A study of transport of hydroxyl ion in a chlor-alkali diaphragm

Chandran, Ramkumar; Chin, D.‐T.; Viswanathan, K.V.

doi:10.1007/bf00610817

Cited by 3 publications

(6 citation statements)

References 7 publications

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“…Except for the measurements of Chandran & Chin [3], the non-ohmic behaviour of the membranes is confirmed by the current strength dependence cited by Heitz & Kreysa [4] and by the measurements of Rondinini & Ferrari [5], who found that the specific resistance of the membranes decreases with increasing current density.…”

Section: ------------------supporting

confidence: 70%

“…The authors have, nevertheless, drawn straight lines that pass through the origin and are therefore based on an equation similar to our eqn (to). Thus Chandran & Chin [3] have assumed ohmic behaviour for the membranes and explain the deviations of the measured values from their straight lines as errors of measurement.…”

Section: ------------------mentioning

confidence: 98%

“…By our own measurements [2] and references from the literature [3-S] it has been proven that the voltage drop across the membrane AEM is not caused only by an ohmic resistance. Rather, in the current density range above 1 kA/m2, AEM can be described as a linear function of the current density with an intercept on the voltage aXIs: (8) Chandran & Chin [3] measured, at different caustic concentrations, the voltage drop across a NAFION® 901 membrane as a function of current density (2)(3)(4) kA/m 2 ). The graph in their Fig.…”

Section: ------------------mentioning

confidence: 99%

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Voltage-Current Curves: Application to Membrane Cells

Bergner

Hartmann

Kirsch

1990

Modern Chlor-Alkali Technology

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Section: ------------------supporting

confidence: 70%

Section: ------------------mentioning

confidence: 98%

Section: ------------------mentioning

confidence: 99%

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Voltage-Current Curves: Application to Membrane Cells

Bergner

Hartmann

Kirsch

1990

Modern Chlor-Alkali Technology

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“…This ratio denoted here as Nm, has been referred to by others as the formation factor (7) and the labyrinth factor (8). Other diaphragm properties have also been proposed (9)(10)(11)(12)(13)(14)(15), but none of these is measurable directly, even though they have been shown to be equivalent to the product NML (3,4,16). Simple steady-state models of the diaphragm-type cell for chlor-alkali cells have been presented and reviewed recently (3,4).…”

Section: Literaturementioning

confidence: 99%

“…where E is equal to the square root of the inverse of the equilibrium constant for the reaction between H + and OH-, which is assumed to occur at the anolyte face of the diaphragm and where N,(L, t) is given by Eq. [10], evaluated at x = L. Equations [11]- [14] can be simplified by defining the following dimensionless variables and x where…”

Section: Modelmentioning

confidence: 99%

Simple Models for Diaphragm‐Type Chlorine/Caustic Cells: I . Dynamic Behavior

Zee

White

Watson

1986

J. Electrochem. Soc.

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A simple model of the dynamic behavior of a diaphragm-type chlorine/caustic cell is presented. The model is based upon measurable diaphragm properties and the mass transfer of hydroxyl ion through the diaphragm. The anolyte is modeled simply as a region in which the OH-ion concentration is fixed, the diaphragm is modeled as a plug-flow reactor with an electrochemical reaction occurring at the catholyte/diaphragm interface where the cathode is placed, and the catholyte is modeled as a completely stirred flow reactor. Analytical integration of the governing equations for these models yields two mathematical expressions: one for the concentration distribution of hydroxyl ion within the diaphragm and one for the effluent concentration. Both of these expressions are functions of time, independent operating variables, diaphragm properties, and physical constants. They are used to show how the concentration distribution of OH-within the diaphragm and the cell effluent change when subjected to a step change in the current density. Also presented is a numerical method of solution for the model equations to predict the required change of the cell head subject to an arbitrary time-dependent change in the current density at a fixed cell effluent concentration.Diaphragm-type cells are used extensively in the United States to produce chlorine and caustic (1). The diaphragm is the key to efficient cell operation, because the diaphragm properties affect the voltage loss, the yield, and the effluent caustic concentration. Recently (2, 3, 4), measurable diaphragm properties have been proposed and used to predict the performance of these cells under steady-state conditions. A simple model ~ of the cell is presented here to predict the effect of these diaphragm properties on the dynamic behavior of the caustic yield.The time-dependent or dynamic behavior of diaphragm-type cells is of interest during start-up and in situations where a differential cost structure for electricity provides an opportunity to reduce the cost of production by operating the cells accordingly. This may mean a high production rate during the night and a low production rate during the day, for example. The model presented in this paper can be used to predict the changes in the operating conditions (e.g., current density and differential head) which would be required to maintain a fixed caustic effluent concentration or a fixed caustic yield.In a diaphragm-type chlorine/caustic cell (see Fig. 1), hydroxyl ions are produced at the cathode according to the following electrochemical reaction H20 + e--~ OH-+ 1/2 H2[1]The buoyancy of the hydrogen gas causes stirring in the catholyte and this compartment is consequently assumed to be completely mixed. A similar statement could be made concerning the anolyte and the chlorine gas generated at the anode. This is, however, not necessary here since the anolyte is modeled simply as a region in which the OH-ion concentration is fixed at a known value that depends on the fixed anolyte pH. As shown in Fig. 1, a diffe...

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Reactor analysis of a chlor—alkali membrane cell

Chandran

Chin

1986

Electrochimica Acta

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A study of transport of hydroxyl ion in a chlor-alkali diaphragm

Cited by 3 publications

References 7 publications

Voltage-Current Curves: Application to Membrane Cells

Voltage-Current Curves: Application to Membrane Cells

Simple Models for Diaphragm‐Type Chlorine/Caustic Cells: I . Dynamic Behavior

Reactor analysis of a chlor—alkali membrane cell

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