JPH0450860B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to strongly acidic cation exchange resins, and in particular to prevention of the release of minute amounts of impurities remaining in the strongly acidic cation exchange resin particles resulting from the manufacturing process of the strongly acidic cation exchange resins. Regarding how to. [Prior art] Strongly acidic cation exchange resins have been 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., but with the refinement of industry in recent years, Strongly acidic cation exchange resins have also come to be used in processes that aim for more precise separation and purification than conventional applications. However, with regard to strongly acidic cation exchange resins, it is known that trace amounts of impurities are liberated during the treatment process, 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 strongly acidic cation exchange resin granules resulting from the manufacturing process of the strongly acidic cation exchange resin. During the treatment process, it gradually becomes liberated outside the grain. Therefore, in ultrapure water production processes, pharmaceutical purification processes, etc. that require particularly careful and precise purification/separation processes, strong acid cation exchange resins are used, with very few impurities being released into the processing solution. There is a need to provide ion exchange resins. Therefore, as one method of providing a strongly acidic cation exchange resin with less release of these impurities, various methods have been investigated to completely remove trace amounts of impurities remaining in the strongly acidic cation exchange resin particles. . For example, methods such as (1) treatment with mineral acid alkali, (2) treatment with heated water, and (3) treatment with chemical agents have been used. Although all of these methods are effective, they cannot completely remove the extremely small amount of impurities that remain deep within the pores within the strongly acidic cation exchange resin particles. This method could not be said to be sufficient to provide a strongly acidic cation exchange resin without oxidation. [Purpose of the Invention] Therefore, the inventors of the present invention conducted extensive 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 cation exchange resin particles and 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 provides a first step in which a strongly acidic cation exchange resin is made into a regenerated form, a second step in which the strongly acidic cation exchange resin is brought into contact with heated water, and a strong acid obtained in the second step. The above-mentioned problem is attempted to be solved by a third step in which an anion exchange resin is added to a cation exchange resin, the two are mixed, and the mixture is immersed in pure water. The present invention will be explained in more detail below. A small amount of solvent and unreacted monomers derived from the resin manufacturing process remain as impurities in the strongly acidic cation exchange resin particles. When ion exchange treatment is performed, impurities are gradually liberated during the treatment process and are entrained in the treatment liquid. Such a phenomenon is extremely inconvenient in particularly high-purity purification processes such as ultrapure water production processes and pharmaceutical purification processes. Therefore, in order to remove the impurities remaining in these strongly acidic cation exchange resins, in the present invention, the strongly acidic cation exchange resins are first brought into contact with a mineral acid solution to form a regenerated form (H type). The strongly acidic cation exchange resin swells when it is converted into a regenerated form, and the pores within the particles are expanded at this time, making it easier to remove impurities in subsequent steps. In this process, it is essential to keep the strongly acidic cation exchange resin in a completely regenerated form for the subsequent steps to be effective, so it is necessary to regenerate it with an excess of mineral acid solution above the normal regeneration level. is preferred. In addition, if there is a possibility that a large amount of impurities remain in the strongly acidic cation exchange resin particles, complete the process by repeating the steps of passing mineral acid solution, washing with water, passing alkaline solution, and washing with water several times alternately. It is best to keep it in the regenerated form (H form). Next, a second step is performed in which the strongly acidic cation exchange resin, which has been regenerated in the previous step, is brought into contact with heated water.
The purpose of this step is to dissolve impurities in the heated water by bringing the regenerated strongly acidic cation exchange resin into contact with the heated water. The temperature of the heated water is 40
The temperature is ~80°C, preferably 50-60°C, and the contact time is 1-8 hours, preferably 1-2 hours. Next, as a third step, an anion exchange resin is added to the strongly acidic cation exchange resin that has been treated up to the second step, the two are mixed as uniformly as possible, and the resin is immersed in pure water. In this case, the anion exchange resin to be added may be strong basic, medium basic, weak basic, regenerated form (OH form), salt form, styrene type, or acrylic type, but the basicity of the anion exchange resin Since the time required for immersion in pure water is shorter when the size is large, it is most preferable to use a regenerated form (OH form) of strongly basic anion exchange resin, regardless of the properties of the resin matrix, and its addition The amount should be 0.5 to 2.0 times the volume of the strongly acidic cation exchange resin. The quality of pure water used for immersion is electrical conductivity.
It is sufficient that the temperature is 1 μS/cm or less and the immersion time is at least 24 hours or more. The reason why the remaining impurities after contacting the regenerated strongly acidic cation exchange resin with warm water are promoted to be released into the pure water when they coexist with the anion exchange resin in the pure water. Although it is not clear why, it is thought that the anion exchange resin acts catalytically in pure water to release impurities remaining in the strongly acidic cation exchange resin particles, promoting the release of impurities. At this time, the strongly basic cation exchange resin is used after being sufficiently washed to prevent contamination of the strongly acidic cation exchange resin with other impurities. By the above operation, the impurities remaining in the strongly acidic cation exchange resin are almost completely discharged and removed, so the mixed resin of the strongly acidic cation exchange resin and anion exchange resin is then separated by backwashing or other means. After separating and fractionating the strongly acidic cation exchange resin, it is thoroughly washed with water and then supplied to various uses. Furthermore, since the anion exchange resin used in the present invention is contaminated with free impurities, it can be used for various purposes after being regenerated with a slightly excess regenerant to remove these impurities. 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 a strongly acidic cation exchange resin treated according to the present invention is used, most impurities will be released from the strongly acidic cation exchange resin. Since there is no need for processing, it is possible to obtain extremely high-purity processing liquid. Example 1 One part of each of the commercially available strong acidic cation exchange resins shown in Table 1 was packed into a jacketed column, and two
3 passes with normal hydrochloric acid, washing with water, 1N caustic soda 5
After repeating the operations of passing liquid and washing with water twice, a first step was carried out in which each strongly acidic cation exchange resin was made into a regenerated form by passing 2N hydrochloric acid 7 therethrough and washing with water. Subsequently, as a second step, pure water heated to 60°C was passed through each column at a space velocity of 10 Hr ^-1 for 1 hour. Next, after regenerating 2 of each of the strong basic anion exchange resins shown in Table 1 to a regenerated form by a conventional method,
Each was added to the corresponding strongly acidic cation exchange resin bed that had been treated as described above. After mixing as uniformly as possible using the usual method, the electrical conductivity is 0.1μS/
A third step was performed in which the sample was immersed in pure water at room temperature. Soaking time of 3rd step: 12 hours, 24 hours, 120 hours
A certain amount of the mixed resin is taken out every hour, and only the strongly acidic cation exchange resin is separated and fractionated by backwashing.
They each have an electrical conductivity of 0.1μS/cm and a TOC of 0.1mg/
It was immersed in the following pure water and left at 40°C for 24 hours. During this time, the amount of free impurities was evaluated using TOC using the pure water in which it was immersed. The results were as shown in Table 2. Comparative Example 1 One strong acidic cation exchange resin of the same brand as that used in the example was taken and packed into a jacketed column. After filling, the first step and the second step were performed in the same manner as in the example. Next, each of these strongly acidic cation exchange resins 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. After standing, the TOC of the immersed pure water was measured and the amount of released impurities was compared. The results were as shown in Table 3.

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Claims (1)

[Claims] 1. A first method using a regenerated form of a strongly acidic cation exchange resin.
step, then a second step of bringing the strongly acidic cation exchange resin into contact with warm water, adding an anion exchange resin to the strongly acidic cation exchange resin obtained in the second step, and purifying both in a mixed state. A method for preventing the release of impurities from a strongly acidic cation exchange resin, comprising a third step of immersing it in 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. The method according to claim 1, wherein the strongly acidic cation exchange resin and the anion exchange resin are immersed in pure water in a mixed state for 24 hours or more.