GB948915A - Improvements in or relating to the electrodialysis apparatus - Google Patents

Abstract

A multi-compartment electrodialysis apparatus according to the parent Specification is modified in that not all the intermediate plates A, B, interrupt the continuity of the internal electrolyte conduits. Each internal conduit comprises a plurality of parallel conduits formed by cooperating holes 13-16 in adjacent membranes and intervening gaskets, the gaskets having suitably arranged slots leading from the holes to the compartments to ensure the required supply and removal of liquid to and from alternate compartments, Fig. 11 (not shown). A support, e.g. of perforated, corrugated, plastic material, is located in each compartment. The holes 13-16 also occur in each plate A, B, and may be blind or through holes. If blind, they are spaced along transverse conduits 131-161 in the plate, these conduits being open at one or both ends and connected to an external pipe 2131-2161. If the holes 13-16 are through holes, at least one supply and withdrawal pipe 2131-2161 is provided at each pair of adjacent plates A. B. The separate rinsing compartment in the plates A, B and the separate liquid connections 27, 271, 28, 281 thereto are retained, but are not shown in Fig. 1, and the rinsing compartments contain a grid, Fig. 5 (not shown). The end electrodes, and intermediate electrodes if provided, are mounted in frames similar to the plates A, B, except that the holes corresponding to 13-16 are not connected to the internal electrolyte conduits, but communicate with <PICT:0948915/C3/1> <PICT:0948915/C3/2> transverse ducts in the frames for the supply and removal of rinsing liquid to and from each face of the electrodes. The electrodes comprise a plurality of abutting graphite plates secured by graphite bosses to the sides of the electrode frames. End electrodes are separated from the rest of the apparatus by a plate A or B, and intermediate electrodes are sandwiched between plates A, B, membranes intervening. The plates A, B and the electrode frames are of beech wood impregnated with phenolformaldehyde containing 50-68% solids. The apparatus is suspended from hooks engaging holes 105 in the plates A, B which have rollers running on rails extending the length of the apparatus.ALSO:Insulating material for electrodialytic cells (see Division C7) is made by subjecting European or English beech to a vacuum of within 1 or 2 inches of mercury of absolute vacuum for 2 to 3 hours and then impregnating with an unpolymerized phenolformaldehyde resin solution containing 50% to 68% solids by weight at a pressure of 80 pounds per square inch gauge for 12 to 24 hours. After drying, the wood is heat cured for four days at at least 200 DEG F.