Electrodialysis Cell, Schematic

Figure 14.3 Schematic drawing of an electrodialysis cell. A, Anion-exchange membranes C, cation-exchange membranes.

Figure 10.7 Schematic of the concentration and potential gradients in a well-stirred electrodialysis cell...

The membranes in an electrodialysis cell are separated by spacer gaskets as indicated in Figure 5.3, which shows schematically the design of a so-called sheet flow electrodialysis stack. The spacer gasket consists of a screen that supports the membranes and controls the flow distribution in the cell and a gasket that seals the cell to the outside and also contains the manifolds to distribute the process fluids in... 

The basic principle of electrodialysis for desalination is to drive the cations and anions from saline water feeds under the influence of an electric potential gradient through cation- and anion-selective membranes. The electric potential prevents diffusion of oppositely charged ions in the other direction. A schematic of the process is shown in Figure 29.7. In a typical electrodialysis cell to deionize a salt solution, anion- and cation-exchange membranes are arranged alternatively in a... 

Figure 1. Schematic diagram of (a) electrodialysis cell and (b) experimental arrangements... 

To illustrate the concentration polarization phenomenon, we consider an infinitely long electrodialysis cell pair having parallel channels in which the flow is fully developed and laminar. The qualitative behavior of the development of the salt concentration and potential distributions along the channels of a dialysate and concentrate cell pair are shown schematically in Fig. 6.2.3 for the case where the inlet salt concentrations are the same in both channels (Probstein 1972). 

Fig. 18 Schematic drawing illustrating an electrodialysis cell arrangement with bipolar...

Figure 14.9 Schematic diagram of electrodialysis cell. Cations from untreated (right) effluent move under the influence of the magnetic field. Metal ions are exchanged in the ion-exchange...

FIG. 22-56 Schematic diagram of electrodialysis. Solution containing electrolyte is alternately depleted or concentrated in response to the electrical field. Feed rates to the concentrate and dduate cells need not be equal. In practice, there would he many cells between electrodes. 

A schematic of the production of acid and base by electrodialytic water dissociation is shown in Fig. 20-84. The bipolar membrane is inserted in the ED stack as shown. Salt is fed into the center compartment, and base and acid are produced in the adjacent compartments. The bipolar membrane is placed so that the cations are paired with OH" ions and the anions are paired with H. Neither salt ion penetrates the bipolar membrane. As is true with conventional electrodialysis, many cells may be stacked between the anode and the cathode. 

Figure 10.2 Schematic diagram of a plate-and-frame electrodialysis stack. Alternating cation- and anion-permeable membranes are arranged in a stack of up to 100 cell pairs...

Stack design in bipolar membrane electrodialysis The key component is the stack which in general has a sheet-flow spacer arrangement. The main difference between an electrodialysis desalination stack and a stack with bipolar membranes used for the production of acids and bases is the manifold for the distribution of the different flow streams. As indicated in the schematic diagram in Figure 5.10 a repeating cell unit in a stack with bipolar membranes is composed of a bipolar membrane and a cation- and an anion-exchange membrane and three flow streams in between, that is, a salt... 

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