JPS60172388A - Purifying method of aqueous liquid - Google Patents

Abstract

PURPOSE:To remove efficiently endotoxin by passing to be treated through a layer packed with a hydrophilic polyolefin porous hollow staple fiber having specified porosity, and then passing the water through a polyolefin porous hollow yarn membrane having specified porosity. CONSTITUTION:The water to be treated is passed through a layer packed with a hydrophilic polyolefin porous hollow staple fiber having >=20vol% porosity measured by a mercury porosimeter. Then the water to be treated is passed through a polyolefin porous hollow yarn membrane having 20-90vol% porosity, filtered, and purified. The water to be treated can be passed through an activated carbon layer before the water is introduced into the layer packed with the porous hollow staple fiber. The length of the polyolefin porous hollow staple fiber is preferably regulated to <=10mm., the inner diameter to 7-400mum, and the wall thickness to 3-100mum.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field The present invention relates to a method for purifying an aqueous liquid that easily and efficiently removes endotoxins and other harmful substances from the aqueous liquid.

(Ill) Prior Art Since aqueous liquids containing substances dissolved in water or in water contain trace amounts of various substances harmful to living organisms, medical water,
Precise purification is required for water for pharmaceutical industry and other uses. Among these, pyrogenic substances (pyrothycones) have not been easily removed so far, and a simple and efficient purification method has been desperately needed.

Various compounds exist naturally as Qp, NO'H substances (pyrothicones), but the main component of pyrothicones present in water is ribopolyzasocaride, which is present in the cell membranes of Gram-negative bacteria. , end't;1; called thin. Therefore, pyrocicon is generally considered to be a bacterium.
~It is considered to be the same word as xin.

Even a small amount of endo1-xin enters the bloodstream and causes fever.
It is extremely dangerous because it is imprisoned by the power of chills, soyosoku, etc.
Removal of endotoxins from various pharmaceutical products such as hospital water, pharmaceutical industry water, transfusions, and vaccines is an important issue. Conventionally, precise distillation methods, reverse osmosis membrane methods, adsorption methods, etc. have been used to remove endotoxins from water. However, the distillation method has a high energy cost and cannot sufficiently remove endotoxins with one dilution. The reverse osmosis method 1 requires large-scale equipment and requires a lot of effort for maintenance.

In the adsorption method, adsorbents such as activated carbon are used, but the removal effect is not sufficient. For example, JP-A-52-102414 describes a method for adsorption and removal of endotoxin using an olefin polymer, but this method is not suitable for completely removing endotoxin from a large amount of liquid to be treated. Additionally, the same issue describes adsorption through a microporous film, but there are problems with clogging and endotoxin adsorption capacity riI, so it is still unsuitable for removing endotoxin from a large amount of liquid to be treated. be.

(c) Purpose of the invention The purpose of the present invention is to dramatically improve efficiency compared to conventional methods.
The object of the present invention is to provide a method capable of removing endo-1-xin in a large amount of aqueous liquid.

(d) Structure of the Invention In accordance with the present invention, the method for purifying a free liquid is characterized in that water to be treated is made of hydrophilic polyolefin pores having a porosity of 20% or more and 41% or more as measured by a mercury viscometer. After passing through the layer filled with hollow short fibers, the hollow fibers are further passed through a layer filled with hollow fibers.
It is characterized by filtration through a hollow fiber membrane with ~90% polyolefin porosity.

As an alternative to the above-mentioned purification method, the water to be treated can be passed through the above-mentioned polyolefin porous hollow short 1! The water to be treated may first be passed through a layer of activated carbon before being passed through the layer filled with string. Instead of a layer, it is also possible to pass through a layer filled with a mixture of the short fibers and activated carbon.

(P) Effects of the Invention The present inventors have found that polyolefin porous hollow short fibers with a special structure and a porosity of 20% or more have a remarkable effect on removing endotoxins from aqueous liquids. The patent application was filed on the same date as the present patent application, but according to the present invention, by a combination of passing through the polyolefin porous hollow short fiber layer and membrane filtration using the polyolefin porous hollow fiber, A dramatic improvement in endotoxin processing ability, which was previously unavailable, was achieved. Furthermore, the method of the present invention can eliminate harmful substances other than endotoxin in aqueous liquids.
For example, relatively highly hydrophobic organic substances such as organic chlorine compounds, phthalate esters, and other organic substances can be efficiently removed.

(f) Specific explanation of the structure of the invention The aqueous liquid to be purified by the method of the present invention includes water such as medical water and pharmaceutical water, as well as physiological saline and human water.
These include dialysis fluid, medical sugar solution, antibacterial substance aqueous solution, vaccines, and various other medical aqueous solutions.

The porous polyolefin hollow short fiber used in the present invention has a large number of strip-shaped micropores formed by microfibrils arranged in the longitudinal direction and knots connected at almost right angles to the microfibrils. J7 A micro-laminated structure interconnected in the horizontal direction is shown. The porosity of the hollow short fibers measured with a mercury voluminometer must be 20% by volume or more. When the porosity is 20% by volume, the removability of endo[-1-syn is insufficient. In particular, it is preferable that the porosity is 40% by volume or more from the viewpoint of endotoxin removal ability.

Porous polyolefin fibers having the above-mentioned special structure are produced by melt-spinning polymers such as polypropylene and polyethylene using a special nozzle for producing hollow fibers, resulting in highly oriented crystalline undrawn hollow fibers. It is manufactured by appropriately controlling each process condition in the main steps of cold stretching (having a microstructure called "heart elastic fiber") and then heating stretching.

As the polyolefin, polyethylene, polypropylene, and copolymers containing these as main components are preferably used, and blends of these polymers mixed with other polymers in small proportions can also be used.

Next, the special microstructure of the polyolefin porous fiber used in the present invention will be explained in more detail with reference to the drawings.

Figure 1 is a schematic diagram of a layered structure of short 1111-shaped micropores, in which (1) is a microfibril, (2) is a (1)
Nodules connected almost at right angles to microfibrils,
(3) is a rectangular micropore, and the rectangular micropore (3) composed of microfibrils and nodules has a laminated structure with each nodule interposed therebetween.

In addition, the laminated structure of micropores means that the fibers are laminated in the length direction of the fibers in one plane via the nodules, and at the same time, planes with such a structure are stacked in the 7-way direction of the wall membrane of the hollow fibers. .

Next, the polyolefin porous hollow fibers having a special structure obtained as described above are cut into short fibers.

The fiber length is 7 mm or less, preferably 5 mm or less, particularly preferably 0.5 to 3 mm.

If the fiber length is too long, the endotoxin removal ability will not be sufficient. The hollow fibers may be cut using a cutting machine, or the fibers may be crushed at low temperatures. The cut surface of the hollow fiber is preferably in a state where the hollow part is open, but it can also be used with the hollow part closed.

Further, the shape of the hollow fibers may be completely hollow, semicircular, or partially crushed.

The inner diameter of the hollow fiber is 7μm in terms of endotoxin removal ability.
~400 μm is preferable, and the wall thickness is preferably 3 μIn to 100 μm from the viewpoint of the ability to remove entodo-4-syn.

There is no limit to the micropore diameter of the hollow fibers pulled out, but when expressed in terms of valve points, it is 1.0 to 20 kg.
/cnl is suitable in terms of endotoxin removal ability.

The polyolefin porous hollow short fibers used in the present invention need to be made hydrophilic. Normally, making an adsorbent hydrophilic is thought to reduce the adsorption ability of lipophilic substances and is expected to be disadvantageous for endotoxin removal, but in the case of the polyolefin porous hollow short fibers used in the present invention, unexpected results , the ability to remove endotoxins is extremely low unless hydrophilicization is performed, so hydrophilicization is essential. Hydrophilization can be carried out by impregnating the short fibers into a liquid or an aqueous solution thereof that has an affinity for polyolefins and is miscible with water.

Examples of the hydrophilic liquid include alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, and ethylene glycol, and various surfactants.

The water to be treated passes through the layer of polyolefin porous hollow short fibers as described above, and then has a porosity of 20 to 90% by volume.
filtered through a porous polyolefin medium membrane.

The porous polyolefin hollow fibers used in the second stage treatment can be manufactured in the same process as the polyolefin porous hollow fibers used in the first stage treatment. However, when the porosity exceeds 90%, the mechanical performance of the hollow fibers decreases,
It becomes unsuitable for use as a filter. In addition, the micropore diameter of the hollow fiber is 1.5 when expressed at the valve point 1-.
A range of 15 kg/ctA is appropriate in terms of endod:1-syn removal ability and water permeability. The structure of the membrane 414 is similar to that of the hollow short fibers in the first stage treatment.

The inner diameter of the hollow fiber is 100 μl to 500 μl from the viewpoint of processing capacity as a filter. Wall j7 is preferably 10 tl rn to 10 (ltJ m).

The abrasive quality of the polymer constituting the hollow fibers is the same as that of the first stage polyolefin porous 1 hollow short fibers, but the
The short fibers in the step and the hollow fiber pattern in the second step may be made of the same polymer or may be made of different polymers. Usually, the first step is polypropylene hollow knowledge! filffi, a polyethylene hollow fiber membrane in the second stage, or polyethylene in both the first and second stages.

As mentioned above, by the combination of the polyolefin porous hollow short fibers and the polyolefin porous hollow fibers 11,
Endotoxin processing ability is significantly improved. The details of why such an excellent effect occurs are not yet clear, but endotoxins are removed extremely efficiently by the polyolefin porous short fiber layer in the first stage, and the polyolefin porous hollow fiber layer in the second stage removes endotoxins extremely efficiently. The membrane completely captures ml of endotoxin leaking from the first hollow short fiber layer. In this case, factors such as the state of existence of endotoxin (difference in molecular weight distribution, change in chemical structure of endotoxin, state of binding with other substances, etc.), concentration of other organic matter in the water, temperature, etc. are considered to be involved. Although this is not simple, the combination of the first and second stages can be said to be a method of cleverly adjusting these complexities.

The first stage polyolefin porous hollow short fiber layer does not become clogged and the adsorbed substances can be easily washed. The endotoxin removal ability is easily restored by washing with ethanol or alkaline ethanol. Therefore, the practical processing capacity is dramatically higher than that of a polyolefin porous hollow short fiber layer alone or a hollow fiber membrane alone.

Thus, the two-stage treatment system of the present invention has a particularly low
It is extremely useful for processing large amounts of water, and has extremely high processing accuracy and reliability.

Furthermore, by using an activated carbon layer in combination with the above-mentioned polyolefin porous hollow short fiber layer and multi-rL hollow fiber membrane, the processing ability of Entod:1-Syn can be further dramatically improved. In other words, the water to be treated is first treated with 611 carbon +
After passing through a polyolefin porous hollow short fiber layer, the water to be treated is filtered through a polyolefin porous hollow fiber membrane, or the water to be treated is passed through a 71 metal material made of activated carbon and polyolefin porous hollow short fiber. After passing through the layer, the endotoxin treatment ability is further improved by filtration through a polyolefin porous hollow fiber membrane.

Although the details of the reason why such an unexpected effect occurs are not yet clear, it is presumed that the organic adsorption effect of activated carbon acts synergistically on the endotoxin treatment ability of the polyolefin porous hollow short fibers.

(G) Examples Hereinafter, the method of the present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1, Comparative Example 1.2.3.4, density polyethylene with a density of 0.968 g/ctA and a melt index of 5.5 was spun at a spinning temperature of 156° using a hollow fiber spinneret having a double tube structure. It was spun at C.

The obtained undrawn hollow fibers were annealed at 112°C and then cold-stretched at room temperature by 50%.

Next, hot stretching was performed at 100°C until the total stretching ratio was 3.
．． I made it 8 times. Further, after constant length heat centrifugation at 113"C, the fibers were cut into short fibers using a cutting machine.

The obtained porous hollow short polyethylene fibers have a large number of strip-shaped micropores formed by nodules in which microfibrils arranged in the longitudinal direction are connected at almost right angles to the microfibrils, and are arranged in the longitudinal direction of the membrane. It had an interconnected micro-N structure, the porosity measured with a water root porosimeter was 60% by volume, and the valve point was 4.8 kg/cal. In addition, the shape of the hollow short fibers is that the inner diameter is 270 μm,
wall! The length was 55 μm and 2III+1.

50 g γ of the polyethylene porous hollow short fibers thus obtained were packed in a column with a diameter of 5 cm and made hydrophilic with 70% ethanol to form a first stage filter.

Next, the polyethylene porous hollow fiber produced in the same manner as in "2" was made into a fiber without cutting it into short fibers, formed into a loop shape, and the ends were bonded with polyurethane resin to form an effective direct area (
A 1,3+n hollow fiber filter was produced, made hydrophilic with ethanol, and used as a second stage filter.

Synthesis) Coned I = 1-syn mud layer measured by paleo'('j method (I1 Kagaku Kogyo Co., Ltd.)
Tap water of nB/m 1 was continuously passed through the first and second stage filters connected in series at a flow rate of 0.512/min.

The water from the first stage filter D (Comparative Example 1) and the second stage filter [J (Example 1) was collected, and the endotoxin depth was measured by the synthetic substrate method.

Also, for comparison, it is passed through the first stage filter,
- Pass water through the second stage filter manufactured in the same manner as
The filtered water was analyzed (Comparative Example 2).

Further, as a first stage filter, polypropylene fibers (not hollow fibers) having a ζ fineness of 10 deniers were cut into 2 mm lengths, and 50 g γ of the fibers were packed into a column with a diameter of 5 cm and made hydrophilic in the same manner as above. This is similar to the above, but the filtration area is 0.
．． 3 rri hollow fiber filters were connected in series and water was passed through, and the water at the outlet of the second stage filter was analyzed (Comparative Example 3)
Also shown are the results when a hollow fiber filter with an effective filtration area of 0.3 rrl similar to the second stage filter was used as the first stage filter (Comparative Example 4).

As shown in Table 1, Comparative Example 3 using a common volipt cobilene fiber for the first stage filter is different from Comparative Example using only the second stage filter. There is no big difference between 2 and 2.

Example 1 of the method of the present invention is extremely stable and completely (99% even after 10r+? water flow) compared to Comparative Example 1.2.
Endotoxin is removed. Furthermore, Example 1 shows clearly superior performance compared to Comparative Example 4, which uses two stages of hollow fiber filters.

Example 2, Comparative Example 5 Polypropylene ([η
] = 1.40) was spun at a spinning temperature of 260'' C using a hollow fiber spinneret with a double tube structure.The obtained undrawn yarn was annealed at 1456 C, and then cold drawn (
Stretching was carried out under the conditions of room temperature)/hot stretching (145°C)' = 12/8B and a total stretching ratio of 2.2 times. The drawn hollow fibers were then heat centrifuged at 155° C. and then cut into short fibers using a cutter.

The obtained porous hollow short polypropylene fiber has a large number of short m+-shaped micropores formed by knots in which microfibrils arranged in the longitudinal direction are connected at almost right angles to the microfibrils, and has a thickness of IIQ. It has a single-layer structure with 11 layers interconnected in the horizontal direction, and the porosity measured with a water root porosimeter is 45%, and the valve point is ε 12.5.
/ cnl. The hollow short fibers had an inner diameter of 190 μm, a wall thickness of 25 μm, and a length of 2 mm.

50 g of the thus obtained Volip 1 Copylene porous hollow short fibers were packed into a column with a diameter of 5 cm and made hydrophilic with 70% ethanol to form a first stage filter. As the second stage filter, the same one as the second stage filter of Example 1 was used. Entod4-syn concentration 3.8 ng/m
(L of tap water was continuously passed through the first and second stage filters connected in series, and the centration of the filtered water from the second stage filter was measured. Example 1)
.

A comparison was also conducted in the case where only the second stage filter was used (Comparative Example 5). The results are shown in Table 2.

Table 2 Endotoxin concentration in filtrate water (IIJ!/m
j! )2, (After water flow 4IT? After water flow 10M water flow Example 2 after water flow 0.04 0.04 0.07 Comparative example 5
0.6 +, 2 2.6 *Endotoxin concentration of raw water 3.8 ng/me Example 3.4, Comparative Example 6 In addition to the first and second stage filters similar to Example 1, the first stage Coconut shell active Ji 650B before filter
A prefilter filled with water was installed, and tap water with an endotoxin concentration of 4.2 ng/mβ was continuously passed through. The endotoxin concentration of the water at the outlet of the activated carbon column (Comparative Example 6) and the filtered water at the outlet of the second stage filter (Example 3) was measured. Further, a case was also conducted in which the activated carbon prefilter was not used (Example 4). The results are shown in Table 3.

Below are the margins - Ec:; % 4 \ "ε5d→ Tomoe・Sa ′ε664 +1-8 Mu agent Δ Article 11") TOH shell oO ■ e 'ε5d6 Article! Despite the fact that the ability of old activated carbon itself to remove endo I/xins is hardly recognized, as shown in Example 3, activated carbon is used as a pre-filter. Compared to Example 4, which did not use this method, the endotoxin removal effect was greatly improved.

Example 5 50 g of polyethylene porous hollow short fibers obtained in the same manner as in Example 1 and 30 h of coconut shell activated carbon were mixed and packed in a column with a diameter of 5 mm to prepare a first stage filter. A filter similar to the second stage filter of Example 1 was used as the second stage filter. A continuous water flow experiment similar to that in Example 3 was conducted. The results are shown in Table 4.

Table 4 Endotoxin concentration of filtered water (ng/mβ) 5d I
on (through 15m through 20+n through 30M through water flow water time water time water time water time water time 0.04 0.06 0.10 0.12 0.19 From Table 4, compared to Example 4, the mixing of activated carbon It can be seen that the endotoxin removal ability has been significantly improved.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of one plane of a stacked structure of strip-shaped micropores. Patent applicant Mitsubishi Rayon Co., Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate Patent attorney Yukio Akira Yamaguchi Patent attorney Masaya Nishiyama (−＋＋＋／−１

Claims (1)

[Scope of Claims] I. After passing the water to be treated through a layer filled with hydrophilized polyolefin porous hollow short fibers having a porosity of 20% by volume or more as measured by a mercury porosimeter, and further A method for purifying an aqueous liquid, characterized by filtering it through a polyolefin porous hollow fiber membrane having a porosity of 20 to 90% by volume. 2. The fiber length of the polyolefin porous hollow short fiber is 10
2. The method for purifying an aqueous liquid according to claim 1, wherein the aqueous liquid has a particle size of 1 mm or less. 3. The inner diameter of the polyolefin porous hollow short fiber is 7p.
m to 400 p m, wall thickness 3prn to 100μ
The method for purifying an aqueous liquid according to claim 1 or 2, wherein m. 4. The method for purifying an aqueous liquid according to claim 1, wherein the polyolefin porous hollow short fibers are in a crushed form. 5. The method for purifying an aqueous liquid according to any one of claims 1 to 4, wherein the polyolefin is polyethylene. 6. The method for purifying an aqueous liquid according to any one of claims 1 to 4, wherein the polyolefin is polypropylene. 7. The water to be treated is passed through a layer of activated carbon and then passed through a column filled with polyolefin porous hollow short fibers with a porosity of 20% by volume or more as measured by a mercury porosimeter. A method for purifying an aqueous liquid, comprising filtration through a porous hollow fiber membrane containing 20 to 90% by volume of polyolefin. 8. After passing the water to be treated through a layer of a mixture of activated carbon and polyolefin porous hollow short fibers with a porosity of 20% by volume or more as measured by a mercury porosimeter, the water is further passed through a layer with a porosity of 20 to 90% by volume. A method for purifying an aqueous liquid, characterized by filtering it through a polyolefin porous hollow fiber membrane.