Electrodeionization apparatus
AssigneeIP Holding Company
InventorsGary C. Ganzi, Frederick Wilkins, Anthony J. Giuffrida, Christopher Griffin
Life of this patent
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Abstract
An electrodeionization apparatus is provided for removing ions from liquids. The apparatus is particularly well-adapted for the removal of large, heavily hydrated, highly charged or weakly ionized molecules or complexes from feed water. Such removal is achieved by substituting, in at least one section of the apparatus, ion exchange membranes and/or resins having lower crosslinking and/or lower selectivity, for the ion exchange membranes commonly used in electrodeionization systems. Methods for reducing the electrical resistance across the membrane also are provided.
Claims164
An electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the membranes having a conductance, wherein at least one membrane, comprises means for allowing an increase in the transfer of large or highly charged ions across the membrane on an equivalent weight basis of at least 25%, when subjected to an increase in voltage across the membrane causing an increase in electric current across the membrane of the order of two times or less.
An electrodeionization apparatus for the removal of ions from a liquid comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, wherein the apparatus includes means for removing at least about 70% by weight of sulfate ions contained in the liquid when operated under standard operating conditions.
An electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the membranes having a conductance, wherein at least one membrane comprises an ion exchange resin selected from the group consisting of anion exchange resins that are crosslinked at less than about 6% and cation exchange resins that are crosslinked at less than about 8%.
In a process for conducting electrodeionization in an electrodeionization apparatus comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the membranes having a conductance, the improvement comprising,
- using at least one membrane which comprises means for allowing an increase in the transfer of large or highly charged ions across the membrane on an equivalent weight basis of at least 25%, when subjected to an increase in voltage across the membrane causing an increase in electric current across the membrane of the order of two times or less.
The improvement of claim 100 further characterized in that the ion exchange resin in the depleting compartment is a cation exchange resin.
In a process for conducting electrodeionization in an electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the improvement comprising,
- using apparatus which includes means for removing at least about 80% by weight of silica ions contained in a liquid, said apparatus including at least one membrane comprising an ion exchange resin selected from the group consisting of anion exchange resins that are crosslinked at less than about 6% and cation exchange resins that are crosslinked at less than about 8%.
In a process for conducting electrodeionization in an electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the improvement comprising,
- using apparatus which includes means for removing at least about 70% by weight of sulfate ions contained in a liquid while operating the apparatus under standard operating conditions.
In a process for conducting electrodeionization in an electrodeionization apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the membranes having a conductance, the improvement comprising,
- using a permeable membrane which comprises an ion exchange resins selected from the group consisting of anion exchange resins crosslinked at less than about 6% and cation exchange resins crosslinked at less than about 8%.
Electrodeionization apparatus for the removal of ions from a liquid, the apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the cation exchange membrane containing a cation exchange resin, said resin having a moisture content of at least about 45%.
Electrodeionization apparatus for the removal of ions from a liquid, the apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the anion exchange membrane containing an anion exchange resin, said resin having a moisture content of at least about 45%.
Electrodeionization apparatus for the removal of ions from a liquid, the apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the apparatus further containing at least one neutral ion exchange membrane comprising an anion exchange resin and a cation exchange resin, at least one of said resins having a moisture content of at least about 45%.
Electrodeionization apparatus comprising a plurality of electrodeionization stages, each stage comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, each ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the membranes having a conductance, at least one stage including a permeable membrane which comprises means for allowing an increase in the transfer of large or highly charged ions across the membrane an equivalent weight basis of at least 25%, when subjected to an increase in voltage across the membrane causing an increase in electric current across the membrane of the order of two times or less.
Electrodeionization apparatus comprising a plurality of electrodeionization stages, each stage comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, at least one stage including an anion permeable membrane containing an ion exchange resin, when the resistance of the anion exchange resin contained in the membrane to silica relative to hydroxide ions is less than about 4:1 when measured using a DC conductance test.
Electrodeionization apparatus comprising a plurality of electrodeionization stages, each stage comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, at least one stage including an anion permeable membrane containing an anion exchange resin, wherein the resistance of the anion exchange resin contained in the membrane to sulfate relative to hydroxide ions is less than about 2:1 when measured using a DC conductance test.
Electrodeionization apparatus comprising a plurality of electrodeionization stages, each stage comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, at least one stage including a permeable membrane which comprises an ion exchange resin selected from the group consisting of anion exchange resins crosslinked at less than about 6% and cation exchange resins crosslinked at less than about 8%.
In the method of using electrodeionization apparatus for the removal of ions from a liquid, the apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the improvement which comprises providing the apparatus with at least one membrane which comprises an ion exchange resin selected from the group consisting of anion exchange resins crosslinked at less than about 6% and cation exchange resins crosslinked at less than about 8%, and operating the apparatus under conditions that permit removal of silica ions to a level of less than about 50 parts per billion.
Electrodeionization apparatus for the removal of ions from a liquid, the apparatus comprising at least one ion concentrating compartment positioned adjacent to at least one ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the apparatus further comprising at least one neutral ion exchange membrane, wherein at least one ion exchange resin contained in the depleting compartment comprises a resin selected from the group consisting of anion exchange resins crosslinked at less than about 6% and cation exchange resins crosslinked at less than about 8%.
In a process for conducting electrodeionization in an electrodeionization apparatus comprising at least one stage, said at least one stage comprising an ion concentrating compartment positioned adjacent to an ion depleting compartment, the ion depleting compartment comprising an ion exchange resin positioned between an anion exchange membrane and a cation exchange membrane, the apparatus further including a concentrate stream, the improvement comprising,
- applying an AC overlay to at least one electrodeionization stage, and further wherein said at least one electrodeionization stage includes either one or both of an ion exchange resin or an ion exchange membrane which comprises an ion exchange resin selected from the group consisting of anion exchange resins crosslinked at less than about 6% and cation exchange resins crosslinked at less than about 8%.
Dependencies are inferred from the claim text.