Method for adjusting cation exchange resin

Abstract

To provide an adjustment method of a weakly acidic cation exchange resin capable of reducing a washing period after performing a regeneration process of an H type weakly acidic cation exchange resin.SOLUTION: There is provided an adjustment method of a cation exchange resin comprising: a regeneration process for bringing an acid aqueous solution into a cation exchange resin, for converting the cation exchange resin into an H type; and a washing process for bringing washing water into contact with the H type cation exchange resin converted into the H type, for washing the H type cation exchange resin, in which the cation exchange resin is a weakly acidic cation exchange resin, and a normality of the acid aqueous solution is 0.10 to 0.50 N.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a conditioning method for converting a cation exchange resin into an H form, and more particularly to a conditioning method for a cation exchange resin used for purifying treated water containing ionic impurities, for regenerating or pretreating the cation exchange resin.

Background Art

[0002] In the cleaning process of silicon during semiconductor manufacturing, ultrapure water with a concentration of each cation impurity of 1 ng / L or less is required. As a primary treatment method for reducing the concentration of cation impurities mainly composed of hardness components such as calcium and magnesium in water, a method using a weakly acidic cation exchange resin is generally used.

[0003] For example, Patent Document 1 discloses an example of ultrapure water production using a weakly acidic cation exchange resin, a strongly acidic cation exchange resin, a weakly basic anion exchange resin, and a strongly basic anion exchange resin as primary treatment for ultrapure water production.

[0004] When the removal of cation impurities in the treated water is continued using a weakly acidic cation exchange resin, the acidic ion exchange groups in the weakly acidic cation exchange resin are consumed by binding to the cation impurities, and the amount of ion exchange groups capable of adsorbing weakly acidic cation impurities decreases.

[0005] When all the ion exchange groups in the weakly acidic cation exchange resin are consumed, the removal performance of the weakly acidic cation impurities is lost. Therefore, before that, the treatment of the treated water is once interrupted, and the weakly acidic cation exchange resin is brought into contact with an aqueous acid solution such as hydrochloric acid, sulfuric acid, or nitric acid to be regenerated into the H form, and it is necessary to restore the adsorptivity of the weakly acidic cation exchange resin.

[0006] Furthermore, after the weakly acidic cation exchange resin is regenerated into the H form by contacting it with an acidic aqueous solution, anions derived from the acidic aqueous solution remain in the weakly acidic cation exchange resin. For example, when a hydrochloric acid aqueous solution is used as the acidic aqueous solution, chloride ions remain. Therefore, it is necessary to wash the ion exchange resin after the regeneration treatment with ultrapure water or the like to remove the anions derived from the acidic aqueous solution from the weakly acidic cation exchange resin and suppress the elution of anions.

[0007] For example, Reference Document 2 describes the regeneration method recommended by the manufacturer, and it is described that a 3 to 6 mass% hydrochloric acid or a 0.5 to 0.8 mass% sulfuric acid aqueous solution is used as the regenerant.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Disclosure of the Invention

Problems to be Solved by the Invention

[0009] However, in the method of Reference Document 1, since the weakly acidic cation exchange resin is regenerated with a 3 - 5% acidic aqueous solution, and in Reference Document 2, since the weakly acidic cation exchange resin is regenerated with a 3 - 6 mass% hydrochloric acid or a 0.5 - 0.8 mass% sulfuric acid aqueous solution, there is a problem that a long time is required for washing after regenerating the ion exchange resin. And the time required for washing after regeneration leads to inefficiency in the entire purification process of ultrapure water by the weakly acidic cation exchange resin.

[0010] Therefore, an object of the present invention is to provide a method for adjusting a weakly acidic cation exchange resin capable of reducing the washing time after performing the regeneration step of the H - form weakly acidic cation exchange resin.

Means for Solving the Problems

[0011] Under such a technical background, as a result of intensive studies, the inventors of the present invention have found that by setting the concentration of the aqueous acid solution brought into contact with the weakly acidic cation exchange resin within a specific range during the regeneration process of the cation exchange resin, the washing time after the regeneration process can be shortened, and thus the present invention has been completed.

[0012] That is, the present invention (1) includes a regeneration step of converting the cation exchange resin into the H form by bringing an aqueous acid solution into contact with the cation exchange resin, and a washing step of washing the H-form cation exchange resin converted into the H form by bringing washing water into contact with the H-form cation exchange resin. The present invention is characterized by having these steps. The cation exchange resin is a weakly acidic cation exchange resin. The normality of the aqueous acid solution is 0.10 to 0.50 N. The acid aqueous solution is passed through at a flow rate of SV of 8 to 40 h -1 to perform the regeneration step, in the regeneration step, the relationship between the normality A of the acid aqueous solution and the flow rate B of the acid aqueous solution is represented by the following formula (1): A × B ≤ 4.5 (1) (wherein, A is the normality (N) of the acid aqueous solution, and B is the flow rate SV (h -1 ) of the acid aqueous solution.) satisfies The present invention provides a method for adjusting a cation exchange resin, which is characterized by the above.

[0015] Further, the present invention ( 2 ) provides a method for adjusting a cation exchange resin, which is characterized in that the cation exchange resin has a carboxyl group as an ion exchange group ( 1 ).

[0016] Further, the present invention ( 3 ) provides a method for adjusting a cation exchange resin, which is characterized in that the substrate of the cation exchange resin is an acrylic acid or methacrylic acid-divinylbenzene copolymer (1) or (2) .

Advantages of the Invention

[0017] According to the present invention, it is possible to provide a method for adjusting a weakly acidic cation exchange resin capable of reducing the washing time after performing the regeneration step of the H-form weakly acidic cation exchange resin.

Mode for Carrying Out the Invention

[0018] The method for adjusting a cation exchange resin of the present invention includes a regeneration step of converting the cation exchange resin into an H-form by bringing an acid aqueous solution into contact with the cation exchange resin, and a washing step of washing the H-form cation exchange resin by bringing washing water into contact with the H-form cation exchange resin converted into the H-form, and having the cation exchange resin is a weakly acidic cation exchange resin, the normality of the acid aqueous solution is 0.10 to 0.50 N, which is a method for adjusting a cation exchange resin, characterized by the above.

[0019] The method for adjusting a cation exchange resin of the present invention includes a regeneration step and a washing step.

[0020] The regeneration step is a step of converting the cation exchange resin into an H-form by bringing an acid aqueous solution into contact with the cation exchange resin.

[0021] In the regeneration step, the cation exchange resin brought into contact with the acid aqueous solution is a weakly acidic cation exchange resin. Since the degree of dissociation of weakly acidic functional groups such as carboxyl groups, thiol groups, phenol groups, and alcohol groups possessed by the weakly acidic cation exchange resin is low, the regeneration efficiency by an acid for adsorbed ions mainly composed of hardness components such as calcium and magnesium is superior to that of strongly acidic cation exchange resins.

[0022] The cation exchange group related to the weakly acidic cation exchange resin is not particularly limited, and examples thereof include a carboxyl group, a thiol group, a phenol group, and an alcohol group. Among these, as the cation exchange group, a carboxyl group is preferable.

[0023] The weakly acidic cation exchange resin is not particularly limited as long as it is an ion exchange resin in which a cation exchange group is introduced into a resin substrate, and it may be in various forms such as powdery, bead-like, or film-like, and may be either a gel-type ion exchange resin or a porous-type ion exchange resin.

[0024] The gel-type ion exchange resin and the porous-type ion exchange resin are classifications based on the microstructure of the ion exchange resin. Among them, the gel-type ion exchange resin refers to an ion exchange resin having a matrix of a product obtained by polymerizing styrene and divinylbenzene without a solvent and having a non-uniformly crosslinked gel-like structure, meaning the most classical ion exchange resin. Also, the porous-type ion exchange resin means an ion exchange resin having a matrix of a resin in which macropores with a pore diameter of about 20 nm to 100 nm are formed by using a solvent during polymerization, and includes those called MP type (macroporous type) and MR type (macroreticular type). The porous-type ion exchange resin has a lower ion exchange capacity than the gel-type resin because the macropores are not continuous and lack uniformity, but has high physical strength and excellent resistance to osmotic pressure and mechanical pressure.

[0025] As the substrate to which the cation exchange group binds, for example, one or more selected from styrene-based compounds such as crosslinked polystyrene and styrene-divinylbenzene copolymers, condensates of phenols and aldehydes, and crosslinked polyacrylic acids such as acrylic acid or methacrylic acid-divinylbenzene copolymers are preferred, crosslinked polyacrylic acid is more preferred, and acrylic acid or methacrylic acid-divinylbenzene copolymer is particularly preferred.

[0026] As the weakly acidic cation exchange resin, an MR-type weakly acidic cation exchange resin having a weakly acidic functional group and having a matrix of acrylic acid or methacrylic acid-divinylbenzene copolymer is preferred.

[0027] The shape of the weakly acidic cation exchange resin is not particularly limited. For example, when it has a granular shape, its average particle size is preferably 0.2 to 1.0 mm, more preferably 0.4 to 0.8 mm.

[0028] The weakly acidic cation exchange resin may be a commercially available product. Examples of such weakly acidic cation exchange resins include AMBERLITE HPR8400, AMBERLITE IRC76, AMBERLITE IRC86 manufactured by DuPont, and DIAION WK60L manufactured by Mitsubishi Chemical Corporation.

[0029] In the regeneration process, the weakly acidic cation exchange resin to be contacted with the aqueous acid solution is the weakly acidic cation exchange resin that has become in need of regeneration by being used for the purification of the water to be treated, that is, the weakly acidic cation exchange resin in which cation impurities are adsorbed on the cation exchange groups.

[0030] In the regeneration process, the aqueous acid solution to be contacted with the weakly acidic cation exchange resin is an aqueous solution of an acid such as hydrochloric acid, sulfuric acid, or nitric acid.

[0031] The normality of the aqueous acid solution is 0.10 to 0.50 N (equivalent / L), preferably 0.10 to 0.20 N. When the normality of the aqueous acid solution is within the above range, the washing time in the washing process can be shortened. On the other hand, if the normality of the aqueous acid solution is less than the above range, the conversion of the weakly acidic cation exchange resin to the H form will be insufficient, and if it exceeds the above range, the washing time in the washing process will be prolonged.

[0032] In the regeneration process, the temperature of the aqueous acid solution to be contacted with the weakly acidic cation exchange resin is not particularly limited and is appropriately selected according to the type of the aqueous acid solution, the heat-resistant temperature of the ion exchange resin, etc.

[0033] In the regeneration process, as a method of bringing an acidic aqueous solution into contact with a weakly acidic cation exchange resin, the weakly acidic cation exchange resin is filled into a cation exchange resin filling container to form a resin bed of the cation exchange resin in the cation exchange resin filling container. Then, an acidic aqueous solution is passed through the cation exchange resin filling container filled with the cation exchange resin bed to bring the acidic aqueous solution into contact with the cation exchange resin in the cation exchange resin filling container, and the acidic aqueous solution after being brought into contact with the cation exchange resin is discharged from the cation exchange resin filling container.

[0034] Alternatively, in the regeneration process, as a method of bringing an acidic aqueous solution into contact with a weakly acidic cation exchange resin, the weakly acidic cation exchange resin is filled into a cation exchange resin filling container, and the acidic aqueous solution is introduced and immersed into the cation exchange resin filling container filled with the cation exchange resin bed to bring the acidic aqueous solution into contact with the cation exchange resin in the cation exchange resin filling container, and the acidic aqueous solution after being brought into contact with the cation exchange resin is discharged from the cation exchange resin filling container.

[0035] When bringing an acidic aqueous solution into contact with a weakly acidic cation exchange resin by passing the acidic aqueous solution through the weakly acidic cation exchange resin bed filled in the cation exchange resin filling container, the liquid hourly space velocity SV of the acidic aqueous solution to the cation exchange resin bed is preferably 8 to 40 h -1 is.

[0036] And in the regeneration process, the normality of the acidic aqueous solution is 0.10 to 0.50 N, preferably 0.10 to 0.20 N, and the liquid hourly space velocity SV of the acidic aqueous solution to the cation exchange resin bed is 8 to 40 h -1 is preferable in that the specific resistance can reach a predetermined value in a short time after washing without extending the time of the regeneration process.

[0037] When bringing an acidic aqueous solution into contact with a weakly acidic cation exchange resin by passing the acidic aqueous solution through the weakly acidic cation exchange resin bed filled in the cation exchange resin filling container, the relationship between the normality A of the acidic aqueous solution and the liquid hourly space velocity B of the acidic aqueous solution to the cation exchange resin bed is represented by the following formula (1): A × B ≤ 4.5 (1) (wherein, A is the normality (N) of the aqueous acid solution, and B is the liquid hourly space velocity SV (h -1 -1) of the aqueous acid solution.) It is preferable to satisfy the above condition. By making the relationship between the normality A of the aqueous acid solution and the liquid hourly space velocity B of the aqueous acid solution flowing through the cation exchange resin bed satisfy the general formula (1), the time of the regeneration step can be shortened. A more preferable range is 0.01 ≤ A × B ≤ 4.5, and a particularly preferable range is 0.1 ≤ A × B ≤ 4.0. When the value of A × B is less than 0.01, the liquid hourly space velocity SV becomes 1 or less with respect to the total amount of acid required for regeneration and the range of the normality A of the aqueous acid solution of 0.10 to 0.50, so the time of the regeneration step becomes very long. On the other hand, when the value of A × B exceeds 4.5, the SV becomes high, that is, the flow velocity of the passing water becomes high, so that regeneration failure is likely to occur due to a decrease in the contact time between the aqueous acid solution required for regeneration and the ion exchange resin.

[0038] By performing the regeneration step, cation impurities are desorbed from the cation exchange groups of the cation exchange resin, and the cation impurities are removed from the cation exchange resin, so that the cation exchange groups of the cation exchange resin are converted into the H form. Therefore, the cation exchange resin is converted into an H-form cation exchange resin, and the cation exchange resin is regenerated.

[0039] The washing step is a step of washing the H-form cation exchange resin (hereinafter, also referred to as the H-form cation exchange resin) obtained by performing the regeneration step and converted into the H form by bringing the washing water into contact with the H-form cation exchange resin. Since anions derived from the aqueous acid solution remain inside and on the surface of the H-form cation exchange resin after the regeneration step and in the gaps between the particles of the cation exchange resin, it is necessary to remove the anions derived from the aqueous acid solution remaining in the H-form cation exchange resin before purifying the water to be treated using the H-form cation exchange resin. Therefore, by performing the washing step, the anions derived from the aqueous acid solution remaining inside and on the surface of the H-form cation exchange resin and in the gaps between the particles of the cation exchange resin are removed.

[0040] In the washing process, the washing water brought into contact with the H-form weakly acidic cation exchange resin is preferably less in impurity content, and more preferably less in metal content in the washing water.

[0041] In the washing process, the temperature of the washing water brought into contact with the H-form cation exchange resin is not particularly limited, and is appropriately selected according to the heat-resistant temperature of the ion exchange resin and the like.

[0042] In the washing process, as a method of bringing the washing water into contact with the H-form cation exchange resin, the washing water is passed through a cation exchange resin filling container filled with the H-form cation exchange resin, and the washing water is brought into contact with the H-form cation exchange resin in the cation exchange resin filling container, and the washing water after being brought into contact with the H-form cation exchange resin is discharged from the cation exchange resin filling container.

[0043] Alternatively, in the washing process, as a method of bringing the washing water into contact with the H-form cation exchange resin, the H-form cation exchange resin is filled into a cation exchange resin filling container, the washing water is introduced into and immersed in the cation exchange resin filling container filled with the H-form cation exchange resin bed, the washing water is brought into contact with the H-form cation exchange resin in the cation exchange resin filling container, and the washing water after being brought into contact with the H-form cation exchange resin is discharged from the cation exchange resin filling container.

[0044] When the washing water is brought into contact with the H-form cation exchange resin by passing the washing water through the H-form cation exchange resin bed filled in the cation exchange resin filling container, the liquid passing rate SV of the washing water through the H-form cation exchange resin bed is preferably 1 to 100 h -1 is.

[0045] And by performing the washing process, the cation exchange resin is adjusted to the H-form cation exchange resin used for purifying the water to be treated.

[0046] After performing the method for adjusting the cation exchange resin of the present invention, a purification process for purifying the water to be treated is performed using the H-form cation exchange resin that has been subjected to the regeneration process and the washing process, and treated water is obtained.

[0047] In the purification process, the purification treatment conditions such as the temperature of the water to be treated, the flow rate of the water to be treated through the H-type cation exchange resin, the water passing time, the resin amount of the H-type cation exchange resin, and the resin bed height are appropriately selected based on the water quality of the water to be treated.

[0048] It is the content of cation impurities mainly composed of hardness components in the treated water of the weakly acidic cation exchange resin, and the content of each cation impurity is preferably 100 μg / L or less, particularly preferably 10 μg / L or less. The treated water of the weakly acidic cation exchange resin is preferably used as ultrapure water for semiconductor manufacturing that requires an extremely low concentration of ionic impurities after being treated by a strongly acidic cation exchange resin, a basic anion exchange resin, or a reverse osmosis (RO) membrane or an electrodialysis desalination device.

[0049] And in the purification process, since the cation impurities in the water to be treated are adsorbed on the cation exchange groups of the H-type cation exchange resin, if the purification continues, the amount of cation exchange groups capable of adsorbing cation impurities in the H-type cation exchange resin will decrease. Therefore, before all the cation exchange groups capable of adsorbing cation impurities in the H-type cation exchange resin are used for the adsorption of cation impurities and the cation impurity removal performance disappears, the purification process is interrupted and the adjustment method of the cation exchange resin of the present invention is performed again.

[0050] In the adjustment method of the cation exchange resin of the present invention, in the washing step after the regeneration step, the amount of anions derived from the aqueous acid solution remaining in the H-type cation exchange resin can be rapidly reduced, so the washing time can be shortened. For example, in the adjustment method of the cation exchange resin of the present invention, in the washing step after the regeneration step, the time until the specific resistance value of the washing water reaches 10 MΩ·cm after contacting the cation exchange resin is shortened. Also, for example, in the adjustment method of the cation exchange resin of the present invention, in the washing step after the regeneration step, the specific resistance value of the washing water after contacting the cation exchange resin 1 hour after the start of washing is higher than that of the conventional regeneration method of the cation exchange resin.

Example

[0051] Hereinafter, examples are shown to explain the present invention in more detail, but the present invention is not limited thereto.

[0052] (Example 1) To a column filled with 500 mL (500 mL-R) of weakly acidic cation exchange resin (AMBERLITE HPR8400-HG, manufactured by Organo Corporation), 1.0 N aqueous NaOH solution was passed through for 70 minutes at a liquid hourly space velocity (SV) of 4 hr -1 so that all ionic forms of the functional groups were converted to the Na form. Thereafter, 0.50 N aqueous HCl solution was passed through for 70 minutes at a liquid hourly space velocity (SV) of 8 hr -1 so that all ionic forms of the functional groups were converted to the H form. Thereafter, ultrapure water was passed through the resin converted to the H form at a liquid hourly space velocity (SV) of 50 hr -1 and the specific resistance value (MΩ·cm) of the obtained treated water was measured. The results are shown in Table 1.

[0053] (Examples 2 to 3, Comparative Examples 1 to 2) Instead of setting the normality of the HCl aqueous solution to 0.50 N and the liquid hourly space velocity (SV) to 8 hr -1 it was carried out in the same manner as in Example 1 except that the normality and the liquid hourly space velocity were as described in Table 1. The results are shown in Table 1.

[0054]

Table 1

[0055] In Examples 1 to 3 and Comparative Example 1, they were sufficiently regenerated from the normality, the liquid hourly space velocity, and the liquid passing time of the HCl aqueous solution passed through in the regeneration step.

Claims

1. A regeneration step of converting the cation exchange resin to the H form by bringing an acidic aqueous solution into contact with the cation exchange resin, and A washing step of washing the H-form cation exchange resin by bringing washing water into contact with the H-form cation exchange resin converted to the H form, Having, The cation exchange resin is a weakly acidic cation exchange resin, The normality of the acidic aqueous solution is 0.10 to 0.50 N, Performing the regeneration step by passing the acidic aqueous solution at a flow rate of SV 8 to 40 h-1, In the regeneration step, the relationship between the normality A of the acidic aqueous solution and the flow rate B of the acidic aqueous solution is represented by the following formula (1): A × B ≤ 4.5 (1) (In the formula, A is the normality (N) of the acidic aqueous solution, and B is the flow rate SV (h-1) of the acidic aqueous solution.) Satisfying, A method for adjusting a cation exchange resin, characterized by the above.

2. The method for adjusting a cation exchange resin according to claim 1, characterized in that the cation exchange resin has a carboxyl group as an ion exchange group.

3. The method for adjusting a cation exchange resin according to claim 1 or 2, characterized in that the substrate of the cation exchange resin is an acrylic acid or methacrylic acid-divinylbenzene copolymer.

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