JP5895962B2 - Method for preventing boron contamination of ion exchange resin - Google Patents

Description

The present invention relates to boron Pollution how the ion-exchange resin, in particular, boron pollution effective ion exchange resin in a manufacturing process for ultrapure water used as washing water or the like of the electronic component members rocks in the semiconductor manufacturing field, etc. about the mETHODS.

  In the fields of semiconductors and chemicals that use ultrapure water for general purposes, high-purity water quality is increasingly required in recent years. In other words, water (ultra-pure water) for cleaning semiconductor substrates and various electronic materials and impurities in chemicals affect the electrical characteristics of silicon substrates such as semiconductors and are therefore strictly controlled. In particular, among the water quality items of ultrapure water, boron is desired to be reduced to 1 ng / L or less.

  Ultrapure water generally treats treated water such as river water, groundwater and industrial water in a pretreatment process to remove most of the suspended matter and organic matter in the treated water. It is manufactured by sequentially processing with a system pure water manufacturing apparatus and a secondary system pure water manufacturing apparatus (sometimes called a subsystem). In the secondary pure water production equipment, in order to remove trace amounts of ions, organic substances, fine particles, etc. remaining in the primary pure water, the treatment is further combined with ultraviolet irradiation, ion exchange, ultrafiltration membrane, etc. Desired ultrapure water can be obtained.

  In such an ultrapure water production apparatus, a non-regenerative ion exchange apparatus subjected to special conditioning is provided downstream of the regenerative ion exchange apparatus to reduce impurities. Here, the non-regenerative ion exchanger is used for treating water that has already been sufficiently treated in the previous stage, so it is highly purified by special conditioning and does not regenerate. This is because the exchange apparatus is effective, and the non-regenerative ion exchange apparatus is used so that a chemical solution for regeneration does not flow into the use point near the outlet of the ultrapure water production apparatus.

However, in recent years, the required water quality of ultrapure water has been improved and the impurity concentration has been suppressed to a very small amount, resulting in the following problems.
-Impurities that cannot be removed even with non-regenerative ion exchangers remain, and the required water quality of ultrapure water cannot be satisfied.
If an attempt is made to remove such impurities with a non-regenerative ion exchange device to a high degree, the BTC (Break through capacity) of the non-regenerative ion exchange device is very small and the exchange frequency is high.

  For example, for a weakly acidic substance such as boron, when the BTP (Break through point) is 1 ng / L, the BTC is on the order of μg / L-anion exchange resin, and the exchange frequency of the non-regenerative ion exchange apparatus is It becomes extremely high once a month.

  JP-A-8-84986 describes that ultrapure water having a boron concentration of 1 ng / L or less is produced by using a boron selective ion exchange resin. However, when a mixed bed ion exchange resin is used after or mixed with the boron selective ion exchange apparatus, the boron concentration is reduced by boron elution from the anion exchange resin used in the mixed bed ion exchange resin. As a result, the above-described problem has occurred in the non-regenerative ion exchange apparatus in the subsequent stage.

  In JP-A-2005-177564, in the ultrapure water production process, in order to reduce the boron concentration of the obtained ultrapure water and reduce the frequency of regeneration of the ion exchanger, Although it is described that a heat exchanger is provided and the temperature of water flowing through the ion exchange device is controlled to 25 ° C. or less, it does not solve the problem of boron elution from the ion exchange resin itself.

  Japanese Patent Laid-Open No. 2003-31596 discloses a regenerative agent used for regeneration in order to suppress the outflow of Na and Cl ions from the regenerated ion exchange resin in a condensate demineralizer of a pressurized water nuclear power plant. However, it belongs to a completely different technical field from the regeneration of the ion exchange resin in the production of ultrapure water. There is no description about reduction of boron.

JP-A-8-84986 JP 2005-177564 A JP 2003-31596 A

The present invention aims to boron concentration to provide a boron pollution how the ion-exchange resin for obtaining the ion-exchange resin can be stably produced the following ultrapure water 1 ng / L.

  As a result of intensive studies to solve the above problems, the present inventors have found that boron in ultrapure water is caused by leakage from the ion exchange resin, and boron in the ion exchange resin is brought about by the regenerant. I found out.

  Thus, prior to the regeneration of the ion exchange resin, the present inventors remove boron from the regenerant used for regeneration, and regenerate the ion exchange resin using the regenerant from which boron has been removed. It has been found that the resulting ion exchange resin can be prevented from being contaminated with boron and can be free from the problem of boron leakage during the production of ultrapure water.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] Prevention of boron contamination of the ion exchange resin caused by the regenerant when the ion exchange resin used in the production process of ultrapure water is regenerated by bringing the regenerant into contact with a regenerant diluted with water. In this method, an ion exchange resin is characterized in that, prior to regeneration, the regenerant is treated with a boron removing means to remove boron so that the regenerant after boron removal satisfies the following condition (1) . Boron contamination prevention method.
Condition (1): Inductively coupled plasma for the outflow water when ion exchange resin regenerated using the regenerant after boron removal is packed into a column and ultrapure water (boron concentration <1 ng / L) is passed through. Boron concentration measured by mass spectrometry is 1 ng / L or less
[2] When the ion exchange resin used in the production process of ultrapure water is regenerated by bringing the regenerant into contact with a regenerant diluted with water, boron contamination of the ion exchange resin due to the regenerant is prevented. In this method, an ion exchange resin characterized in that, prior to regeneration, the regenerant is treated with a boron removing means to remove boron so that the regenerant after boron removal satisfies the following condition (2). Boron contamination prevention method.
Condition (2): For ion exchange resin regenerated using the regenerant after boron removal, the boron content measured by the following method is 10 μg / L ion exchange resin (wet state) or less.
<Boron content of ion exchange resin>
Collect 100 mL of ion exchange resin in a clean polypropylene container, add 500 mL of high-purity nitric acid (4% by weight) to this and shake for 1 hour (5 strokes / second), and then adjust the boron concentration in nitric acid. Measured by inductively coupled plasma mass spectrometry, and the boron concentration in the ion exchange resin is calculated from the following equation.
Boron content of resin (μg / L-ion exchange resin)
= [ICPMS analysis value (μg / L) × nitric acid amount (0.5 L)] / resin amount (0.1 L)

[3] A method for preventing boron contamination of an ion exchange resin according to [1] or [2], wherein the ion exchange resin is an anion exchange resin and the regenerant is an aqueous sodium hydroxide solution .

  According to the present invention, prior to regeneration of the ion exchange resin, the boron in the regenerant is removed by treating the regenerant with a boron removing means, thereby preventing boron contamination of the ion exchange resin caused by the regenerant. An ion exchange resin free from boron leakage can be obtained.

  It is preferable that boron is removed so that the boron concentration in the regenerant is 30 μg asB / L-0.1N alkaline solution or less by treating the regenerant with a boron removing means (Claim 2).

The present invention is particularly effective when an anion exchange resin in which boron contamination is a problem is regenerated with an aqueous sodium hydroxide solution (claim 3) .

The boron contamination prevention method of the ion exchange resin of the present invention is particularly effective for the regeneration of the ion exchange resin of the regenerative ion exchange device, and the ion exchange resin of the regenerative ion exchange device is regenerated according to the present invention, and there is no boron leak. By adjusting the regenerative ion exchange apparatus, leakage of boron from the regenerative ion exchange apparatus is prevented. As a result, in the ultrapure water production apparatus, the non-regenerative type provided in the subsequent stage of the regenerative ion exchange apparatus It is possible to reduce the load of the ion exchange device and reduce the replacement frequency of the non-regenerative ion exchange device.

It is a systematic diagram which shows embodiment of the ultrapure water manufacturing apparatus of this invention. It is a block diagram of the electrolyzer using a cation exchange membrane.

  Hereinafter, embodiments of the present invention will be described in detail.

First, a method for preventing boron contamination of the ion exchange resin of the present invention will be described.
The method for preventing boron contamination of an ion exchange resin according to the present invention is characterized in that when the ion exchange resin is brought into contact with a regenerant and regenerated, the regenerant used for regeneration is treated with a boron removing means to remove boron. It is.

  In the present invention, the ion exchange resin to be subjected to the regeneration treatment is an anion exchange resin that adsorbs boron by ion exchange, and the regeneration agent for this anion exchange resin is sodium hydroxide, potassium hydroxide, water. Examples include lithium oxide, ammonia, tetramethylammonium hydroxyside, monoethanol, etc. Among them, sodium hydroxide is preferable. When using sodium hydroxide (NaOH) as a regenerant, an aqueous solution having a NaOH concentration of about 1 to 10% by weight is usually used.

  The boron removing means used for removing boron from the regenerant in the present invention is not particularly limited as long as it can remove boron in water to a high degree, and examples thereof include the following. These boron removing means may be used in combination of two or more as required.

-Boron selective ion exchange resin-Electrolyzer using cation exchange membrane-Continuous electrodeionization device-Anion exchange resin-Anion exchange filter-Anion exchange membrane

  The boron-selective ion exchange resin is not particularly limited as long as it has an ability to adsorb boron and selectively adsorbs boron, but has an N-methylglucamine group as an exchange group. A boron selective resin is most preferred. Examples of the boron-selective resin having an N-methylglucamine group include Diaion (registered trademark: Mitsubishi Chemical Corporation) CRB01, CRB02, CRB03, CRB05, Amberlite (registered trademark; Rohm and Haas) IRA743, Duo. It can be appropriately selected from commercially available products such as Wright (registered trademark: Rohm and Haas) ES-371N and Uniselec (registered trademark: Unitika Ltd.) UR-3500.

As shown in FIG. 2, the electrolysis apparatus using the cation exchange membrane is one in which the inside of the electrolysis cell 10 is partitioned into an anode chamber 12 and a cathode chamber 13 by a cation exchange membrane 11. For example, the anode chamber 12 contains boron. When a crude NaOH aqueous solution is introduced, boron-free ultrapure water is introduced into the cathode chamber 13, and a voltage is applied between the anode 12A and the cathode 13A by a DC power source (not shown), the crude NaOH aqueous solution in the anode chamber 12 Na ⁺ ions permeate the cation exchange membrane 11 and move to the cathode chamber 13, and combine with OH ⁻ ions generated at the cathode 13A to become NaOH.

  On the other hand, since boron in the crude NaOH aqueous solution in the anode chamber 12 exists in the form of borate ions, it does not move to the cathode chamber 13 side, but remains in the anode chamber 12. As a result, a high-purity NaOH aqueous solution containing no boron is obtained from the cathode chamber 13, and a boron-containing crude NaOH aqueous solution having a reduced NaOH concentration is obtained from the anode chamber 12.

A continuous type electrodeionization device is formed by alternately arranging a plurality of anion exchange membranes and cation exchange membranes between an anode and a cathode to alternately form a concentration chamber and a desalting chamber. An anion exchanger and cation exchanger composed of exchange fibers or graft exchangers are mixed or packed in multiple layers, and boron ions and Na ⁺ ions are concentrated using this continuous electrodeionization device. Thus, an aqueous NaOH solution containing no boron can be obtained. That is, Na ⁺ ions in the crude NaOH aqueous solution containing boron introduced into the continuous electrodeionization apparatus permeate the cation exchange membrane and are concentrated in the cathode-side concentration chamber, and the boron in which boron is reduced from this concentration chamber. An aqueous solution is obtained, while boron in the form of borate ions permeates the anion exchange membrane and is concentrated in the concentration chamber on the anode side.

  In the present invention, it is preferable that the boron concentration in the regenerant is 30 μg asB / L-0.1N alkaline solution or less by treating the regenerator with such boron removing means. The lower the boron concentration of this regenerant, the better. However, in consideration of the processing cost for making the boron concentration extremely low, if it is 30 μg asB / L-0.1N alkaline solution or less, 1 μg asB / L- A sufficient effect can be obtained even with a 0.1N alkaline solution or more. That is, when the anion exchange resin is regenerated with a regenerant, the amount of boron taken into the anion exchange resin from the regenerant is smaller than the amount of boron in the regenerant, so that the boron concentration is 1 to 30 μg asB / If the regenerant is about an L-0.1N alkaline solution, a sufficient effect of preventing boron contamination of the anion exchange resin can be obtained.

  Usually, the boron concentration of a NaOH aqueous solution having a concentration of about 4% by weight obtained by diluting sodium hydroxide as a commercially available reagent with ultrapure water (boron concentration <1 ng / L) is about 50 μg / L. It is. In the present invention, it is preferable to treat such an aqueous NaOH solution with the above boron removing means to obtain an aqueous NaOH solution having a boron concentration of 30 μg asB / L-0.1N alkaline solution or lower.

  The regenerative agent is usually used by diluting a regenerative drug with water (usually water having a boron concentration of about 30 μg / L) to an appropriate concentration. It is preferable to perform a boron removing process on the adjusted regenerant by a boron removing unit because boron contained in the diluted water can also be removed by the boron removing unit.

  In the regeneration of the ion exchange resin, as described above, it is not necessary to perform the regeneration using only the regenerant that has been subjected to the boron removal treatment, and using the regenerant that has not been subjected to the boron removal treatment in the initial stage of the regeneration. Regeneration may be carried out using a regenerant that has been subjected to a boron removal treatment, and the boron removal treatment cost per regenerant used for regeneration can be reduced by switching the regenerant in this way. Can be achieved.

  In addition, after regeneration with a regenerant, extrusion cleaning is usually performed, but the cleaning water used for this extrusion cleaning is also preferably water with a sufficiently reduced boron concentration, and the boron concentration is 1 ng / L or less. It is preferable to use ultrapure water.

  In the present invention, by regenerating the ion exchange resin using the regenerant from which boron has been removed as described above, the boron content measured by the measurement method shown in the section of the below-described example is 50 μg / L-ion. It is preferable to obtain an ion exchange resin having an exchange resin (wet state) or less, particularly 10 μg / L ion exchange resin (wet state) or less.

  Such a method for regenerating an ion exchange resin of the present invention is effective for regenerating an ion exchange resin of a regenerative ion exchange apparatus. However, a boron content regenerated according to the method of the present invention is 50 μg / L-ion exchange resin ( Wet state) or less, in particular, an ion exchange resin of 10 μg / L ion exchange resin (wet state) or less is also suitably used as an ion exchange resin for a non-regenerative ion exchange apparatus.

  Next, the ultrapure water production apparatus of the present invention will be described with reference to the drawings.

  1 (a) to 1 (d) are system diagrams showing an ion exchange device (regenerative ion exchange device) showing an embodiment of the ultrapure water production apparatus of the present invention and its regenerant supply line portion. This ion exchange apparatus 1 is incorporated in a normal ultrapure water production apparatus, and is provided with an ultraviolet oxidation apparatus, a deaeration apparatus, etc. in the preceding stage, and a non-regenerative ion exchange apparatus or a limiter in the subsequent stage. A filtration membrane separator or the like is provided. 1A is a treated water inflow line of the ion exchange apparatus 1, and 1B is an ion exchange treated water outflow line.

  In FIG. 1A, the boron removing means 4 described above is provided in a line 3 for supplying the regenerant from the regenerant storage tank 2 to the ion exchanger 1 by the pump P. The regenerant is the boron remover. After boron is removed in step 4, the ion exchange apparatus 1 is supplied to regenerate the ion exchange resin in the apparatus 1.

  FIG. 1B shows a case where the regenerant supply line 3 of FIG. 1A is provided with a dilution water injection line 6, and the regenerative medicine from the regenerative medicine (regenerant stock solution) storage tank 5 is diluted with dilution water. After that, boron is removed by the boron removing means 3 and supplied to the ion exchange device 1.

  FIG. 1 (c) shows a case where the regenerant supply line 3 in FIG. 1 (a) is provided with a diluting water injection line 6 and a diluting water tank 8, and the regenerative medicine from the regenerative medicine (regenerant stock solution) storage tank 5 is After being supplied to the dilution water tank 8 through the line 3A, diluted with the dilution water from the line 6A, further diluted with the dilution water from the line 6, and then boron is removed by the boron removing means 4, then the ions The ion exchange resin in the apparatus 1 is regenerated by being supplied to the exchange apparatus 1.

  FIG. 1 (d) shows the regeneration agent diluted with dilution water in FIG. 1 (b), wherein the regenerant supply line 3 is provided with a bypass line 9 for bypassing the boron removing means 4 and a flow path switching valve V. The agent is supplied to the ion exchange device 1 through the bypass line 9 at the beginning of regeneration, and then supplied to the ion exchange device 1 after boron is removed by the boron removing means 4 by switching the valve V. The regeneration of the ion exchange resin is performed.

  As described above, in the case of an ultrapure water production apparatus provided with a boron removing means in the regenerant supply line, regeneration of the ion exchange resin in the ion exchange apparatus 1 in the apparatus is performed by removing boron by the boron removing means 4. Regeneration can be performed with an agent, and boron contamination of the ion exchange resin due to regeneration can be prevented.

  As shown in FIGS. 1B to 1D, by providing the boron removing means 4 on the downstream side of the regenerant diluting means, the boron in the diluted water can also be removed by the boron removing means 4.

  Further, as shown in FIG. 1 (d), by making it possible to switch the flow path of the regenerant, at the initial stage of regeneration, regeneration is performed with a regenerant that has not been subjected to boron removal treatment, and thereafter, boron removal means 4 Regeneration can be performed with a regenerant from which boron has been removed.

  In FIGS. 1A to 1D, a heat exchanger may be provided before or after the boron removing means 4 to adjust the temperature of the regenerant.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

  In the following, sodium hydroxide used as a regenerative agent is food additive NaOH (purity 98%) manufactured by Kishida Chemical Co., Ltd., and the regenerated anion exchange resin is “Monosphere 650 CUUPW (H) manufactured by Dow Chemical Co., Ltd. ) ”.

  The boron concentration in water was analyzed by inductively coupled plasma mass spectrometry (ICPMS) after concentrating the sample as necessary. Moreover, the boron content of the anion exchange resin was measured by the following method.

<Boron content of anion exchange resin>
Collect 100 mL of anion exchange resin in a clean polypropylene container, add 500 mL of high-purity nitric acid (4% by weight) and shake for 1 hour (5 strokes / second), and then adjust the boron concentration in nitric acid. Measured by ICPMS, the boron concentration in the anion exchange resin was calculated from the following formula.
Boron content of resin (μg / L-anion exchange resin)
= [ICPMS analysis value (μg / L) × nitric acid amount (0.5 L)] / resin amount (0.1 L)

[Example 1]
The regenerative agent NaOH was diluted with ultrapure water (boron concentration <1 ng / L) to a concentration of 4% by weight to obtain a regenerant (hereinafter referred to as “regenerant A”).
When the boron concentration of the regenerant A was measured, it was 20 μg asB / L-4 wt% NaOH aqueous solution.
This regenerant A was passed through a column packed with boron-selective ion exchange resin (boron chelate resin “Diaion (registered trademark) CRB03” manufactured by Mitsubishi Chemical Corporation) at SV = 10 hr ⁻¹ to remove boron. (Regenerant A subjected to boron removal treatment is referred to as “regenerant B”.)
The boron concentration of this regenerant B was 10 μg asB / L-4 wt% NaOH aqueous solution.

  An anion exchange resin was packed in a regeneration column, and regeneration was performed by passing a regeneration agent B. The regeneration level was 50 g asNaOH / L-anion exchange resin.

A part of the regenerated anion exchange resin was measured for boron content by the method described above. The remainder of the anion exchange resin is packed in an acrylic column (diameter 40 mm, height 800 mm), and ultrapure water (boron concentration <1 ng / L) is flowed into this anion exchange resin packed column at a flow rate of 833 mL / min (SV = 50 hr ⁻¹ ), and the boron concentration in the effluent water was measured.
These results are shown in Table 1.

[Comparative Example 1]
In Example 1, except that the regenerant A was used in place of the regenerant B, the regenerated anion exchange resin was similarly regenerated, and the boron content of the anion exchange resin was measured in the same manner. Ultrapure water was passed through the packed column to measure the boron concentration in the effluent, and the results are shown in Table 1.

  From Table 1, it is possible to obtain an anion exchange resin having a remarkably low boron content by performing regeneration using a regenerant from which boron has been removed. It turns out that pure water can be obtained.

[Example 2]
The regenerant boron removal treatment was performed using an electrolysis apparatus using the cation exchange membrane shown in FIG.
The specification of each part of the used electrolyzer (square cell) is as follows.
Effective area: ² dm ²
Anode: Ti-Pt plated plate Cathode: SUS316 plate Cation exchange membrane: "Nafion (registered trademark) 112" manufactured by Diyupon

NaOH is made into an aqueous solution of 48 wt% with ultrapure water (boron concentration <1 ng / L). / Hr.
The operation was performed at a current of 2.0 A and a voltage of 5 V. As a result, a boron-removed NaOH aqueous solution having a NaOH concentration of 24 wt% and a boron concentration of 12 μg asB / L (2 μg asB / L-4 wt% NaOH aqueous solution) can be obtained from the cathode chamber, and NaOH of 24 wt%, A NaOH aqueous solution enriched with boron having a boron concentration of 860 μg asB / L was obtained.

Using this boron-removed NaOH aqueous solution, the anion exchange resin was regenerated in the same manner as in Example 1, and the boron content of the regenerated anion exchange resin was measured to be 8 μg asB / L-anion exchange resin.
After washing this anion exchange resin with ultrapure water (boron concentration <1 ng / L), 500 mL was weighed out, and a cation exchange resin having a H-type conversion rate of 99.95% or more (“Monosphere CUWP” manufactured by Dow Chemical Company). (H) ") Mixed with 500 mL and filled into an acrylic column (diameter 40 mm, height 800 mm) to produce a mixed bed ion exchanger.

When ultrapure water (boron concentration <1 ng / L) was passed through the produced mixed bed type ion exchanger at a flow rate of 2.7 mL / min (SV = 160 hr ⁻¹ ), the boron concentration of the effluent water was less than 1 ng / L. The water quality was high enough.

DESCRIPTION OF SYMBOLS 1 Ion exchange apparatus 2 Regenerant storage tank 4 Boron removal means 5 Regenerative medicine storage tank 8 Dilution water tank 10 Electrolysis cell 11 Cation exchange membrane 12 Anode chamber 13 Cathode chamber

Claims (3)

In a method for preventing boron contamination of the ion exchange resin caused by the regenerant when the ion exchange resin used in the production process of ultrapure water is regenerated by bringing the regenerant into contact with a regenerant diluted with water. Prior to regeneration, the regenerant is treated with boron removing means, and the regenerator after boron removal removes boron so that the following condition (1) is satisfied. Method.
Condition (1): Inductively coupled plasma for the outflow water when ion exchange resin regenerated using the regenerant after boron removal is packed into a column and ultrapure water (boron concentration <1 ng / L) is passed through. Boron concentration measured by mass spectrometry is 1 ng / L or less In a method for preventing boron contamination of the ion exchange resin caused by the regenerant when the ion exchange resin used in the production process of ultrapure water is regenerated by bringing the regenerant into contact with a regenerant diluted with water. Prior to regeneration, the regenerant is treated with a boron removing means, and boron is removed so that the regenerant after boron removal satisfies the following condition (2). Method.
Condition (2): For ion exchange resin regenerated using the regenerant after boron removal, the boron content measured by the following method is 10 μg / L ion exchange resin (wet state) or less.
<Boron content of ion exchange resin>
Collect 100 mL of ion exchange resin in a clean polypropylene container, add 500 mL of high-purity nitric acid (4% by weight) to this and shake for 1 hour (5 strokes / second), and then adjust the boron concentration in nitric acid. Measured by inductively coupled plasma mass spectrometry, and the boron concentration in the ion exchange resin is calculated from the following equation.
Boron content of resin (μg / L-ion exchange resin)
= [ICPMS analysis value (μg / L) × nitric acid amount (0.5 L)] / resin amount (0.1 L)   3. The method for preventing boron contamination of an ion exchange resin according to claim 1, wherein the ion exchange resin is an anion exchange resin and the regenerant is an aqueous sodium hydroxide solution.

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