Current dependence of water transport in cation-exchange membranes

Lakshminarayanaiah, N.; Subrahmanyan, V.

doi:10.1021/j100850a031

Cited by 29 publications

(16 citation statements)

References 5 publications

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“…From Figure 15, for NaCl transfer at this point, total osmosis differs by <5% at the two voltages. Osmotic flux generally decreases with increased current densities (George and Courant, 1976;Lakshminarayanaiah, 1965;Lakshminarayanaiah and Subrahmanyan, 1968), which corresponds to increased voltage, consistent with the small effect observed here.…”

Section: Concentrate Concentrationsupporting

confidence: 85%

Use of electrodialysis to deionize acidic wastewater streams

Shah¹

1987

Ind. Eng. Chem. Res.

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The use of electrodialysis to deionize an acidic process water stream is discussed. Direct electrodialysis of the stream containing hydrochloric acid was studied, as well as electrodialysis of a stream containing NaCl, which would result from neutralization of the process stream with caustic. Current efficiency, stack resistance, and osmotic water transfer were measured at various concentrations and stack voltages. If the ions are being transferred into a stream with low electrolyte concentration, direct electrodialysis of acid is the preferred route because of lower stack resistance. However, if the purpose of operation is reuse of process water, the electrolyte must be transferred into a very concentrated stream. In this case, neutralization prior to electrodialysis is preferred because, otherwise, very low current efficiency and high osmotic water transfer are observed.

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Section: Concentrate Concentrationsupporting

confidence: 85%

Use of electrodialysis to deionize acidic wastewater streams

Shah¹

1987

Ind. Eng. Chem. Res.

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“…What role these additional species play in determining the values of E,, remain to be assessed. Assumption (i) stated above is generally made by every investigator although it is commonly recognized that the most homogeneous membrane shows functionally characteristics that are typical of a heterogeneous membrane (Lakshminarayanaiah & Subrahmanyan, 1968). Assumptions (ii) and (iv) have been found to be quite drastic or rather unrealistic (Hills et aL, 1961 a, b;Lakshminarayanaiah, 1963;Lakshminarayanaiah & Subrahmanyan, 1964); whereas assumption (iii) has been shown to have little effect on the membrane parameters (Mackie &Meares, 1955;Boyd &Bunzl, 1967).…”

Section: Discussionmentioning

confidence: 99%

Potentiometric estimation of charges in barnacle muscle fibers under internal perfusion

Lakshminarayanaiah

1974

J. Membrain Biol.

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Single barnacle muscle fibers from Megabalanus Psittacus (Darwin) were internally perfused with a number of solutions of K-acetate of concentration 6"2 which was increased from 100 to 600 mM maintaining a pH of 7.5. The external solutions at the same pH contained 40 mM MgAc 2 and K-acetate of concentration C1 which was varied from 10 through 60 mM. The tonicity of both internal and external fluids was maintained at 1,000 mosmole with sucrose. The membrane potential E m (the potential was referred to the external solution as ground) arising across the fiber membrane was measured using those internal and external solutions which maintained the ratio (C2/C1) at 10. Similar measurements but now maintaining the ratio (C2/C~) at 2, where C~ was the concentration of Tris-C1 in the internal perfusion fluid and was increased from 100 to 250 mM and C2 was the concentration of total C1 in the external fluid which contained 40 mM MgC12 and different amounts of Tris-C1 (120 to 420 raM), were also made using various isotonic solutions at pH 4.0. The measured values of E m corrected for the liquid junction potentials, on interpolation with the theoretical curves of E m plotted against log (1/C1) derived from the theory of membrane potential developed by Teorell and by Meyer and Sievers, gave values of 0.019 and 0.7 M for the density of fixed charges present on the membrane at pH 7.5 (cation selective) and 4.0 (anion selective), respectively. Also, values of 2.3 at pH 7.5 and 1.0 at pH 4.0 were derived for the mobility ratio of cation to anion.It is well recognized that charges present on the surface of biological membranes influence various aspects of biological behavior. A surface charge model has been used by Gilbert and Ehrenstein (1969) to explain some of the voltage-dependent characteristics of the conductance of the nerve fiber. Other biological phenomena, e.g. muscle contraction, protoplasmic streaming, etc., are likely to be greatly influenced by the nature of the charged membrane surfaces. Consequently, a number of techniques, mostly electrokinetic in nature, have been utilized by a number of investigators (see Gilbert, 1971 for a brief review) to estimate the density of charges present in membranes of various biological preparations. Recently,

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“…The industrial glass pipings of the two half-cells holding the membrane were wide enough (diameter = 2.0 cm) to make this manipulation of the rotating bars possible. The details of the arrangement of the magnetic stirrers and the placement of the rotating bars in the two half-cells for efficient stirring can be found elsewhere (Lakshminarayanaiah & Subrahmanyan, 1968).…”

Section: Methodsmentioning

confidence: 99%

Measurement of membrane potential and estimation of effective fixed-charge density in membranes

Lakshminarayanaiah

1975

J. Membrain Biol.

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Electrical potentials Em arising across cross-linked phenolsulfonate membrane separating NaCl solutions of molality M1 and M2 have been measured at 25 degrees C. These values of Em have been used in the Nernst equation to calculate values for the apparent transport number ti(app) for the counterion or the co-ion in the membrane. Values of ti(app) together with the limiting value for the cation transport number in the aqueous phase have been used in the equation developed by Kobatake and co-workers to evaluate the membrane permselectivity Ps as a function of external electrolyte concentration. With the help of the equation relating Ps to phiX, the effective fixed-charge density in the membrane (where phi is a constant, 0 less than phi less than 1, and X is the membrane stochiometric charge density and can be evaluated by chemical analysis of the membrane phase), values for phiX and phi have been determined. Values of phi were low in dilute solutions and increased with increase in the concentration of the external solution. Similar behavior was noted in the case of another membrane system, cross-linked polymethacrylic acid in contact with KOH solutions. On the other hand, the membrane system, "untreated" collodion in contact with KCl solutions, exhibited a behavior in which the values of phi, low in dilute solutions, increased and then decreased following a gradual increase in the external concentration. This slight divergence in its behavior was attributed to the heterogeneity of the collodion membrane structure. The reliability of this potentiometric method to estimate effective fixed-charge density in membranes has been discussed in relation to a similar but old method due to Teorell, Meyer and Sievers. Also the significance of the values derived for phi has been pointed out.

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Current dependence of water transport in cation-exchange membranes

Cited by 29 publications

References 5 publications

Use of electrodialysis to deionize acidic wastewater streams

Use of electrodialysis to deionize acidic wastewater streams

Potentiometric estimation of charges in barnacle muscle fibers under internal perfusion

Measurement of membrane potential and estimation of effective fixed-charge density in membranes

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