Classifications

• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
  • C02F1/4691—Capacitive deionisation
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D57/00—Separation, other than separation of solids, not fully covered by a single other group or subclass, e.g. B03C
  • B01D57/02—Separation, other than separation of solids, not fully covered by a single other group or subclass, e.g. B03C by electrophoresis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
  • B01D61/44—Ion-selective electrodialysis
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
  • B01D61/44—Ion-selective electrodialysis
  • B01D61/46—Apparatus therefor
  • B01D61/461—Apparatus therefor comprising only a single cell, only one anion or cation exchange membrane or one pair of anion and cation membranes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
  • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
  • B01D61/44—Ion-selective electrodialysis
  • B01D61/46—Apparatus therefor
  • B01D61/50—Stacks of the plate-and-frame type
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F1/00—Treatment of water, waste water, or sewage
  • C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
  • C02F1/461—Treatment of water, waste water, or sewage by electrochemical methods by electrolysis
  • C02F1/46104—Devices therefor; Their operating or servicing
  • C02F1/46109—Electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/0029—Processes of manufacture
• • C—CHEMISTRY; METALLURGY
  • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
  • C02F2201/00—Apparatus for treatment of water, waste water or sewage
  • C02F2201/002—Construction details of the apparatus

Definitions

• the invention relates to an apparatus for removal of ions, the apparatus being provided with a housing, the apparatus comprising:
• a water outlet for letting water out of the interior of the housing
• a first electrode being provided with a current collector
• a connector to connect the current collector inside the housing to an electrical source outside the housing.
• a method for water purification is by capacitive deionisation, using an apparatus provided with a flow through capacitor (FTC) for removal of ions in water.
• the FTC functions as an electrically regenerable cell for capacitive deionisation.
• ions are removed from an electrolyte and are held in an electric double layers at the electrodes.
• the electrodes can be (partially) electrically regenerated to desorb such previously removed ions without adding chemicals.
• the apparatus for removal of ions comprises one or more pairs of spaced apart electrodes (a cathode and an anode) and a spacer, separating the electrodes and allowing water to flow between the electrodes.
• the electrodes are provided with current collectors or backing layers that are generally adjacent to or very near the electrodes and a material to store the ions.
• Current collectors are electrically conductive and transport charge in and out of the electrodes.
• the apparatus is provided with a housing comprising a water inlet for letting water in the housing and a water outlet for letting water out of the housing.
• a housing comprising a water inlet for letting water in the housing and a water outlet for letting water out of the housing.
• a charge barrier may be placed adjacent to an electrode of a flow-through capacitor.
• the term charge barrier refers to a layer of material which is permeable or semi-permeable and is capable of holding an electric charge. Ions are retained or trapped, on the side of the charge barrier towards which the like-charged ions migrate.
• a charge barrier may allow an increase in ionic efficiency, which in turn allows energy efficient ion removal.
• a problem with the apparatus for removal of ions is that the efficiency may be low and/or that the efficiency may deteriorate over time.
• the present invention provides an apparatus for removal of ions, the apparatus being provided with a housing, the apparatus comprising:
• a water outlet for letting water out of the interior of the housing
• a first electrode being provided with a current collector
• a connector to connect the current collector to an electrical source outside the housing, wherein the connector is provided with metal and the current collector is clamped by the connector constructed and arranged to conduct the electricity to and from the current collector and the apparatus is constructed and arranged to avoid contact between the water and the metal of the connector.
• Figure 1 shows a schematic cross-section of an apparatus for removal of ions according to the invention
• Figure 2 shows a schematic cross-section of an apparatus for removal of ions according to another embodiment of the invention
• Figure 3 discloses a cross section along the line A-A of the apparatus of figure 1 ; and, Figure 4 shows a schematic cross-section of an apparatus for removal of ions according to a further embodiment of the invention.
• Figure 1 shows a schematic cross-section of an apparatus for removal of ions according to the invention.
• the apparatus may have a housing comprising a first housing part 1 and a second housing part 3 made of a relatively hard material e.g. a hard plastic.
• a relatively hard material e.g. a hard plastic.
• Adhesive, seals or O-rings may be used to improve the watertightness of the housing.
• the housing is provided with a water inlet 7 and a water outlet 9. During ion removal from the water, the water will flow from the inlet 7 to the outlet 9 through the spacers 1 1 which separates the first electrode and the second electrode from each other.
• the electrodes are clamped within the housing to provide a water leakage free apparatus.
• the ions (anions and cations) will be removed from the water flowing through the spacer 1 1.
• the electrodes may be regenerated by releasing the potential difference and electrically discharging the electrodes. This will the ions will be released form the electrodes into the water flowing through the spacer. This will result in an increase in the ion content in the water in the spacer and this water will be flushed out of the spacer.
• the electrodes are regenerated and can be used again for attracting ions.
• the electrical potential differences between the anode and the cathode are rather low, for example lower than 2 Volt, preferably lower than 1 ,7 Volt and even more preferably lower than 1 ,4 Volt. It is important that the electrical resistance of the electrical circuit is sufficiently low.
• the current collectors 13 of the first electrode are bundled together with the first connector 17 and the current collectors 15 of the second electrode are bundled together with the second connector 19.
• the first connector 17 is provided with two connector portion e.g. clamps 18 for clamping the first electrodes portions 13 between the clamps 18.
• the clamps 18 may be made from carbon, for example graphite blocks.
• the clamps 18 may be provided with a recess so as to better clamp the current collectors 13 of the first electrode and to optimize the contact surface between the current collector 13 of the first electrodes and the clamps 18.
• two clamps 18 may be pressed against multiple current collectors of the first electrode 13 so as to press the current collectors 13 together and subsequently an adhesive may be used to permanently fix the clamps 18 with the current collectors 13 in a watertight manner.
• a nut and bolt may be used to press the current collectors 13 together with the clamps so as to avoid water metal contact of the connector.
• the contact surface of the current collector and the connector may be made of the same material, for example carbon.
• An advantage of carbon is that it does not corrode in the water and that it is relatively cheap compared to non-corrosive metals.
• the pressure to clamp the current collector 13, 15 to the connector 17, 19 may be at least 0.1 Bar, preferably at least 0.5 Bar and less than 15 Bar preferably less than 10 Bar and most preferably less than 5 Bar.
• the first connector 17 may be provided with a metal insert 24 which provides a good electrical connection between the carbon and the insert.
• the connector may be provided with a screw 20 for providing contact with the insert 24 through a feed through in the housing.
• the connector 17 may be glued against the housing so as to avoid contact of the water in the housing with the metal insert 24 or the screw 20 which may also be made out of metal. In this way corrosion of the metal insert and the screw may be prevented. If both the insert 24 and the screw 20 are made from metal good electrical contact between the two is assured.
• the second connector 19 may be provided with three connector portions e.g. clamps 18 according to a further embodiment of the invention.
• the clamps 18 may be box shaped and may be used to clamp the current collectors 15 of the second electrodes in between.
• the clamps 18 may be made from carbon, for example graphite.
• the second connector 19 may be pressed against multiple current collectors 15 so as to press the collectors 15 together and subsequently an adhesive may be used to permanently fix the clamps 18 with the current collectors 15 in, optionally, a watertight manner.
• the second connector 19 may be provided with the clamps provided with a recess of the first connector 17.
• the box shaped clamps of the second connector 19 may also be used as an alternative to the clamps with a recess of the first connector 17.
• the second connector 19 may be positioned against the housing 1 , 3.
• the second connector 19 may be connected to an electrical power source.
• a water tight connection may be provided between the housing and the second connector 19 at a position where the connector 19 is positioned against the housing.
• a feed through is provided through the housing 1 , 3 at a position where the second connector is positioned against the housing 1 ,3.
• the feed through may be provided with a metal screw 20 on which the cable 22 connecting to the electrical power source PS may be connected.
• the source PS may be controlled by controller CN to control the operation of the apparatus for removal of ions.
• the electrodes may be made substantially metal free to keep them corrosion free in the wet interior of the housing and at the same time cheap enough for mass production.
• the electrodes may be produced from a current collector 13, 15 provided with a substantially metal free electrically conductive high surface area layer, or self supporting film, which may contain activated carbon, carbon nanotubes or carbon aerogels on both sides which are in contact with the water.
• the electrode is provided with a material to store ions, for example a high surface area layer which is a layer with a high surface area in square meter per weight of layer material e.g.>500m 2 /gr.
• Figure 2 discloses a second connector 19 according to a further embodiment of the invention.
• the connector 19 is provided with multiple clamps 18 which are used to clamp multiple current collectors 15 of the second electrode individually together.
• the connectors 19 may be produced by pressing the current collectors 15 of the second electrode and the clamps 18 together and providing an adhesive around it to make a permanent connection, which optionally may be watertight to avoid water metal contact.
• the connector 19 may also be mounted against the housing 3 with the adhesive. Subsequently a feed through for example a metal screw 20 may be provided through the housing 3 into the clamp and the multiple current collectors 15 of the second electrode so as to connect the electrode with a power source via the cable 22.
• Figure 3 discloses a the cross-section along line A-A of the apparatus of figure 1. It shows the second electrode 15 with the second connector 19.
• the housing is provided with a space 21 for allowing water to flow around the electrodes and the spacers 1 1 and a second passage 23 for allowing water to collect from all the spacers 1 1 and flow through the outlet 9 (of figure 1 ).
• the connector 17 for connecting the first electrode portions 13 is also shown.
• Figure 1 is a cross section along the line B-B of figure 3.
• Figure 4 shows a schematic cross-section of an apparatus for removal of ions according to a further embodiment of the invention with a part of the housing removed.
• the apparatus is build up out of 10 flow through capacitor stacks 41.
• the flow through capacitor stack may be provided with repeating units of a first electrode, a spacer and a second electrode.
• the first current collectors 43 of the first electrode are bundled and/or clamped together with a connector 45.
• the second current collectors of the second electrode may be equally bundled/clamped together.
• the connector 45 comprises connector parts 49 provided with carbon e.g. graphite to clamp the current collectors together.
• the pressure to clamp the current collector 43 to the connector 45 may be at least 0.1 Bar, preferably at least 0.5 Bar and less than 15 Bar preferably less than 10 Bar and most preferably less than 5 Bar. This range is advantageous because it assures a good electrical conductivity while not damaging the connector parts.
• the current collectors 43 and the connector parts 49 may both be made of the same material e.g. carbon to lower the electrical resistivity between the current collector 43 and the connector 45.
• the connector part may be provided with metal e.g. copper inserts 51 .
• the inserts 51 are prefabricated inside the connector parts 49 so as to assure low electrical resistivity between the metal insert 51 and the connector part 49.
• the connector 45 may be provided with a metal rod 53 made of, for example copper to electrically connect all the connector parts 49 via their metal inserts 51 to a power source (not shown).
• the metal inserts 51 and the metal rod 53 will be shielded of from the water inside the apparatus by resin 52 which is applied to the connector 45.
• the metal e.g. copper rod and/or the metal insert may improve the conductivity of the connector.
• resin petroleum jelly paraffin or wax may be provided to the connector so as to avoid water metal contact.
• An advantage of petroleum jelly, paraffin or wax may be that it may be applied in liquid form at a high temperature whereby it solidifies after cooling. Whenever the apparatus needs to be opened for repair or investigation the petroleum jelly, paraffin or wax may be melted away.
• the apparatus is provided with a housing 56 comprising the top and bottom part 55,
• the top and/or bottom part 55, 57 of the housing is provided with a feed-through 59 allowing the connector 45 to make a connection with the power source outside the housing 56.
• a plastic insert may be provided in the housing to make it water tight.
• Water may be provided to an interior of the apparatus via a water inlet, the water is allowed to flow around the flow through capacitor stacks 41 and may enter the stacks via the spacers.
• the flow through capacitor stack 41 is provided with a square hole in the middle of the stack.
• a circular tube 65 is provided, via the space between the square hole and the tube the water will flow to an outlet.
• the interior of the tube 65 may be provided with a nut and bold so as to clamp the capacitor stacks 41 between the upper and bottom part 57, 55 of the housing.
• the efficiency of the apparatus may be guarantied for a relatively long period since the water in the interior of the housing is not in contact with the metal insert 51 and rod 53 and therefore corrosion will not deteriorate the operation of the apparatus.
• the electrodes may be made metal free by making them from carbonaceous material, for example activated carbon, which may be bound together in a polytetrafluoroethylene (TeflonTM) matrix or carbon aerogels.
• the electrodes, which may be used in FTC cells may be treated with a concentrated salt solution to promote the ion removal capacity of the electrodes as well as ion conductivity and hence speed of removal.
• the material to store the ions may comprise a high surface area layer e.g. a porous carbon layer, which can be a flexible layer, or a non flexible layer.
• a high surface area layer e.g. a porous carbon layer, which can be a flexible layer, or a non flexible layer.
• the carbon used in the electrode layer may comprise activated carbon, and optionally any other carbonaceous material, such as carbon black, carbon aero-gels, carbon nanofibres graphene or carbon nanotubes.
• the carbon may be chemically activated carbon or may be steam activated carbon.
• the carbon may have a high surface area of at least 500 m2/g, preferably at least 1000 m2/g, and more preferable at least 1500 m2/g.
• the anode and cathode may even be made out of different carbonaceous materials.
• Well known non-flexible carbon layers are made from carbon aerogels. These aerogels are often manufactured as composite paper: non-woven paper made of carbon fibers, impregnated with resorcinol- formaldehyde aerogel, and pyrolyzed. Depending on the density, carbon aerogels may be electrically conductive, making composite aerogel paper useful for electrodes in capacitors or deionization electrodes.
• the carbon may be present in the electrode in a concentration of at least 60%, preferably at least 70%, more preferable at least 80%, or even at least 85% by weight of the dry electrode.
• thermoplastic or viscoelastic material such as latex or curable resins to form monoliths from powdered material is common.
• Examples of carbon layers that use Poly Fluor Tetra Etheen (PTFE) as binder material are the PACMMTM series (from Material Methods).
• One embodiment of the invention comprises an active carbon fiber woven layer or carbon cloth, e.g. the Zorflex ® range (from Chemviron Carbon).
• One preferred embodiment of the invention comprises a carbon coating comprising: polyelectrolyte; binder; and, carbon, which can be coated directly onto the current collector with a method described in a patent application with application number PCT/EP2008/06 incorporated herein by reference.
• the electrode may comprise a current collector.
• the current collector may be made from an electrically conducting material. Suitable metal free materials are e.g. carbon, such as graphite, graphene, graphite sheets or carbon mixtures with high graphite content. It is advantageous to use a metal free electrode because metals are expensive and introduce a risk of corrosion.
• the current collector is generally in the form of a sheet. Such sheet is herein defined to be suitable to transport at least 33 Amps/m 2 and up to 2000 Amps/m 2 . The thickness of a graphite current collector then typically becomes from 100 to 1000 micrometer, generally 200 to 500 micrometer.
• the spacer material may comprise an, inert type material, such as an open space synthetic material and can be any material made from a polymer, plastic or fiberglass.
• the spacer can be a porous or non porous, woven or non woven material .
• the spacer may be prepared from a material that is electrically insulating, but allows ion conductance. Suitable spacers are for example the Nitex ® range or Petex ® range (from Sefar), which are open mesh fabrics or filter fabrics, made from polyamide or polyetheentereftalate.
• the flow through capacitor may comprise a charge barrier.
• the charge barrier comprises a membrane, selective for anions or cations, or certain specific anions or cations and which may be placed between the electrode and the spacer.
• the charge barrier may be applied to the high surface area electrode layer as a coating layer or as a laminate layer.
• Suitable membrane materials may be homogeneous or heterogeneous.
• Suitable membrane materials comprise anion exchange and/or cation exchange membrane materials, preferably ion exchange materials comprising strongly dissociating anionic groups and/or strongly dissociating cationic groups.
• examples of such membrane materials are NeoseptaTM range materials (from Tokuyama), the range of PC-SATM and PC-SKTM (from PCA GmbH), ion exchange membrane materials ex Fumatec, ion exchange membrane materials RalexTM (from Mega) or the ExcellionTM range of heterogeneous membrane material (from Snowpure).
• a FTC may comprise at least one repeating unit of:
• the number of repeating units in a FTC stack is limited by the number of electrode layers than can be practically bundled and connected to the connector. It is preferred that the number of repeating units in a FTC is at least 1 , preferably at least 5, more preferably at least 10, still more preferably at least 20. For practical reasons, the number of repeating units is generally not more than 200, preferably not more than 150, not more than 100, or even not more than 50.
• the stack may be compressed at a pressure of less than 4 bar, preferably not more than 1 .5 bar.
• the stack may be provided with, so called, floating electrodes.
• Floating electrodes are electrodes not directly being connected to a power source but receiving their charge from other electrodes in the stack which are connected to a power source.
• Floating electrodes may be positioned parallel and in between the master electrodes in the stack.
• the invention may be used to connect the master electrodes in the stack to the power source.
• An advantage of using floating electrodes is that the voltages through the connector will be higher while the currents through the connector will be lower. Electrical resistivity in the connector may be lowered significantly by using floating electrodes.
• the electrodes can also be in the configuration of an FTC stack in spirally wound form.
• the invention may take the form of a computer program containing one or more sequences of machine-readable instructions describing a method as disclosed above, or a data storage medium (e.g. semiconductor memory, magnetic or optical disk) having such a computer program stored therein.
• a data storage medium e.g. semiconductor memory, magnetic or optical disk

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Water Supply & Treatment (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• Electrochemistry (AREA)
• Urology & Nephrology (AREA)
• Hydrology & Water Resources (AREA)
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• Molecular Biology (AREA)
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• Water Treatment By Electricity Or Magnetism (AREA)

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Citations (6)

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• 2010
  • 2010-04-29 EP EP10161497.2A patent/EP2383757B1/en active Active
• 2011
  • 2011-04-28 US US13/641,608 patent/US8968544B2/en active Active
  • 2011-04-28 JP JP2013506666A patent/JP5881086B2/ja active Active
  • 2011-04-28 EP EP11718017A patent/EP2564406A1/en not_active Withdrawn
  • 2011-04-28 WO PCT/EP2011/056782 patent/WO2011135048A1/en not_active Ceased
  • 2011-04-28 CN CN201180020914.9A patent/CN102884007B/zh active Active

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