Chlor-alkali cells membrane

If there is a gap situated between electrode and membrane (or in other cases diaphragm), this is called finite gap principle. A minimum gap of roughly 1 mm is needed to ensure sufficient mass transport. Some tenth of a volt in cell voltage can be saved, if the zero gap principle is applied to chlor-alkali membrane cells. According to this principle, electrodes, which can be transmitted by the feed, are arranged directly on the surface of the membrane on both sides with adjacent transport and contact elements. This principle is used... 

Membranes can be characterized by their structure and function, that is how they form and how they perform. It is essential that the cation exchange membranes used in chlor-alkali cells have very good chemical stability and good structural properties. The combination of unusual ionic conductivity, high ionic selectivity and resistance to oxidative hydrolysis, make the perfluorinated ionomer materials prime candidates for chlor-alkali membrane cell separators. 

The measurement and control of transport properties for ion exchange membranes is the key element in optimizing the operating conditions for modern chlor-alkali membrane cells. Ideally, a membrane should allow a large anolyte-catholyte sodium ion flux under load, while at the same time the hydroxide ion and water fluxes are kept minimal. Under these conditions, high current efficiency and low membrane resistance can be realized simultaneously in a cell producing concentrated caustic and chlorine gas. 

Parameter Correlations for A Multicomponent Transport Model for Chlor-Alkali Membrane Cells," Presention at the 157th Meeting of the Electrochemical Society, St. Louis, Mo. 5-11, 16, 1980, Olin. 

When chlor-alkali membrane cells are operated on an industrial scale it is desirable that the membrane be cross-linked so that the activation energy barrier to microstructure transition becomes extremely high. This will ensure that the transport properties of the membrane are invariant with time, even at high current densities. 

A newer chlor-alkali membrane-cell process, in which the diaphragm is replaced by a polymeric membrane to separate the cell compartments, has been adopted in much of the industrialized world. The membrane allows only cations to move through it and only from anode to cathode compartments. Thus, as CF ions are removed at the anode through oxidation to CL, Na ions in the anode compartment move through the membrane to the cathode compartment and form an NaOH solution. In addition to forming purer NaOH than the older diaphragmcell method, the membrane-cell process uses less electricity. 

Y. Nishiki, S. Nakamatsu, K. Aoki and K. Okuda, Estimation of optimum anode geometry in chlor-alkali membrane cells, J. Appl. Electrochem., 1984, 19, 90-94. 

The principle of the chlor-alkali membrane cell has been known for a considerable time, and patents for this approach to chlor-alkali manufacture were granted in the early 1960s. Membrane cells combine the purity of mercury cell caustic with the power efficiency of diaphragm cells, while... 

A. Nidola and R. Schira. Deactivation of Low Hydrogen Overvoltage Cathodes in Chlor-Alkali Membrane Cell Technology by Metallic Impurities, In M.M. Silver and E.M. Spore (eds), Advatutes in the Chlor-Alkali and Chlorate Industry, The Electrochemical Society Inc., Princeton, NJ (1984), p. 206. 

N. Funiya, H. Syojaku, H. Aikawa, and O. Ichinose, Ag Based Oxygen Cathodes for Chlor-Alkali Membrane Cells. In J.W. Van Zee, P.C. Foller, T.F. Fuller, and F. Hine (eds.). Advances in Mathematical Modelling and Simulation of Electrochemical Processes and Oxygen Depolarized Cathodes and Activated Cathodes for Chlor-Alkali and Chlorate Processes, Proc. vol. 98-10, The Electrochemical Society, Pennington, NJ (1998), p. 243. 

K. Saiki, A. Sakata, H. Aikawa, and N. Furuya, Reduction in Power Consumption of Chlor-Alkali Membrane Cell Using Oxygen Depolarized Cathode. In H.S. Bumey, N. Furuya, F. Hine, and K.-I. Ota (eds.), Chlor-Alkali and Chlorate Technology R.B. MacMullin Symposium, Proc. vol. 99-21, The Electrochemical Society, Pennington, NJ (1999), p. 188. 

Figure 6.3 Schematic showing the chemistry of a single chlor-alkali membrane cell.

Figure 20.22 shows a modaii chlor-alkali membrane cell, a cell for the electrolysis of aqueous sodium chloride in which the anode and cathode compartments... 

The introduction of membrane technology into chlor-alkali electrolysis has dramatically increased the demands on brine purity [141]. The lifetime of chlor-alkali membrane cells is determined by the operating conditions and the quality and purity of the feed into the electrolyzers. Good long-term performance of the cells may be obtained if brine impurities are kept within the limits recommended in Table 14. 

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