Intradiffusion coefficients for perchlorate ions in zinc perchlorate and zinc chloride solutions at 25°C: Comparing transport properties of zinc chloride and zinc perchlorate systems

Intradiffusion coefficients for³⁶ClO ₄ ^– have been measured in solutions of zinc perchlorate of concentration 0.1 to 3 mol dm^–3 at 25°C by the diaphragm cell technique. In addition, intradiffusion coefficients for perchlorate ions in zinc chloride solutions have been measured over a concentration range at 25°C. The results confirm previous work on the effect of complexation on diffusion in zinc chloride solutions above a salt concentration of 0.1M. The present data, together with literature data for diffusion coefficients of the other species present in the zinc perchlorate electrolyte system, have enabled a simple analysis of the hydration around the zinc ions to be carried out. This indicates that the water diffusion data are consistent with the zinc ions having an effective hydration sphere of 11 (±2) water molecules. This is in keeping with values obtained for other simple divalent electrolytes using the same model. The model is extended here to allow analysis of water diffusion in zinc chloride solutions taking into account the presence of complexed chloro-zinc species. The experimental data are consistent with the effective hydration of the chloro-zinc complexes being independent of the number of chloride ligands and equal to 18±3 over a concentration range of 0 tol mol-dm^–3. This postulate is discussed in terms of its consequences on the water ligand dynamics for the complex equilibria.     

Entropy characteristic of solvation and thermal diffusion of hydrogen chloride in water-1-propanol solutions: A thermoelectrochemical determination

Thermogalvanic cells with silver chloride and quinhydrone electrodes in the HCl-H₂O-1-PrOH system are studied experimentally. The results are used to determine standard entropies of thermal diffusion transport of hydrogen chloride, entropies of mobile H⁺ and Cl^? ions, and Soret coefficients of the electrolyte at 298 K. Thermal diffusion entropies and partial molar entropies of said ions in water-1-propanol solutions are calculated within the Agar model. The results are interpreted with the application of basic concepts of the De Bethune theory concerning thermal diffusion transport in electrolytes.     

Efficiency enhancement with chloride to iodide ion exchange of benzimidazolium salt as a redox mediator

The new benzimidazolium derivative (SM-1) salt with ion exchange from the (SM-0) was fabricated and characterized by proton-nuclear magnetic resonance (¹H-NMR), carbon-nuclear magnetic resonance (¹³C-NMR), Fourier-transform infrared spectroscopy (FT-IR), electrospray ionization (EIS-MS), thermal analysis (TG), cyclic voltammetry (CV), and ultraviolet-visible spectroscopy (UV-vis), for electrolytes (liquid or dried) in the DSSC charge transportation mechanism. Also, the influence of ion exchange from chloride to iodine in the synthesized electrolytes, compared to other electrolytes (conventional or commercial), was investigated about DSSC performance efficiency. When using as a liquid electrolyte (SM-1), the power conversion efficiency (ƞ) of the working DSSC device was recorded as 1.980% and it was observed that the performances of DSSCs increased up to 56% when comparing dried electrolyte for SM-1 without conventional redox material (I^-/I₃^-). In the future, different molecular modifications of this type of benzimidazole derivatives or mixtures with conventional redox couples may further improve the performance of DSSC devices.     

C.I. Reactive Orange 16-dodecylpyridinium chloride interactions in electrolytic solutions

The effect of electrolytes on the interaction between an anionic dye and a cationic surfactant was investigated spectrophotometrically in submicellar concentration range at certain temperature. The spectral change of the azo dye C.I. Reactive Orange 16 (RO16) exhibits a high sensitivity to the polarity of dye's environment. Dodecylpyridinium chloride (DPC) affects the electronic absorption spectra of dye solution that is dye-surfactant interaction results formation of complex and therefore a decrease in maximum absorption spectra (1.577 at 494 nm). The electrolyte cations cause an increase of the absorbance of DPC-RO16 ion-pair complex in the following order: Ca(2+)>Na(+)>NH(4)(+)>K(+)>Mg(2+), also for electrolyte anions Br(-)>Cl(-)>SO(4)(2-). Furthermore, this order can be changeable with increasing electrolyte concentration. The increase on absorbance value with increasing electrolyte concentration is explained as charge screening. The increase or decrease on absorption spectra of RO16-DPC solution depends on concentration range of the electrolyte added. As an increase on absorbance value with increasing electrolyte concentration is explained as charge screening, a decrease in this value for higher concentration of electrolyte is attributed as the charge of micelle shape.     

Diffusion of electrolytes of different natures through the cation-exchange membrane

Diffusion of different electrolytes through a negatively charged (cation-exchange) membrane into distilled water has been studied. It has been established theoretically (with no regard to the presence of diffusion layers) that the integral diffusion permeability coefficient of an electrolyte depends on the diffusion coefficients and the ratio between the charge numbers of a cation–anion pair, the ratio between the density of charges fixed in the membrane and electrolyte concentration, and the averaged coefficient of equilibrium distribution of cation?anion ion pairs in the membrane matrix. It has been found that, when co-ions have a higher mobility, the dependence of diffusion permeability on electrolyte concentration passes through a maximum. Derived equations have been compared with experimental dependences of the diffusion permeability of an MC-40 membrane with respect to different solutions of inorganic 1: 1 and 2: 1 electrolytes. The developed method has been shown to be applicable for describing diffusion of any electrolytes (including asymmetric ones) through arbitrary uniformly charged membranes.     

Binary Diffusion Coefficients for Aqueous Solutions of l-Aspartic Acid and Its Respective Monosodium Salt

Although aspartic acid is a non-essential amino acid, its importance is crucial for a major metabolic pathway and it is present in different types of foods. This highlights the need of a better knowledge of its transport properties. A Taylor dispersion technique has been used for measuring mutual diffusion coefficients of binary aqueous solutions of l-aspartic acid, an associated electrolyte, and the corresponding salt sodium l-aspartate, which behaves as a non-associated electrolyte, at 298.15 K and concentrations ranging from (0.001 to 0.100) mol·dm^?3. Thermodynamic factors for the diffusion of aspartic acid and sodium aspartate have been estimated on the basis of the Onsager–Fuoss equation. Furthermore, experimental diffusion coefficients of aspartic acid are compared with those computed by the modified Onsager–Fuoss equation, applied for partially dissociated electrolytes.     

Estimation of activity and osmotic coefficients of strong electrolytes in water at elevated temperatures

It was found over a wide concentration and temperature range that differences between osmotic coefficients of a given electrolyte and a standard electrolyte, - ^st , can be approximated by a linear relation. Sodium chloride, calcium chloride and sodium sulfate were chosen as standard electrolytes for 1:1, 2:1 and 1:2 electrolytes, respectively. Special numerical procedures were developed for the prediction and estimation of activity and osmotic coefficients at elevated temperatures based on data at two temperatures or on data at room temperature only. Reasonable agreement was found between activity coefficients estimated by the present procedure and those correlated by Pitzer's and Meissner's equations.     

Diffusion studies of cobalt ions and their salts in agar gel medium: Obstruction effect and gel hydration

The obstruction effect in the electrolyte diffusion of cobalt halides and in tracer diffusion of Co²⁺ ions in the presence of different supporting electrolytes at various concentrations has been studied at 25 °C using the zone diffusion technique. It has been observed that obstruction effect expressed in terms of increases with concentration and is higher for electrolyte diffusion than in tracer diffusion. Further, for a given concentration it is found to decrease with increasing charge density of an anion. These observations are explained on the basis of competitive hydration between ions and agar molecules.     

Electrokinetic studies on testosterone/aqueous electrolyte interface : Part 1. Electro-osmosis,electrophoresis, streaming potential and streaming current

The electrical properties of testosterone interfaces were investigated. For this purpose, measurements of electro-osmosis, hydrodynamic permeation, streaming potential and streaming currents of metabolically important solutions of the electrolytes NaCl, KCl and MgCl₂ (in the concentration range 10^?4?10^?3 mol/l) across a testosterone plug were carried out. Electrophoretic mobility of testosterone particles suspended in these electrolyte solutions was also studied. The data were analysed from the viewpoint of nonequilibrium thermodynamics. Phenomenological coefficients were evaluated from the linear transport equations and Saxen's relationship was verified. Dependence of phenomenological coefficients on electrolyte concentration was examined. Electro-osmotic and electrophoretic transport coefficients were found to vary linearly with concentration, whereas hydrodynamic permeation and membrane conductance coefficients show non-linear variation. The results are explained on the basis of structural modifications occurring during the passage of the permeating species through the membrane. The nature of the electrical double layer formed at the testosterone/solution interface was ascertained on the basis of the direction of electro-osmotic permeation and electrophoretic migration of testosterone particles.Zeta potentials were estimated in order to obtain a plausible picture of the electrical double layer at the testosterone/solution interfaces. Dependence of zeta potentials on concentration was examined and membrane parameters calculated. The double layer thickness was estimated, which reveals that the diffuse double layer is more compact in the case of MgCl₂ than in that of KCl.     

Determination of Activation Energy for the Diffusion of Fe<Superscript>3+</Superscript> Ions in Agar Gel Medium Containing Various Transition Metal Sulfates

The study of the diffusion of ferric ions in agar gel containing transition metal sulfates was carried out. The effect of gel concentration, electrolyte concentration and temperature on the diffusion of Fe³⁺ ions in various transition metal sulfates was studied with a view to verify Wang’s model of diffusion and the applicability of transition state theory to diffusion in a gel medium. The diffusion coefficients were measured using the zone diffusion technique. For a given concentration of electrolyte the activation energy (E) is found to decrease with an increase in the charge density of the cation of the supporting electrolyte and for a given system it is found to decrease with increasing electrolyte concentration in agreement with Wang’s model. This observation is explained on the basis of the distortion in the water structure caused by ions and agar molecules. At a given electrolyte concentration the magnitude of the Arrhenius parameters, E and D _o, is found to decrease with increasing gel concentration in agreement with the transition state theory of diffusion.     

Synthesis and performance of proton conducting chitosan/NH4Cl electrolyte

The polymer electrolytes based on chitosan and ammonium chloride were prepared by solution casting technique and the properties were studied. The addition of ammonium chloride results in: (1) the enhancement of the amorphous nature of the polymer electrolytes; (2) the shift of the absorption bands of amino group at 1566 cm^?1 and the carbonyl group at 1640 cm^?1 towards lower wave number, and the appearance of a new absorption band at 1759 cm^?1; (3) a decrease of the glass transition temperature. The 20 wt % ammonium chloride doped polymer electrolyte has the best room temperature electric property, the lowest activation energy and the highest ionic conductivity. Placing the as‐prepared polymer electrolyte in a dryer is adverse for the sample's moisture content, and results in higher activation energy and lower ionic conductivity. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 260–266, 2010     

Mutual diffusion coefficients of aqueous MnCl2 and CdCl2, and osmotic coefficients of aqueous CdCl2 at 25°C

Volume-fixed mutual diffusion coefficients have been measured for aqueous MnCl₂ and CdCl₂ solutions from 0.004 to 4.93–5.00 mol-dm^–3 (M) at 25°C. Diffusion coefficients for MnCl₂ decrease to a minimum, rise to a maximum, and then decrease rapidly; such behavior is typical for strong electrolytes. In contrast CdCl₂ diffusion coefficients decrease continuously with concentration; similar behavior is known for certain other associated electrolytes. Since thermodynamic diffusion coefficients for both salts are qualitatively similar, diffusion differences may be primarily due to thermodynamic rather than mobility factors. Isopiestic data were measured for CdCl₂ from 1.79 to 7.29 mol- (kg H₂O)^–1, and critically compared to other isopiestic and emf data for CdCl₂. Higher quality emf data are completely consistent with isopiestic data. Recommended smoothed values of activity coefficients, osmotic coefficients, water activities, and activity derivatives are given for CdCl₂ at 25°C.Work performed under the auspices of the Office of Basic Energy Sciences (Geosciences) of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract number W-7405-ENG-48.     

Ni-Al layered double hydroxides electrodeposition from a chloride solution

Ni-Al LDHs was electrodeposited from a NiCl₂-AlCl₃ solution. In order to analyze the electrodeposition process, electrolytes with initial Al content range of 0–20% were used. With increasing Al content in the sample, the preferred orientations of (0 0 3) and (0 0 6), increased crystallinity, and decreased interlayer spacing were observed from the XRD results. A dissolution–recrystallization of (0 0 3) plane was detected among the Ni-Al LDHs from the strongly alkaline solution soaking results, which was found to be conducted easily in high Al-containing samples. The pH of the Al-containing electrolyte was much lower than that of pure NiCl₂ solution because lower pH was needed to start a precipitation reaction in the AlCl₃-NiCl₂ solution. The electrodeposition yield and current efficiency were found to decrease obviously in the electrolytes with initial Al content higher than 10%, which was attributed to the increasing Al content in the sample and diffusion of the complex ions. The electrodeposition pattern was in-situ in the electrolyte initially containing 10% Al, then, it developed toward and off in-situ in electrolytes initially containing 0–10% and 10–20% Al.     

Ion and water transport during lithium chloride concentration from aqueous organic solutions by electrodialysis

The concentration of lithium chloride from aqueous organic solutions with different volume concentrations of N,N-dimethylacetamide (DMAA) was studied experimentally. An extended model of the limiting electrodialysis concentration of electrolytes from mixed media was developed. The model takes into account the osmotic and electroosmotic mechanisms of the transfer of water and organic solvent, as well as the electromigration and diffusion mechanisms of the salt transfer. Using the experimental data and the extended model, we evaluated the transport parameters of the MK-40/MA-40 membrane pair in aprotic solutions of variable compositions and studied how they changed with an increase in the volume fraction of DMAA in a mixed solution. The contribution of each of these mechanisms of ion and water transport to the electrodialysis concentration of electrolyte from aqueous and organic aqueous solutions was determined. Electroosmotic transfer was found to be the main mechanism of the solvent transfer that limits the stage of the electrodialysis concentration of the electrolyte from aqueous and organic aqueous solutions.     

Two-cation competition in ionic-liquid-modified electrolytes for lithium ion batteries

It is a common observation that when ionic liquids are added to electrolytes the performances of lithium ion cells become poor, while the thermal safeties of the electrolytes might be improved. In this study, this behavior is investigated based on the kinetics of ionic diffusion. As a model ionic liquid, we chose butyldimethylimidazolium hexafluorophosphate (BDMIPF(6)). The common solvent was propylene carbonate (PC), and lithium hexafluorophosphate (LiPF(6)) was selected as the lithium conducting salt. Ionic diffusion coefficients are estimated by using a pulsed field gradient NMR technique. From a basic study on the model electrolytes (BDMIPF(6) in PC, LiPF(6) in PC, and BDMIPF(6) + LiPF(6) in PC), it was found that the BDMI(+) from BDMIPF(6) shows larger diffusion coefficients than the Li(+) from LiPF(6). However, the anionic (PF(6)(-)) diffusion coefficients present little difference between the model electrolytes. The higher diffusion coefficient of BDMI(+) than that of Li(+) suggests that the poor C-rate performance of lithium ion cells containing ionic liquids as an electrolyte component can be attributed to the two-cation competition between Li(+) and BDMI(+).     

Sorption of rubidium chloride by crown-containing polymer

The kinetics and mechanism of the sorption of rubidium chloride from ethanol by granulated polymer containing immobilized dibenzo-18-crown-6 are studied. The sorption of RbCl is controlled by internal diffusion accompanied by complex formation in the polymer. The equilibrium constants of the sorption and diffusion coefficients of the electrolyte in the sorbent are calculated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1025–1028, June, 1995.     

The Micellization and Clouding Phenomena of a Nonionic Surfactant,Poly(ethylene glycol) t-octylphenyl ether (Triton X-100): Effect of (Chloride Salt) Electrolytes

Herein, we report the micellization and the clouding of a nonionic surfactant, poly(ethylene glycol) t-octylphenyl ether (Triton X-100), in aqueous solutions in the absence and presence of (chloride salt) electrolytes. In the absence and presence of electrolytes, the critical micelle concentration (CMC) of Triton X-100 was measured by surface tension measurements. Upon increasing the temperature as well as the concentration of electrolytes, the CMCs decreased. The surface properties and the thermodynamic parameters of the micellar systems were evaluated. From these evaluated thermodynamic parameters, it was found that in the presence of an electrolyte, the stability of the micellar system is high. The cloud points (CPs) of Triton X-100 were also measured in the absence and presence of metallic ions of electrolytes. Upon the addition of metallic ions of chloride salts (electrolytes), the decrease in CP values was observed and the order was found to be: K⁺ > Na⁺ > Li⁺ > NH⁺₄.     

Determining Solubility and Diffusivity by Using a Flow Cell Coupled to a Mass Spectrometer

One of the main challenges in metal–air batteries is the selection of a suitable electrolyte that is characterized by high oxygen solubility, low viscosity, a liquid state and low vapor pressure across a wide temperature range, and stability across a wide potential window. Herein, a new method based on a thin layer flow through cell coupled to a mass spectrometer through a porous Teflon membrane is described that allows the determination of the solubility of volatile species and their diffusion coefficients in aqueous and nonaqueous solutions. The method makes use of the fact that at low flow rates the rate of species entering the vacuum system, and thus the ion current, is proportional to the concentration times the flow rate (c?u) and independent of the diffusion coefficient. The limit at high flow rates is proportional to . Oxygen concentrations and diffusion coefficients in aqueous electrolytes that contain Li⁺ and K⁺ and organic solvents that contain Li⁺, K⁺, and Mg²⁺, such as propylene carbonate, dimethyl sulfoxide tetraglyme, and N‐methyl‐2‐pyrrolidone, have been determined by using different flow rates in the range of 0.1 to 80 μL s^?1. This method appears to be quite reliable, as can be seen by a comparison of the results obtained herein with available literature data. The solubility and diffusion coefficient values of O₂ decrease as the concentration of salt in the electrolyte was increased due to a “salting out” effect.     

Thermal diffusion of hydrogen chloride in aqueous solutions of N,N-dimethylformamide and acetone

The initial and stationary temperature coefficients of voltage were measured at 298.15 K for symmetrical thermogalvanic cells with silver-chloride and quinhydrone electrodes in the HCl-H₂O-S systems (S is N,N-dimethylformamide or acetone) to determine Soret coefficients, the standard entropies of thermal diffusion transfer of hydrogen chloride, and the standard entropies of H⁺ and Cl^? ions moving in water mixtures with N,N-dimethylformamide and acetone. The Agar model was used to calculate the standard entropies of thermal diffusion transfer of ions and the standard partial molar entropies of the H⁺ and Cl^? ions.     

Chronopotentiometry in fused lithium chloride-potassium chloride

Previous work in the application of chronopotentiometry in aqueous and fused salt media has been reviewed. This investigation describes the application of this principle to the reduction of cadmium, cobalt, lead and thallium ions in a fused eutectic mixture of potassium, chloride and lithium. chloride at 450°C. Platinum microelectrodes of different areas and geometry were used. The transition time was limited to the order of 0.2 to 0.7 sec using oscillographic recording.It was found that so long as the dimensions of the electrode were considerably greater than the thickness of the diffusion, layer, linear diffusion theory was obeyed. The transition time constants for cadmium, cobalt, lead and thallium ions were found to be 0.83± 0.02, 0.90 ± 0.03, 0.95 ± 0.04, and 0.59 ± 0.02.10³ amp cm sec$\text{1}\text{2}$ per mole, respectively. The diffusion coefficients of these ions were calculated to be 2.08, 2.42, 2.18 and 3.88.IO^-5 cm² sec^-1, respectively.