JPS63243022A - Method for removing endotoxin in producing pure water - Google Patents

Abstract

PURPOSE:To remove endotoxins, by treating deionized water with a carbonaceous adsorbent prepared by carbonizing a porous spherical crosslinked polymer or further activating the carbonized polymer. CONSTITUTION:A deionized water from treatment with an ion exchange resin is treated with a carbonaceous adsorbent prepared by carbonizing a porous spherical crosslinked polymer (preferably a copolymer consisting of a monovinyl monomer and polyvinyl monomer) or further activating the carbonized polymer to remove endotoxins derived from bacteria growing or propagating in a system for producing pure water. The porous spherical crosslinked polymer is infusibilized with sulfuric acid, nitrogen dioxide, chlorine, etc., thermally decomposed at 300-900 deg.C temperature, directly used or then activated with steam, aqueous solution of zinc chloride, etc., and used as the carbonaceous adsorbent.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to carbonizing a porous spherical crosslinked synthetic polymer of endotoxin derived from bacteria that grows or proliferates in a pure water production system, or to carbonizing and activating a porous spherical crosslinked synthetic polymer. Concerning a removal method using a carbonaceous adsorbent.

[Conventional technology]

Endotoxin (bacterial endotoxin) is a complex phospholipid polysaccharide (lipopolysaccharide) that exists as a cell membrane component of Durum-negative bacteria and is a typical pyrogen (pyrogiene).
It is.

If this directly enters the human blood via intravenous injection, it can cause an intense fever reaction, vasoconstriction, increased sensitivity to adrenaline, acceleration of blood coagulation and subsequent decline, and in some cases, death from shock. . Therefore, each national local government stipulates that water for injection must not contain bacteria or pyrogens.

In order to obtain water that does not contain pyrogens, it is usually done by distillation of pharmacopoeically purified water.
lysate) and endotoxin] is often positive.

In the past, treatments using powdered or granular activated carbon and various ion exchange resins were attempted as pyrogen removal techniques, but leaks often occurred due to fluctuations in the pyrogen load, making it impossible to expect a stable treatment effect. . Recently, as seen in Japanese Patent No. 989,058, ``Method for Obtaining a Purified Saccharide Solution Free of Pyrogenic Substances,'' and Japanese Patent No. 738.632, ``Method for Obtaining an Injectable Aqueous Solution Free of Pyrogens and Microorganisms by Permeabilization''. Membrane separation methods using permeable membranes have come to be used.

The membrane separation method is incorporated as an element of the ultrapure water production system, and specifically involves passing city water, which contains large amounts of pyrogens, various ions, organic substances, etc., through activated carbon or (and) ion exchange resin. After that, the water is stored and further treated with an ultraviolet sterilizer for sterilization, a regenerating mixed bed ion exchange resin column, and then a permeable membrane such as an ultrafiltration membrane or a reverse osmosis membrane. However, bacteria are inherently proliferative, and some bacteria can grow and multiply even in low-nutrient water at the ultrapure level, and even after being sterilized, they remain in the system, and endotoxins increase as the number of dead bacteria increases. It is estimated that if the water is forced to continue rising, it may cause unexpected performance deterioration of the membrane, such as rapid clogging of the permeable membrane at the water intake. Therefore, there is a strong need for a method to effectively prevent water from being contaminated by endotoxins.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a method for removing endotoxin to an ultra-trace concentration in the production of pure water.

Another object of the present invention is to provide an improved method for removing endo]xins that enables the production of ultrapure or ultra-superpure water for various uses.

[Means for solving problems]

The above object of the present invention is achieved by the following endotoxin removal method.

A method for removing endotoxins in pure water production, which comprises treating deionized water from an ion exchange resin treatment step with a carbonaceous adsorbent that has been carbonized or activated by carbonizing a porous spherical crosslinked polymer.

The carbonaceous adsorbent obtained by carbonizing the above-mentioned porous spherical crosslinked polymer by thermal decomposition is disclosed in JP-A-51-126390,
JP-A-49-53594, JP-A-53-50088, JP-A-52-30799, JP-A-51. -6361
It is manufactured by the method described in No. 9 etc.

The most preferred porous spherical polymer is generally a copolymer consisting of a monovinyl monomer and a polyvinyl monomer.

This is produced by using the above monomers by a known suspension polymerization method to obtain a spherical copolymer.

Specifically, one made of styrene and divinylbenzene is the most well-known. and even with other monovinyl monomers and other polyvinyl monomers) hydrothermal invention can be achieved.

In order to obtain porosity, it is important to add known additives sufficient to obtain porosity during suspension polymerization. Typical additives include solvents that dissolve in monomers called precipitants but do not swell the produced copolymer, and solvents that dissolve in monomers called swelling agents and swell the produced copolymer. A solvent or a mixed solvent in which the above-mentioned swelling agent and precipitant coexist, an organic liquid consisting of a monovinyl linear polymer that can form a uniform liquid phase with these swelling agents and the swelling agent, and a monomer mixture that is soluble in the monomer mixture. Examples include, but are not limited to, insoluble polymers such as polyalkylene glycol, which are inert to the produced copolymer, but other known porous forming agents may be used. Of course it is also possible.

The porous crosslinked copolymer produced by such a method may be subjected to sulfonation or chloromethylation by a known method (and then, even if the aminated ion exchange resin is used, the above-mentioned porous These porous spherical crosslinked copolymers may be commercially available.For example, the above-mentioned Anno.
Wright's ion exchange resin series or synthetic adsorbent series may be used, and of course, many commercially available products such as Diaion (registered trademark of Mitsubishi Chemical Corporation) and DOWEX (registered trademark of Dow Chemical Corporation) can also be used. .

The porous spherical crosslinked copolymer thus obtained is carbonized by a known method to produce the desired adsorbent.

The desired carbonaceous adsorbent can be obtained by treating this porous spherical crosslinked polymer with sulfuric acid, nitrogen dioxide, chlorine, etc. to make it infusible, and then thermally decomposing it at a temperature of 300 to 900°C. The adsorbent obtained in this way can be used as is, but
It can also be used by sufficiently activating it with water vapor, zinc chloride aqueous solution, etc. depending on γ.

A specific example of such an adsorbent is Rohm & II
Ambersorb manufactured by Haas
The XE series is known. This adsorbent is spherical, has low ash content, and has strong wear resistance and physical strength. These secondary features have special implications for the treatment of endotoxins in pure water.

These features, in addition to the effective adsorption of endotoxin by the adsorbent, make it possible to treat endotoxin in pure water without degrading water quality.

In other words, activated carbon for normal water treatment not only becomes a breeding ground for bacteria due to its amorphous shape, but also has low physical strength and wear resistance, so it shatters and becomes fine particles that remain in the treatment system, worsening water quality. This may cause other troubles. The biggest difference between this adsorbent and commercially available powdered or granular activated carbon is that its physical structure is fundamentally different from activated carbon in that it retains the skeletal structure of a porous spherical polymer even after carbonization and activation. It is. It is thought that this difference contributes to the large difference in the amount of pyrodiene adsorbed.

To treat deionized water with this carbonaceous adsorbent,
A method can be used in which this adsorbent is packed into a column of an appropriate size and deionized water is passed through it.

In order to incorporate the method of the present invention into a simple water purification system, it is necessary to treat deionized water from ion exchange resin treatment or deionized water from activated carbon treatment and ion exchange resin treatment with the carbonaceous adsorbent. Just do it.

Medical ultrapure water, such as water for injection that does not contain pyrogens, or ultra-ultrapure water, which is required for the production of highly integrated semiconductor devices in recent years, has a viable bacterial count of 0.0, which is the source of endotoxins. A strict standard of 0.02/ml or less is required.

In the production of ultrapure or ultra-superpure water, living bacteria are sterilized by ultraviolet rays, but since endotoxin is released from the dead bacteria into the water, after ultraviolet sterilization treatment, a regenerated mixed bed ion exchange resin column is used. It is preferable to perform the endotoxin removal treatment of the present invention before the treatment, or to perform the endotoxin removal treatment of the present invention before the final stage of permeable membrane treatment.

In other words, in the production of ultrapure water or ultra-ultrapure water, ion exchange resin towers, water storage tanks, ultraviolet sterilizers, regenerative mixed bed ion exchange resin towers, and permeable membranes such as ultrafiltration membranes or reverse osmosis membranes are used. Endotoxin removal according to the present invention may be carried out at any location between the water storage tank and the permeable membrane in a series of treatments.

〔Effect of the invention〕

According to the present invention, endotoxin-free pure water can be stably produced in large quantities by an extremely simple method.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples.

Example 1〜Production of deionized water using tap water as raw water and using a granular activated carbon column, a gel type cation exchange resin column, a gel type anion exchange resin column, and then a mixed bed type ion exchange resin column made of a porous spherical crosslinked polymer. Approximately 4 times per use at room temperature (approximately 20°C)
When operated intermittently with an hourly water intake of approximately 100 liters, approximately 2
Average endotoxin level in deionized water after 1.5 weeks
It leaked at n97ml level.

Therefore, both gel-type cation and anion exchange resins were regenerated according to a conventional method and water flow was started again, but from the 28th point onward, endotoxin leaked into the deionized water at the above level.

An investigation into the cause revealed that the granular activated carbon bed in the activated carbon tower was a breeding ground for bacteria.

Therefore, the treated water pipes are arranged so that the same amount of water flows through three pipes, and the first pipe is filled with 3002 Amber Soap 3.
In the second pipe, a 3002 Calvon Pittsburgh granular activated carbon column was packed, and in the third pipe for comparison, a 300 f non-carbonized porous spherical cross-linked polymer Amberly) XAD. -2 was turned on and water flow started.

The amount of endotoxin processed at the detection limit of 0.01 shuttle/fnl was as follows.

Example 2゜Deionized water 2 using tap water as raw water and treated with an ion exchange resin tower consisting of a granular activated carbon tower, a gel type cation exchange resin tower, an anion exchange resin tower, and a mixed bed type porous spherical crosslinked polymer
007 water storage tank (the deionized water production equipment on the raw water side is automatically activated to maintain 2007 water at all times), an ultraviolet sterilizer, a regenerative mixed bed ion exchange resin tower, an ultraviolet filtration membrane, and then the point of use ( In a small ultrapure water production system for laboratory use, unused water reaches the faucet and returns to the water tank.
Water sampling (approximately 100 A purity 18.2 MΩ-c per day)
m) One week after the start, water was sampled from a sampling point located between the regenerated mixed bed ion exchange resin tower and the ultrafiltration membrane and analyzed, and endotoxin was found to be present at 0.5n2 noa.

Therefore, when a column filled with 500 f Amber Soap XE-340 was placed after the ultraviolet sterilizer, the endotoxin level in the system remained below the detection limit (0
,01n? However, in the case of the same amount of spherical activated carbon BAC-MP manufactured by Kureha Chemical Co., Ltd., endotoxin leakage started within 4 days.

Procedural amendment (voluntary) April 16, 1986

Claims (1)

[Claims] 1. A method for removing endotoxins in pure water production, which comprises treating deionized water from an ion-exchange resin treatment step with a carbonaceous adsorbent obtained by carbonizing a porous spherical crosslinked polymer or by carbonizing and activating it.