How to remove boron

Abstract

To provide a method of effectively removing boron present in water to be treated while suppressing an increase in total organic carbon concentration.SOLUTION: A method of removing boron is characterized by allowing water to be treated containing boron in an amount of not more than 500 μg / L to flow through a boron selective ion exchange resin comprising a glucamine group with its release amount of total organic carbons being not more than 10 μg / L, so that the liquid space velocity (SV) becomes 60 to 700 h-1. Preferably, the method of removing boron uses a boron selective ion exchange resin having been pretreated by contacting the same with an aqueous solution of sodium hydroxide beforehand.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a method for removing boron from water. [Background technology]

[0002] In recent years, there has been a demand for ultrapure water with a boron concentration of 1 ng / L or less in processes such as silicon cleaning during semiconductor manufacturing. As a method for reducing the boron concentration in water, a method using a boron-selective ion exchange resin has been proposed. For example, Patent Document 1 proposes a method for removing boron by contacting pretreated water with a boron-selective ion exchange resin at a position within a pure water or ultrapure water production facility. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-84986 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the inventors of the present invention have found through their investigations that when an attempt is made to treat boron in water using the boron-selective ion exchange resin described in Patent Document 1 and the like, the total organic carbon (TOC) concentration in the treated water is likely to increase compared to before treatment.

[0005] As a result of further investigations, the inventors have found that the increase in the total organic carbon concentration is caused by, for example, the elution of hydrocarbons remaining in the ion exchange resin, and that in particular, when an ion exchange resin having glucamine groups is used as the boron-selective ion exchange resin, unreacted glucamine remaining in the ion exchange resin is eluted, easily causing an increase in the total organic carbon concentration in the treated water.

[0006] Under these circumstances, an object of the present invention is to provide a method for effectively removing boron from water to be treated while suppressing an increase in the total organic carbon concentration. [Means for solving the problem]

[0007] As a result of intensive research to achieve the above-mentioned object, the inventors have discovered that the above-mentioned technical problems can be solved by contacting the treated water with a specific boron-selective ion exchange resin having a glucamine group under specific conditions, and have completed the present invention based on this finding.

[0008] That is, the present invention provides (1) For a boron-selective ion exchange resin with a glucamine group and a total organic carbon release rate of 10 μg / L or less, the treated water with a boron content of 500 μg / L or less is treated at a liquid hourly space velocity (SV) of 60 to 700 h -1 A method for removing boron, comprising: (2) The method for removing boron according to (1) above, wherein the boron-selective ion exchange resin is pretreated by contacting it with an aqueous caustic soda solution. This provides: Effect of the Invention

[0009] According to the present invention, it is possible to provide a method for effectively removing boron from water to be treated while suppressing an increase in the total organic carbon concentration. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for removing boron according to the present invention is to treat water containing 500 μg / L or less of boron with a boron-selective ion exchange resin having a glucamine group and a total organic carbon release rate of 10 μg / L or less at a liquid hourly space velocity (SV) of 60 to 700 h -1 The present invention is characterized in that water is passed through the filter so that the

[0011] In the present invention, the boron content in the water to be treated is 500 μg / L or less, preferably 100 μg / L or less, and more preferably 50 μg / L or less. Although there is no particular lower limit for the boron content in the water to be treated in the present invention, the boron content in the water to be treated is usually 50 ng / L or more.

[0012] In the present invention, by setting the boron content in the water to be treated to 500 μg / L or less, the boron content in the water to be treated can be more effectively reduced while suppressing breakthrough of the boron-selective ion exchange resin.

[0013] In the present application, the boron content in water refers to a value measured using an ICP-MS 8900 manufactured by Agilent Technologies.

[0014] In the present invention, the water to be treated has a pH of suitably 5-9, and more suitably a pH of 6-8. In the present invention, the pH of the water to be treated may be appropriately adjusted before being contacted with the boron-selective ion exchange resin.

[0015] In the present invention, examples of the water to be treated include water used for washing silicon during semiconductor manufacturing.

[0016] In the present invention, the water to be treated is passed through a boron-selective ion exchange resin that has glucamine groups and releases 10 μg / L or less of total organic carbon.

[0017] In the present invention, the boron-selective ion exchange resin having a glucamine group can selectively adsorb boron because the glucamine group is introduced as a chelating group (chelating group) that easily forms a chelate bond with boron, instead of the ion exchange group in the ion exchange resin.

[0018] In the present invention, the boron-selective ion exchange resin is not particularly limited as long as it is an ion exchanger having a predetermined total organic carbon release amount in which glucamine groups have been introduced into a resin substrate, and various forms such as powder, beads, and membrane can be used, and either a gel-type ion exchange resin or a porous-type ion exchange resin can be used.

[0019] Gel-type ion exchange resins and porous-type ion exchange resins are classified based on the microstructure of the ion exchange resin. Among these, the gel-type ion exchange resin is an ion exchange resin based on a solvent-free polymer of styrene and divinylbenzene, has a heterogeneously crosslinked gel-like structure, and refers to the most classical ion exchange resin.

[0020] In addition, the term "porous ion exchange resin" refers to an ion exchange resin based on a resin in which macropores with a pore size of about 20 nm to 100 nm are formed by using a solvent during polymerization, and includes those called MR type. Porous ion exchange resins can be used in non-aqueous systems because even solvents with low polarity can penetrate into the resin, and since the macropores are not continuous and lack uniformity, they have a lower ion exchange capacity than gel-type resins, but they have high physical strength and excellent resistance to osmotic pressure and mechanical pressure.

[0021] In the present invention, the substrate to which the glucamine group, which is the chelating group, is bonded is preferably one or more selected from styrene-based compounds such as cross-linked polystyrene and styrene-divinylbenzene copolymer, condensates of phenols and aldehydes, cross-linked polyacrylic acid, and the like, and more preferably cross-linked polystyrene or styrene-divinylbenzene copolymer.

[0022] In the present invention, the boron-selective ion exchange resin to which the glucamine group, which is a chelating group, is bonded is preferably an MR type ion exchange resin based on a styrene-divinylbenzene copolymer.

[0023] In the present invention, the glucamine group which is the chelating group is not particularly limited, but is preferably an N-alkylglucamine group, more preferably an N-methylglucamine group.

[0024] In the present invention, the boron-selective ion exchange resin having glucamine groups has a total organic carbon release amount of 10 μg / L or less, and more preferably 5 μg / L or less.

[0025] In this application, the total organic carbon release amount is measured by measuring the amount of total organic carbon (TOC) released by ion exchange of test water having a total organic carbon (TOC) of 1.0 μg / L or less at room temperature and at a liquid hourly space velocity of SV50 hr -1 This means the amount of total organic carbon (TOC) (μg / L) in the effluent when water is passed through the effluent for 24 hours.

[0026] In this application, the total organic carbon (TOC) concentration in water refers to a value measured using a Sievers M9e manufactured by Suez.

[0027] In the present invention, by using a specific boron-selective ion exchange resin that has a glucamine group and has a total organic carbon release amount within the above range, boron in the treated water can be effectively removed while suppressing an increase in the total organic carbon concentration.

[0028] In the present invention, the boron-selective ion exchange resin having glucamine groups may be pretreated by contacting it with an aqueous solution of caustic soda. In the present invention, the boron-selective ion exchange resin having glucamine groups is pretreated by contacting it with an aqueous caustic soda solution, so that it is easy to provide one having a desired total organic carbon release amount.

[0029] In the present invention, when the boron-selective ion exchange resin having glucamine groups is pretreated by contacting it with an aqueous caustic soda solution, it is preferable to carry out the pretreatment under the following conditions (1) to (3). (1) 3-5L / LR of 1N NaOH aqueous solution is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 hr -1 The medicine is administered. (1N NaOH aqueous solution is passed through the boron-selective ion exchange resin in an amount 3 to 5 times the volume of the resin, so that the ratio of "volume of NaOH aqueous solution passed through per hour / volume of boron-selective ion exchange resin" is 4.) (2) Next, 1.5 L / LR of ultrapure water or pure water is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 h -1 Water is passed through the boron-selective ion exchange resin at 0.5 to push out any NaOH remaining in the resin. (3) Then, 10 to 20 L / LR of ultrapure water or pure water is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 10 h -1 Then, pass water through the filter and wash it.

[0030] In the present invention, when the boron-selective ion exchange resin having glucamine groups is pretreated by contacting it with an aqueous caustic soda solution, it is more preferable to pretreat it under the following conditions (i) to (iii) prior to the pretreatment under the above conditions (1) to (3). (i) 3-5L / LR of 1N HCl aqueous solution is poured into the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 hr -1 The medicine is administered. (A 1N HCl aqueous solution in an amount 3 to 5 times the volume of the boron-selective ion exchange resin is passed through so that the ratio of "volume of HCl aqueous solution passed through per hour / volume of boron-selective ion exchange resin" is 4.) (ii) Next, 1.5 L / LR of ultrapure water or pure water is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 h -1 Water is passed through the boron-selective ion exchange resin at 0.5° C. to push out the HCl remaining in the resin. (iii) Then, 10 to 20 L / LR of ultrapure water or pure water is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 10 h -1 Then, pass water through the filter and wash it.

[0031] In this application, pure water means water having an electrical resistivity of 1 to 18 MΩ cm as measured by a Foxboro in-line resistivity meter, and ultrapure water means water having an electrical resistivity of more than 18.0 MΩ cm as measured by a Foxboro in-line resistivity meter.

[0032] In the present invention, the boron-selective ion exchange resin having a glucamine group and releasing a total organic carbon amount of 10 μg / L or less may be a commercially available product, and an example of such a boron-selective ion exchange resin is ORLITE X-U653J manufactured by Organo Corporation.

[0033] In the present invention, the shape of the boron-selective ion exchange resin having glucamine groups is not particularly limited. For example, when it has a granular shape, the average particle size is preferably 0.2 to 1.0 mm, more preferably 0.4 to 0.8 mm.

[0034] In the present invention, the liquid hourly space velocity SV ("volume of water to be treated passing through the boron-selective ion exchange resin per hour / volume of boron-selective ion exchange resin") when the water to be treated passes through the boron-selective ion exchange resin is 60 to 700 h -1 75~600hr -1 It is preferable that the temperature is 90 to 600 hours. -1 It is more preferable that the temperature is within a range of 100 to 250 hours. -1 It is even more preferable that:

[0035] In the present invention, by controlling the liquid hourly space velocity SV when the water to be treated is passed through the boron-selective ion exchange resin within the above range, boron in the water to be treated can be effectively removed while suppressing an increase in the total organic carbon concentration.

[0036] Conventionally, when the water to be treated is passed through a boron-selective ion exchange resin, the liquid hourly space velocity (SV) is set to 50 hr -1It was previously believed that boron in the treated water could not be sufficiently removed unless it was suppressed to a level below 10 μg / L. However, according to the study by the present inventors, when a boron-selective ion exchange resin having glucamine groups and a total organic carbon release rate of 10 μg / L or less is used, the liquid hourly space velocity (SV) of the treated water can be reduced to 60 to 700 hr -1 The inventors have found that even when the concentration of boron in water is increased to 100 mg / kg, it is possible to sufficiently remove boron from the water and to suppress an increase in the total organic carbon concentration, and have thus completed the present invention.

[0037] The liquid hourly space velocity (SV) when the water to be treated is passed through the boron-selective ion exchange resin is 60 hr -1 If the liquid hourly space velocity (SV) is less than 700 hr when the water to be treated is passed through the boron-selective ion exchange resin, the increase in the total organic carbon concentration in the treated water cannot be suppressed. -1 If it exceeds this limit, it becomes difficult to sufficiently suppress the boron content in the treated water.

[0038] In the present invention, the boron-selective ion exchange resin that has been passed through a certain amount of treated water can be regenerated by passing a regenerant through it to elute the adsorbed matter, after which the resin is backwashed as necessary. By passing the regenerant through the resin, a regenerated waste liquid containing a high concentration of boron is produced. The regenerant may include sodium hydroxide.

[0039] According to the present invention, it is possible to provide a method for effectively removing boron from water to be treated while suppressing an increase in the total organic carbon concentration.

[0040] (Example) The present invention will now be described in more detail with reference to examples, but these are merely illustrative and do not limit the present invention.

[0041] Example 1 The boron adsorption column was packed with 500mL (500mL-R) of Organo Corporation's boron-selective ion exchange resin "ORLITE X-U653" (total organic carbon release amount is 4μg / L). The treated water with a boron concentration of 50μg / L and a total organic carbon concentration of 2μg / L was passed through the column at a liquid hourly space velocity (SV) of 100hr. -1 The treated water was passed through for 24 hours so that the boron content (μg / L) and total organic carbon content (μg / L) in the treated water were measured. The results are shown in Table 1.

[0042] (Examples 2 to 3, Comparative Examples 1 to 2) The liquid hourly space velocity (SV) when the treated water with a boron concentration of 50 μg / L and a total organic carbon concentration of 2 μg / L is passed through the boron adsorption column is 250 h -1 (Example 2), 500hr -1 (Example 2), 50 hr -1 (Comparative Example 1), 1000hr -1 The water was passed through in the same manner as in Example 1, except that the treatment was changed to (Comparative Example 2), and the amount of boron (μg / L) and the amount of total organic carbon (μg / L) in the treated water obtained at this time were measured. The results are shown in Table 1.

[0043] [Table 1]

[0044] Comparative Example 3 The boron selective ion exchange resin "DIAION CRB03" (total organic carbon release amount 80μg / L) manufactured by Mitsubishi Chemical Corporation was packed in a boron adsorption column with a resin amount of 500mL (500mL-R). The treated water with a boron concentration of 50μg / L and a total organic carbon concentration of 2μg / L was passed through the column at a liquid hourly space velocity (SV) of 50hr. -1 Water was passed through the tube for 24 hours so that the temperature was kept constant. The boron content (μg / L) and total organic carbon content (μg / L) in the treated water were measured. The results are shown in Table 2.

[0045] Comparative Example 4 The liquid hourly space velocity (SV) when the treated water with a boron concentration of 50 μg / L and a total organic carbon concentration of 2 μg / L is passed through the boron adsorption column is -1 The boron amount (μg / L) and the total organic carbon amount (μg / L) in the treated water were measured. The results are shown in Table 2.

[0046] Comparative Example 5 (1) Pretreatment of boron-selective ion exchange resin A boron-selective ion exchange resin "DIAION CRB03" manufactured by Mitsubishi Chemical Corporation (having a total organic carbon release of 80μg / L) was pretreated in advance by contacting it with an aqueous caustic soda solution using the following methods (i) to (iii). By using the methods (i) to (iii), the total organic carbon release of the aforementioned ion exchange resin was reduced to 10μg / L or less. (i) 4L / LR of 1N NaOH aqueous solution is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 hr -1 I was given the medicine. (ii) Next, 1.5 L / LR of ultrapure water was applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 4 h -1 Water was passed through the boron-selective ion exchange resin at 0.05 mL to push out the NaOH remaining in the resin. (iii) Then, 15 L / LR of ultrapure water is applied to the boron-selective ion exchange resin at a liquid hourly space velocity (SV) of 10 h -1 The filter was washed by passing water through it. (2) Treatment of treated water The boron selective ion exchange resin obtained by the above pretreatment was packed in a boron adsorption column with a resin volume of 500 mL (500 mL-R). The treated water with a boron concentration of 50 μg / L and a total organic carbon concentration of 2 μg / L was then passed through the column at a liquid hourly space velocity (SV) of 50 h -1 Water was passed through the tube for 24 hours so that the temperature was kept constant. The boron content (μg / L) and total organic carbon content (μg / L) in the treated water were measured. The results are shown in Table 2.

[0047] Example 5 The liquid hourly space velocity (SV) when the treated water with a boron concentration of 50 μg / L and a total organic carbon concentration of 2 μg / L is passed through the boron adsorption column is -1 The boron amount (μg / L) and the total organic carbon amount (μg / L) in the treated water were measured. The results are shown in Table 2.

[0048] [Table 2]

[0049] From Tables 1 and 2, in Examples 1 to 5, the treated water having a boron content of 500 μg / L or less was treated with a boron-selective ion exchange resin having a glucamine group and a total organic carbon release amount of 10 μg / L or less at a liquid hourly space velocity SV of 60 to 700 h -1 It can be seen that the boron in the treated water can be effectively removed while suppressing an increase in the total organic carbon concentration. Furthermore, from Table 2, it can be seen that in Example 5, the total organic carbon content in the resulting treated water can be more effectively reduced by pretreating the boron-selective ion exchange resin in advance by contacting it with an aqueous caustic soda solution.

[0050] On the other hand, from Tables 1 and 2, in Comparative Examples 1 to 3 and 5, the liquid hourly space velocity SV of the water to be treated passing through the boron-selective ion exchange resin is 60 to 700 h -1 Since the values ​​are outside the range, it is understood that the total organic carbon content in the obtained treated water is high (Comparative Example 1, Comparative Example 3, Comparative Example 5), and the boron content in the obtained untreated water is high (Comparative Example 2).

[0051] In addition, the results of Comparative Example 3 and Comparative Example 4 show that when a boron-selective ion exchange resin with a high total organic carbon content (μg / L) was used, the liquid hourly space velocity (SV) was increased to 50 hr -1 (Comparative Example 3) 100hr ―1It can be seen that even if the concentration was increased to (Comparative Example 4), the effect of reducing the amount of total organic carbon in the treated liquid was low (see Table 2). On the other hand, the results of Comparative Example 5 and Example 5 show that when a boron-selective ion exchange resin in which the total organic carbon content (μg / L) has been reduced in advance by pretreatment is used, the total organic carbon amount in the treated liquid can be effectively reduced by controlling the liquid hourly space velocity within a predetermined range (see Table 2). [Industrial Applicability]

[0052] According to the present invention, it is possible to provide a method for effectively removing boron from water to be treated while suppressing an increase in the total organic carbon concentration.

Claims

1. The boron-selective ion exchange resin has a glucamine group and releases a total organic carbon of 10 μg / L or less. The treated water has a boron content of 500 μg / L or less, and is treated at a liquid hourly space velocity (SV) of 60 to 700 h －１ The method for removing boron is characterized by passing water through the solution so that the boron concentration is 100%.

2. 2. The method for removing boron according to claim 1, wherein the boron-selective ion exchange resin is pretreated by contacting it with an aqueous caustic soda solution.

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