Method and apparatus for capacitive deionization and electrochemical purification and regeneration of electrodes

An electrochemical method for deionizing a fluid comprising ions and regenerating electrodes employed in said method, said method comprising:

• (1) flowing said fluid through an open channel defined between at least three pair of intermediate electrodes of a battery of electrochemical cells to deionize said fluid, said open channel having no dimension open to the exterior of said battery;
• (2) interrupting the flow of said fluid;
• (3) contacting said electrodes with a regenerant fluid comprising an oxidizing agent to regenerate said electrodes of said battery;
• and
• (4) flowing more of said fluid through said battery after step (3) to deionize more of said fluid.

An electrochemical method for deionizing a fluid comprising ions and regenerating electrodes employed in said method, said method comprising:

• (1) flowing said fluid through at least one open channel defined between at least three pair of intermediate electrodes of a battery of electrochemical cells to deionize said fluid at a given applied polarity above about 1.2 V to about 1.8V across said open channels, said open channels having no dimension open to the exterior of said battery and said electrodes comprising a carbon aerogel composite;
• (2) slowing or stopping the flow of said fluid for a period of at least 5 minutes;
• (3) contacting said electrodes with a regenerant fluid and regenerating said electrodes of said battery at a shorted or reversed polarity to produce a waste fluid comprising said ions;
• (4) flowing more of said fluid through said battery after step (3) to deionize more of said fluid;
• and
• (5) interrupting said flow of more of said fluid to electrically regenerate said electrodes in the presence of a second regenerant fluid comprising (a) recycled portions of said waste fluid, (b) inleted or recycled portions of said fluid and/or (c) a fluid comprising a lower concentration of said ions than contained in said waste fluid.

A capacitive deionization-regeneration system adapted for operating a deionization cycle and a regeneration cycle, comprising in combination:

• (1) a battery of at least four electrochemical cells, each cell comprising at least one pair of adjacent electrodes including an electrosorptive medium having a high specific surface area and sorption capacity, formed on one or more surfaces of said electrodes;
• each pair of said adjacent electrodes including at least one aperture;
• and
• each pair of said adjacent electrodes forming an open channel, said open channel adapted to fluidly communicate with a subsequent open channel via said aperture to allow a fluid to flow across said electrosorptive medium and through the battery in a serpentine path,
• (2) an electrical circuit for controlling the operation of said battery of cells, said electrical circuit adapted for shorting or switching the polarity of each pair of said electrodes during said regeneration cycle of said electrodes;
• and
• (3) a fluid circuit for regulating the flow of a fluid through said battery under the control of said electrical circuit, in order to slow or stop a fluid flow through said cells for predetermined time intervals during said regeneration cycle, said fluid circuit comprises an outlet adapted for deionized fluid obtained from a deionization cycle operable at a given polarity, and a second outlet adapted for regenerated waste fluid obtained from said regeneration cycle operable at a shorted or reversed polarity relative to said given polarity and at a slower flow rate than the one used during said deionization cycle.

An electrically regeneratable electrochemical cell for use in a capacitive deionization apparatus, said cell comprising the following corrosion resistant components:

• two end plates, one at each end of the cell;
• two end electrodes comprising ceramics, one at each end of the cell, adjacent to the end plates;
• an insulator layer interposed between one end plate and an adjacent one of said end electrodes;
• an insulator layer interposed between the other end plate and the other one of said end electrodes;
• two or more intermediate electrodes comprising ceramics, disposed between said two end electrodes;
• each end electrode and intermediate electrodes including an electrosorptive medium having a high specific surface area and sorption capacity;
• and
• wherein said corrosion resistant components adapted to withstand deleterious effects of oxidative regenerants contacting said end electrodes or said intermediate electrodes.

An electrochemical method for deionizing a fluid comprising ions and regenerating electrodes employed in said method, said method comprising:

• (1) flowing said fluid through at least one open channel defined between at least three pair of intermediate electrodes of a battery of electrochemical cells to deionize said fluid to produce a deionized fluid, said open channel having no dimension open to the exterior of said battery;
• (2) contacting said electrodes with a regenerant fluid added to said fluid and regenerating said electrodes of said battery to produce a waste fluid comprising said ions;
• and
• (3) flowing said regenerant fluid through said battery at a faster rate than said flowing of said fluid through said battery in step (1).