TWI781227B - Method for removing boron, and method for producing pure water or ultrapure water - Google Patents

Abstract

With the boron BTP corresponding to the preset boron adsorption tower, set the product of the boron concentration of the boron adsorption tower water supply and the water flow SV, or the product of the boron adsorption tower water supply boron concentration, water flow SV and water flow time to a specific value The following conditions are processed. The amount of the boron-selective adsorbent to be filled in the boron adsorption tower is set so that the above-mentioned product becomes a predetermined value or less.

Description

Method for removing boron, and method for producing pure water or ultrapure water

The invention relates to a method for removing boron by introducing boron-containing water into a boron adsorption tower filled with a boron selective adsorption body. The present invention also relates to a method for producing pure water or ultrapure water using the boron removal method.

In this specification, the so-called BTC (Break through capacity) refers to the through-flow replacement capacity of the boron adsorption tower, and the so-called BTP (Break through point) refers to the through-flow point (over critical point).

The ultrapure water manufacturing system is composed of a pretreatment system, a primary pure water system, and a subsystem.

The role of the primary pure water system is to remove most of the ionic components or TOC in the pre-treated water. It is composed of RO devices (reverse osmosis membrane devices), degassing membrane devices, and deionization devices. Among them, the deionization device is selected from multiple bed ion exchange devices using ion exchange resins, mixed bed ion exchange devices, and electrical deionization devices in response to water volume or non-chemical needs.

The subsystem is to improve the pure water obtained from the primary pure water system according to the purpose to become a system of specific ultrapure water quality. It is composed of UV device (ultraviolet oxidation device), non-regenerative ion exchange device, degassing membrane device, and UF device. (ultrafiltration membrane device) and other configurations.

The role of the subsystem is to remove trace ions or TOC and microparticles that cannot be removed by the primary pure water system.

In recent years, ultrapure water with boron concentration below 1ng/L is expected to be required in the most advanced electronics industry.

In the past, one of the means to reduce the concentration of boron in water is the utilization of boron chelating agent resin (boron selective ion exchange resin) or anion exchange resin. Boron chelating agent resin is a resin that fixes and removes boron in water by reacting N-methyl reduced glucosamine group (NMG) inside the resin with boron.

For example, Patent Document 1 describes that boron is removed by bringing pretreatment water into contact with a boron chelating agent resin at any position in pure water or ultrapure water production equipment.

In Patent Document 2, it is described that the non-pharmaceutical regenerative desalination device (2-stage RO, electrical regenerative desalination device, distillation device) is contacted with boron chelating agent resin in the subsequent stage.

Patent Document 3 describes that when boron is removed by using an anion exchange resin, the water temperature of the water to be treated is lowered and the boron BTC is increased.

In Patent Document 4, it is described that boron is desorbed and regenerated by passing warm pure water through an anion exchange resin on which boron is adsorbed, thereby increasing boron BTC.

[Patent Document 1] Japanese Patent Application Laid-Open No. 8-84986 [Patent Document 2] Japanese Patent Application Laid-Open No. 9-192661 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-177564 [Patent Document 4] Japanese Patent Application Laid-Open No. 2009-240891 Bulletin

Since boron selective adsorbents such as boron chelating resins are expensive, it is desired to maximize the boron adsorption capacity, that is, to fully increase the boron BTC of the boron adsorption tower.

Among these technical requirements, the prior art is not sufficient. For example, the methods of the above-mentioned patent documents 1 and 2 can remove boron by simple configuration, but cannot perform optimal operation control for the boron chelating agent resin, and cannot realize appropriateness.

In the method of Patent Document 3, although the boron that is easy to ooze is accumulated in the resin by adjusting the water temperature, and the adsorption capacity of the resin is effectively used, but for the adjustment of the water temperature, the setting of a heat exchanger is required, and its effect Can't say enough.

The method of Patent Document 4 is to re-estimate boron removal based on the amount of boron desorption, but even this method cannot obtain a sufficient effect of improving the adsorption capacity, and also requires the cost of warm water.

The object of the present invention is to provide a boron BTC that can increase the boron adsorption tower filled with a boron selective adsorption body without requiring special equipment, medicines, energy, etc., and can maximize the use of the adsorption capacity of the boron selective adsorption body. A boron removal method that removes more boron with less amount of resin, and a method of producing pure water or ultrapure water using the boron removal method.

As a result of repeated positive examinations by the present inventors in order to solve the above-mentioned problems, it was found that in the process of removing boron by passing boron-containing water through a boron adsorption tower filled with a boron-selective adsorbent, even if the same BTP is set, the boron BTC will follow the flow of water SV However, boron BTC can be increased by reducing the water supply load or water SV, thus completing the present invention.

That is, the gist of the present invention is as follows.

[1] A boron removal method, which is a method for removing boron by introducing boron-containing water into a boron adsorption tower filled with a boron selective adsorption body, and its feature is to correspond to the preset boron BTP of the boron adsorption tower , the boron concentration of the water supplied to the boron adsorption tower and the product of the boron-containing water SV of the water flowing to the boron adsorption tower become below a specific value, and the boron-containing water is fed.

[2] A boron removal method in [1], setting the water flow SV and/or the boron filled in the boron adsorption tower so that the product of the water flow SV and the boron concentration of the feed water becomes below a specific value Selective adsorption volume.

[3] A boron removal method, which is a method for removing boron by passing boron-containing water into a boron adsorption tower filled with a boron selective adsorption body, and its characteristic is to correspond to the boron BTP of the boron adsorption tower set in advance , the boron concentration of the water supplied to the boron adsorption tower and the product of the boron-containing water to the boron-containing water to the boron adsorption tower SV and the water-passing time of the boron-containing water become below a specified value, and the boron-containing water is passed into the condition.

[4] A boron removal method in [3], in which the water flow SV is set and filled with the boron in such a manner that the product of the water flow SV, the boron concentration of the supply water, and the water flow time becomes a specified value or less. Any one of the setting of the boron selective adsorption volume of the adsorption tower and the control of the water passing time.

[5] A boron removal method in [3], using a plurality of the aforementioned boron adsorption towers, while continuing to pass the aforementioned water supply to a part of the plurality of boron adsorption towers, while allowing the aforementioned water flow The stop period of water flow to other boron adsorption towers is set so that the product of the SV, the boron concentration of the supplied water, and the water flow time becomes less than a specific value.

[6] A method for removing boron. In [5], the aforementioned plurality of boron adsorption towers are connected in parallel, and while continuing the aforementioned water supply to one of the plurality of boron adsorption towers, the other boron adsorption towers are set to During the period when the water supply to the boron adsorption tower is stopped.

[7] A method for producing pure water or ultrapure water, which has a step of removing boron by the method for removing boron according to any one of [1] to [6]. [Invention effect]

According to the present invention, the boron adsorption capacity of the boron selective adsorbent such as boron chelating agent resin can be effectively utilized to the maximum extent to reduce the frequency of regeneration or replacement, and more boron can be removed with less amount of resin, and the desired boron can be stably obtained. Treated water with low boron concentration or pure water or ultrapure water.

Embodiments of the present invention will be described in detail below.

<Mechanism> According to the present invention, the boron BTC can be increased by setting the product of the boron concentration in the supplied water and the water flow SV or the product of the boron concentration in the water supply, the water flow SV and the water flow time below a specific value corresponding to the boron BTP The mechanism is considered as follows.

General physical properties of boron selective adsorbents such as boron chelating resins are exemplified below.

That is, for example, when using 1L of resin with an adsorption capacity of 0.7eq/L-R, it should be able to adsorb and remove about 7.5g of boron in theory. When boron BTP is set at 1~10ng/L, boron can only remove about 50~300mg (that is, the adsorption capacity is 50~300mg/L-R).

This is because the reaction of boron is slow, so if it is a resin, the speed of boron adsorbed on the outer periphery to diffuse into the resin becomes very slow, so the inside of the resin cannot be actively used for the adsorption and removal of boron.

When the water supply load is extremely reduced and the water is passed very slowly, boron will diffuse in the resin, so that the inside of the resin can be efficiently used for the adsorption of boron, and the boron BTC can be increased.

This can also be seen from the results of Experimental Examples 1 and 2 described later. Even if it is the same boron BTP, the boron BTC also varies greatly with the water SV (Fig. 1 of Experimental Example 1). By corresponding to the boron BTP, the water supply The boron BTC can be increased by setting the product of the boron concentration and the water flow SV below a certain value (Fig. 2 of Experimental Example 2).

The same applies to the product of the concentration of boron in the supplied water and the product of the water passing SV and the water passing time.

<Operation method of boron adsorption tower> The present invention is to feed boron-containing water into the boron adsorption tower filled with boron selective adsorption body to remove boron in the boron-containing water. The product of the boron concentration of the water (the water flowing into the boron adsorption tower) and the water flow SV, or the product of the boron concentration of the feed water, the water flow SV and the water flow time is treated under the condition that it becomes below a specific value.

As mentioned above, even if the boron selective adsorbent has the same boron BTP and the same supply water boron concentration, if the water flow SV is different, the boron BTC will be significantly different. Therefore, in the present invention, for example, a desired boron BTC is set for a preset boron BTP (this value is the boron concentration of the target boron removal treatment water). The product (loading amount per time) is determined to meet the set value to determine the amount of boron selective adsorption body (the amount of boron selective adsorption body used) that is passed through the water SV or filled in the boron adsorption tower.

When the water flow SV cannot be lowered, for example, by setting a stop time after passing a certain amount of water, it is also possible to respond by reducing the water flow SV per unit time including the stop time.

In the production equipment of ultrapure water used for medicine, food, beverage, and semiconductor water, it is known to connect multiple ion exchange towers in series, and to introduce the highest concentration of ion components when the ion exchange towers are regenerated or replaced. The ion exchange tower in the front stage of the water is regenerated, and the regenerated ion exchange tower is installed in the last stage, or the ion exchange tower in the front stage is removed, and a new ion exchange tower is installed in the last stage of the ion exchange tower. The regeneration or replacement method of the merry-go-round method.

The present invention can also be applied to such a merry-go-round method. A plurality of boron adsorption towers are arranged in series, and when changing the boron adsorption towers that stop water flow sequentially, water flow is not performed for a certain period of time in each boron adsorption tower. If so, the water flow SV in operation can reduce the water flow SV (time average load) per unit time, which can ensure the penetration time of boron into the resin and increase the boron BTC.

It is also possible to connect a plurality of boron adsorption towers in parallel, and when changing the boron adsorption towers that conduct water flow sequentially and the boron adsorption towers that stop water flow, in each boron adsorption tower, do not conduct water flow for a certain period of time. If so, the water flow SV in operation can reduce the water flow SV (time average load) per unit time, which can ensure the penetration time of boron into the resin and increase the boron BTC.

It is especially effective when the water flow SV (time average load) reduction due to the stop of water flow in this way is high when the boron concentration in the water to be treated is high.

<Specific condition setting> In the present invention, corresponding to the boron BTP, the product of the boron concentration in the water supply and the water flow SV, or the product of the boron concentration in the water supply, the water flow SV and the water flow time are set. The boron adsorption energy of the boron selective adsorbent depends on the desired boron BTC. An example of condition setting is as follows.

When it is desired to set the concentration of boron in the treated water, that is, boron BTP, to 10ng/L, the product of the water supply SV (1/h) and the supply water boron concentration (μg/L) is less than 120, so that the water flow SV (1/h) Conditions are set so that the product of boron concentration (μg/L) in water supply and operation time (h) becomes 2880 or less. It is desired to set the product of the water supply SV (1/h) and the water supply boron concentration (μg/L) to be less than 100, and the water supply SV (1/h) and the supply water boron concentration (μg/L) and the operation time (h) The product of the water supply is set to be below 2400, and it is more desirable to set the product of the water supply SV (1/h) and the water supply boron concentration (μg/L) to be below 60, and the water supply SV (1/h) and the supply water boron concentration (μg/L) The product of L) and operating time (h) is set to be 1440 or less.

When it is desired to set the concentration of boron in the treated water, that is, boron BTP, to 1ng/L, the product of the water supply SV (1/h) and the supply water boron concentration (μg/L) is less than 80, so that the water flow SV (1/h) The conditions are set so that the product of the boron concentration (μg/L) and the operation time (h) of the feed water becomes 1920 or less. It is desired to set the product of the water supply SV (1/h) and the water supply boron concentration (μg/L) below 60, and the water supply SV (1/h) and the supply water boron concentration (μg/L) and the operation time (h) The product of the water supply is set to be below 1440, and it is more desirable to set the product of the water supply SV (1/h) and the water supply boron concentration (μg/L) to be below 45, and the water supply SV (1/h) and the supply water boron concentration (μg/L) The product of L) and operating time (h) is set to be 1080 or less.

<Boron Selective Adsorbent> The boron selective adsorbent used in the present invention may be a granular material such as a boron chelating agent resin (boron selective chelating agent resin), or may be a fibrous material.

As the boron selective adsorbent, various ones that adsorb boron by ion exchange or adsorb boron by chelating agent can be used, but for example, commercially available boron selective chelating agent resin "DIAION CRB" (Mitsubishi Chemical Co., Ltd.) can be used. (stock)), boron selective chelating agent fiber "CHELEST FIBER GRY" (CHELEST (stock)), etc.

"DIAION CRB02" has a chemical structure in which an N-reduced glucosamine group is introduced into the skeleton of styrene-divinylbenzene as a chelating agent-forming group with high boron selectivity, as shown below.

The N-reduced glucosamine group and the weakly basic anion exchange resin also become a tertiary amine type, and the boric acid boron is adsorbed by the following reaction.

The boron selective adsorbent that has passed the threshold for adsorbing boron can be regenerated by any method using acids such as HCl, H ₂ SO ₄ , or alkalis such as NaOH and KOH.

<Application to the production of pure water or ultrapure water> By applying the boron removal method of the present invention to the production of pure water or ultrapure water, pure water or ultrapure water with a sufficiently reduced boron concentration can be stably and efficiently obtained. pure water.

The boron adsorption tower of the present invention is installed on the inlet side of the subsystem (the last stage of the primary pure water system), and the water flow SV is sufficiently reduced to operate. In addition to increasing the boron BTC, it can stably produce boron concentrations of 1~10ng/L. High quality pure water or ultrapure water. The boron adsorption tower can usually be replaced every 3 years, preferably every 5 years, and the boron selective adsorption body can be continuously operated. [Example]

[Experimental Example 1] In a boron adsorption tower with a resin volume of 600mL-R filled with a boron chelating agent resin "CRBT03" manufactured by Mitsubishi Chemical Co., Ltd., the boron BTP when the water supply with a boron concentration of 1 μg/L is passed through for treatment is set as 50ng/L, various changes were made to the SV of the water, and the experiment of investigating boron BTC was carried out.

As a result, the relationship between water flow SV and boron BTC is shown in the following Table 1. When these are plotted, as shown in Figure 1, it can be seen that even if the boron BTP is the same, the boron BTC will be greatly different by water flow SV , by reducing the water flow SV, boron BTC can be increased.

[Experimental Example 2] In Experimental Example 1, except that the boron BTP was set to 1ng/L, 10ng/L or 100ng/L, the same experiment was carried out to investigate the relationship between water supply SV (l/h) and water supply boron concentration (μg/L ) product, and the relationship with boron BTC, the results are shown in Figure 2a, 2b, 2c.

From Figures 2a, 2b, and 2c, it can be seen that for any boron BTP, the boron BTC can also be increased by setting the product of the water supply SV and the supply water boron concentration below a certain value.

Specifically, it can be seen that it is better to set the product of the water supply SV and the supply water boron concentration at 80 μg/L/h or less when the boron BTP is 1 ng/L, and to set the product of the water supply SV and the supply water boron concentration at 10 ng/L. The product is set to be less than 120μg/L/h, and the conditions are set so that the product of the SV of the flowing water and the boron concentration of the supply water is set to be less than 200μg/L/h when the boron BTP is 100ng/L.

The present invention has been described in detail using specific aspects, but those skilled in the art can understand that various changes can be made without departing from the intent and scope of the present invention. The present invention is based on Japanese Patent Application No. 2018-027933 filed on February 20, 2018, the entirety of which is incorporated by reference.

Fig. 1 is a graph showing the relationship between the water flow SV and the boron BTC in Example 1. Figures 2a, 2b and 2c are charts showing the relationship between the product of the water supply SV and the boron concentration in the water supply and the boron BTC in Experimental Example 2.

Claims (5)

A boron removal method, which is a method for removing boron by introducing boron-containing water into a boron adsorption tower filled with a boron selective adsorption body. The boron concentration of the water supply to the adsorption tower and the product of the boron-containing water to the boron absorption tower's water-through SV become a condition below a specific value, and the boron-containing water is introduced to reduce the boron concentration of the water supply when the above-mentioned boron BTP is 1ng/L. The product of (μg/L) and water flow SV (1/h) is set to 80 or less. When boron BTP is 10ng/L, the product of water supply boron concentration (μg/L) and water flow SV (1/h) is set to 120 or less, when the boron BTP is 100ng/L, the product of the boron concentration (μg/L) in the water supply and the water flow SV (1/h) is set to be 200 or less, and the water flow SV is set and/or filled in the aforementioned boron adsorption The boron selective adsorption volume of the tower. A boron removal method, which is a method for removing boron by introducing boron-containing water into a boron adsorption tower filled with a boron selective adsorption body. The boron concentration of the water supply of the adsorption tower and the product of the boron-containing water to the boron-containing water to the boron-containing water SV and the water-passing time of the boron-containing water become a condition below a specific value, and the boron-containing water is passed into the above-mentioned boron-containing water. When the BTP is 1ng/L, the product of the boron concentration (μg/L) of the water supply, the water supply SV (1/h) and the operation time (h) is set to be below 1920, and when the boron BTP is 10ng/L, the boron concentration of the water supply (μg/ L) and the product of the water flow SV (1/h) and the operation time (h) are set to be 2880 or less, and the water flow SV is set and filled. Any one of the setting of the amount of boron selective adsorbent charged in the aforementioned boron adsorption tower and the control of the water passing time. The method for removing boron as claimed in claim 2, wherein a plurality of the aforementioned boron adsorption towers are used, and the water supply of the aforementioned water supply is continued to a part of the boron adsorption towers in the plurality of boron adsorption towers, while the aforementioned water flow SV and the water supply boron The water flow stop period to other boron adsorption towers is set so that the product of the concentration and the water flow time becomes below a specific value. As the method for removing boron in claim item 3, wherein the aforementioned plurality of boron adsorption towers are connected in parallel, while continuing the aforementioned water supply to one part of the boron adsorption towers in the plurality of boron adsorption towers, the limit for other boron adsorption towers is set. During the stop of water flow. A method for producing pure water or ultrapure water, which has the step of removing boron by the method for removing boron according to any one of claims 1 to 4.

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