JPH0729051B2 - High-performance fibrous uranium adsorbent - Google Patents

Description

TECHNICAL FIELD The present invention relates to a fibrous uranium adsorbent having excellent adsorption performance and high strength, and more specifically, adsorbing uranium in a dilute solution such as seawater. -It relates to a high-performance fibrous adsorbent used for separation and collection.

(Prior Art) In recent years, high growth has largely depended on cheap and abundant oil. Recently, with the promotion of energy conservation,
Petroleum has become available and the energy situation is improving. However, the resources such as petroleum are limited, and there is a concern that they will be depleted in the future, and energy sources are being diversified.

Uranium, which is the most promising fuel for nuclear power generation as an alternative energy to oil, has a small amount of minable resources, and if the breeder reactor is not developed, there is a risk that the balance of supply will be disrupted in the early 21st century. Therefore, it is necessary to secure new resources, and it is strongly desired to establish a technology to extract useful resources from the ocean, which occupies 70% of the surface.

The concentration of uranium in seawater is as low as about 3 ppb, and it is dissolved as stable uranyl carbonate. In order to collect this uranium, it is necessary to develop an adsorbent that has excellent selectivity and adsorption properties, is in efficient contact with a large amount of seawater, is easy to collect, and has good durability.

(Problems to be solved by the invention) And, recently, it was recognized that the amidoxime type fibrous adsorbent exhibits excellent adsorption performance for uranium in seawater,
Attention has been paid. The fibrous adsorbent adsorbs about 4 mg / g of uranium in 10 days, but it is not practical because it does not have sufficient strength to withstand repeated regeneration use, and problems such as limited usage modes Have a point. On the other hand, when the reaction is not progressing and the fiber strength is high, the adsorption rate of uranium is low, and the adsorption amount is saturated at a very small amount of about 5 mg / g.

The present invention is intended to improve the above-mentioned drawbacks of conventional adsorbents, and has been made with the object of providing a fibrous adsorbent having a high adsorption rate and adsorption capacity for uranium and high strength.

(Means for Solving Problems) The gist of the present invention is to provide a polymer containing at least 96% by weight of acrylonitrile and 40 to 95% of acrylonitrile.
A fibrous uranium adsorbent prepared by reacting a composite fiber composed of a polymer contained by weight% with hydroxylamine.

Generally, acrylic fibers are acrylonitrile as the first component, alkyl acrylate, vinyl acetate, etc. as the second component, and anionic groups such as sulfonic acid, carboxylic acid, etc. as the third component (dyeability improver) or cationic groups such as amino compounds. Is composed of a terpolymer containing
As a special fiber, a high-strength material fiber having a high acrylonitrile content is also commercially available.

The present inventors prepared amidoxime type fibrous adsorbents using the above various acrylic fibers under various conditions, and examined the relationship between the preparation conditions and the fiber strength and uranium adsorbability,
It was found that the reactivity with hydroxylamine varies depending on the type of fiber.

That is, a fiber having a low acrylonitrile content and a non-dense fiber structure, for example, a polymer composed of 50% by weight of acrylonitrile, 49% by weight of vinyl chloride, and 1% by weight of a sulfonic acid vinyl monomer is dissolved in dimethylformamide and wet-spun. The reaction speed of the obtained fiber with hydroxylamine is remarkably large, and a fiber having several meq / g of amidoxime groups can be obtained in about 1 hour.

On the other hand, it was confirmed that a dense fiber having a high acrylonitrile content structure, for example, a fiber obtained by dissolving polyacrylonitrile in dimethylformamide and dry-spinning has a small reaction rate and hardly reacts even after 4 hours.

Conjugate fibers, which are two or more types of composite spun fibers, have been developed as fibers. This is a product with different physical properties spun at the same time using a special spinneret. Side-by-side type, polymer sheathed type core-sheath type sheath core type or block mixed type, uniform mixed type Etc.

In the present invention, the conjugate fiber is used as the composite fiber, and among them, the side-by-side type and the sheath core type are particularly preferably used. That is, the adsorbent of the present invention is a high-strength fibrous adsorbent having excellent uranium adsorption performance, which is prepared by using a conjugate type composite fiber of a polymer that is easy to form amidoxime and a polymer that is slow to form amidoxime. .

EXAMPLES Next, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

Example 1 Acrylonitrile 99.5% by weight, methallyl sulfonate
Polymer (X) consisting of 0.5% by weight and acrylonitrile 9
Side-by-side dry-spun conjugate fiber with polymer (Y) consisting of 3% by weight, methyl acrylate 6% by weight, and methallylsulfonate 1% by weight (weight ratio (X) :( Y) = 1: 1, fineness 3 denier) ) 5 g was added to 200 mL of a 1 M solution of hydroxylamine in methanol, and the mixture was heated under reflux for 8 hours for amidoxime formation. Furthermore, alkali treatment
I went for 24 hours. This amidoxime type fibrous adsorbent (strength
1.6 g / d) 0.2 g was packed in a column having an inner diameter of 2.5 cm, and natural seawater was passed at 250 mL / min. About 85 days as shown in Fig. 1
Adsorbed 10 mg / g uranium. The amount adsorbed was about twice that of conventional amidoxime fibers.

Example 2 Using the same fibers as in Example 1, various amidoxime type fibrous adsorbents were prepared by changing the amidoxime formation time and the alkali treatment time, and the single fiber strength and the uranium adsorption rate were measured. As a result, as shown in FIG. 2, the fibrous adsorbent (B) prepared by using the composite spun fiber of the present invention is a conventional amidoxime-type fibrous adsorbent ( Compared with A), the single fiber strength and the uranium adsorption rate are large, and it is clear that this is an excellent adsorbent.

Reference Example 1 Various amidoximated fibrous adsorbents (A) and (C) were prepared by changing the amidoxime-forming conditions in the same manner as in Example 2 with respect to the fibers composed of the polymer (Y) and the polymer (X). The results of measuring these copper adsorption amounts are shown in FIG. It can be seen that the reaction rates of the two fibers are significantly different. The uranium adsorption rate and single fiber strength were measured for both fibers. The relationship between the adsorption rate and the strength of single fiber is shown in FIG. It is clear that the fiber (C) prepared from fibers with a higher acrylonitrile content has a higher strength.

Comparative Example 1 A fiber comprising 93% by weight of acrylonitrile, 6.5% by weight of vinyl acetate and 0.5% by weight of methallyl sulfonate (fineness 3
Then, amidoxime formation and alkali treatment were performed so that the same strength (1.6 g / d) as in Example 1 was obtained with denier. The uranium adsorption rate of the amidoxime type adsorbent (D) thus obtained was measured. The result is shown in FIG. The adsorbed amount of uranium is not as large as that of the example, and uranium is 2.5 m in 10 days.
Adsorbed g / g.

(Effect of the invention) As described above, the fibrous adsorbent of the present invention has a large fiber strength and a large uranium adsorption capacity in seawater as compared with amidoxime type fibrous adsorbents prepared using conventional acrylic fibers. It has an excellent effect as an adsorbent for collecting uranium. That is, since it has excellent strength, it can withstand repeated repeated use for a long period of time and has practical performance.

[Brief description of drawings]

FIG. 1 shows the uranium adsorption amount of the adsorbent of the present invention obtained in Example 1, and FIG. 2 is the adsorbent of the present invention (B) obtained in Example 2 and the conventional adsorbent. FIG. 3 shows the relationship between the single fiber strength of (A) and the uranium adsorption amount. FIG. 3 shows the copper adsorption amounts of the conventional adsorbents (A) and (C) obtained in Reference Example 1, and FIG. FIG. 5 shows the relationship between the single fiber strength of (A) and (C) and the uranium adsorption amount, and FIG. 5 shows the uranium adsorption amount of the conventional adsorbent (D).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shoichi Nagai 4-chome Sunadabashi, 60, Higashi-ku, Nagoya, Aichi Prefecture Mitsubishi Rayon Co., Ltd. (72) Saburo Hiraoka 4-chome Sunadabashi, Higashi-ku, Nagoya, Aichi Prefecture Mitsubishi Rayon Co., Ltd. (72) Inventor Yasuo Nakamura 2-3-19 Kyobashi, Chuo-ku, Tokyo Mitsubishi Rayon Co., Ltd. Examiner Koji Amamiya

Claims (1)

[Claims] 1. An amidoxime-type fibrous uranium adsorption obtained by reacting a composite fiber composed of a polymer containing at least 96% by weight of acrylonitrile and a polymer containing 40 to 95% by weight of acrylonitrile with hydroxylamine. Agent.