ELECTROLYTE CHEMISTRY CONTROL IN ELECTRODIALYSIS PROCESSING

摘要

Methods for controlling electrolyte chemistry in electrodialysis units having an anode and a cathode each in an electrolyte of a selected concentration and a membrane stack disposed therebetween. The membrane stack includes pairs of cationic selective and anionic membranes to segregate increasingly dilute salts streams from concentrated salts stream. Electrolyte chemistry control is via use of at least one of following techniques: a single calcium exclusionary cationic selective membrane at a cathode cell boundary, an exclusionary membrane configured as a hydraulically isolated scavenger cell, a multivalent scavenger co-electrolyte and combinations thereof.

主权项

1. A method for controlling electrolyte chemistry in operation of an electrodialysis unit comprising an anode and a cathode each in an electrolyte solution of a selected concentration and a membrane stack comprising a plurality of cells in series disposed therebetween, the membrane stack comprising pairs of cationic selective and anionic membranes to segregate increasingly dilute salts streams from concentrated salts stream, the method comprising at least one step selected from the group consisting of disposing a single multivalent cation selective exclusionary membrane at a cathode cell boundary to limit transport of cationic species to the cathode cell, disposing within the electrodialysis unit an exclusionary membrane configured as a part of a hydraulically isolated scavenger cell to selectively scavenge the electrolyte solution in the unit, circulating a multivalent scavenger co-electrolyte within the electrodialysis unit and combinations thereof.