GB860468A - Improvements relating to electrodialysing apparatus - Google Patents

Abstract

860,468. Electrodialysis. NATIONAL RESEARCH DEVELOPMENT CORPORATION. Dec. 1, 1958 [Dec. 6, 1957], No. 38039/57. Class 41. A membrane-supporting spacing element, for electrodialysing apparatus, comprising two or more perforated stacks made of insulating material arranged in face contact with one another and with the perforations in adjacent sheets being adapted to co-operate with adjacent membranes to define channels through which liquid can pass in a tortuous path in a direction generally parallel to the surface of a supported membrane and ions can pass in a direction normal to the membrane surface. Suitable insulating materials are vulcanized rubber, polyethylene, polyvinyl-chloride or a copolymer of vinyl chloride and vinylidene chloride. As shown, Fig. 1 is an exploded diagram of an electrodialysing apparatus and Fig. 3 is a sectional view of a spacing element with supported membranes. The apparatus shown in Fig. 1 comprising two electrode compartments, i.e. a compartment 1 containing a cathode 5 and a compartment 2 containing an anode 6, between which are arranged a number of compartments 3, through alternate members of which dialysis and rinsing liquids are passed. The compartments are defined by ion-permeable membranes 4, supported and separated from each other by spacing elements composed of two rectangular sheets 7 of insulating material which are identically perforated (as at 8 and 9); one of each such pair of sheets being rotated through an angle of 180 degrees about an axis passing through the centre of the sheet and normal to the plane of the sheet and the arrangement of the perforations being such that they thereupon co-operate to define tortuous channels through which liquid can flow in a direction generally parallel to the surface of the membranes 4 in face contact with the elements while ions can travel in a direction normal to the membrane surfaces. In Fig. 3 the two membranes are shown at 4, the two co-operating sheets of the spacing element at 7 and the tortuous channel through which liquid can flow being indicated by the vertical sinuous arrow. The sheets 7 (Fig. 1) include border portions 10, some of which are provided at the corners with holes 11 which co-operate with each other and with holes at the corners of the membranes to provide manifolds through which the dialysis and rinsing liquids can enter and leave their respective compartments.