DEVICE AND METHOD FOR THE ELECTRODEIONIZATION OF A LIQUID

Abstract

A device for the electrodeionization of a sample liquid. The device has an anode chamber having two openings and an anode, a cathode chamber having two openings and a cathode, and a treatment chamber, that is arranged between the anode chamber and the cathode chamber and has two openings and ion exchanger. The anode chamber and the cathode chamber are separated from the treatment chamber in each case by a permselective membrane and an energy source is operatively connected to the anode and the cathode. In addition, a method for the electrodeionization of a sample liquid is provided.

Claims

1. A device (1) for electrodeionization of a sample liquid comprising: an anode chamber (10) comprising two openings (11, 12) and an anode (13); a cathode chamber (20) comprising two openings (21, 22) and a cathode (23); a treatment chamber (30) located between the anode chamber (10) and the cathode chamber (20) comprising two openings (31, 32) and ion exchanger, wherein the anode chamber (10) and the cathode chamber (20) are in each case separated from the treatment chamber (30) by a permselective membrane (33); and an energy source (40) operatively connected to the anode (13) and the cathode (23); wherein one of the openings (31; 32) of the treatment chamber (30), the openings (21, 22) of the cathode chamber (20) and one of the openings (11; 12) of the anode chamber (10) are connected to each other such that the treatment chamber (30) is operatively connected to the cathode chamber (20) and the cathode chamber (20) is operatively connected to the anode chamber (10).

2. A device (1) for electrodeionization of a sample liquid comprising: an anode chamber (10) comprising two openings (11, 12) and an anode (13); a cathode chamber (20) comprising two openings (21, 22) and a cathode (23); a treatment chamber (30) located between the anode chamber (10) and the cathode chamber (20) comprising two openings (31, 32) and ion exchanger, wherein the anode chamber (10) and the cathode chamber (20) are in each case separated from the treatment chamber (30) by a permselective membrane (33); and an energy source (40) operatively connected to the anode (13) and the cathode (23); wherein one of the openings (31; 32) of the treatment chamber (30), the openings (11, 12) of the anode chamber (10) and one of the openings (21; 22) of the cathode chamber (20) are connected to each other such that the treatment chamber (30) is operatively connected to the anode chamber (10) and the anode chamber (10) is operatively connected to the cathode chamber (20).

3. Device (1) according to claim 1, wherein the one opening (31; 32) of the treatment chamber (30), the openings (11, 12) of the anode chamber (10) and the one opening (21; 22) of the cathode chamber (20) are connected to each other in such a way that the supplied sample liquid in the treatment chamber (30) is guided substantially in the direction of gravity and is guided in the anode chamber (10) and the cathode chamber (20) substantially against the direction of gravity.

4. Device (1) according to claim 1, wherein a conductivity sensor (51) is arranged in front of the unconnected openings (31; 32) of the treatment chamber (30).

5. Device (1) according to claim 2, wherein a conductivity sensor (52) is arranged between the treatment chamber (30) and the anode chamber (10).

6. Device (1) according to claim 5, comprising a degassing unit (41) arranged after the conductivity sensor (52), wherein a further conductivity sensor (53) is arranged after the degassing unit (41).

7. Device (1) according to claim 4, wherein at least one of the conductivity sensors (51; 52; 53) comprises a temperature sensor.

8. Device (1) according to claim 1, comprising at least one flow sensor arranged in front of at least one of the following: one of the openings (31; 32) of the treatment chamber (30); one of the openings (11; 12) of the anode chamber (10); one of the openings (21; 22) of the cathode chamber (20).

9. Device (1) according to claim 2, wherein the ion exchanger is a cation exchange resin.

10. Device (1) according to claim 1, wherein the ion exchanger is a color-indicating ion exchanger, in particular a color-indicating cation exchange resin.

11. Device (1) according to claim 1, wherein the treatment chamber (30) is formed at least partially transparent, in particular along the openings (31, 32) of the treatment chamber (30).

12. Device (1) according to claim 11, comprising an optical sensor for monitoring the ion exchanger.

13. Device (1) according to claim 4, comprising an electronic measuring system, which records and processes at least one of the following: signal from at least one of the conductivity sensors; signal from at least one of the temperature sensors; signal from at least one of the flow sensors; signal from at least the optical sensor; a voltage of the power source (40); a current of the power source (40).

14. Device (1) according to claim 1, wherein at least one of the openings (31, 32) of the treatment chamber (30) comprises a filter unit.

15. Device (1) according to claim 1, comprising at least one ion-conducting membrane, arranged in at least one of the following: anode chamber (10) between the anode (13) and the permselective membrane (33) facing the anode (13); cathode chamber (20) between the cathode (23) and the permselective membrane (33) facing the cathode (23).

16. Device (1) according to claim 1, wherein the treatment chamber (30) is exchangeable.

17. Treatment chamber (30) for use in a device (1) according to claim 1, having a substantially cuboid base structure and comprising two mutually spaced apart openings (31, 32) and two mutually opposite side surfaces, each substantially formed by a permselective membrane (33).

18. Treatment chamber (30) according to claim 17, wherein the mutually opposite side surfaces each comprise a substantially rectangular frame forming part of the basic structure on which a permselective membrane (33) is adhesively applied.

19. Treatment chamber (30) according to claim 17, wherein a further opening for filling ion exchanger and/or a further opening for degassing is provided adjacent one of the openings (31; 32), wherein preferably at least one of the further openings is closable in a water-tight and gas-tight manner.

20. Treatment chamber (30) according to claim 17, wherein at least one of the openings is covered by a filter unit.

21. Treatment chamber (30) according to claim 17, wherein the outer sides of the side surfaces formed substantially by a permselective membrane (33) each are provided with detachably fixed protective elements, in particular with rigid plates.

22. Method for the electrodeionization of a sample liquid, comprising the steps of: applying a voltage to an anode (13) and cathode (23) spatially separated from each other by two permselective membranes (33a, 33b); the at least partial flow of the sample liquid through a treatment chamber (30) which is at least partially filled with ion exchangers and is bounded by the two permselective membranes (33a, 33b); then the at least partial flow of the sample liquid through an anode chamber (10), which is arranged between the anode (13) and one of the permselective membranes (33a); then the at least partial flow of the sample liquid through a cathode chamber (20), which is arranged between the cathode (23) and the other permselective membrane (33a).

23. Method for the electrodeionization of a sample liquid, comprising the steps of: applying a voltage to an anode (13) and cathode (23) spatially separated from each other by two permselective membranes (33a, 33b); the at least partial flow of the sample liquid through a treatment chamber (30) which is at least partially filled with ion exchangers and is bounded by the two permselective membranes (33a, 33b); then the at least partial flow of the sample liquid through a cathode chamber (20), which is arranged between the cathode (23) and the other permselective membrane (33b); the at least partial flow of the sample liquid through an anode chamber (10), which is arranged between the anode (13) and one of the permselective membranes (33a).

24. Method according to claim 22, wherein the at least partial flow through the treatment chamber (30), which is at least partially filled with ion exchangers, takes place substantially in the direction of gravity; the at least partial flow through the anode chamber (10) takes place against the direction of gravity; and the at least partial flow through the cathode chamber (20) takes place against the direction of gravity.

25. Method according to claim 22, comprising the further step of: measuring the specific conductivity of the sample liquid before the step of the at least partial flow of the sample liquid through the treatment chamber (30) which is at least partially filled with ion exchangers and is bounded by the two permselective membranes (33a, 33b).

26. Method according to claim 22, comprising the further step of: measuring the specific conductivity of the sample liquid after the step of the at least partial flow of the sample liquid through the treatment chamber (30) which is at least partially filled with ion exchangers and is bounded by the two permselective membranes (33a, 33b).

27. Method according to claim 26, comprising the further steps of: degassing of at least a part of the sample liquid; and subsequently additional measurement of specific conductivity after the step of measuring the specific conductivity of the sample liquid.

28. Method according to claim 22, comprising the further step of: integrated, continuous measurement of the sample liquid flow rate.

Description

[0067] Embodiment examples of the present invention are explained in more detail below by reference to the figures, wherein:

[0068] FIG. 1 shows a schematic representation of an embodiment of a device according to the invention;

[0069] FIG. 2 shows a schematic representation of an embodiment of a device according to the invention;

[0070] FIG. 3 shows a schematic representation of an embodiment according to FIG. 2 of a device according to the invention with two conductivity sensors;

[0071] FIG. 4 shows a schematic representation of an embodiment according to FIG. 3 of a device according to the invention with three conductivity sensors;

[0072] FIG. 5 shows a schematic representation of an embodiment of a treatment chamber according to the invention in a perspective view;

[0073] FIG. 6 shows another schematic representation of an embodiment of a treatment chamber according to the invention in a side view;

[0074] FIG. 7 shows the treatment chamber according to invention according to FIG. 5 in a side view;

[0075] FIG. 8 shows a schematic representation of an embodiment of a device according to the invention with an exchangeable treatment chamber in a perspective view.

[0076] FIG. 1 shows a schematic representation of an embodiment of a device for the electrodeionization of a sample liquid.

[0077] Device 1 comprises an anode chamber 10 with an anode 13 and two openings 11, 12, a cathode chamber 20 with a cathode 23 and two openings 21, 22 and a treatment chamber 30 with two openings 31, 32. The treatment chamber 30 is located between the anode chamber 10 and the cathode chamber 20 and is filled with ion exchanger. The chambers are spatially separated from each other by permselective membranes 33. The anode 13 and the cathode 23 are operatively connected to an energy source 40. The energy source 40 provides a DC voltage applied between anode and cathode. One of the openings 31, 32 of the treatment chamber serves to supply the sample liquid to device 1, or the treatment chamber 30 respectively, whereas one of the openings 21, 22 of the cathode chamber 20 serves to discharge the sample liquid from device 1, or the cathode chamber 20 respectively. The remaining openings can be used to create an operative connection between the chambers. If, for example, opening 31 is used to admit the sample liquid, opening 32 can be used to achieve an operative connection between treatment chamber 30 and anode chamber 10, either by means of opening 11 or 12. If, for example, said operative connection has been made via opening 12, opening 11 can be connected to opening 21 or 22 to achieve an operative connection between anode chamber 10 and cathode chamber 20. For example, if openings 12 and 22 are connected to each other, opening 21 may be used to discharge the sample liquid from device 1. Alternatively, the openings can be connected to each other so that the treatment chamber is operatively connected to the cathode chamber and the cathode chamber is in turn operatively connected to the anode chamber. An opening of the treatment chamber 31, 32 then also serves to supply the sample liquid, whereas an opening of the anode chamber 11, 12 then serves to discharge the sample liquid. In the embodiment shown, all openings are located in the underside or the upper side of the chambers. It is also conceivable that the openings are arranged on one of the side walls of the chambers, for example, one opening per chamber in the lower third of the chamber and one opening per chamber in the upper third of the chamber.

[0078] FIG. 2 shows a device according to the invention as shown in FIG. 1, which is used to explain an embodiment of the method according to the invention. For the clarity of the representation, not all elements already introduced in FIG. 1 by means of reference numerals are also designated in FIG. 2, even if they are identical elements. This applies in particular to the shown openings 11, 12, 21, 22, 31 and 32.

[0079] In the illustrated device 1 shown by way of example, a DC voltage is applied between the anode 13 and the cathode 23 by means of an energy source 40. A sample liquid 50 is fed to the treatment chamber 30 via the opening 31 and flows through the treatment chamber 30, which is at least partially filled with cation exchange resin, along the openings 31 and 32 in the direction of gravity. Since the openings 32 and 11 are operatively connected, the sample liquid 50 flows into the anode chamber 10 after it has flowed through the treatment chamber 30 and flows through it along the openings 11 and 12 in the direction opposite to gravity. The sample liquid 50 then enters the cathode chamber 20 via opening 21 and flows through it along openings 22 and 21 against the direction of gravity. The sample liquid emerges from the cathode chamber 20 via opening 22.

[0080] Alternatively, the chambers could also be flowed through in the opposite direction to that described above, and the openings of the chambers could be operatively interconnected as desired, provided that it is ensured that the sample liquid first flows through the treatment chamber 30, then the anode chamber 10 and then the cathode chamber 20. The sample liquid 50 flows through the anode chamber 10 in such a way that it flows between the anode 13 and the permselective membrane 33a, which is permeable to cations and faces the anode 13. The cathode chamber 20 is flowed through by the sample liquid 50 analogous to the anode chamber 10 with respect to the cathode 23 and the membrane 33b. The sample liquid 50 flows through the treatment chamber 30 in parallel to the membranes 33a and 33b. The sample liquid crosses the electric field between the anode 13 and the cathode 23 at least partially three times. If the treatment chamber is at least partially filled with cation exchange resin and the permselective membranes are cation-permeable membranes, the described cation exchange process can be used.

[0081] In the method shown in FIG. 2, the processes described in more detail below occur:

[0082] An ion exchange of the ions dissolved in the sample liquid takes place in the treatment chamber. If the ion exchanger, as in this example, is a cation exchange resin, the anions (e.g. Cl.sup.−) remain in the sample solution, but the cations (e.g. NH.sub.4.sup.+, Na.sup.+) are replaced by the cations provided by the cation exchange resin (e.g. H.sup.+). Within the cation exchange resin, the cations (e.g. NH.sub.4.sup.+, Na.sup.+) then move along the electric field in the direction of the cathode and migrate through the permselective membrane permeable to cations and facing the cathode into the cathode chamber. The cation-exchanged sample liquid is transferred from the treatment chamber to the anode chamber. There, protons (H.sup.+) are generated by electrolysis of the water in the sample liquid. These protons (H.sup.+) can then migrate towards the cathode, first through the permselective cation-permeable membrane facing the anode, then through the permselective cation-permeable membrane facing the cathode. On their way, the protons (H.sup.+) pass through the treatment chamber where they are available to regenerate the ion exchanger. Once the cation exchange resin has been regenerated and there are no (more) cations in the sample water in the treatment chamber, the protons migrate further into the cathode chamber. The anions and the gas (e.g. O.sub.2) also formed during electrolysis in the anode chamber are transported with the sample liquid into the cathode chamber. Hydroxide ions (OH.sup.−) and gas (e.g. H.sub.2) are formed in the cathode chamber by electrolysis of the water. The hydroxide ions neutralize the protons (H.sup.+) migrated into the cathode chamber and/or form as counterion the corresponding hydroxides (e.g. NH.sub.4OH, NaOH) of the cations (e.g. NH.sub.4.sup.+, Na.sup.+) migrated into the cathode chamber.

[0083] FIG. 3 shows a schematic representation of an embodiment of a device according to the invention for the electrodeionization of a sample liquid. The flow path of the sample liquid is also shown.

[0084] Before the sample liquid 50 enters the treatment chamber 30, it passes through a conductivity sensor 51 arranged in front of the opening 31 of the treatment chamber 30, which serves to let in the sample liquid 50, to measure the specific conductivity of the sample liquid 50. If the conductivity sensor 51 comprises a temperature sensor, the temperature-compensated specific conductivity can be determined. Another conductivity sensor 52 is located between the treatment chamber 30 and the anode chamber 10. If a temperature sensor is present, this conductivity sensor 52 can also measure the temperature-compensated specific conductivity and not just the specific conductivity.

[0085] FIG. 4 shows a schematic representation of an embodiment of a device according to the invention for the electrodeionization of a sample liquid comparable to FIG. 3.

[0086] However, the shown devices 1 differ from the device shown in FIG. 3 in that they have another conductivity sensor 53. Conductivity measurement with this conductivity sensor 53 differs from measurements with conductivity sensors 51 and 52 in that the “degassed” (temperature-compensated) specific conductivity can be determined. This means that the conductivity sensor 53 is preceded by a degassing unit 41, which degasses the sample liquid. It is completely sufficient to feed only part of the sample liquid 50 to the degassing unit and the conductivity sensor 53. This branched-off part can then simply be returned to the remaining sample liquid before entering the anode chamber 10 or fed into the anode chamber 10 via a separate further opening without prior mixing with the remaining sample liquid or can simply be discarded, i.e. disposed of. However, the entire undivided sample flow can also be conducted sequentially through the conductivity sensor 51, the degassing unit 41 and the conductivity sensor 53 and then fed into the anode chamber.

[0087] FIG. 5 schematically shows an embodiment of a treatment chamber according to the invention for use in a device for the electrodeionization of a sample liquid.

[0088] The illustration is a frontal view of a treatment chamber 30 with a transparent front and an upper side. The upper side comprises an opening 31, which in this example is used to let in the sample liquid 50. Furthermore, the upper side of the treatment chamber 30 comprises an opening 34 for filling in the ion exchanger and an opening 35 for degassing the sample liquid 50 located in the treatment chamber 30. In the underside there is also an opening 32. This is used to create an operative connection with the anode chamber 10 or the cathode chamber 20. The opening 32 is covered by a filter unit 36. The filter unit 36 is a filter plate made of sintered polyethylene whose pore size is only 5% to 50% of the grain size of the ion exchanger to be filled into the treatment chamber 30. The area and edge length of the filter plate 36 substantially correspond to the area and edge length of the underside of the treatment chamber 30. However, the filter plate 36 does not rest directly on the underside of the treatment chamber but is supported on support elements, in this example on interrupted support rings. All openings 31, 32, 34, 35 of the treatment chamber are designed so that they can be closed water-tight and air-tight.

[0089] FIG. 6 schematically shows another embodiment of a treatment chamber according to the invention for use in a device for the electrodeionization of a sample liquid.

[0090] The illustration shows a view of two mutually opposite side surfaces of a treatment chamber 30. The rectangular frames can be seen, on each of which a permselective membrane 33 is adhesively applied in a gas-tight and water-tight manner. In addition, two round filters 36 are visible, which are plane-parallel to the side surfaces and are located between them, which on the one hand cover a degassing opening 35 and the opening 31 for the inlet of the sample liquid and on the other hand cover the opening 32 for the outlet of the sample liquid or for passing it on into the anode or cathode chamber. On the upper side, there is also an opening 34 for filling in the ion exchanger 60. On one side, behind each of the filters 36, there is a collection chamber 39 for the sample liquid. The supply and discharge of the sample liquid take place through a short hole in the respective collection chamber 39. The axis of these holes runs substantially within the frame parallel to the surfaces of the permselective membranes and exits on the narrow side of the frame.

[0091] FIG. 7 shows a schematic side view of an embodiment of the treatment chamber according to the invention from FIG. 5.

[0092] The side surface of the treatment chamber 30 shown comprises a plastic frame 37 with a circumferential groove 28 and a permselective membrane 33 adhesively applied to this frame 37. If the membrane 33 is attached to the frame 37 by means of an adhesive, excess adhesive can flow into the groove 38 and does not swell out along the side edges of the membrane 33. The membrane 33 can also be attached to the frame 37 by means of ultrasonic welding.

[0093] Alternatively, a side surface of a treatment chamber 30 can also consist of two congruently arranged frames 37, between which a permselective membrane 33 is attached, for example by gluing or clamping. The frame 37 and the membrane 33 can also be connected by laminating.

[0094] FIG. 8 schematically shows an embodiment of a device according to the invention for the electrodeionization of a sample liquid according to the invention, which comprises a treatment chamber comparable to the one shown in FIG. 5.

[0095] The device comprises an anode chamber 10, a cathode chamber 20 and an exchangeable treatment chamber 30, which is inserted with a precise fit into a space between anode and cathode and thus causes the actual spatial subdivision of the device 1 into three chambers by its side surfaces comprising the permselective membranes 33.

[0096] In particular, a snapshot of the insertion of the treatment chamber 30 is shown. The straight, dashed lines indicate where the treatment chamber 30 will be located after correct placement, between anode 13 and cathode 23, and is fixed by means of quick-release fasteners.

[0097] In this example, the anode chamber 10 and cathode chamber 20 are integrally connected by a common underside. On this underside, for example, two parallel rails can be attached, which can serve as guide elements for the side surfaces of the treatment chamber 30 provided with the permselective membranes 33.

[0098] Similarly, those embodiments and examples, which are intended for cation exchange, can also be modified within the framework of the invention in such a way that they can be used for anion exchange. If, for example, an anion exchange were desired as a form of electrodeionization, the opening of the treatment chamber not intended for the inlet of the sample liquid would be connected to one opening of the cathode chamber, the other opening of the cathode chamber would be connected to one of the openings of the anode chamber, and the other opening of the anode chamber not connected to the cathode chamber would, in turn, serve as an outlet opening for the sample liquid.

[0099] For example, a conductivity sensor and optionally another conductivity sensor with a degassing unit arranged in front of it would be arranged between the treatment chamber and the cathode chamber.

[0100] In addition, anion exchangers could be used instead of cation exchangers in the treatment chamber. The permselective membranes, which limit the treatment chamber, would be permeable for anions instead of cations.

[0101] Further analogous modifications within the scope of the invention can be easily recognized by the person skilled in the art.