WO2001090443A1 - Capacitive deionization cell structure for control of electrolysis - Google Patents

Capacitive deionization cell structure for control of electrolysis Download PDF

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Publication number
WO2001090443A1
WO2001090443A1 PCT/US2001/016383 US0116383W WO0190443A1 WO 2001090443 A1 WO2001090443 A1 WO 2001090443A1 US 0116383 W US0116383 W US 0116383W WO 0190443 A1 WO0190443 A1 WO 0190443A1
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Prior art keywords
fluid
cells
array
cell
apparatus
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PCT/US2001/016383
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French (fr)
Inventor
Aaron M. Jungreis
Mohamed Y. Haj-Maharski
Colin E. J. Bowler
John Tarnawski
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Abb Power T & D Company Inc.
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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
    • C02F1/4691Capacitive deionisation
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F1/00Treatment of water, waste water, or sewage
    • C02F1/46Treatment of water, waste water, or sewage by electrochemical methods
    • C02F1/469Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis

Abstract

The present invention is directed to, in part, systems and apparatuses for the removal of ions from a fluid that comprises an electrical and fluid flow structure that allows for voltage sharing in a long series stack of cells. Also disclosed are apparatuses and systems for the removal of ions from a fluid that incorporated in active cells in order to proved increased electrical resistance in a series stack of capacitive deionization cells. Further, the present invention also discloses systems and apparatuses for a series of capactive deionization cells that limit the flow of current within the dielectric fluid between alternate capacitor layers. Specifically, there is one embodiment of an apparatus (130) that comprises at least pair of CDT stacks (137, 138) that are disposed within top and bottom plates (131, 132) and are in fluid communication with fluid inlets (134) and fluid outlets (135).

Description

CAPACITIVE DEIONIZATION CELL STRUCTURE FOR CONTROL OF ELECTROLYSIS

Cross Reference to Other Applications: This application is related to co-pending applications, "Capacitive

Deionization Cell Structure with Voltage Distribution Control" Attorney Docket No. ABTT-0219/B000131; "Capacitive Deionization Cell Power Supply" Attorney Docket ABTT-0220/B000161; and "Integrated Electrode for Electrolytic Capacitor Applications" Attorney Docket ABTT-0221/B000171, filed herewith and incorporated by reference in their entireties.

Field of the Invention

The present invention relates generally to capacitive deionization cells that are used for water purification. Specifically, the present invention relates generally to apparatuses and systems incorporating more than one capacitive deionization cell that allow for the control of electrolysis.

Background of the Invention

It is generally known to use capacitive deionization technology ("CDT") electro-static cell devices to purify water of ionic species for applications such as water desalination, purification of water for human consumption, and other related industrial and commercial applications. Water may contain impurities such as, for example, ionic salts that include calcium, calcium carbonate, sodium, sodium chloride, and magnesium; or other impurities such as copper, iron, zinc, silica, nitrates, arsenic, chrome, potassium, carbonates, cadmium, cesium, and biological organisms such as bacteria and/or microbes that need to removed. CDT cells may be effective in removing such impurities from water or any other aqueous-based system.

CDT cells are essentially capacitors or electrical charge storage devices. These devices store electric energy in the form of an electric field generated in the space between two separated, oppositely charged electrodes. Capacitance itself is a property of space whereby two conductors that are separated by a dielectric layer store charge. Capacitance is measured in units called Farads, calculated according to equation (1) for a parallel plate capacitor, where C equals capacitance, k is the dielectric constant, A is the area of the parallel charged plates, and d is the distance between the plates.

C =kA/d (l) According to equation (1), capacitance "C" increases with the surface area "A" of the conductive plates, and is inversely proportional to the distance "d" between the plates. When an electric potential is applied across the conductive plates, the capacitors store charge according to equation (2), where Q equals charge, and V equals voltage.

Q = C V (2) Briefly, a typical CDT cell may be comprised of an electric charge capacitor that contains electrodes, such as activated carbon electrodes, and a water dielectric. The application of an electrical potential to the electrodes can cause the hydrated ions of one or more salts within the water dielectric to be electrostatically attracted to the electrodes based upon the electric potential of the salt ions. For example, a salt such as sodium chloride ("NaCl") is hydrated when mixed with water to produce dissociation of the sodium cation from the chloride anion. The positively charged sodium cations are electro-statically attracted to the negatively charged plate whereas the negatively charged chloride anion is attracted to the positive plate potential. This ion attraction can proceed with the water flowing until all of the storage locations on the electrode surface are covered with ions. During this time, the output water ion content may be reduced or purified by the ions that remain within the CDT cell. After the ion storage locations are exhausted, the cell potential can be reduced to zero and the output water can be switched to a waste stream. When this occurs, the salt ions are re-hydrated within the water and swept out of the cell. This cycle, of alternatively purifying and discharging a waste, can be repeated indefinitely. CDT cells, sometimes referred to as flow through capacitors, are essentially capacitors of the electric double layer type designed to provide a flow path for water. There are many examples of CDT cells that are used in the art for water purification or similar purposes. In this regard, U. S. Pat. Nos., 5192432, 5186115, 5200068, 5360540, 5415768, 5547581, 5620597, 5415768, 5,779,891 issued to Andelman (referred to herein as the "Andelman patents" and incorporated herein by reference in their entireties) and U. S. Pat. No. 5538611 to Toshiro Otowa (referred to herein as the "Otowa patent" and incorporated herein by reference in its entirety) disclose traditional cylindrical structure capacitors. Other examples of geometries in the prior art include electric double layer capacitors with facing electrodes that may include spiral wound, stacked disk, flat plate, or bundles of polygonal electrodes. These capacitors may differ in terms of the pathway of fluid through the device. Generally, however, the ionic contaminants are pulled perpendicular to the flow path of the fluid or drawn into the electrode such as the activated carbon surface.

FIG. 1 (prior art) provides an illustration of a typical CDT cell. The CDT cell 10 consists of layers 11 that are held together by a mechanical clamp arrangement 12. FIG. 2 (prior art) provides a detailed illustration of a typical layer structure for a CDT cell. Water, or another electrolytic fluid, is retained within cell 10 through a manifold 13.

Referring to FIG. 2, each layer 11 consists of a conductive substrate 14, conductive silver- loaded resin glue 15, a carbon aerogel 16, and a water sealing gasket 17. Silver-loaded resin glue 15 bonds carbon aerogel 16 to one or more surfaces of conductive substrate 14. As FIG. 1 and FIG. 2 illustrate, water, or another electrolytic fluid, passes into fluid inlet 8 of manifold 13 through each layer of the cell in the direction shown by arrow 18 through open slots 19 before exiting the cell at fluid outlet 9 of manifold 13. Each conductive substrate 14 in the layer is connected either to an electrical input terminal 20 or an electrical output terminal 21. The electrical input terminal 20 and electrical output terminal 21 are of opposite polarity with respect to each other as shown in FIG. 1. Terminals 20 and 21 are typically connected across a DC power source (not shown in FIG.

1).

Upon applying a DC voltage across terminals 20 and 21, ionic contaminants electrostatically absorb to the carbon aerogel 16, with an equivalent amount of electronic charge. The CDT cell holds the charge and stores energy when disconnected from the power source, in the same manner as an ordinary capacitor. Typical voltages for a CDT cell for purifying water range from about 1.0 to about 2.0 V. The amount of voltage that an individual CDT cell can withstand is limited by the Nernst potential of the water or electrolytic fluid that flows through the cell. For example, the Nernst potential for the breakdown of water is 1.24V. As long as the charging voltage does not exceed the Nernst potential for electrochemistry to occur, the ions contained within the water absorb electrostatically to the charged surface. When the voltage of the cell exceeds the Nernst potential for the fluid that is processed through the cell, the fluid may generate hydrogen bubbles or draw excess current due to electrolysis at this voltage. Further, the electrodes within the cell may become corroded and will not perform as effectively in removing ions or other impurities from the fluid.

As described above, capacitive deionization of water, or another electrolytic fluid, involves inducing an electrical field across capacitor plates which surround a section of water, or other electrolytic fluid to be de-ionized, such that ions are electrostatically pulled out of the fluid and onto the capacitor plates. For systems in which water is the electrolytic fluid, the low breakdown voltage of water limits the allowable capacitor voltage to its Nernst potential, or 1.24 V, if no electrolysis of water is allowed to take place. To minimize the electrical losses and cost of a power conversion system, it would be beneficial to electrically connect a plurality of CDT cells in series. However, in such an arrangement, there are voltage balancing problems between the cells. The resistance of a CDT cell varies with the salinity of the water of the electrolytic fluid that passes through the cell. Due to the deionization process, the water or fluid at the input of the structure will have more ions, and therefore less resistance, than the water at the output of the structure. This resistance gradient normally makes it difficult to share voltage across a series stack of cells. There is a need in the art to provide methods and systems to allow even voltage sharing in an electrical series of cells. There is a further need in the art to maintain the resistance or balance the resistance of the fluid as it progresses through the cell.

Current systems incorporating CDT cells are low voltage, high current systems. In this regard, these systems require a large power supply to operate. Further, because of the power supply constraints, most purification systems are portable or small scale (i.e., purify small volumes of water of other fluids at one time). There is a need in the art to provide systems incorporating CDT cells that allow smaller power supplies, or commercial power supplies, to operate economically and reliably. Moreover, there is a need in the art to provide systems incorporating CDT cells that allow for the purification of water at higher volumes.

Summary of the Invention

The present invention satisfies these needs in the art by providing systems and apparatuses for the removal of ions from a fluid. Specifically, in one embodiment, the system comprises a first array of capacitive deiomzation cells and a second array of capacitive deionization cells. Both the first array and second array comprise a fluid inlet, a fluid outlet, and a plurality of capacitive deionization cells wherein the capacitive deionization cells within the array are connected electrically and hydraulically in series. Fluid travels through the first series of capacitive deionization cells within the first array and then travels through the second series of capacitive deionization cells within the second array such that the cell in the first array in which the fluid has the highest ionic content is in parallel with the cell in the second array in which the fluid has the lowest ionic content. In certain embodiments, the system further comprises an additional capacitor that is electrically connected in parallel with the first array and the second array. A further aspect of the present invention is directed to an apparatus for the removal of ions from a fluid wherein the apparatus comprises: a manifold comprising an at least one fluid inlet and an at least one fluid outlet and a pair of capacitive deionization stacks comprising a first stack and a second stack. The pair of capacitive deionization stacks are disposed within the manifold and are in fluid communication with the at least one fluid inlet and the at least one fluid outlet, wherein the first stack and second stack each comprise a plurality of capacitive deionization cells. The capacitive deionization cells are comprised of a plurality of layers, a pair of electrodes that are disposed upon a portion of each surface of the layers, and an at least one opening wherein the fluid is directed between the layers and contacts a portion of the electrodes prior to passing through the at least one opening to the adjoining cell. Each capacitive cell within the first and second stacks is connected electrically and hydraulically in series. Additionally, the cells within the first stack and the second stack are electrically connected in parallel and are in fluid communication with each other such that the cell in the first stack in which the fluid has the highest ionic content is in parallel with the cell in the second stack in which the fluid has the lowest ionic content.

Another aspect of the present inventions is directed to an apparatus for the removal of ions from a fluid wherein the apparatus comprises: a manifold comprising an at least one fluid inlet and an at least one fluid outlet; a plurality of capacitive deionization cells disposed within the manifold and in fluid communication with the at least one fluid inlet and an at least one fluid outlet wherein each of the capacitive deionization cells comprises a pair of layers, a pair of electrodes that are disposed upon a portion of the facing surfaces of each of the layers, and an at least one opening within each layer wherein the fluid is directed between a portion of the electrodes prior to passing through the at least one opening to the adjoining cell, and a plurality of inactive cells. The inactive cells are connected hydraulically and electrically in series with the capactive deionization cells and each of the inactive cells comprises a pair of insulating layers and an at least one opening within each layer such that the fluid is directed between the insulating layers prior to passing through the at least one opening to the adjoining cell. In certain embodiments of the apparatus, the inactive cells are interposed between the capacitive deionization cells within the series. In other embodiments of the present invention, the fluid flows through the active capacitive deionization cells in the series prior to flowing through the inactive cells.

These and other aspects of the invention will become more apparent from the following detailed description.

Brief Description of the Drawings

The foregoing summary, as well as the following detailed description of the preferred embodiments, is better understood when read in conjunction with the appended drawings.

FIG. 1 (prior art) shows a typical CDT cell of the prior art. FIG. 2 (prior art) provides a detailed view of a layer structure for a typical

CDT cell of the prior art.

FIG. 3 provides a side view of one embodiment of a CDT cell of the present invention.

FIG. 3 a provides an electrical schematic of the CDT cell of FIG. 3. FIG. 3b provides a view of the CDT cell taken along line A- A of FIG. 3.

FIG. 4a provides a top view of a further embodiment of a CDT cell of the present invention.

FIG. 4b provides a side view of a further embodiment of a CDT cell of the present invention. FIG. 5 provides an illustration of a deionization system that may incorporate one or more CDT cells of the present invention. FIG. 6 provides an embodiment of an apparatus of the present invention comprising a plurality of CDT cells of FIG. 3.

FIG. 6a provides an electrical schematic of the apparatus of FIG. 5.

FIG. 7 provides an embodiment of a series stack of CDT cells of the present invention that incorporates a plurality of CDT cells of FIG. 3.

FIG. 8 provides another embodiment of a series stack of CDT cells of the present invention that incorporates a plurality of CDT cells of FIG. 3.

FIG. 9 provides an embodiment of a series stack of CDT cells of the present invention that incorporates a plurality of CDT cells of FIG. 4a and FIG. 4b. FIG. 10 provides an embodiment of an array of the present invention that incorporates a series stack of FIG. 9.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and are intended to provide further explanation of the invention as claimed. The accompanying drawings are included to provide a further understanding of the invention. In the drawings, like reference characters denote similar elements throughout several views. It is to be understood that various elements of the drawings are not intended to be drawn to scale.

A more complete understanding of the present invention, as well as further features of the invention, such as its application to other electrical or mechanical devices, will be apparent from the following Detailed Description and the accompanying drawings.

Detailed Description of Preferred Embodiments

The present invention overcomes the difficulties in the art in providing systems, apparatuses, and methods for the removal of ions from a fluid that may control electrolysis while allowing the use of commercial, off-the-shelf power supplies.

Specifically, in one embodiment, the apparatuses of the present invention allow for voltage balancing of the CDT cell voltages as the fluid progresses through the cell with varying salinity by electrically connecting the CDT cells that experience fluid with the least resistance, or have the highest amount of ions, with the cells that experience fluid with the highest resistance, or have the lowest amount of ions. In other embodiments, the apparatuses of the present invention use inactive, or insulating, cells that are in series with active CDT cells for increasing the resistance between adjacent series cells. The systems and apparatuses of the present invention comprise a plurality of CDT cells that are electrically and hydraulically connected in series. FIG. 3 provides an example of one embodiment of a CDT cell 100 that may be used in the systems and apparatuses of the present invention. FIG. 3 a provides an electrical schematic of CDT cell 100 that may be used in the systems and apparatuses of the present invention.

Referring to FIG. 3 a, the power supply of the CDT cell 100 is shown as a DC power source 101 and an external resistance Rs 102. CDT cell 100 is depicted as two double layer capacitors 103 and 104, each of which represent the electrodes of the cell with opposite polarity. Resistance R 105 is shown in parallel within capacitors 103 and 104, respectively, to represent that the cell electrical performance has a steady state DC current after the capacitors are fully charged. Resistance 105 within CDT cell 100 is undesirable because it implies that electrolysis may be occurring within cell 100 that can damage the cell components after continuous cycles. For example, in CDT cells where the electrolytic fluid may be salt water, chloride oxidation may occur at the anode and sodium reduction may occur at the cathode which creates gaseous by-products as well as other chemical species. Water gap resistance, Rw 106, is shown as a variable representing the variability of the ions within the electrolyte and the physical dimensions of gap length, or distance between the electrodes within the cell 100 and surface area of the electrode.

Referring now to FIG. 3, in one embodiment, individual cell 100 is comprised of a plurality of layers of conductive substrates 107. FIG. 3 provides a side view of cell 100 with gasket material 99 removed to reveal the cell structure. Conductive substrates 107 are supported by rod 108. Rod 108 may comprise any retaining structure, such as a threaded screw or bolt, that acts to align more than one CDT cells within a series. Rod 108 is encased on one or both sides by a gasket material 99. Preferably, there are at least four rods 108, or at least one rod per side, to effectively retain and align the CDT cells within the series of cells. Gasket material 99 may be comprised of, but not limited to, silicone, rubber, or any other water impermeable material to retain the electrolytic fluid within the stack or array of CDT cells. Depending upon the modulus of the gasket material, gasket material 99 may further comprise an underlying structural support (not shown) to comprise the sidewalls of CDT cell 100.

Rods 108 hold and align conductive substrates 107 in place within the overall structure through one or more alignment holes, 109 within the substrate 107. FIG. 3b provides a top view of conductive substrate 107 taken along line A-A in FIG. 3 (with front gasket material 99 removed). Although conductive substrate 107 is shown has having a rectangular shape, it is understood that other geometries for conductive substrate 107 may be used without departing from the spirit of the present invention. Conductive substrate 107 also includes one of more apertures, 110, for the passage of an electrolyte or fluid through the cell. In a series of CDT cells, for example, it is preferable that the alignment holes 109 for support rods 108 and apertures 110 for electrolyte flow for each CDT cell be of uniform dimensions to allow for maximum alignment of the cells contained within the manifold or other housing. Conductive substrates 107 are generally flat, thin corrosion resistant, metallic sheets. In some embodiments, conductive substrates 107 may be comprised of titanium metal. While conductive substrate 107 may be a solid conductive material such as a metal, a fiberglass composite sheet with copper plated material may be preferred to reduce manufacturing cost and to ease solderability or bonding of substrate 107 to the high surface area material 111. Conductive substrates 107 are preferably electrically connected to a DC power source (not shown in FIG. 3 and FIG. 3b). Alternatively, conductive substrates 107 may be connected to an AC power source with a controlled rectifier. Preferably, conductive substrates 107 further comprise terminals (not shown in FIG. 3 and FIG. 3b) that may be either an electrical input terminal or an electrical output terminal which are, in turn, electrically connected to a power source. The electrical input terminal and electrical output ten nals are of opposite polarity with respect to each other so that the alternating conductive substrates may also be of opposite polarity (refer to FIG. 3). The amount of voltage that is applied to cell 100 is limited by the Nernst potential of the electrolyte that is passed through the cell as well as other factors such as, for example, the voltage drop in cell 100 components. The CRC Handbook of Chemistry and Physics (79th ed. 1998), pp. 8.21-8.31, provides Nernst potential values for a variety of reactions measured at 25°C and at a pressure of 1 atm. Using a DC constant power source, a voltage of about 0.5 to about 5 V may be applied to cell 100, depending upon the Nernst potential of the electrolytic fluid and other variables such as the voltage drop in cell 100 components. For cells in which the electrolytic fluid is water, the amount of voltage that may be applied to the terminals attached to the conductive substrate may range from about 1 V to about 2 V. Referring to FIG. 3, a high surface area material 111 is bonded to one or both surfaces of conductive substrate 107 to comprise the electrode and serve as either the cathode or anode depending upon its electrical polarity. High surface area material 111 may be a thin sheet that preferably covers a substantial portion of the surface of conductive substrate 107. Preferably, material 111 comprises a porous, conductive, monolithic material, such as a carbon aerogel or carbon aerogel composite. Carbon aerogels or carbon aerogel composites are preferable because the porosity, surface area, pore size, and/or particle size may be tailored over a broad range. The BET specific surface area of high surface area material 111 may range from about 400 to about 2,600 m2/g, preferably from about 600 to about 2,000 m2/g, more preferably from about 800 to about 1,600 m2/g. The pore size of the high surface area material may preferably be about 100 nm or less, more preferably about 75 nm or less, or more preferably about 50 nm or less. In certain embodiments, high surface material 111 may be comprised of a solid matrix having interconnected colloidal-like particles or continuous intersecting fibrous chains having a fiber diameter of about 10 nm or less. Examples of high surface area materials that may be suitable for the CDT cells that are incorporated into the present invention may include, for example, the materials found in U. S. Pat. Nos. 5,190,610, 5,260,855, 5,385,802, 5,980,977, 5,993,996, and the article entitled "Carbon Aerogel Composite Electrodes, by Joseph Wang et al., in Anal. Chem. 1993, vol. 65, pp. 2300-03, the disclosures of which are incorporated herein by reference in their entireties. Further materials that may be suitable as high surface area material 111 include carbon nanotubes, or carbon tubes that are a few nanometers across and have a high surface area relative to its volume.

In a preferred embodiment of the present invention depicted in FIG. 3, there is provided an electrode that comprises a high surface area material 111 such as a carbon aerogel and an insulating spacer 112 both of which are conductively bonded to conductive substrate 107 with solder or other means of attachment known in the art. Even though FIG. 3 shows insulating spacer 112 and carbon aerogel layer 111 as distinctive layers, it is understood, however, that insulating spacer 112 and carbon aerogel 111 may be integrated into or be incorporated within carbon aerogel 111 to form one layer. Insulating spacer 112, which is preferably a thin layer that allows the flow of current to aerogel 111, may be comprised of any electrically insulating material, including but not limited to, alumina, polypropylene, polyester, polyimide, polycarbonate, PVC, polyamide, PBTP, KEVLAR® (a poly-paraphenylene terephthalamide manufactured by DuPont Corporation of Wilmington, Delaware), NOMEX® (a poly-metaphenylene diamin manufactured by DuPont Corporation of Wilmington, Delaware), and DELRTN® (an acetal resin manufactured by DuPont Corporation of Wilmington, Delaware). In some embodiments, insulating spacer 112 is comprised of a polyester cloth weave lay-up. Preferably, insulating spacer 112 is porous to increase the bonding surface area between spacer 112 and carbon aerogel 111 as well as allow current to flow freely to carbon aerogel 111. Insulating spacer 112 may preferably be comprised of a reticulated foam insulation spacer. The bond between the carbon aerogel 111, and insulating spacer 112, depending upon the embodiment, with conductive substrate 107 to farm the electrode may be formed via any bonding method known in the art. These methods may include, for example, the sputtering, plasma-spraying, vapor deposition, chemical vapor deposition, electroplating, or electroless plating of a thin layer of a high melting point temperature metal (not shown in FIG. 3) that is preferably applied to the side of each carbon aerogel element 111 that faces conductive substrate 107. The term, "high melting point temperature metal", as used herein relates to metals whose melting point is at least about 260°C or greater. This thin layer of a high melting point temperature material facilitates the low temperature solder bonding of aerogel 111 to conductive substrate 107 and may also avoid a wickmg effect of the solder into the pores of the material 111. The term "low temperature solder bonding", as used herein, relates to solder bonding that occurs at temperatures of at least about 156°C or lower. Insulating spacer 112 also aids in avoiding the wicking effect of the solder into the pores of the material as well as enhances the electrical connection between conductive substrate 107 and aerogel 111. In certain embodiments of the present invention, the high temperature melting point surface that is applied to conductive substrate 107 may be additionally plated with a further high temperature melting point alloy, such as, but not limited to a tin lead alloy, to facilitate the low temperature solder bond to conductive substrate 107.

In other embodiments of the present invention, CDT cell 100 may comprise an integral conductive substrate 107 and high surface area material 111. In this embodiment, conductive substrate 107 may comprise a porous micro-mesh metal fabric, such as copper or other electrically conductive metal, that is surrounded by two layers of an electrically insulating material, such as a fiber-glass veil, prior to the application of the aerogel resin preparation. The micro-mesh metal fabric preferably has a conductivity value that is an order of magnitude higher than the high surface area material 111. The micro-mesh metal fabric may be made from a metal wire drawn from about 5 to about 20 micron diameter, preferably about 7 to about 15 micron diameter, and more preferably about 10 to about 13 micron diameter. The metal wire is then chopped to lengths of about 20 mm or below, preferably about 15 mm or below, and more preferably about 10 mm or below to provide metal fibers. The metal fibers are then calendered, to provide a cloth of uniform thickness, and sintered to provide a porous, stable cloth material. The micro mesh metal fabric and surrounding electrically insulating material may be infused with an electrically conductive resin material, such as a carbon aerogel, cured and pyrolized in a reducing furnace to form the carbon aerogel with an integral conductive substrate.

FIGs. 4a and 4b provide the top and side view, respectively, of another embodiment of a CDT cell 200 that may be used in the present invention. As FIG. 4a and 4b illustrate, CDT cell 200 is comprised of a plurality of T-shirt shaped conductive substrates 201 having alignment holes 202 and fluid flow aperture 203; high surface area materials 204 having a central aperture for fluid flow; and a porous separator 205 having a central aperture for fluid flow. When assembled as shown in FIG. 4b, the apertures within the substrates 201, high surface area materials 204, and porous separator 205 are in alignment. T-shirt shaped conductive substrates 201 are preferably comprised of a thin, non-corrosive metal such as, for example, the materials used for conductive substrate 107 in CDT cell 100 of FIG. 3. Substrates 201 are electrically connected to a power source such as a DC power source via terminals on conductive substrates 201 (not shown in FIG. 4a and FIG. 4b) and during operation are of opposite electrical polarity with respect to each other. High surface area materials 204 are comprised of an electrically conductive, porous material such as a carbon aerogel, or any of the materials previously discussed in connection with the high surface area material 111 in CDT cell 100 of FIG. 3. High surface area materials 204 are held in mechanical compression with substrates 201. Porous separator 205 is inserted between high surface area materials 205 as shown in FIG. 4b. Porous separator 205 is comprised of an electrically insulating material, or any of the materials previously discussed in connection with insulating spacer 112 in CDT cell 100 of FIG. 3. Examples of suitable electrically insulating material may include, but are not limited to, any of the electrically insulating materials previously discussed. Unlike CDT cell 100 wherein the electrolytic fluid flows through the cell in a serpentine fashion, the electrolytic fluid in CDT cell 200 flows through aperture 203 in the center of the cell where it is directed through porous separator 205 from aperture 203 to the outside edges of the cell and adjacent to and in intimate contact with the high surface area materials 204 or electrodes.

CDT cells that are used in the present invention may operate in a variety of different ways to remove ions from an electrolytic fluid. Preferably, the CDT cells that are used in the present invention operate in two bipolar cycles that are composed of three phases: clean, static rinse, and dynamic rinse phases. The cycles are bipolar in that the three phases, the clean, static rinse, and dynamic rinse phases, are each conducted in two opposite electric polarities.

FIG. 5 provides an illustration of a deionization system that may incorporate one or more CDT cells of the present invention. It is understood, however, that the present invention is not limited to the system of FIG. 5. As FIG. 5 illustrates, one or more CDT cells 100 is preferably in a system that comprises an electrical circuit 113 and a fluid circuit 114 wherein fluid circuit 114 regulates the flow of the fluid stream through one or more CDT cells 100 under the control of electrical circuit 113. Electrical •circuit 113 comprises, inter alia, a power supply 115 to power one or more CDT cells 100 and an amplifier 116, which is electrically connected across positive terminal 117a and negative terminal 117b and in electrical communication with processor 128 and switch 118 to control the flow of power and fluid to the cell(s) depending upon whether the cell(s) is charging (i.e., during the cleaning or deionization phase) or discharging (i.e., during the static rinse phase).

Fluid circuit 114 comprises, inter alia, a pump 119 to direct the flow of feed fluid in the direction of the arrows through the CDT cell(s), a valve 120 that is interposed between pump 119 and a electrolytic fluid feed reservoir 121, a pressure flow meter 122 to measure the pressure of the input fluid into the CDT cell(s), a fluid input conductivity meter 123 to measure the amount of ions present in the fluid at the input end of the cell(s), a fluid output conductivity meter 124 to measure the amount of ions present in the fluid at the output end of the cell(s), a plurality of output valves 125 to direct the outgoing flow of fluid from the cell(s) to either a clean fluid output 126, a waste fluid output 127, or into the electrolytic fluid reservoir 121. The system further comprises a processor 128 that is in electrical communication (see dashed lines on FIG. 5) with the conductivity meters 123 and 124, pressure flow meter 124, and the input 120 and output valves 125 to control the different phases of the process cycle. Additional components that may be added to fluid circuit 114 may include, for example, thermocouples to monitor the temperature at the fluid inlet and/or outlet end and pH sensors to measure the pH level at the inlet and/or outlet end which are in electrical communication with processor 128 for process control and monitoring. Processor 128 is also operatively connected to amplifier 116 which is connected across terminals 117a and 117b to switch 118 to control the charging or discharging of CDT cell(s) 100 based upon the readings from conductivity meters 123 and 124 and other criteria.

Based upon the measurements from conductivity meters 123 and 124, and/or other criteria, processor 128 will control amplifier 116 to either open switch 118 to charge cell(s) 100 for the clean, or deionization phase, of operation or close switch 118 or disconnect power from power supply 115 for discharge of cell(s) 100 i.e., the rinse phase. During the clean phase, a continuous supply of power is applied to the electrodes of CDT cell(s) 100. The clean phase can be viewed as the "charging" stage in which the electrodes of the CDT cell(s) are being charged during the process of removing the ions from the electrolytic fluid. Using the CDT cell 100 depicted in FIG. 3, an electrolytic fluid such as water travels through cell 100 in a serpentine fashion in the direction shown by the arrows. This allows the fluid to be in intimate contact with the high surface area materials 111 of opposite polarity that act as electrodes. The ions or other impurities within the electrolytic fluid become ionized and are electrostatically attracted to the electrodes, or the high surface area material 111, as the fluid progresses through cell 100. Referring to FIG. 5, the "clean" fluid, or fluid in which the ions are removed, progresses through and out of the cell(s) to clean fluid output 126. After a sufficient amount of ions are extracted from the fluid and become stored upon high surface area material 111, and the amount of ions in the output fluid begins to rise as the ion removal rate is reduced below the ion arrival rate in the input fluid, the "clean phase" is ended. A conductivity meter such as 124, or similar means to detemiine the amount of ions within the output water, may be used in conjunction with cell(s) 100 to detect the end of the clean phase. Thus, the time duration of the clean phase varies based a variety of factors that include the initial level of ions within the electrolyte, measured by conductivity meter 123 in comparison to the level of ions within the clean output, if any, and the ion storage locations of high surface area material 111.

During the next phase of operation of the CDT cell(s), or the static rinse phase, the flow of the electrolytic fluid is stopped by, for example, closing inlet valve 120, and the power supply is turned off by, for example, closing switch 118. This leads to a residual decaying voltage resulting from the capacitance energy discharge of the previous phase, or clean phase. The static rinse phase can be viewed as the "discharging" stage in which power is turned off to the electrodes of the CDT cell(s) and the stored energy of the cell(s) is being discharged. Energy is returned from the cell(s), a portion of which is being consumed by the internal and external resistive losses of the cell(s) and power supply. The other portion of energy allows for the rehydration of the ions stored on the high surface area material 111 in the static water that remain within the cell(s). This cycle may continue for a fixed period of time.

The last phase, or the dynamic rinse phase, begins after the static rinse phase is completed. During this phase, the electrolytic fluid flow is turned on to allow fluid to flow through the cell(s). However, the output of the cell(s) is directed to the waste fluid output 127. Power is supplied to the cell but the electrical polarity and value is chosen to reverse the residual cell voltage experienced during the static rinse phase. For example, a static rinse that begins at 0.5 V will be followed by a dynamic rinse at -0.5 V. The ionic concentration of the "waste" fluid output reaches its highest concentration, or peak release, due to the static rinse phase in which the ions were accumulating within the water trapped in the cell(s). The dynamic rinse phase continues for a fixed period of time during which the ions from the previous clean cycle are removed from the high surface area material, or electrodes. FIG. 6 provides an embodiment of one apparatus 130 of the present invention comprised of a plurality of CDT cells similar to the CDT cell 100 depicted in FIG. 3. Apparatus 130 is comprised of a top plate 131 and bottom plate 132 that are held together by screw clamp assemblies 133. Top and bottom plates 131 and 132 have at least one fluid inlet 134 and at least one fluid outlet 135 to allow the flow of an electrolytic fluid to be deionized through the apparatus. Sidewalls 136 are comprised of alignment rods to align the CDT cells 100 within a series and electrically connect CDT cells 100 to an outside power source. Sidewalls 136 are preferably encased with a gasketing material such as, but not limited to, silicone, rubber, or any other water impermeable material to retain the electrolytic fluid within the stack or array of CDT cells.

Apparatus 130 is further comprised of at least one pair of CDT stacks, or 137 and 138, that are disposed within the top and bottom plates 131 and 132 and are in fluid communication with the fluid inlets 134 and fluid outlets 135 as shown in FIG. 6. CDT cells 100 within stacks 137 and 138 are electrically connected and hydraulically connected with respect to each other in series. Apparatus 130 further comprises one or more dividers 139 that are preferably encased in or comprised of a fluid impermeable, non- corrosive material. Dividers 139 may provide additional structural support to the conductive substrates of the CDT cells within stacks 137 and 138 and may further electrically connect the CDT cells, or other electrical components contained within apparatus 130. Preferably, apparatus 130 further comprises an electrical input terminal or an electrical output terminal (not shown in FIG. 6) which are, in turn, electrically connected to a DC power source that are in electrical communication with the terminals on conductive substrates 107 of each CDT cell 100 within stacks 137 and 138. The electrical input terminal and electrical output terminals are of opposite polarity with respect to each other so that the alternating conductive supports may also be of opposite polarity.

Stacks 137 and 138 within apparatus 130 are aligned with each other such that adjacent cells share conductive substrates and are therefore in parallel electrically. Although apparatus 130 is shown as a monolithic structure in which stacks 137 and 138 share conductive substrates, it is anticipated that other arrangements of stacks 137 and 138 may be used to electrically connect stacks 137 and 138 in parallel. For example, stacks 137 and 138 may be housed in separate apparatuses but may still be electrically connected in parallel with respect to each other. During operation of the apparatus of FIG. 6, the electrolytic fluid to be deionized passes down through the left series of cells, or stack 137, and then back up through the right series of cells, or stack 138 in the direction shown by the arrows. The fluid flows first through water inlet 134 at top surface 131, then through stack 137, then through fluid outlet 135 at bottom surface 132, then through fluid inlet 134 at bottom surface 132, then through stack 138, and, finally out through water outlet 135 at top surface 131. The output fluid from the first stack, or stack 137, within the apparatus is in fluid communication with the input fluid for the second stack, or stack 138. Preferably, the output fluid from stack 137 becomes the input water for stack 138. The ionic content of electrolytic fluid decreases with the number of cells through which the water has passed. The ionic content is therefore greatest at the top left cell of stack 137 (or the CDT cell closest to water inlet 134 at top surface 131) and lowest at the top right cell of stack 138 (or the CDT cell closest to water inlet 134 at bottom surface 132). The cell beneath the top left cell has the second greatest ionic content and the cell beneath the top right cell has the second lowest ionic content.

FIG. 6a shows an equivalent circuit model of the apparatus of FIG. 6. As FIG. 6a illustrates, Rj has the lowest value and R^ has the highest value, R2 has the second lowest value and R^ has the second highest value, and so forth through the series of cells within the stack. When a voltage is placed across the entire stack, the parallel combination of Rt with R„ is similar in value to the parallel combination of R2 with R^. The parallel combination of resistances in adjacent cells will generally be similar throughout the stack. The voltage thus tends to be shared in all of the cells. The electrical arrangement of apparatus 130, in which the voltage is balanced as the fluid with variable ionic content progresses through the system, allows apparatus 130 to be powered by high voltage, low current power supplies rather than low voltage, high current power supplies, although, of course one can use the latter if desired. The amount of power to be supplied to apparatus 130 may vary depending upon the number of pairs of stacks within the apparatus and the number of cells in series within the each stack. For example, an apparatus, similar to the apparatus depicted in FIG. 6 but comprising 500 cells operating at a maximum of 100 volts per string or lower, may be powered using a commercially available, 100 kW, high voltage power supply.

Referring back to FIG. 6, the apparatus shown also includes an additional capacitor(s)140 that is electrically connected in parallel with each pair of CDT stacks or stacks 137 and 138. Capacitor 140, which is optional, may be used to further balance cell voltages during the de-ionizing process. The size of additional capacitor 140 may be determined by the ratio of ions in the fluid input and fluid output of the first CDT stacks, or 137, of the pair. For example, if the ratio of ions is low, such as a factor of 2, then capacitor 140 will be small or not required at all; however, if the ratio of ions is high, such as a factor of 100, then the additional capacitor size may have to be relatively large to effectively balance the cell voltages. In certain embodiments, the capacitance of the additional capacitor may be equal to the highest capacitance cell within the series. Additional capacitor 140 is shown to be comprised of the same material as the CDT cells of stacks 137 and 138, i.e., a conductive substrate and a high surface area material such as a carbon aerogel that forms the electrode. In other embodiments of the present invention, an external capacitor(s) (not shown in FIG. 6) may be used in addition to, or in lieu of capacitor 140. Capacitor 140 is preferably a "no flow" capacitor and may contain highly ionic water, or a different electrolyte, as its dielectric.

FIGs. 7, 8, and 9 illustrate different embodiments of series stacks comprised of the CDT cells of the present invention. The embodiments of FIG. 7, 8, and 9 are electrically and hydraulically connected in series. These series stacks may be, for example, used by themselves, used in an apparatus similar to the embodiment of FIG. 6, or used in systems similar to the embodiment depicted in FIG. 10. The series stacks of CDT cells in FIG. 7, 8, and 9 incorporate inactive cells, within the electrical and hydraulic series of cells, to provide increased electrical resistance in the fluid column between levels of CDT cells. This increased resistance within the cell may allow, inter alia, for control of electrolysis. Preferably, the number of inactive cells is equal to the number of active cells within the series stack.

FIG. 7 provides one embodiment of a series stack of CDT cells, such as CDT cell 100 in FIG. 3. CDT cells 100 are disposed within a fluid manifold 141 having a top surface 142 and bottom surface 143. Top surface 142 and bottom surface 143 each comprise at least one fluid inlet 144 and fluid outlet 145. Top surface 142 and bottom surface 143 are held together by screw clamp assembly 146. Fluid manifold 141 further comprises sidewalls 147 that extend between top surface 142 and bottom surface 143. Sidewalls 147 are preferably encased with a gasketing material such as, but not limited to, silicone, rubber, or any other water impermeable material to retain the electrolytic fluid within the stack or array of CDT cells. CDT cells 100 and inactive cell 148 are disposed within fluid manifold 141 and are in fluid communication with fluid inlet 144 and fluid outlet 145. Sidewalls 147 may be comprised of alignment rods to align the CDT cells 100 and inactive cells 148. In FIG. 7, the conductive substrates within each active CDT cell 100 may are in electrical communication with an input electrode 150 and an output electrode 151. Inactive cell 148 is comprised of a substrate which includes one or more alignment holes and one or more fluid apertures that are in the same arrangement as the conductive substrate in CDT cells 100. This allows the electrolytic fluid to flow through the series of alternating active CDT cells and inactive cells 148 in a serpentine fashion in the direction of the arrows in FIG. 7. For ease of manufacturing, the substrate in inactive cell 148 may be comprised of the same material as the conductive substrate in CDT cell 100. Inactive cell differs from an active CDT cell 100 in that it has an electrically insulating layer 149, rather that a high surface area material, that substantially covers the substrate. Insulating layer 149 may be comprised of any electrically insulating material including, but not limited to, alumina, polypropylene, polyester, polyimide, polycarbonate, PVC, polyamide, PBTP, KEVLAR® (a poly-paraphenylene terephthalamide manufactured by DuPont Corporation of Wilmington, Delaware), NOMEX® (a poly- metaphenylene diamin manufactured by DuPont Corporation of Wilmington, Delaware), and DELRTN® (an acetal resin manufactured by DuPont Corporation of Wilmington, Delaware). Unhke the high surface area material in active CDT cell 100, electrically insulating layer 149 does not remove any ions from the electrolytic fluid as it passes through the cell. Further, insulating layer 149 does not expose the electrolytic fluid to any electrical current, but rather, tries to maintain the electrolytic fluid at the same electrical potential as in the previous active cell 100 in the series. FIG. 8 provides another embodiment of a series stack incorporating CDT cells 100 of FIG. 3 and inactive cells 148. FIG. 8 differs from FIG. 7 in that inactive cells are placed at the end of the series of cells.

FIG. 9 provides a further embodiment of a series stack of the present invention incorporating CDT cells 200 of FIG. 4a and 4b. Similar to FIG. 7 and FIG. 8, substrate and a porous separator. Inactive CDT cells 217, similar to inactive cells 148 in FIG. 7 and FIG. 8, do not carry an electrical charge nor remove ions from the electrolytic fluid. In operation, fluid to be deionized flows through fluid inlet 211 and through the porous separators of CDT cells 200 wherein the ions within the fluid are attracted to the high surface area material, such as the carbon aerogel, of active cell 200 and are removed. The fluid, once it is passes through active cells 200, passes through the active cell container 215, and into the inactive cell container 216. The fluid then passes through the inactive CDT cells 217 prior to passing through fluid outlet 212.

FIG. 10 provides an embodiment of a system incorporating the series stack of active and inactive cells of FIG. 9. The system of FIG. 10 may be suitable, for example, for removing ions from high volumes of fluid, i.e., processing about one million or more gallons per day. As FIG. 10 illustrates, system 220 is comprised of an array 221 of series strings of manifolds 210, having active 200 and inactive cells 217, that are connected electrically in parallel with another array 222 of series string of manifolds 210. System 220 further comprises an input fluid header 223, an intermediate fluid header 224, and an output fluid header 225. Input fluid header 223 and output fluid header 225 are at the same voltage potential. The input electrical connection 213 and output electrical connection 214 of each manifold 210 is electrically connected to two voltage buses of opposite polarity 226 and 227 and one or more intermediate voltage buses 228. Voltage buses 226, 227, and 228 may comprise standard, commercially available high voltage power supplies. During operation, fluid to be deionized flows from fluid input header 223, through the first array 221 of manifolds to the intermediate fluid header 224, and then through the second array 222 of manifolds to the output fluid header 225. Both first array 221 and second array 222 may further comprise a blocked series of manifolds, or a"no flow" series of manifolds, that act as an additional capacitor to maintain the linear voltage division among the cells of the array. The additional capacitor is analogous to capacitor 140 in the apparatus of FIG. 6.

While the present invention has been particularly shown and described with reference to the presently preferred embodiments thereof, it will be understood by those skilled in the art that the invention is not limited to the embodiments specifically disclosed herein. Those skilled in the art will appreciate that various changes and adaptations of the present invention may be made in the form and details of these embodiments without departing from the true spirit and scope of the invention as defined by the following claims.

Claims

We claim:
1. A system for the removal of ions from a fluid, the system comprising: a first array of capacitive deionization cells, wherein the first array comprises: a first fluid inlet and a first fluid outlet, a plurality of capacitive deionization cells disposed between the first fluid inlet and the first fluid outlet, where each of the capacitive deionization cells within the array are connected electrically and hydraulically in series; and a second array of capacitive deionization cells, wherein the second array comprises a second fluid inlet that receives the fluid from the first fluid outlet and a second fluid outlet, a plurality of capacitive deionization cells disposed between the second fluid inlet and the second fluid outlet, wherein each of the cells within the second array are connected electrically and hydraulically in series, and the cells within the second array are electrically connected in parallel to the cells within the first array, such that the cell in the first array in which the fluid has the highest ionic content is in parallel with the cell in the second array in which the fluid has the lowest ionic content.
2. The system of claim 1 further comprising an additional capacitor that is electrically connected in parallel with the first array and the second array.
3. The system of claim 2 wherein the additional capacitor is comprised of the same material as the capacitive deionization cells in the first array and the second array.
4. The system of claim 2 wherein the additional capacitor is external to the system comprising the first and second arrays.
5. The system of claim 2 wherein the size of the additional capacitor is directly proportional to the ratio of ions at the first inlet to the ions at the second outlet. system of claim 1 further comprising: a third array of capacitive deionization cells, wherein the third array comprises: a third fluid inlet that receives the fluid from the second fluid outlet and a third fluid outlet, a plurality of capacitive deionization cells disposed between the third fluid inlet and the third fluid outlet, wherein each of the capacitive deionization cells within the array are connected electrically and hydraulically in series; and a fourth array of capacitive deionization cells, wherein the second array comprises a fourth fluid inlet that receives water from the third fluid outlet and a fourth fluid outlet, a plurality of capacitive deionization cells disposed between the fourth fluid inlet and the fourth fluid outlet, wherein each of the cells within the fourth array are connected electrically and hydraulically in series, wherein the cells within the third and fourth array are electrically connected in parallel to the cells within the first and second arrays, such that the cell in the first array in which the fluid has the highest ionic content is in parallel with the cell in the fourth array in which the fluid has the lowest ionic content.
apparatus for the removal of ions from a fluid, the apparatus comprising: a manifold comprising an at least one fluid inlet and an at least one fluid outlet; and an at least one pair of capacitive deionization stacks comprising a first stack and a second stack that are disposed within the manifold and are in fluid communication with the at least one fluid inlet and the at least one fluid outlet, wherein the first stack and second stack each comprises a plurality of capacitive deionization cells, the cells further comprising a plurality of layers, a pair of electrodes that are disposed upon a portion of each surface of the layers, and an at least one opening wherein the fluid is directed between the layers and contacts a portion of the electrodes prior to passing through the at least one opening to the adjoining cell, wherein each capacitive cell within the first stack and the second stack are connected electrically and hydraulically in series, and wherein the first stack and the second stack are electrically connected in parallel and are in fluid communication with each other such that the cell in the first stack in which the fluid has the highest ionic content is in parallel with the cell in the second stack in which the fluid has the lowest ionic content.
The apparatus of claim 7 further comprising an additional capacitor that is electrically connected in parallel to the capacitive deionization cells in the first stack and the second stack.
The apparatus of claim 8 wherein the layers of the first stack and the layers of the second stack comprise the same material.
The apparatus of claim 9 wherein the additional capacitor is comprised of the same material as the capacitive deiomzation cells in the first array and the second array.
The apparatus of claim 8 wherein the additional capacitor is external to the apparatus.
The apparatus of claim 8 wherein the additional capacitor is a no-flow capacitor.
The apparatus of claim 7 wherein the electrodes within the pair of electrodes comprises a high surface area material, a reticulated foam insulation spacer, and a conductive substrate that is conductively bonded with solder.
The apparatus of claim 13 wherein the conductive substrate is bonded to the high surface area material via sputtering, plasma spray, electro-plating, or an electro-less plating process.
The apparatus of claim 13 further comprising an additional layer of tin-lead alloy. The apparatus of claim 13 wherein the conductive substrate comprises a fiberglass composite sheet with a copper plated material adhered thereupon.
An apparatus for the removal of ions from a fluid, the apparatus comprising: a manifold comprising an at least one fluid inlet and an at least one fluid outlet; and a plurality of capacitive deionization cells disposed within the manifold and in fluid communication with the at least one fluid inlet and an at least one fluid outlet cells wherein each of the capacitive deionization cell comprises a pair of layers, a pair of electrodes that are disposed upon a portion of the facing surfaces of each of the layers, and an at least one opening within each layer wherein the fluid is directed between a portion of the electrodes prior to passing through the at least one opening to the adjoining cell, and a plurality of inactive cells that are connected hydraulically and electrically in series with the capactive deionization cells, wherein each of the inactive cells comprises a pair of insulating layers and an at least one opening within each layer wherein the fluid is directed between the insulating layers prior to passing through the at least one opening to the adjoining cell.
The apparatus of claim 17 wherein the inactive cells are interposed inbetween the capactive deionization cells.
The apparatus of claim 17 wherein the fluid flows through the capacitive deionization cells in the series prior to flowing through the inactive cells.
The apparatus of claim 17 wherein the number of capacitive deionization cells within the apparatus is equal to the number of the inactive cells.
The apparatus of claim 17 wherein the electrodes within the pair of electrodes comprises a high surface area material, a reticulated foam insulation spacer, and a conductive substrate that is conductively bonded with solder. The apparatus of claim 21 wherein the conductive substrate is bonded to the high surface area material via sputtering, plasma spray, electro-plating, or an electro-less plating process.
The apparatus of claim 17 further comprising an additional layer of tin-lead alloy.
The apparatus of claim 17 wherein the conductive substrate comprises a fiberglass composite sheet with a copper plated material adhered thereupon.
PCT/US2001/016383 2000-05-22 2001-05-21 Capacitive deionization cell structure for control of electrolysis WO2001090443A1 (en)

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US6781817B2 (en) 2000-10-02 2004-08-24 Biosource, Inc. Fringe-field capacitor electrode for electrochemical device
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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6628505B1 (en) 2000-07-29 2003-09-30 Biosource, Inc. Flow-through capacitor, system and method
US6781817B2 (en) 2000-10-02 2004-08-24 Biosource, Inc. Fringe-field capacitor electrode for electrochemical device
US7833400B2 (en) 2001-04-18 2010-11-16 Biosource, Inc. Method of making a flow through capacitor
US8002963B2 (en) 2001-04-18 2011-08-23 Biosource, Incorporated Charge barrier flow-through capacitor-based method of deionizing a fluid
US7368191B2 (en) 2001-07-25 2008-05-06 Biosource, Inc. Electrode array for use in electrochemical cells
WO2006121348A2 (en) * 2005-05-09 2006-11-16 Alan Teehu Wichman Improvements to water treatment processes
WO2006121348A3 (en) * 2005-05-09 2007-03-29 Alan Teehu Wichman Improvements to water treatment processes
WO2010014615A1 (en) * 2008-07-31 2010-02-04 Lawrence Livermore National Security, Llc Captacitive de-ionization electrode
US8398840B2 (en) 2008-07-31 2013-03-19 Lawrence Livermore National Security, Llc Capacitive de-ionization electrode
EP2738142A1 (en) * 2012-11-29 2014-06-04 Samsung Electronics Co., Ltd Capacitive deionization apparatus and methods of treating fluid using the same
US10023479B2 (en) 2013-06-12 2018-07-17 Samsung Electronics Co., Ltd. Capacitive deionization apparatus and methods of treating a fluid using the same

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