Patent ID: 6224731
Filing Date: 2001-05-01
Classification: B01D,C01C,C01D,C02F,C07C,C12P,C25B

Abstract:
A process for converting an incoming feed of a salt of a monovalent cation and a weak acid anion into an acidified product stream which is reduced in its monovalent cation content, said process comprising the steps of:(a) obtaining an input feedstream which is freed of suspended solids;(b) passing the feed of step (a) through a salt/acid compartment of a two compartment electrodialysis cell containing at least a bipolar membrane and two cation membranes, said bipolar membrane having a cation side and an anion side, said salt/acid compartment being located between said cation side of the bipolar membrane and one of said cation membranes, the other of said two compartments being a base compartment coupled in a base loop, said base compartment being located between said anion side of the bipolar membrane and the other of said cation membranes;(c) supplying a liquid including water to the base compartment of the cell, said base compartment having an output stream in communication with an ion exchange column in said base loop, said column being packed with a material capable of removing multivalent cations that may enter the base loop;(d) passing a direct current through the electrodialysis cell for causing an acidification of the feed salt and a concurrent transport of monovalent cations to the base loop;(e) producing a base product through a combination of the transported cation with a hydroxyl ion generated by the bipolar membrane in the base loop; and(f) withdrawing the acidified feed and the base product.