Mehrzellige Elektrodialysevorrichtung

In an electrodialysis apparatus comprising dilution and concentration chambers defined by alternating anion - and cation-selective membranes forming a horizontal stack, preferably with chamber defining separators, and with electrodes at each outer end of the stack in separate electrode chambers; supply and exhaust conduits situated at the lower and upper parts of the chambers to carry concentration and dilution solutions for passage through alternate chambers and means for supplying the electrode compartments either in series or parallel with a rinsing solution along the length of the electrodes either from an external source or from one of the exhaust conduits, preferably that for the concentration stream; at least one of the electrodes is composed of a plurality of substantially vertical conducting cords 1 having a maximum transverse dimension of 5 mms and spaced by 0.5 to 50 mms, the upper and lower parts of the cords being mechanically connected to at least one electrode plug connection as at 3. As shown the cords 1 are threaded through apertures 10 in flow alignment plates 9 attached to spacers 11 rinsing solution being fed in at 7a or 5a and removed at 7 or 5. Insoluble compounds formed at the electrodes are removed by the rinsing solution and may be recovered in external precipitation tanks. Thus Mg (OH)2 may be recovered from the cathode rinse solution when sea water is treated and stearic acid may be recovered from the anode rinse solution when a solution of sodium stearate is treated. The electroconductive cords, which may be curved or non parallel used in the cathode may be of Cu, Al, Ti, Pb, Fe, Ni, Pt or alloys of Pb-Sb, Pb-Ag, Fe-Si, stainless steel, or Pt-plated Ti, while cords of anodically insoluble metals may be used in an anode. If desired only the electrode at which an insoluble compound is formed need be of the cord form described, the counter electrode being a plate of graphite or platinum. Reversal of applied potential and flow path of the concentration and dilution solutions may be effected at intervals for flushing the membranes and chambers.