Patent ID: 9586841
Date: 2017-03-07
CPC Classifications: B01D,C02F,Y02A

Claim:
1. An electrodialysis device for use in improving the current efficiency of desalination of salty waters, the device comprising: a) a plurality of ion exchange membranes for placement adjacent to one another within the device, each ion exchange membrane creating a concentrate compartment on one side and a diluate compartment on the other side when the device is filled with solution and acted upon by a direct current passing therethrough; b) a plurality of spacers for compressing between and structurally supporting each of the plurality of ion exchange membranes, each of the plurality of spacers comprising a single piece construction completely filling the volume between adjacent ion exchange membranes and including a central portion and a gasket, each central portion having minimal compressibility in the planar direction for structurally supporting the ion exchange membranes when compressed, each gasket adapted to seal the volume between adjacent ion exchange membranes when compressed, wherein compression of the spacers creates a sealed constant volume compartment between adjacent ion exchange membranes, thereby preventing volume change in the concentrate and the diluate compartments; c) a first electrode compartment and a second electrode compartment, each electrode compartment including an electrode; d) a support structure for compressing and holding the electrode compartments, the spacers and the ion exchange membranes together, the support structure including passages for input lines and output lines, wherein compression of the spacers by the support structure creates the sealed constant volume compartments between adjacent ion exchange membranes; e) a plurality of input lines for supplying solution to the diluate, concentrate and electrode compartments; f) a plurality of output lines for removing solution from the diluate, concentrate and electrode compartments, wherein each of the input lines and output lines include a valve for controlling the flow into and out of the diluate, concentrate and electrode compartments; and g) a direct current electric power supply for establishing a potential difference between the two electrodes and thus causing the passage of electric current through the device when the device is filled with solution, wherein simultaneous closing of the valves for the input and output lines to the concentrate compartments causes automatic hydrostatic pressure buildup in the concentrate compartments and reduced flow from the diluate compartments to the concentrate compartments during passage of direct current through the device, thereby improving current efficiency.