JPH0450859B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a method for preventing the release of impurities such as trace amounts of solvent and unreacted monomers remaining in strongly acidic cation exchange resin particles resulting from the manufacturing process of strongly acidic cation exchange resins. . [Prior art] Strongly acidic cation exchange resins are widely used in the production process of boiler water, the treatment process of precious metal-containing waste liquids, the purification process of sugar solutions, etc. However, with the refinement of industry in recent years, strong acidic cation exchange resins Exchangeable resins have also come to be used for more precise separation and purification processes. However, it is known that a trace amount of impurities are liberated from strongly acidic cation exchange resins during use, regardless of the chemical properties or physical structure of the strongly acidic cation exchange resin. These impurities are thought to be trace amounts of solvent and unreacted monomers remaining in the micropores of the strongly acidic cation exchange resin particles resulting from the manufacturing process of the strongly acidic cation exchange resin. During use, it gradually becomes liberated from the fine pores of the resin particles. Therefore, especially in ultrapure water manufacturing processes and pharmaceutical manufacturing processes that require careful and precise purification and separation, the release of impurities from these strongly acidic cation exchange resins into the processing solution has a direct impact on the product yield. Therefore, it is desired to provide a strongly acidic cation exchange resin that releases extremely few impurities. Therefore, as one method of providing a strongly acidic cation exchange resin that releases less of these impurities, various methods have been investigated to completely remove trace amounts of impurities remaining in the strongly acidic cation exchange resin. Currently, the micropores in the strongly acidic cation exchange resin particles are formed by contacting the strongly acidic cation exchange resin with a mineral acid solution and an alkaline solution several times alternately, causing the strongly acidic cation exchange resin to rapidly swell and contract. A method has been adopted to provide a strongly acidic cation exchange resin in which residual impurities are discharged and removed outside of the grains, resulting in less release of impurities. However, even with this method, it is not possible to completely eliminate the extremely small amount of impurities remaining deep within the micropores, and it cannot be said that this method provides a strongly acidic cation exchange resin without the release of impurities. [Purpose of the Invention] Therefore, the inventors of the present invention conducted intensive studies with the aim of providing a strongly acidic cation exchange resin that does not release impurities. The inventors have discovered that it is possible to almost completely eliminate impurities remaining in the micropores of the exchange resin, and that it is possible to provide a strongly acidic cation exchange resin that does not release impurities, and has thus arrived at the present invention. [Structure of the Invention] The present invention involves contacting a strongly acidic cation exchange resin with a mineral acid solution and then an alkaline solution in this order, or in the reverse order, at least once or twice or more. A strongly acidic cation exchange resin is regenerated by a conventional method to obtain a regenerated form, and then an anion exchange resin is added to the regenerated form of the strongly acidic cation exchange resin, and the mixture is mixed and immersed in pure water. This is an attempt to solve the above problem. The present invention will be explained in more detail below. A small amount of impurities such as a small amount of solvent and unreacted monomers derived from the resin manufacturing process remain in the micropores within the particles of strongly acidic cation exchange resin. When ion exchange treatment is carried out using the ion exchange treatment, impurities are gradually liberated from the micropores during the treatment process and are entrained in the treatment liquid. Such a phenomenon is extremely inconvenient in processes that perform high-purity purification, such as ultrapure water production processes and pharmaceutical purification processes. Therefore, in order to remove these impurities, in the present invention, a strongly acidic cation exchange resin is first brought into contact with a mineral acid solution and then an alkaline solution in this order, or at least once with an alkaline solution and then a mineral acid solution in this order. Or repeat it two or more times. The operation method is to fill a column with strongly acidic cation exchange resin, pass a mineral acid solution (alkaline solution) through it, wash with water, and use an alkaline solution (mineral acid solution).
This is carried out by repeating the operations of passing liquid and washing with water once or several times. At that time, the mineral acid solution should be 100 to 600 g/mineral acid/-resin/time, and the concentration should be about 10% by weight, and the alkaline solution should be 100 to 600 g/alkali/resin/time.
-Resin/time, and its concentration is approximately 4% by weight. Through this operation, the strongly acidic cation exchange resin repeatedly swells and contracts, and most of the impurities in the micropores are discharged to the outside of the grains, but the impurities deep in the micropores inside the grains are still removed. remains. Therefore, the strongly acidic cation exchange resin that has been subjected to the above-described operation to remove these impurities is first regenerated by a conventional method to form a regenerated form (H form). At this time, it is desirable to regenerate the strongly acidic cation exchange resin using a rich mineral acid solution so that all the exchange groups become H-type. Next, an anion exchange resin is added to the strongly acidic cation exchange resin which has become a regenerated form (H form), and the mixture is mixed as uniformly as possible by a conventional method, and then immersed in pure water. In this case, the anion exchange resin added is strongly basic, medium basic, weakly basic, or regenerated (OH
Form) Either salt form is fine. Further, it may be a styrene-based material, an acrylic-based material, a gel type or a porous type, but a styrene-based material is usually used. A regenerated form (OH form) of strongly basic anion exchange resin is most preferable because the time required for immersion in pure water is shorter when the anion exchange resin has a high degree of basicity. The amount of anion exchange resin added is 0.5 to 0.5 of the volume of the strongly acidic cation exchange resin.
Aim for 2.0x. The quality of the pure water to be immersed should be such that the electrical conductivity is 1 μs/cm or less and the immersion time is at least 24 hours. It is not clear why impurities remaining in the fine pores in the recycled form of strongly acidic cation exchange resin particles coexist with anion exchange resin in pure water, promoting the release of impurities. It is thought that the ion exchange resin acts catalytically in pure water to release impurities remaining in the fine pores of the regenerated strongly acidic cation exchange resin particles, promoting the release of impurities. Further, in order to prevent contamination of the strongly acidic cation exchange resin with other impurities, the anion exchange resin to be added should be thoroughly washed. By the above operation, the impurities remaining in the regenerated strongly acidic cation exchange resin are almost completely discharged and removed, so the mixed resin of the regenerated strongly acidic cation exchange resin and anion exchange resin is then backwashed. After separating and fractionating the regenerated strongly acidic cation exchange resin by means such as the above, it is thoroughly washed with water and supplied to various uses. Furthermore, since the anion exchange resin used in the present invention is somewhat contaminated with free substances, it is regenerated with a slightly larger amount of regenerant to remove these impurities before being used for various purposes. The strong acidic cation exchange resins to which the present invention is applied are those based on styrene, phenol, and acrylic, and both gel and porous types can produce good effects. When using a strongly acidic cation exchange resin in a high-purity purification process, if it is used after the treatment according to the present invention, there will be almost no release of impurities from the strongly acidic cation exchange resin. A purified product can be obtained. [Example] Example 1 One part of each of the commercially available strong acidic cation exchange resins shown in Table 1 was packed into a column, and 3 parts of 2N hydrochloric acid was added.
After repeating the operations of passing liquid, washing with water, passing 5 parts of 1N caustic soda, and rinsing with water twice, 7 parts of 2N hydrochloric acid was passed therethrough and then washed with water to regenerate each strongly acidic cation exchange resin into a regenerated form. Next, 2 of each of the strong basic anion exchange resins shown in Table 1 were made into regenerated forms by a conventional method, and each was added to a column filled with the corresponding regenerated strong acid cation exchange resin to form a mixed state. After that, soak a certain amount in pure water with an electrical conductivity of 0.1μS/cm at room temperature for 12 hours.
It was taken out after 1 hour, 24 hours, and 120 hours. Each mixed resin taken out is backwashed to separate and fractionate only the strongly acidic cation exchange resin, and each of them is tested for electrical conductivity.
0.1μS/cm, TOC 0.1mg/or less, 40 immersed in pure water.
It was left at ℃ for 24 hours. TOC of this pure water after standing
was as shown in Table 2.

【table】

[Table] Comparative Example 1 Each column was filled with strongly acidic cation exchange resins of the same brand as those used in the example, and the same procedure as in the example was carried out, followed by 3 passes of 2 N hydrochloric acid, water washing, and 1 N caustic soda 5 times. After repeating the operations of passing liquid and washing with water twice, each strongly acidic cation exchange resin was regenerated into a regenerated form by passing 2N hydrochloric acid 7 through it. Next, each of the strongly acidic cation exchange resins was immersed in pure water with an electrical conductivity of 0.1 μS/cm for 24 hours. After soaking in pure water, each strongly acidic cation exchange resin was immersed in pure water with an electrical conductivity of 0.1 μS/cm and a TOC of 0.1 mg/or less, and left at 40°C for 24 hours. The TOC of this pure water after standing was as shown in Table 3.

〔Effect of the invention〕

According to the method of the present invention, impurities remaining in the micropores of the strongly acidic cation exchange resin particles can be almost completely eliminated, and a strongly acidic cation exchange resin without release of impurities can be provided.

Claims (1)

[Claims] 1. An operation of contacting a strongly acidic cation exchange resin with a mineral acid solution and then an alkaline solution in this order, or in the reverse order, at least once or twice.
After repeating the process several times, the strongly acidic cation exchange resin is regenerated by a conventional method to obtain a regenerated form, and then an anion exchange resin is added to the regenerated form of the strongly acidic cation exchange resin to form a mixed state. A method for preventing the release of impurities from a strongly acidic cation exchange resin, which comprises soaking the resin in pure water. 2. The method according to claim 1, wherein the anion exchange resin added is a regenerated strongly basic anion exchange resin. 3. The method according to claim 1, wherein the amount of the anion exchange resin added is 0.5 to 2.0 times the volume of the strongly acidic cation exchange resin. 4. Claim 1, wherein the recycled strongly acidic cation exchange resin and the anion exchange resin are immersed in pure water for 24 hours or more in a mixed state.
The method described in section.