Seawater uranium extraction needle-punched fabric based on dry-method PAN fibers and preparation method and application thereof

Abstract

The invention belongs to the technical field of novel adsorption materials, and particularly relates to needle-punched cloth for extracting uranium from seawater based on dry-process PAN fibers and a preparation method and application of the needle-punched cloth. The needle-punched fabric for extracting uranium from seawater comprises chemical modified functional fibers and supporting fibers, the chemically modified functional fiber with amidoxime groups is obtained by chemically modifying a dry polyacrylonitrile short fiber. The invention discloses the needle punched cloth for extracting uranium from seawater based on the dry PAN fiber for the first time, the material has the advantages of low production cost, batch production and large-scale implementation, can be directly soaked in seawater, can be rolled into components such as a filter element and the like, and can be used for enriching and separating uranium from seawater in forms of single-layer filtration, multi-stage filtration and the like; the industrial popularization and application are easy.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel adsorption materials, and in particular relates to a seawater uranium extraction needle-punched cloth based on dry-process PAN fibers, and a preparation method and application thereof. Background Art

[0002] Nuclear fission generates approximately 400 million gigawatts of electricity, accounting for approximately 11% of global electricity generation. Uranium is an essential element for fission fuel and radioactive waste, making the acquisition of natural uranium crucial. Natural uranium obtained through traditional uranium mining and smelting is a finite resource due to its non-renewable nature. Extracting uranium from seawater is crucial for ensuring the stability of natural uranium. Uranium extraction from seawater by adsorption is currently considered the most effective method for extracting uranium from seawater. The key lies in the adsorbent material used for seawater extraction. However, achieving the mass production and portable deployment of adsorbent materials in real seawater remains a major obstacle to the development of uranium extraction materials. Summary of the Invention

[0003] The purpose of the present invention is to solve the above problems. By mixing modified functional fibers having amidoxime groups with supporting fibers, seawater uranium extraction needle-punched cloth is obtained through a needle-punching process. The seawater uranium extraction needle-punched cloth has the advantages of low production cost, batch production, and large-scale implementation, and can realize the large-scale application of seawater uranium extraction.

[0004] To this end, the first aspect of the present invention provides a seawater uranium extraction needle-punched cloth based on dry-process PAN fiber, the seawater uranium extraction needle-punched cloth comprising:

[0005] Chemically modified functional fibers and supporting fibers;

[0006] The chemically modified functional fiber is a chemically modified functional fiber having amidoxime groups obtained by chemically modifying dry-process polyacrylonitrile staple fibers.

[0007] As a preferred embodiment, in the aforementioned dry-process PAN fiber-based seawater uranium extraction needle-punched fabric, the chemically modified functional fiber containing amidoxime groups has a functional group content of 3.8-5.3 mmol / g. In this case, the resulting seawater uranium extraction needle-punched fabric can ensure both high adsorption performance and high mechanical strength.

[0008] As a preferred embodiment, in the above-mentioned seawater uranium extraction needle-punched cloth based on dry-process PAN fiber, the supporting fiber is a hydrophilic fiber substrate, optionally selected from at least one of viscose fiber and polyester fiber.

[0009] As a preferred embodiment, in the above-mentioned seawater uranium extraction needle-punched cloth based on dry-process PAN fiber, the mass ratio of the chemically modified functional fiber to the supporting fiber is 9 to 6:1.

[0010] As a preferred solution, the above-mentioned sea water uranium extraction needle-punched fabric based on dry-process PAN fiber satisfies at least one of the following characteristics:

[0011] The thickness of the sea water uranium extraction needle-punched fabric is 3-8 mm;

[0012] The grammage of the sea water uranium extraction needle-punched fabric is 100-270 g / m 2 .

[0013] The second aspect of the present application provides a preparation method of the above-mentioned sea water uranium extraction needle-punched fabric, which comprises:

[0014] First, the dry-process polyacrylonitrile staple fiber is chemically modified to obtain chemically modified functional fiber containing amine oxime groups, and then the chemically modified functional fiber is mixed with support fiber, and the mixture is needle-punched and then activated by an alkaline solution to obtain the sea water uranium extraction needle-punched fabric with adsorption performance.

[0015] As a preferred solution, the preparation method of the sea water uranium extraction needle-punched fabric comprises:

[0016] (1) Chemical modification of dry-process PAN fiber

[0017] Hydroxylamine sulfate or hydroxylamine hydrochloride, sodium hydroxide and deionized water are uniformly mixed, and the pH value of the solution is controlled to be 7;

[0018] The dry-process polyacrylonitrile staple fiber is placed in the reaction solution for reaction;

[0019] After washing, the chemically modified functional fiber is obtained;

[0020] (2) Needle-punching

[0021] The chemically modified functional fiber is mixed with the support fiber, and is opened and carded to prepare a web with a predetermined grammage and uniformity, and then is cross-laid and conveyed to a needle-punching machine to prepare a chemically modified functional fiber / support fiber mixed needle-punched fabric;

[0022] (3) Alkaline activation treatment

[0023] The chemically modified functional fiber / support fiber mixed needle-punched fabric is placed in an alkaline solution for alkaline activation treatment;

[0024] After washing, the sea water uranium extraction needle-punched fabric is obtained.

[0025] As a preferred solution, in step (1) of the above-mentioned preparation method of the sea water uranium extraction needle-punched fabric, the dry-process polyacrylonitrile staple fiber is placed in the reaction solution for reaction, which satisfies at least one of the following characteristics:

[0026] The reaction temperature is 65-75℃;

[0027] The reaction solution is circulated;

[0028] The reaction time is 1 to 4 hours.

[0029] As a preferred embodiment, in step (2) of the method for preparing the seawater uranium-extracted needle-punched cloth, the needle-punching process after transporting the cloth to the needle-punching machine satisfies at least one of the following characteristics:

[0030] The needling depth is 8 to 12 mm;

[0031] The acupuncture density is 150 to 400 punctures / cm 2 ;

[0032] The frequency of acupuncture is 800 to 1500 times per minute.

[0033] As a preferred embodiment, in step (3) of the above-mentioned method for preparing needle-punched cloth for extracting uranium from seawater, the alkali used in the alkali activation treatment includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide, and optionally satisfies at least one of the following characteristics:

[0034] The mass concentration of alkali in the alkali solution is 0.5% to 1%;

[0035] The temperature of the alkali activation treatment is 20-50°C;

[0036] The time of alkali activation treatment is 0.8 to 1.5 hours.

[0037] A third aspect of the present invention provides the use of the seawater uranium extraction needle-punched cloth or its preparation method in seawater uranium extraction.

[0038] Compared with the prior art, the present invention has at least the following beneficial effects:

[0039] The present invention discloses for the first time a seawater uranium extraction needle-punched cloth based on dry-process PAN fiber. This material has the advantages of low production cost, mass production, and large-scale implementation. It can be directly immersed in seawater, or it can be rolled into components such as filter elements to carry out uranium enrichment and separation in seawater through single-layer filtration, multi-stage filtration, etc., and is easy to promote and apply industrially.

[0040] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are specifically listed below. DETAILED DESCRIPTION

[0041] In the following description, a number of specific details are provided to provide a more thorough understanding of the technical solutions provided by the present invention. However, it is obvious to those skilled in the art that the technical solutions provided by the present invention can be implemented without one or more of these details.

[0042] Unless otherwise specified, the raw materials described in the examples of the present invention are conventional raw materials available on the market, the equipment used are commonly used equipment in the field, the reaction conditions are normal conditions; and the identification of the products is by conventional methods.

[0043] Example 1

[0044] (1) Chemical modification of dry-process PAN fibers

[0045] Take 10 kg of dry PAN fiber and carry out amidoxime chemical modification. The modification solution is an aqueous solution of hydroxylamine sulfate. The specific ratio of the reaction solution is as follows: 5 kg of hydroxylamine sulfate, 5.05 kg of sodium hydroxide, 50 liters of deionized water, stir until completely dissolved, and the pH value of the solution is 7. Add the dry PAN fiber to the reaction solution, heat to 70 ° C, circulate the reaction solution, and react for 3 hours. Subsequently, use deionized water to repeatedly rinse the fiber modification product until the pH of the rinse liquid is 7. After dehydration, dry it naturally to obtain a chemically modified functional fiber. Among them, the adsorption functional group is amidoxime group, and the functional group content is 5.3 mmol / g.

[0046] (2) Needle punching

[0047] 9 kg of chemically modified functional fibers and 1 kg of viscose fibers were mixed at a mass ratio of 9:1, opened and carded to prepare a fiber web with a predetermined weight and uniformity. After cross-lapping, the web was sent to a needle loom. The fiber web was needle-punched using a needle board with barbed needles, with a needle depth of 9 mm and a needle density of 300 needles / cm. 2 The needle punching frequency is 1200 times / minute. Through the needle punching process, the chemically modified functional staple fibers and the viscose fibers are entangled and embraced with each other, and finally a chemically modified functional fiber / viscose fiber mixed needle punched cloth is obtained. The obtained needle punched cloth has a thickness of 5mm and a gram weight of 171g / m 2 .

[0048] (3) Alkali activation treatment

[0049] An alkali solution is prepared for alkali activation treatment of the chemically modified functional fiber / viscose fiber mixed needle-punched fabric. Specifically, an alkali solution is prepared, with sodium carbonate as the alkali substance and a mass concentration of 1%; 200 g of the chemically modified functional fiber / viscose fiber mixed needle-punched fabric is weighed and added to the alkali solution, the alkali solution is circulated, the treatment temperature is 40°C, and the treatment time is 1 h; then, deionized water is injected into the reaction container, and repeated washing is performed until the pH value of the washing liquid is 7, to obtain an adsorption material (I) for uranium extraction from seawater and the like.

[0050] Example 2

[0051] (1) Chemical modification of dry-process PAN fiber

[0052] 50 kg of dry-process PAN fiber is subjected to amidoxime chemical modification. The modification solution is an aqueous solution of hydroxylamine sulfate, and the specific proportion of the reaction solution is as follows: hydroxylamine hydrochloride 21.2 kg, sodium hydroxide 46.67 kg, deionized water 200 L, stirring until completely dissolved, and the pH value of the solution is 7. The dry-process PAN fiber is added to the reaction solution, heated to 70°C, the reaction solution is circulated, and the reaction is performed for 1 h. Then, the fiber modification product is repeatedly washed with deionized water until the pH of the washing liquid is 7. After dehydration, natural air drying is performed to obtain chemically modified functional fiber. The adsorption functional group is amidoxime group, and the functional group content is 3.8 mmol / g.

[0053] (2) Needle-punched forming

[0054] 60 kg of chemically modified functional fiber and 10 kg of polyester fiber are mixed at a mass ratio of 6:1, opened and carded to prepare a web with a predetermined gram weight and uniformity, and then transferred to a needle-punching machine after cross-laying. The web is needle-punched and reinforced by a needle plate with barbed needles, wherein the needle punching depth is controlled to be 12 mm, the needle punching density is 200 needles / cm 2 , and the needle punching frequency is 900 times / min; after the needle punching process, the chemically modified functional short fiber and the polyester fiber are entangled and bonded with each other, and finally a chemically modified functional fiber / polyester fiber mixed needle-punched fabric is obtained. The thickness of the obtained needle-punched fabric is 8 mm, and the gram weight is 267 g / m 2 .

[0055] (3) Alkali activation treatment

[0056] An alkali solution is prepared for alkali activation treatment of the chemically modified functional fiber / viscose fiber mixed needle-punched fabric. Specifically, an alkali solution is prepared, with sodium carbonate as the alkali substance and a mass concentration of 1%; 200 g of the chemically modified functional fiber / viscose fiber mixed needle-punched fabric is weighed and added to the alkali solution, the alkali solution is circulated, the treatment temperature is 40°C, and the treatment time is 1 h; then, deionized water is injected into the reaction container, and repeated washing is performed until the pH value of the washing liquid is 7, to obtain an adsorption material (I) for uranium extraction from seawater and the like.

[0057] Comparative Example 1

[0058] (1) Chemical modification of dry-process PAN fibers

[0059] Take 10 kg of dry PAN fiber and carry out amidoxime chemical modification. The modification solution is an aqueous solution of hydroxylamine sulfate. The specific ratio of the reaction solution is as follows: 5 kg of hydroxylamine sulfate, 5.05 kg of sodium hydroxide, 50 liters of deionized water, stir until completely dissolved, and the pH value of the solution is 7. Add the dry PAN fiber to the reaction solution, heat to 70 ° C, circulate the reaction solution, and react for 3 hours. Subsequently, the fiber modification product is repeatedly rinsed with deionized water until the pH of the rinse liquid is 7. After dehydration, it is naturally dried to obtain a chemically modified functional fiber. Among them, the adsorption functional group is amidoxime group, and the functional group content is 5.6 mmol / g.

[0060] (2) Alkali activation treatment

[0061] An alkaline solution was prepared to perform an alkaline activation treatment on the chemically modified functional fiber. Specifically, the alkaline solution was first prepared, wherein the alkaline substance was sodium carbonate with a mass concentration of 1%. Then, 200 grams of the chemically modified functional fiber was weighed and added to the alkaline solution. The alkaline solution was circulated at a treatment temperature of 40°C for 1 hour. Subsequently, deionized water was injected into the reaction vessel and the cleaning solution was repeatedly rinsed until the pH value of the cleaning solution was 7, thereby obtaining an adsorbent material (III) for uranium extraction from seawater, etc.

[0062] The adsorption materials (I), (II) and (III) prepared in Example 1, Example 2 and Comparative Example 1 were subjected to uranium adsorption tests in seawater under the same conditions. The results are shown in the following table:

[0063] Table 1

[0064]

[0065] Seawater Uranium Extraction Adsorption Test: 500.0 g each of the prepared adsorbent materials (I), (II), and (III) were accurately weighed and loaded into a seawater uranium extraction apparatus (the needle-punched fabric material was in sheet form, wrapped on both sides with polypropylene mesh cloth; the modified fibers were in loose fiber form, loaded into a polypropylene mesh bag with uniform pore size). Uranium extraction adsorption tests were conducted in real seawater from the South China Sea (analysis revealed a uranium concentration of 3.3 μg / L in the seawater). After 25 days of adsorption testing, the adsorbent materials were recovered, washed, and dried. The uranium adsorption capacity of the fibers was analyzed using inductively coupled plasma mass spectrometry (ICP-MS).

[0066] After recovering the adsorbed materials, it was found that adsorption material (I) and adsorption material (II) still maintained a flaky structure and had uniform adsorption, while adsorption material (III) had serious fiber agglomeration, and the adsorption capacity outside the loose fiber agglomerates was significantly different from the internal capacity, resulting in uneven adsorption effect.

[0067] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A seawater uranium extraction needle-punched cloth based on dry-process PAN fiber, characterized in that: The seawater uranium extraction needle-punched cloth includes: Chemically modified functional fibers and supporting fibers; The chemically modified functional fiber is a chemically modified functional fiber having amidoxime groups obtained by chemically modifying dry-process polyacrylonitrile staple fibers.

2. The seawater uranium extraction needle-punched cloth based on dry-process PAN fiber according to claim 1, characterized in that: In the chemically modified functional fiber having amidoxime groups, the content of the functional groups is 3.8-5.3 mmol / g.

3. The seawater uranium extraction needle-punched cloth based on dry-process PAN fiber according to claim 1, characterized in that: The supporting fiber is a hydrophilic fiber substrate, optionally selected from at least one of viscose fiber and polyester fiber.

4. The seawater uranium extraction needle-punched cloth based on dry-process PAN fiber according to claim 1, characterized in that: Satisfy at least one of the following characteristics: The mass ratio of chemically modified functional fibers to supporting fibers is 9 to 6:1; The thickness of the seawater uranium extraction needle-punched cloth is 3 to 8 mm; The seawater uranium extraction needle-punched cloth has a gram weight of 100 to 270 g / m 2 .

5. The method for preparing the seawater uranium-extracted needle-punched cloth according to any one of claims 1 to 4, characterized in that: The preparation method comprises: First, the dry-process polyacrylonitrile staple fiber is chemically modified to obtain chemically modified functional fibers containing amidoxime groups. The chemically modified functional fibers are then mixed with supporting fibers, needle-punched, and then activated with an alkaline solution to obtain seawater uranium extraction needle-punched cloth with adsorption efficiency.

6. The method for preparing seawater uranium-extracted needle-punched cloth according to claim 5, characterized in that: The preparation method comprises: (1) Chemical modification of dry-process PAN fibers Mix hydroxylamine sulfate or hydroxylamine hydrochloride, sodium hydroxide and deionized water evenly, and control the pH value of the solution to 7; placing dry-process polyacrylonitrile staple fibers in a reaction solution to react; After washing, chemically modified functional fibers are obtained; (2) Needle punching The chemically modified functional fiber is mixed with the supporting fiber, opened and carded to prepare a fiber web with a predetermined weight and uniformity, and then transported to a needle loom after cross-lapping to obtain a chemically modified functional fiber / support fiber mixed needle-punched cloth; (3) Alkali activation treatment The chemically modified functional fiber / support fiber mixture is needle-punched in an alkaline solution for alkaline activation treatment; After washing, the seawater uranium extraction needle-punched cloth is obtained.

7. The method for preparing seawater uranium-extracted needle-punched cloth according to claim 6, characterized in that: In step (1), the dry-process polyacrylonitrile staple fibers are placed in a reaction solution to react to meet at least one of the following characteristics: The reaction temperature is 65-75°C; circulating reaction solution; The reaction time is 1 to 4 hours.

8. The method for preparing seawater uranium-extracted needle-punched cloth according to claim 6, characterized in that: In step (2), the needling process after being transported to the needling machine satisfies at least one of the following characteristics: The needling depth is 8 to 12 mm; The acupuncture density is 150 to 400 punctures / cm 2 ; The frequency of acupuncture is 800 to 1500 times per minute.

9. The method for preparing seawater uranium-extracted needle-punched cloth according to claim 6, characterized in that: In step (3), the alkali used in the alkali activation treatment includes at least one of sodium carbonate, potassium carbonate, sodium hydroxide and potassium hydroxide, and optionally satisfies at least one of the following characteristics: The mass concentration of alkali in the alkali solution is 0.5% to 1%; The temperature of the alkali activation treatment is 20-50°C; The time of alkali activation treatment is 0.8 to 1.5 hours.

10. Use of the needle-punched cloth for uranium extraction from seawater according to any one of claims 1 to 4 or the preparation method according to any one of claims 5 to 9 in extracting uranium from seawater.

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