Mutual Diffusion Coefficients of Various ZnCl2  ( 0.5M )  ‐ KCl ‐  H 2 O  Mixtures at 298.15 K by Rayleigh Interferometry

Miller, Donald G.; Ting, Alexander; Rard, Joseph A.

doi:10.1149/1.2095822

Cited by 21 publications

(7 citation statements)

References 29 publications

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“…The four diffusion coefficients can be determined from a, b, s 1 , and s 2 by using the equations [46][47][48][49][50] We note that if the eigenvalues of the diffusion coefficient matrix are exactly equal or nearly equal, then a different analysis will be required. …”

Section: Resultsmentioning

confidence: 99%

Multicomponent Diffusion in Crowded Solutions. 2. Mutual Diffusion in the Ternary System Tetra(ethylene glycol)−NaCl−Water

et al. 2004

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Multicomponent diffusion properties for the tetra(ethylene glycol) (PEG4)-sodium chloride-water ternary system are investigated at constant salt concentration (0.5 mol dm ) and a wide range of PEG4 concentration approaching 3.0 mol dm -3 (60% volume fraction). Cross-velocity correlation (counterflows) for any pair of components in this ternary system is determined. Comparison between the exact multicomponent approach and the pseudobinary approximation, which is based on the assumption that the PEG4-water mixed solvent can be treated as one component, shows how the latter approach is misleading in describing the electrolyte diffusion properties in mixed solvents. Our results show strong coupling between the fluxes of NaCl and PEG4, which is attributed to the NaCl-PEG4 nonpreferential interactions in water. Moreover, the behavior of the NaCl and PEG4 chemical potentials as a function of the system composition can be quantitatiVely extracted from our diffusion measurements with the help of some interesting observations about the viscosity and conductivity properties of the system.

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Section: Resultsmentioning

confidence: 99%

Multicomponent Diffusion in Crowded Solutions. 2. Mutual Diffusion in the Ternary System Tetra(ethylene glycol)−NaCl−Water

et al. 2004

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“…Mallinckrodt AR KCl (purity, 99.9%; molecular weight, 74.55 g mol −1 ) was dried by heating at 450°C for 7 h and used without further purification. 42 Mallinckrodt AR NaCl (purity, 99.9%; molecular weight, 58.44 g mol −1 ) was dried by heating at 400°C for 4 h and used without further purification. 43,44 Fisher Scientific NH 4 Cl (A.C.S.…”

Section: Methodsmentioning

confidence: 99%

Amplification of Salt-Induced Polymer Diffusiophoresis by Increasing Salting-Out Strength

2014

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The role of salting-out strength on (1) polymer diffusiophoresis from high to low salt concentration, and (2) salt osmotic diffusion from high to low polymer concentration was investigated. These two cross-diffusion phenomena were experimentally characterized by Rayleigh interferometry at 25 °C. Specifically, we report ternary diffusion coefficients for polyethylene glycol (molecular weight, 20 kg·mol(-1)) in aqueous solutions of several salts (NaCl, KCl, NH4Cl, CaCl2, and Na2SO4) as a function of salt concentration at low polymer concentration (0.5% w/w). We also measured polymer diffusion coefficients by dynamic light scattering in order to discuss the interpretation of these transport coefficients in the presence of cross-diffusion effects. Our cross-diffusion results, primarily those on salt osmotic diffusion, were utilized to extract N(w), the number of water molecules in thermodynamic excess around a macromolecule. This preferential-hydration parameter characterizes the salting-out strength of the employed salt. For chloride salts, changing cation has a small effect on N(w). However, replacing NaCl with Na2SO4 (i.e., changing anion) leads to a 3-fold increase in N(w), in agreement with cation and anion Hofmeister series. Theoretical arguments show that polymer diffusiophoresis is directly proportional to the difference N(w) - n(w), where n(w) is the number of water molecules transported by the migrating macromolecule. Interestingly, the experimental ratio, n(w)/N(w), was found to be approximately the same for all investigated salts. Thus, the magnitude of polymer diffusiophoresis is also proportional to salting-out strength as described by N(w). A basic hydrodynamic model was examined in order to gain physical insight on the role of n(w) in particle diffusiophoresis and explain the observed invariance of n(w)/N(w). Finally, we consider a steady-state diffusion problem to show that concentration gradients of strong salting-out agents such as Na2SO4 can produce large amplifications and depletions of macromolecule concentration. These effects may be exploited in self-assembly and adsorption processes.

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“…In this section, we discuss the computational details of our model, including the initial conditions and loads used for the simulations. More information on this topic, as well as ac omplete list of the physical, chemical, and numerical parameters [13,14,20,21,27,28,42,43,[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] implemented in the model, is presented in greater detail in the Supporting Information.…”

Section: Computational Detailsmentioning

confidence: 99%

Rational Development of Neutral Aqueous Electrolytes for Zinc–Air Batteries

2017

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Neutral aqueous electrolytes have been shown to extend both the calendar life and cycling stability of secondary zinc–air batteries (ZABs). Despite this promise, there are currently no modeling studies investigating the performance of neutral ZABs. Traditional continuum models are numerically insufficient to simulate the dynamic behavior of these complex systems because of the rapid, orders‐of‐magnitude concentration shifts that occur. In this work, we present a novel framework for modeling the cell‐level performance of pH‐buffered aqueous electrolytes. We apply our model to conduct the first continuum‐scale simulation of secondary ZABs using aqueous ZnCl2–NH4Cl as electrolyte. We first use our model to interpret the results of two recent experimental studies of neutral ZABs, showing that the stability of the pH value is a significant factor in cell performance. We then optimize the composition of the electrolyte and the design of the cell considering factors including pH stability, final discharge product, and overall energy density. Our simulations predict that the effectiveness of the pH buffer is limited by slow mass transport and that chlorine‐containing solids may precipitate in addition to ZnO.

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Mutual Diffusion Coefficients of Various ZnCl2 ( 0.5M ) ‐ KCl ‐ H 2 O Mixtures at 298.15 K by Rayleigh Interferometry

Cited by 21 publications

References 29 publications

Multicomponent Diffusion in Crowded Solutions. 2. Mutual Diffusion in the Ternary System Tetra(ethylene glycol)−NaCl−Water

Multicomponent Diffusion in Crowded Solutions. 2. Mutual Diffusion in the Ternary System Tetra(ethylene glycol)−NaCl−Water

Amplification of Salt-Induced Polymer Diffusiophoresis by Increasing Salting-Out Strength

Rational Development of Neutral Aqueous Electrolytes for Zinc–Air Batteries

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