JP2009018289A - Operation method of electric demineralizer, and electric demineralizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an operation method of an electric demineralizer, which prevents high concentration ions remaining in a concentration chamber from diffusing and flowing back into a treatment chamber and prevents the deterioration of treating water quality even when the electric demineralizer is stopped. <P>SOLUTION: An electric demineralizer has the treatment chamber 13 and the concentration chamber 14, both partitioned by a cation exchange membrane 12 and a bipolar membrane 11 between a cathode and an anode. A cation exchange resin 16 is packed in the concentration chamber 14. An aqueous solution of sodium citrate is introduced from the inlet of the treatment chamber 13 and discharged from the outlet of the treatment chamber 13, and pure water is introduced from the inlet of the concentration chamber 14 and discharged from the outlet of the concentration chamber 14. After stopping treatment of a liquid to be treated by the electric demineralizer, pure water is made to flow through the concentration chamber 14 to carry out regeneration operation of the cation exchange resin 16. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for operating an electrical desalting apparatus that removes anions or cations from a liquid to be treated, such as selectively removing cations from a plating solution additive. The present invention also relates to an electrodeionization apparatus for removing anions or cations from a liquid to be treated.

  Copper sulfate plating bath uses copper sulfate and sulfuric acid as basic raw materials, and various additives such as reducing agents, complexing agents, buffering agents, brighteners, smoothing agents, etc. are added to them for decorative plating and printed wiring boards. Wiring formation is performed. In addition to these additives, chloride ions may be required. By adding an appropriate amount of each of these, it is possible to form a plating film having desired glossiness, smoothness and physical properties.

Representative examples of the additive include a sulfonate having a sodium sulfonate group (—SO ₃ Na) such as disodium bis (3-sulfopropyl) disulfide, and sodium hypophosphite and hydrogen as a reducing agent. Various strong electrolyte salts such as sodium borohydride, citrate, tartrate and lactate as complexing agents and acetate, propionate and ammonium salts as pH adjusters are added to the plating bath.

  These plating bath additives are often sodium or potassium salt compounds because of their shape stability and ease of transport, but the active ingredient in these additives is an acid that is a counter ion, Sodium and potassium are not necessary. For this reason, while the anion of the counter ion is consumed as an active ingredient, cations such as sodium ions and potassium ions are gradually accumulated. If unnecessary cations accumulate in the plating bath in this manner, the balance of the plating bath is lost, and appearance defects such as plating blistering and peeling occur. For this reason, when it becomes impossible to control the plating bath by an operation management method such as addition of other chemicals, it is discarded as waste water.

  However, since this plating bath drainage contains not only the above-mentioned cations but also a large amount of acid, base, etc., the drainage has a very large environmental load, and it is desired to reduce the environmental load. Therefore, various studies have been made to remove unnecessary cation components such as sodium and potassium from the plating solution additive in advance to reduce cations accumulated in the plating bath.

  For example, it is conceivable to selectively remove cations by treating the plating solution additive aqueous solution with a cation exchange resin, but the amount of cations that can be removed is determined by the ion exchange capacity of the cation exchange resin, If a predetermined amount of cations are removed, the breakthrough occurs. Therefore, if a certain amount of cations are adsorbed, it is necessary to replace the cation exchange resin column and regenerate the resin. However, the plating solution aqueous solution has a very high cation concentration, so it is necessary to replace the cation exchange resin column in a short time. There is a problem that it is very troublesome and costly.

  Moreover, it is possible to obtain the plating solution additive aqueous solution which removed the cation continuously by using an electrodialyzer. However, since the plating solution additive is a strong electrolyte, it is necessary to increase the applied current density in order to remove it with an electric desalting apparatus. Then, hydrogen ions also move, so that the cation that is originally desired to move is removed. This hinders the movement of the cation and prevents the cation concentration from being kept below a certain level.

  Further, a plurality of anion exchange membranes and cation exchange membranes are alternately arranged between the electrodes (anode and cathode) to alternately form a desalting chamber and a concentration chamber, and the desalting chamber is filled with an ion exchange resin. It is conceivable to use an electrodeionization device. However, in this method, it is necessary to separate both the anion and the cation by permeating each ion exchange membrane. However, an acid that is a counter ion having a molecular weight exceeding 200 is difficult to permeate, and it is difficult to permeate an acid or an alkali. There is a problem that the yield deteriorates.

  For the purpose of removing such cations of the plating solution additive, the present applicant has proposed a desalination chamber (processing chamber) and a concentration chamber partitioned between a cathode and an anode by a cation exchange membrane and a bipolar membrane. And a cation recovery mechanism communicating with the concentration chamber of the electrodialyzer, and a cation removal mechanism for the plating solution additive. The device was previously proposed (Japanese Patent Application No. 2007-0505559).

  This electrodialyzer can selectively remove cations from the plating solution additive. However, in this electrodialyzer, although the concentration chamber is partitioned, the concentration of cations in the concentration chamber is high. It was found that when the operation of the apparatus was stopped, cations returned from the concentration chamber to the desalting chamber (processing chamber) due to back diffusion, and the quality of the processing liquid after the operation was resumed may be deteriorated.

  Such a problem is also a problem that occurs when an alkali or acid is selectively removed from various salt solutions in the food and pharmaceutical fields.

  The present invention solves the above-mentioned problem, and even if the electrodeionization apparatus is stopped, the high-concentration ions remaining in the concentration chamber do not diffuse back flow into the processing chamber, and the quality of the processing solution is reduced. An object is to provide a method of operating an electrodesalination apparatus that does not. Another object of the present invention is to provide an electrodeionization apparatus capable of suitably performing the above operation method when the liquid to be treated is a high concentration ionic solution.

  In order to solve the above-mentioned problems, first, the present invention has a treatment chamber and a concentration chamber partitioned by a cation exchange membrane and / or an anion exchange membrane and a bipolar membrane between a cathode and an anode, The concentration chamber is filled with an ion exchanger, the liquid to be processed is introduced from the inlet of the processing chamber and the processing liquid flows out from the outlet of the processing chamber, and the ion recovery water is introduced from the inlet of the concentration chamber and the concentration is performed. An operation method of an electric desalination apparatus for flowing out from a chamber outlet, wherein the ion exchanger is regenerated after the treatment of the liquid to be treated by the electric desalination apparatus is stopped. A method is provided (claim 1).

  Here, the bipolar membrane in this specification is a kind of composite membrane having a structure in which a cation exchange membrane and an anion exchange membrane are bonded together. This bipolar membrane has been widely used as a separation membrane for electrolysis of water or as a separation membrane for regenerating acid and alkali from an aqueous solution of a salt that is a neutralized product of acid and alkali. It is a known ion exchange membrane, and various production methods have been proposed.

  In the present invention, such a bipolar membrane is installed in the concentration chamber so that the cation exchange layer surface is located on the cathode side of the electrodeionization apparatus and the anion exchange layer surface is located on the anode side. In such a bipolar membrane, when a voltage equal to or higher than the theoretical water electrolysis voltage (0.83 V) is applied, water dissociation occurs and current flows.

  According to the above invention (Invention 1), by supplying an aqueous solution of an organic acid salt or inorganic acid salt such as a plating solution additive to the treatment chamber of the electric desalting apparatus, sodium ions and potassium ions in the treatment liquid are supplied. Or the like, or an anion such as an organic acid such as sulfonate ion or citrate ion, an inorganic acid, or a carbonate ion is discharged from the anion exchange membrane. Further, anions or cations that are counter ions of the ions to be removed do not permeate through the bipolar membrane and remain as they are. In this way, cations or anions can be selectively removed from the liquid to be treated. Moreover, since dissociation of water occurs in the bipolar membrane, hydrogen ions or hydroxide ions are replenished in the processing chamber, and the ion balance is maintained. On the other hand, cations or anions in the processing chamber are concentrated in the concentration chamber. Therefore, when the operation of the electric desalination apparatus is stopped, the concentration chamber has a high concentration of cations or anions to be removed. Therefore, the back diffusion of these ions from the concentration chamber to the treatment chamber occurs, so that the treatment is resumed when the operation is resumed. The concentration of cations or anions to be removed in the room is increased, and this causes a decrease in the quality of the treatment liquid. Therefore, in the present invention, after the treatment of the liquid to be treated by the electrodialysis apparatus is stopped, the ion exchanger in the concentrating chamber is regenerated, the residual ion concentration in the concentrating chamber is reduced, and ions are transferred from the concentrating chamber to the processing chamber. By suppressing the reverse diffusion, the processing chamber can be kept ionically clean. As a result, it is possible to prevent a decrease in the quality of the processing liquid when the operation is resumed.

  In the said invention (invention 1), the regeneration operation method of the said ion exchanger in the said electrical desalination apparatus is a method of distribute | circulating the said ion recovery water to the said concentration chamber after the process of the said to-be-processed liquid is stopped. (Claim 2).

  According to the above invention (Invention 2), after the treatment of the liquid to be treated is stopped, the ion collection water is circulated through the concentration chamber, and the current is applied and held for a certain period of time in the same manner as during the treatment. Since the ion exchanger is regenerated and the residual ion concentration in the concentration chamber decreases, the back diffusion of ions from the concentration chamber to the processing chamber can be suppressed, and the processing chamber can be kept ionically clean.

  In the said invention (invention 2), it is preferable to distribute | circulate the said ion recovery water for 1 to 3 hours (invention 3). According to this invention (invention 3), the ion exchanger in the concentration chamber is sufficiently regenerated and the residual ion concentration in the concentration chamber is greatly reduced, so that back diffusion of ions from the concentration chamber to the treatment chamber is prevented, The processing chamber can be kept ionically clean.

  Moreover, in the said invention (Invention 1-3), the regeneration operation method of the said ion exchanger in the said electrical desalination apparatus is the said electrical desalination apparatus after the process of the to-be-processed liquid by the said electrical desalination apparatus is stopped. It is preferable to use a method in which a weak current is allowed to flow through (Claim 4).

  According to the above invention (invention 4), the ion exchanger in the concentrating chamber is regenerated and the residual ion concentration in the concentrating chamber is reduced by applying a weak current by the electrodeionization apparatus after stopping the processing of the liquid to be processed. Therefore, the back diffusion of ions from the concentration chamber to the processing chamber can be suppressed, and the processing chamber can be kept ionically clean.

  Secondly, the present invention has a treatment chamber and a concentration chamber defined by a cation exchange membrane or an anion exchange membrane and a bipolar membrane between a cathode and an anode, and the concentration chamber is filled with an ion exchanger. In addition, the present invention provides an electric desalination apparatus characterized in that a spacer that does not hinder the flow of the liquid to be processed is disposed in the processing chamber.

  According to the said invention (invention 5), by supplying to-be-processed liquids, such as a plating solution additive which consists of the aqueous solution of an organic acid salt or an inorganic acid salt, to the process chamber of an electrical desalination apparatus, Cations such as sodium ion and potassium ion are discharged from the cation exchange membrane, or organic acids such as sulfonate ion and citrate ion, anions such as inorganic acid or carbonate ion are discharged from the anion exchange membrane. Is done. Further, anions or cations which are counter ions of the ions to be removed do not permeate through the bipolar membrane and remain as they are. In this way, cations or anions can be selectively removed from the liquid to be treated. In addition, since dissociation of water occurs in the bipolar membrane, hydrogen ions or hydroxide ions are replenished in the processing chamber, and the ion balance is maintained.

  At this time, when a liquid having a high ion concentration is used as the liquid to be processed, electricity passes without filling the inside of the processing chamber with an ion exchanger. Therefore, the structure of the electric desalination apparatus can be simplified by holding the space between the cells narrow and sandwiching a spacer such as a mesh in the processing chamber. Furthermore, by holding the cells narrow in this manner and sandwiching a spacer such as a mesh in the processing chamber, even if ion reverse diffusion occurs, the rise (normalization) can be accelerated.

  According to the operation method of the electric desalting apparatus of the present invention, the regeneration operation of the ion exchanger in the concentrating chamber is performed even after the processing of the liquid to be processed by the electric desalting apparatus is stopped, thereby reducing the residual ion concentration in the concentrating chamber. In addition, it is possible to suppress the back diffusion of ions from the concentration chamber to the processing chamber and to keep the processing chamber ionically clean, thereby preventing a decrease in the quality of the processing liquid when the operation is resumed.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic system diagram showing a plating solution additive cation removing apparatus equipped with an electrical desalting apparatus according to an embodiment of the present invention.

The cation removing apparatus according to this embodiment is a sodium removing apparatus that removes Na from a sodium citrate aqueous solution, which is a plating solution additive, as a liquid to be treated. In this specification and the drawings, for convenience, sodium citrate may be represented as “RCONa”, citric acid as “RCOOH”, and citrate ion as “RCOO ⁻ ”.

  The sodium citrate aqueous solution removal apparatus in this embodiment includes a sodium citrate (RCONona) aqueous solution storage tank 1, an electric desalting apparatus 2, and a citric acid (RCOOH) aqueous solution storage tank 4.

  The RCOONa aqueous solution storage tank 1 communicates with the treatment chamber 13 of the electric desalting apparatus 2 through a flow path 3 having a liquid feed pump and a protective filter 7 (not shown). RCOOH) is connected to the aqueous solution storage tank 4.

  Further, a sodium (Na) ion recovery mechanism 5 serving as a cation recovery mechanism as a flow path provided with a liquid feed pump (not shown) communicates with the concentration chamber 14 of the electric desalting apparatus 2. In addition, the flow path 6 is connected to the anode chamber C of the electric desalination apparatus 2, and the hydroxide ion generated by water dissociation is oxidized and oxygen gas is generated.

  In the sodium removal apparatus as described above, the electrodeionization apparatus 2 has bipolar membranes 11 and cation exchange membranes 12 alternately arranged between electrodes (anode and cathode) as shown in FIGS. Thus, the processing chambers 13 and the concentration chambers 14 are alternately formed. The bipolar membrane 11 has the cation exchange layer 11A side so as to face the cathode side, that is, the processing chamber 13, and the anion exchange layer 11B side so as to face the anode side, that is, the concentration chamber 14. Note that, at both ends of the electric desalting apparatus 2, there are an anode chamber (not shown) partitioned by the anode and the bipolar film 11 and a cathode chamber (not shown) partitioned by the cathode and the bipolar film 11. Is formed.

Here, as the bipolar membrane 11 and the cation exchange membrane 12 used in the present invention, conventionally known ones can be used as appropriate, and membranes effective for salt separation and water dissociation may be selected. The bipolar membrane 11 may be anything as long as it has a cation exchange layer 11A and an anion exchange layer 11B and can be water-dissociated. The cation exchange membrane 12 may be any conventional membrane as long as it is permeable to cations and contains a functional group exhibiting acidity such as a sulfone group (—SO ₃ H).

  The processing chamber 13 is filled with a mesh spacer or filled with an ion exchanger. When the ion exchanger is filled, the voltage is lower and the concentration polarization is relaxed, so the desalting efficiency is better. However, when the RCOONa aqueous solution has a high concentration and a high ion concentration, electricity passes sufficiently without filling the ion exchanger. Therefore, the structure of the electrodeionization device 2 may be simplified by forming the processing chamber 13 and the concentration chamber 14 narrow.

  Further, the concentration chamber 14 is filled with an ion exchanger. This ion exchanger may be a conventionally known one, and may be an ion exchange resin or ion exchange fiber, or an ion exchanger produced by introducing an ion exchange group after radiation or electron beam graft polymerization on an arbitrary substrate. . Among them, an ion exchange resin available at a low cost is preferable.

  Specifically, the treatment chamber 13 is preferably filled with a cation exchange resin 15 as a cation exchanger. As a result, the voltage of the electric desalting apparatus 2 can be reduced, and the concentration polarization of sodium (cation) in the processing chamber 13 is suppressed, so that sodium ions can be more efficiently removed. The concentrating chamber 14 is preferably filled with a cation exchange resin 16 as an ion exchanger or a mixed resin of a cation exchange resin and an anion exchange resin.

  Next, an operation method of the cation removing apparatus having such a configuration will be described. The RCOONa aqueous solution is passed from the RCOONa aqueous solution storage tank 1 through the flow path 3 to the treatment chamber 13 of the electric desalting apparatus 2.

  At this time, since a predetermined DC voltage is applied to the electric desalting apparatus 2 and a current flows, cations such as sodium ions move to the cathode side in the processing chamber 13 and pass through the cation exchange membrane 12 to be concentrated. It is discharged into the chamber 14.

Further, water dissociation of the following formula (1) occurs in the bipolar membrane 11, but in the processing chamber 13, since the bipolar membrane 11 faces the cation exchange layer 11 </ b> A side, hydrogen ions are supplied into the processing chamber 13.
H ₂ O → OH ⁻ + H ⁺ (1)

Further, although citrate ions (RCOO ⁻ ) as counter ions move to the anode side, they cannot pass through the cation exchange layer 11A on the processing chamber 13 side of the bipolar membrane 11 and remain in the processing chamber 13. To do. As a result, the citric acid (RCOOH) aqueous solution obtained in the processing chamber 13 is stored in the citric acid (RCOOH) aqueous solution storage tank 4 as a processing liquid.

  At this time, the sodium ion concentration of the treatment liquid is measured by a sodium ion sensor or the like (not shown), and sodium ions that could not be removed in the treatment chamber 13 are measured. For example, as shown by a broken line in FIG. 1, by providing a flow path from the RCOOH aqueous solution storage tank 4 to the RCOONa aqueous solution storage tank 1, when the residual sodium ion concentration is high, the RCOOH aqueous solution storage tank 4 is connected to the RCOONa aqueous solution. The treatment liquid may be circulated through the storage tank 1 and circulated until a treatment liquid having a desired sodium ion concentration is obtained.

  Moreover, even if the removal rate of sodium ions is improved by providing an ion exchanger having a cation removing function such as a cation exchange resin on the outlet side of the processing chamber 13 in the flow path 3 and polishing the treated water. Good.

  On the other hand, pure water stored in a pure water storage tank (not shown) by the sodium ion recovery mechanism 5 (water having a lower ion concentration than the RCOONa aqueous solution, which is the water to be treated) is passed through the concentration chamber 14 as ion recovery water. Sodium ions discharged from the processing chamber 13 flow into the concentration chamber 14.

  Further, the water dissociation of the above formula (1) occurs in the bipolar membrane 11, and the anion exchange layer 11B side of the bipolar membrane 11 faces the concentration chamber 14, so that hydroxide ions are supplied into the concentration chamber 14. The As a result, a sodium hydroxide (NaOH) aqueous solution is discharged from the concentration chamber 14.

Note that the anode chamber (not shown) is partitioned by the anode and the bipolar membrane 11, and since the anion exchange layer 11B faces the anode chamber, only hydroxide ions (OH ⁻ ) are supplied into the anode chamber. However, this hydroxide ion is oxidized at the anode and discharged to the outside environment as oxygen gas (O ₂ ).

On the other hand, the cathode chamber (not shown) is partitioned by the cathode and the bipolar membrane 11 and the cathode chamber side is the cation exchange layer 11A, so that only hydrogen ions (H ⁺ ) are supplied. And is discharged to the external environment as hydrogen gas (H ₂ ).

  In the selective removal method of sodium ions from the aqueous sodium citrate solution as described above, the pH and current of the treatment liquid are controlled by controlling the voltage and current applied in the electrodeionization apparatus 2, so that the treatment liquid can be used as a treatment liquid. It is preferable to control the ratio of citric acid and sodium in the citric acid (RCOOH) aqueous solution. A plating solution additive having a desired composition can be obtained by controlling the treatment solution treated by the electric desalting apparatus 2 based on data of a pH sensor (not shown).

  Furthermore, it is preferable to provide the protective filter 7 on the upstream side of the electric desalting apparatus 2 as in this embodiment. Thereby, pH etc. fluctuate | deviated rapidly by the malfunction of the electrical desalination apparatus 2, the fluctuation | variation of an operating condition, or the change of the plating solution additive used as a process target, and organic acid salt or inorganic acid salt precipitated as acidic salt However, these deposits are prevented from being mixed into the electric desalting apparatus 2. The pore diameter of the protective filter 7 is preferably 0.45 μm to 100 μm, particularly preferably 0.2 μm to 50 μm.

Next, the operation when the electric desalination apparatus 2 is stopped will be described.
As described above, hydroxyl ions and sodium ions are present in the concentration chamber 14 at high concentrations. Therefore, when the treatment of the aqueous sodium citrate solution is stopped, the electric attractive force is released, and therefore, the concentration chamber 14 and the treatment chamber 13 cause a difference in ion concentration between the concentration chamber 14 and the treatment chamber 13 via the cation exchange membrane 12. As a result, back diffusion of sodium ions occurs, and sodium ions are present in the processing chamber 13. This was a cause of deterioration in liquid quality when a citric acid solution was obtained from a sodium citrate aqueous solution at the time of restarting operation. Therefore, in the present embodiment, the electric desalination apparatus 2 is operated while supplying pure water to the concentration chamber 14 immediately after stopping the supply of the sodium citrate aqueous solution or before restarting the operation. As a result, the cation exchange resin 16 in the concentration chamber 14 is electrically regenerated and no residual sodium ions in the concentration chamber 14 are discharged without further sodium ions being supplied to the concentration chamber 14. The back diffusion of sodium ions from 14 to the processing chamber 13 can be suppressed, and the inside of the processing chamber 13 can be kept ionically clean. Further, when the regeneration operation is performed after stopping for a long time, the back diffusion of sodium ions into the processing chamber 13 occurs. However, since the regeneration operation discharges the concentration into the concentration chamber 14 again, It can be ionically cleaned.

  As a result, it is possible to prevent a decrease in liquid quality when the citric acid solution is obtained from the sodium citrate aqueous solution in the processing chamber 13 when the operation is resumed.

  The regeneration operation of the cation exchange resin 16 in the concentration chamber 14 after the supply of the sodium citrate aqueous solution is stopped is preferably performed for about 1 to 3 hours. Thereby, the cation exchange resin 16 can be fully regenerated. Even if the regeneration operation is performed for more than 3 hours, no further improvement in the effect can be obtained, which is not economical.

  Further, when the concentration of the sodium citrate aqueous solution is low and the residual sodium ion concentration in the concentration chamber 14 is low, a weak current may continue to flow after the treatment of the sodium citrate aqueous solution by the electric desalting apparatus 2 is stopped. . Thereby, the regeneration operation of the ion exchanger in the processing chamber 13 and the cation exchange resin 16 in the concentration chamber 14 can be performed. In this case, a weak current may continue to flow while flowing pure water in the concentration chamber 14, or a weak current may continue to flow without flowing pure water in the concentration chamber 14.

  On the other hand, when the concentration of the aqueous sodium citrate solution is high, electricity passes without filling the inside of the processing chamber 13 with a cation exchange resin, and sodium can be removed. In such a case, the cell between the processing chamber 13 and the concentrating chamber 14 is kept narrow, and a spacer such as a mesh is sandwiched between the concentrating chamber 14 to ensure an ion removal rate and to prevent back diffusion. Furthermore, even if it happens, the space between the cells is kept narrow, so that the discharge rate of sodium ions from the processing chamber 13 is improved, and the liquid quality when the citric acid solution is obtained from the sodium citrate aqueous solution when the operation is resumed is improved. The time required for recovery can be shortened.

  According to the cation removing apparatus according to the present embodiment as described above, a treatment liquid in which only sodium ions are selectively removed from an aqueous sodium citrate solution can be prepared and added to the plating bath as a plating solution additive. Since it can do, it can suppress that the cation resulting from the said additive accumulates in a plating bath, and can reduce the replacement frequency of a plating bath.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, in the above embodiment, the case where sodium citrate is used as the plating solution additive has been described, but it goes without saying that the cation derived from the salt can be similarly removed if it is a salt of an organic acid or an inorganic acid. A sodium salt having a sodium sulfonate group (—SO ₃ Na), sodium hypophosphite, sodium borohydride, sodium tartrate, or a potassium salt of these acid groups can be similarly treated as an aqueous solution. .

  Further, the electrodeionization device 2 is not limited to the one shown in FIGS. 2 and 3, and an anion exchange membrane 12A and a cation exchange membrane 12B are provided between a pair of bipolar membranes 11 as shown in FIG. The three chambers may be arranged as one unit, the center may be the processing chamber 13, the anode side may be the anion concentration chamber 14A, and the cathode side may be the cation concentration chamber 14B. In this case, pure water is discharged from the processing chamber 13, an aqueous citric acid (RCOOH) solution is discharged from the anion concentration chamber 14A, and an aqueous sodium hydroxide (NaOH) solution is discharged from the cation concentration chamber 14B. The discharged water may be used as the treatment liquid.

  Furthermore, in the above embodiment, the case of removing cations has been described as an example. However, by forming the treatment chamber 13 and the concentration chamber 14 with an anion exchange membrane and a bipolar membrane, similarly, an organic acid ion, a chlorine ion In addition, anions such as carbonate ions can be selectively removed.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to the following Example at all.

[Example 1]
[1] Electrodemineralization apparatus The following were used as the ion exchange membrane and ion exchanger of the electrodesalination apparatus 2.
(1) Cation exchange membrane 12: Neoceptor (registered trademark) CMB (manufactured by Astom)
(2) Bipolar membrane 11: Neoceptor (registered trademark) BP-1E (manufactured by Astom)
(3) Cation exchange resin filled in the processing chamber 13: SK1B (manufactured by Mitsubishi Chemical Corporation)
(4) Cation exchange resin filled in the concentration chamber 14: SK1B (manufactured by Mitsubishi Chemical Corporation)

The specifications of the electric desalting apparatus 2 used in Example 1 are as follows.
(1) Number of desalting chambers: 1 chamber (2) Total membrane area of the cation exchange membrane 12 through which sodium ions can permeate: 1.7 dm ²
(3) Desalination chamber: Filled with 100 mL of cation exchange resin

[2] Test conditions and results In the apparatus shown in FIG. 1 and FIG. 2, sodium citrate (RCONona) aqueous solution (concentration: 2.2 g / L) was used, and sodium ions on the inlet side of the treatment chamber 13 of the electrodeionization apparatus 2 were used. Removal of sodium from the aqueous sodium citrate solution was performed for 6 hours under the conditions of a concentration of 600 ppm, an applied current density of 33 mA / cm ² and an LV (linear velocity) of 4 m / h. At this time, pure water was circulated through the concentration chamber 14 under the condition of LV (linear velocity) 4 m / h.

  Thereafter, the operation of the electric desalting apparatus 2 is temporarily stopped, and after 24 hours, the aqueous solution of sodium citrate is not circulated in the treatment chamber 13, but the electric demineralization is similarly performed while pure water is circulated in the concentration chamber, the anode chamber and the cathode chamber. The apparatus 2 was operated for 2 hours to regenerate the ion exchange resin.

Thereafter, the removal of sodium from the aqueous sodium citrate solution was resumed.
Changes in sodium ion concentration in the aqueous citric acid solution recovered from the outlet of the electrodeionization apparatus 2 during the removal of sodium from the aqueous sodium citrate solution were measured.
The results are shown in FIG.

[Comparative Example 1]
In Example 1, the sodium citrate aqueous solution treatment was performed in the same manner except that the removal treatment of sodium from the sodium citrate aqueous solution was resumed immediately after stopping for 24 hours without performing the regeneration operation of the ion exchange resin.

Changes in sodium ion concentration in the aqueous citric acid solution recovered from the outlet of the electrodeionization apparatus 2 during the removal of sodium from the aqueous sodium citrate solution were measured.
The results are shown in FIG.

  As is apparent from FIG. 5, in the operation method of the electrical desalting apparatus of Example 1, the sodium ion concentration at the outlet of the electrical desalting apparatus was hardly changed before and after the operation was stopped, whereas the ion exchange was performed. In Comparative Example 1 in which the resin regeneration operation was not performed, an increase in sodium ion concentration was observed after resumption, and it was confirmed that the liquid quality had deteriorated.

  The operation method of the electrical desalting apparatus and the electrical desalting apparatus of the present invention removes acids or alkalis from various salt solutions in the food and medical fields, for example, treatment of plating bath additives such as copper / cobalt plating solutions. This is useful for stable operation.

It is a schematic system diagram which shows the cation removal apparatus of the plating solution additive applicable to the operating method of the electric desalination apparatus which concerns on one Embodiment of this invention. It is the schematic which shows the electrical desalting apparatus of the cation removal apparatus of the said plating solution additive. It is the schematic which shows the flow of the ion in the said electrical desalination apparatus. It is the schematic which shows the flow of the ion in the electrodeionization apparatus of the cation removal apparatus of the plating solution additive which concerns on other embodiment of this invention. It is a graph which shows the change of the sodium ion concentration of the process liquid in Example 1 and Comparative Example 1.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Sodium citrate aqueous solution (processed liquid) storage tank 2 ... Electrodesalination apparatus 4 ... Citric acid aqueous solution (processing liquid) storage tank 11 ... Bipolar membrane 11A ... Cation exchange layer 11B ... Anion exchange layer 12 ... Cation exchange membrane 12A ... Anion Exchange membrane 12B ... Cation exchange membrane 13 ... Processing chamber 14 ... Concentration chamber 14A ... Anion concentration chamber 14B ... Cation concentration chamber 16 ... Cation exchange resin (ion exchange resin)

Claims (5)

A treatment chamber and a concentration chamber defined by a cation exchange membrane and / or an anion exchange membrane and a bipolar membrane between the cathode and the anode, and the concentration chamber is filled with an ion exchanger; Is introduced from the processing chamber inlet to cause the processing liquid to flow out from the processing chamber outlet, and ion recovery water is introduced from the concentration chamber inlet and discharged from the concentration chamber outlet. ,
An operation method of an electrical desalting apparatus, wherein the ion exchanger is regenerated after the treatment of the liquid to be treated by the electrical desalting apparatus is stopped.   The method for regenerating the ion exchanger in the electric desalination apparatus is a method of circulating the ion recovery water into the concentration chamber after the treatment of the liquid to be treated is stopped. Operation method of the electric desalination apparatus.   The operation method of the electric desalting apparatus according to claim 2, wherein the ion-recovered water is circulated for 1 to 3 hours.   The method for regenerating and operating the ion exchanger in the electric desalting apparatus is a method in which a weak current continues to flow through the electric desalting apparatus after the treatment of the liquid to be treated by the electric desalting apparatus is stopped. The operation method of the electrical desalting apparatus according to any one of claims 1 to 3. A treatment chamber and a concentration chamber defined by a cation exchange membrane or an anion exchange membrane and a bipolar membrane between the cathode and the anode;
The concentration chamber is filled with an ion exchanger,
An electric desalination apparatus characterized in that a spacer that does not hinder the flow of the liquid to be treated is disposed in the treatment chamber.

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