hydrotrope due to changed co-ion exclusion. The Donnan equilibrium has been incorporated to estimate the activity coefficient of counter ion, yp m, and solute, y± m in the membrane phase along with the parameter, so called Ф expressing non-ideality. Solute rejection performance of the membrane is examined when electrolyte concentration remains constant and hydrotrope concentration varies and vice-versa. In both cases, membrane specific conductance depends on NaCl and hydrotrope concentrations differently. Friction caused through the membrane by the variation in concentration of hydrotrope is greater than friction caused by the variation in concentration of NaCl. Zeta potential is sensitive to the variation of hydrotrope concentration but insensitive to the variation of electrolyte concentration. The membrane system shows the behavior of NF membrane because Pe≪1 is estimated in both cases. [Copyright &y& Elsevier]

Abstract: Anion exchange membranes (PE/VBC) are successfully synthesized by pore-filling a porous polyethylene (PE) substrate with poly(4-vinylbenzyl chloride) followed by amination with pyridyl functional groups for vanadium redox flow battery (VRFB) applications. The membrane crosslinked with 10% of DVB content (PE/VBC(10)), 33μm in thickness, exhibits a low swelling ratio of 3.4% and a water uptake of 23%. In addition, the vanadium crossover rate of the PE/VBC(10) membrane is lower than Nafion 117 by 48% at a similar electrical area resistance. Electrochemical properties of the PE/VBC membranes are examined in terms of the transport number and migration of ions as well as the electrical area resistance. Transport numbers for anions of the PE/VBC(10) membranes are 0.96 and 0.97 in NaCl and NaOH solutions, respectively. In acidic solutions of HCl and H2SO4, the membrane shows remarkably higher cation transport numbers of 0.20 and 0.72, which imply that the membrane allows high proton permeation and it is advantageous in VRFB operations. Furthermore, the migration of ions reveals reasonably low fluxes of other cations through the anion exchange membrane. Finally, the energy efficiency of the PE/VBC (10) membrane is 90.2%, higher than Nafion 117 by 5.4%. [Copyright &y& Elsevier]

Abstract: The hybrid direct carbon fuel cell is a direct carbon fuel cell concept that combines a solid oxide fuel cell with a molten carbonate fuel cell electrode. This offers efficient conversion of coal or biomass derived carbons to electricity. In this study we aim to improve the electrical performance of this cell by using gadolinia doped ceria (GDC) as either a protection layer over a YSZ electrolyte or as the electrolyte itself. In our study, the electrical performance of several tubular cell geometries were investigated using impedance spectroscopy both with and without gas flows of carbon dioxide or nitrogen. Integrity of microstructure including possible layer delamination effects were investigated by SEM. Promising values of power and resistance were observed using a GDC material as electrolyte at intermediate temperature reducing the operation temperature compared to YSZ, doubling the power of each cell. [Copyright &y& Elsevier]

Abstract: In this study, poly(vinylchloride) (PVC) based heterogenous strong acidic cation exchange membranes were prepared by the solution casting technique by using suspension polymerized polyvinylchloride (S-PVC) and emulsion polymerized polyvinylchloride (E-PVC) as binders, dioctyl phthalate (DOP) and ionic liquid (IL) tetradecyl(trihexyl)phosphoniumdecanoate as plasticizers and ion exchange resin as functional group agent. The main goal of this work was to evaluate the effects of polymer binder type, plasticizer type and bider/plasticizer ratio on pyhsicochemical, morphological and electrochemical properties of the prepared membranes. Physicochemical characterization consisted of water contents, dry and wet densities, porosities, ion exchange capacities of membranes and isotherm studies. Scanning Electron Microscopy (SEM) analysis was used to perform morphological characterization. Water contents of the membranes were found between 30% and 40% while density values were in the 0.7–1.2g/cm3 range. Porosities were found between 0.2 and 0.4 and ion exchange capacities changed between 1.2 and 2.8meq Na+/g-dry. Electrochemical characterization included transport numbers of membranes determined by the membrane potential method. Transport number for the membranes prepared with dioctyl phthalate (DOP) was found to be around 0.5 whereas this figure was 1.0 for the membranes prepared with IL. Diffusivity values of Na+ ions across the membrane were calculated by using the Donnan dialysis method and found in order of magnitude-5. [Copyright &y& Elsevier]

Abstract: The water uptake of different aqueous salt solutions in different Nafion membranes, and the salt transport through those membranes under the driving force of a concentration gradient, have been studied. These experiments have been performed by using the following salts: lithium chloride, sodium chloride, potassium chloride and cesium chloride. Different homogeneous Nafion membranes, NF111, NF112, NF115 and NF117, have been used in this work, with the aim of studying the membrane thickness influence. It has been observed that the membrane water uptake increases with the membrane thickness and decreases with the size of the cation. The integral permeability coefficient has been determined from the time evolution of the salt concentration in the dilute solution. The results show that the integral permeability coefficient decreases with the membrane thickness. In general, the influence of the type of electrolyte on the integral permeability coefficient is not significant for the membranes with larger thickness (that is, NF115 and NF117). Average apparent cation transport number has been determined for the same salt solutions, and from that membrane apparent permselectivity has been estimated. In general, in membranes with large thickness, the average apparent cation transport number increases with the cation size. Finally, from fluxes and membrane potentials membrane negative ionic permeabilities have been determined finding also that they decrease with membrane thickness. Salt diffusion coefficient has been also determined from membrane negative ionic diffusion coefficient. [Copyright &y& Elsevier]

Abstract: Novel aliphatic-hydrocarbon-based anion-exchange membranes (AEMs) were prepared from glycidyl methacrylate (GMA)/divinylbenzene (DVB) by changing their cross-linker content (CLC). Their ion-transport and anti-organic-fouling properties were compared with those of aromatic-hydrocarbon-based AEMs prepared from chloromethylstyrene (CMS)/DVB copolymers. Aliphatic AEMs with CLCs less than 11.5 have excellent ion-transport properties: anion transport numbers >0.95 and membrane resistances <3.5Ωcm2. In an electrodialysis (ED) system consisting of an AEM and an NaCl solution containing sodium dodecylbenzenesulfonate (DBS) as an aromatic foulant, the change in the voltage drop through the aliphatic AEMs during ED was lower than that with aromatic AEMs. This means that adsorption of DBS on the surface of the aliphatic AEMs is lower than that on aromatic AEMs. The aliphatic AEMs have much lower permeability coefficients for DBS in the ED system than the aromatic AEMs have. These results indicate that the anti-organic-fouling properties of aliphatic AEMs are better than those of aromatic AEMs. [Copyright &y& Elsevier]

Abstract: The transport properties of a cation-exchange membrane in the presence of nickel sulphate solutions were investigated by means of chronopotentiometry. The interest of this study relies on the application to the treatment of chromium plating rinse baths. The presence of chromic acid in the solutions and the initial concentration of nickel sulphate affect significantly the shape of the chronopotentiograms. The different shape of chronopotentiograms as well as the values of different parameters is thereby justified by the calculation of the speciation diagrams of Ni(II). Parameters like the limiting current density, resistance of the ohmic region, plateau length, and nickel transport numbers through the cation-exchange membrane were calculated from the chronopotentiometric and the current–voltage curves. The obtained results show an important competence between Ni2+ and H+ ions, with increases of the nickel transport numbers when the [Ni2+]/[H+] ratio corresponding to the initial equilibrium exceeds the unity. The increase in the Ni2+ concentration brings about a facilitated arising of electroconvection, which promotes overlimiting currents and additional mixing at the membrane surface. [Copyright &y& Elsevier]

Abstract: The growth of barrier anodic film is considered theoretically with regard to the migration of three ionic carriers: oxygen and metal ions and electrolyte anions. It is shown that the consideration of anion transport leads to the conclusion that the film grows at three interfaces: the metal/oxide and oxide/electrolyte interfaces and the interface between an oxide layer containing electrolyte anions (contaminated layer) and the oxide layer free of them (“pure” layer). The error in the measured transport numbers of metal and oxygen, which is caused by ignoring a contribution of electrolyte anions to the total charge transport, is maximum in the absence of anion motion. [Copyright &y& Elsevier]

Abstract: BaCe0.2Zr0.7Y(0.1− ξ)NiξO(3− δ) compounds with ξ =0.01 and 0.02 have been synthesized by solid state reaction at 1400°C and sintered at 1450°C. TEM analyses were performed and showed a segregation of nickel at the grain boundaries for ξ =0.02. This apparent solubility limit of Ni in the B-site of the perovskite is in agreement with similar data obtained earlier for the two compositions. The first aim of this work was to evaluate the conductivity of BaCe0.2Zr0.7Y(0.1− ξ)Ni ξ O(3− δ) at temperature between 500 and 900°C, using impedance spectroscopy at different oxygen partial pressures and water vapor pressures, as well as the emf technique. The compounds exhibit p-type conduction in oxidizing atmosphere, and ionic conduction elsewhere. The oxide ion contribution of the conductivity is negligible only for temperatures below 600°C. The determination of hydration enthalpies, our second goal, was achieved by modelling of the conductivity data and by thermogravimetric measurements (TG-DSC). [Copyright &y& Elsevier]

Abstract: This study examines the effects of biofouling on the electrochemical properties of cation exchange membranes (CEMs), such as membrane electrical resistance (MER), specific proton conductivity (SC), and ion transport number (t+ ), in addition to on microbial fuel cell (MFC) performance. CEM biofouling using a 15.5±4.6μm biofilm was found to slightly increase the MER from 15.65Ωcm2 (fresh Nafion) to 19.1Ωcm2, whereas an increase of almost two times was achieved when the electrolyte was changed from deionized water to an anolyte containing a high cation concentration supporting bacterial growth. The simple physical cleaning of CEMs had little effect on the Coulombic efficiency (CE), whereas replacing a biofouled CEM with new one resulted in considerable increase of up to 59.3%, compared to 45.1% for a biofouled membrane. These results clearly suggest the internal resistance increase of MFC was mainly caused by the sulfonate functional groups of CEM being occupied with cations contained in the anolyte, rather than biofouling itself. [ABSTRACT FROM AUTHOR]