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CN-122010239-A - Method for producing ultrapure water

CN122010239ACN 122010239 ACN122010239 ACN 122010239ACN-122010239-A

Abstract

The present invention relates to a process for producing purified water, said process comprising a step (a) of passing water through a first mixed bed ion exchanger comprising beads having a diameter between 0.5 and 0.7mm and a step (b) of passing water through a second mixed bed ion exchanger comprising beads having a diameter of less than 0.5 mm. The invention further relates to a module comprising a first and a second mixed bed ion exchanger and to a water treatment system for producing ultrapure water comprising a first and a second mixed bed ion exchanger.

Inventors

  • Kajiki Ichiro
  • G. Duma
  • Y. Latiyuvelle

Assignees

  • 默克专利股份公司

Dates

Publication Date
20260512
Application Date
20180213
Priority Date
20170213

Claims (18)

  1. 1. A process for producing purified water, the process comprising the step (a) of passing water through a first mixed bed ion exchanger comprising beads having a diameter between 0.5 and 0.7 mm and the step (b) of passing water through a second mixed bed ion exchanger comprising beads having a diameter less than 0.5 mm.
  2. 2. The method according to claim 1, characterized in that the purified water is ultrapure water.
  3. 3. A method according to claim 1 or 2, characterized in that step (a) is carried out before step (b).
  4. 4. A process according to one or more of claims 1-3, characterized in that the first mixed bed ion exchanger consists of a mixture of anion exchange particles and cation exchange particles.
  5. 5. The process according to one or more of claims 1 to 4, characterized in that the second mixed bed ion exchanger consists of a mixture of anion exchange particles and cation exchange particles.
  6. 6. The process according to one or more of claims 1 to 5, characterized in that said first mixed bed ion exchanger is based on styrene divinylbenzene copolymer.
  7. 7. The process according to one or more of claims 1 to 6, characterized in that said second mixed bed ion exchanger is based on styrene divinylbenzene copolymers.
  8. 8. The process according to one or more of claims 1 to 7, characterized in that the ratio of the volume of the first mixed bed ion exchanger to the volume of the second mixed bed ion exchanger is between 10:1 and 1:5.
  9. 9. The process according to one or more of claims 1 to 8, characterized in that it comprises a further step (c) of passing water through the activated carbon bed.
  10. 10. The process according to one or more of claims 1 to 9, characterized in that the process comprises a further step (d) of treating the water by reverse osmosis and/or a further step (e) of treating the water by electrodeionization, wherein step (d) and step (e) are carried out before steps (a) and (b).
  11. 11. A module comprising a first mixed bed ion exchanger comprising beads having a diameter between 0.5 and 0.7 mm and a second mixed bed ion exchanger comprising beads having a diameter less than 0.5 mm.
  12. 12. The module according to claim 11, characterized in that said first mixed bed ion exchanger is based on styrene divinylbenzene copolymer.
  13. 13. Module according to claim 11 or 12, characterized in that the second mixed bed ion exchanger is based on styrene divinylbenzene copolymer.
  14. 14. Module according to one or more of claims 11 to 13, characterized in that it further comprises an activated carbon bed, optionally mixed with the first mixed bed ion exchanger.
  15. 15. A water treatment system for producing ultrapure water, the system comprising a first mixed bed ion exchanger comprising beads having a diameter between 0.5 and 0.7 mm and a second mixed bed ion exchanger comprising beads having a diameter less than 0.5 mm.
  16. 16. A water treatment system according to claim 15, characterized in that the first and second mixed bed ion exchangers are provided in a single module according to one or more of claims 11-14.
  17. 17. The water treatment system of claim 15, wherein said first and second mixed bed ion exchangers are provided in at least two modules.
  18. 18. A water treatment system according to one or more of claims 15-17, said system further comprising an activated carbon bed.

Description

Method for producing ultrapure water The present invention relates to a process for producing purified water, said process comprising a step (a) of passing water through a first mixed bed ion exchanger comprising beads having a diameter between 0.5 and 0.7mm and a step (b) of passing water through a second mixed bed ion exchanger comprising beads having a diameter of less than 0.5 mm. The invention further relates to a module comprising a first and a second mixed bed ion exchanger and to a water treatment system for producing ultrapure water comprising a first and a second mixed bed ion exchanger. Laboratory ultrapure water was prepared from municipal water by a combination of several techniques. Typically, activated carbon, reverse osmosis, ion exchange resins, microfiltration/ultrafiltration, ultraviolet irradiation and sterile grade microfiltration are used alone or in combination to purify water. The purification of ultrapure water is the final step of water purification. Milli-Q (commercially available from MERCK KGAA of Darmstadt, germany) employs ion exchange resins, activated carbon, bactericidal and/or photooxidative UV lamps, microfiltration and/or ultrafiltration. Ultrapure water (or type 1 water) is generally characterized by a resistivity of greater than 18M Ω -cm (at 25 ℃) and a Total Organic Compound (TOC) value of less than 20 parts per billion (ppb). Type 2 water is typically characterized by a resistivity greater than 1.0M Ω·cm and a TOC value less than 50 ppb. Type 3 water is the lowest grade laboratory water recommended for use, for example, in glassware rinsing or heating baths, or to supply type 1 laboratory water systems. It is characterized by a resistivity greater than 0.05M Ω cm and a TOC value less than 200 ppb. In the prior art, the final refining step in the production of ultra pure water is accomplished by using ion exchange media that allow for the removal of anions and cations. Ion exchangers, also known as ion exchange resins, are known throughout the present invention and have proven to be useful in the removal of ionic impurities from water in the production of pure water and ultra-pure water. Typically, these are spherical polymerized styrene beads, with 0-16% divinylbenzene crosslinking, functionalized by sulfonation (for cation exchange) and amination (for anion exchange), and regenerated by strong acid and strong base solutions, respectively, or other techniques such as electrochemical regeneration. In the following, the term "resin" or "resin beads" is used for the ion exchange material itself (i.e., ion exchange beads), while the term "resin bed" or "resin layer" is used for a resin bed used in a specific arrangement. The "resin" is typically a mixed medium of both anion and cation exchange resins in sufficient mixing ratio to result in equal capacity for both types of ions or asymmetric capacity for a particular water application. Resins for pure water and ultra-pure water production require a high degree of regeneration, such as 95-99%, or even higher. This means that this percentage of the ion exchange sites regenerate to the H form (for cation exchange) and to the OH form (for anion exchange). For ultra-pure water purification, high resin purity, i.e. with very low levels of contaminants, and very low leaching of total organic carbon, is required. For this reason, the resin is generally further purified. In science and industry, water deionization for the production of pure water and ultrapure water is generally performed by ion exchange resin beads. The size of the deionization cartridge depends on the desired flow rate, the volume to be treated and the quality of the water produced. For example, disposable cartridges for small laboratory water systems may contain 1-3L resins, while resin bottles for large industrial scale typically contain 5-20L resins. Today, particulate bead type resins are the only medium available in industry and market. All granular media contain particles of about 600-700 μm in diameter, which is the standard size used in the industry for ion exchange water deionization. Typically, when RO pre-treated municipal water (5-25 μS/cm conductivity) is used to feed the ultrapure water system, the cartridge height should be 700-1000 mm for achieving water quality exhibiting a resistivity of 18.2M Ω cm. To allow sufficient contact time to eliminate ions in a single pass process, the diameter of the barrel is determined. For example, the earlier Milli-Q zone system (Millipore) with 4 basins had an inner barrel diameter of 69 mm and a total resin bed height of 900 mm, reflecting the minimum necessary resin bed height for achieving ultra-pure water quality. Reducing the cartridge height can result in reduced water quality (i.e., an ultrapure grade cannot be achieved) or reduced cartridge life. Over the life of an ion exchange cartridge for water deionization, three zones may be defined, as illustrated in fig. 8. The minimum resin bed height is referr