阅读说明：本技术 胺基和偕胺肟基聚丙烯腈纳米纤维及其制备方法和用途 (Amino and amidoxime group polyacrylonitrile nano-fiber and preparation method and application thereof ) 是由 宋艳 陈树森 宿延涛 王凤菊 常华 李子明 于 2021-09-06 设计创作，主要内容包括：本发明公开了一种胺基和偕胺肟基聚丙烯腈纳米纤维及其制备方法和用途。该制备方法包括以下步骤：(1)将聚丙烯腈溶液I和含两个以上亚乙基的多元胺溶液混合,在100～120℃下反应1.5～5h,得到胺基聚丙烯腈纺丝液；(2)将聚丙烯腈溶液II和盐酸羟胺溶液混合,并加入碳酸盐,然后在65～85℃下反应20～40h,冷却,离心,取上清液,得到偕胺肟基聚丙烯腈纺丝液；(3)采用双喷头静电纺丝机将步骤(1)所得的胺基聚丙烯腈纺丝液和步骤(2)所得的偕胺肟基聚丙烯腈纺丝液进行静电纺丝,干燥,得到胺基和偕胺肟基聚丙烯腈纳米纤维。本发明的制备方法制得的胺基和偕胺肟基聚丙烯腈纳米纤维可用于海水提铀,对铀的吸附容量大。(The invention discloses amino and amidoxime group polyacrylonitrile nano-fibers and a preparation method and application thereof. The preparation method comprises the following steps: (1) mixing the polyacrylonitrile solution I and a polyamine solution containing more than two ethylene groups, and reacting for 1.5-5 h at 100-120 ℃ to obtain an amino polyacrylonitrile spinning solution; (2) mixing the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution, adding carbonate, reacting at 65-85 ℃ for 20-40 h, cooling, centrifuging, and taking supernatant to obtain amidoxime-based polyacrylonitrile spinning solution; (3) and (3) performing electrostatic spinning on the amino polyacrylonitrile spinning solution obtained in the step (1) and the amidoxime group polyacrylonitrile spinning solution obtained in the step (2) by using a double-nozzle electrostatic spinning machine, and drying to obtain the amino and amidoxime group polyacrylonitrile nanofibers. The amino and amidoxime polyacrylonitrile nano-fiber prepared by the preparation method can be used for extracting uranium from seawater, and has large adsorption capacity to uranium.)

1. The preparation method of the amino and amidoxime polyacrylonitrile nanofiber is characterized by comprising the following steps of:

(1) mixing the polyacrylonitrile solution I and a polyamine solution containing more than two ethylene groups, and reacting for 1.5-5 h at 100-120 ℃ to obtain an amino polyacrylonitrile spinning solution;

(2) mixing the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution, adding carbonate, reacting at 65-85 ℃ for 20-40 h, cooling, centrifuging, and taking supernatant to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) and (3) performing electrostatic spinning on the amino polyacrylonitrile spinning solution obtained in the step (1) and the amidoxime group polyacrylonitrile spinning solution obtained in the step (2) by using a double-nozzle electrostatic spinning machine, and then drying to obtain the amino and amidoxime group polyacrylonitrile nano-fibers.

2. The method of claim 1, wherein:

in the polyacrylonitrile solution I, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of polyacrylonitrile is 15-22 wt%;

in the polyamine solution containing more than two ethylene groups, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of the polyamine containing more than two ethylene groups is 35-55 wt%.

3. The method according to claim 2, wherein the polyamine containing two or more ethylene groups is one or more selected from the group consisting of diethylenetriamine, triethylenetetramine and tetraethylenepentamine.

4. The process according to claim 3, wherein the polyamine containing two or more ethylene groups is triethylenetetramine or tetraethylenepentamine.

5. The preparation method according to claim 2, wherein in the step (1), the mass ratio of polyacrylonitrile in the polyacrylonitrile solution I to polyamine containing two or more ethylene groups is 1: 1.5-5.

6. The method of claim 1, wherein:

in the polyacrylonitrile solution II, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of polyacrylonitrile is 12-17 wt%;

in the hydroxylamine hydrochloride solution, the solvent is dimethyl sulfoxide or dimethyl formamide, and the mass percentage concentration of the hydroxylamine hydrochloride is 7-11 wt%.

7. The preparation method according to claim 6, wherein in the step (2), the mass ratio of polyacrylonitrile to hydroxylamine hydrochloride in the polyacrylonitrile solution II is 1.5-3: 1; the carbonate is alkali metal carbonate, and the molar ratio of the carbonate to the hydroxylamine hydrochloride is 1: 1.8-2.3.

8. The preparation method according to any one of claims 1 to 7, characterized in that in the step (3), the amino polyacrylonitrile spinning solution and the amidoxime polyacrylonitrile spinning solution are respectively added into a spraying device with the inner diameter of a spray orifice of a double-nozzle electrostatic spinning machine being 0.6-0.72 mm, electrostatic spinning is carried out at 40-50 ℃, and then vacuum drying is carried out at 50-60 ℃ to obtain amino and amidoxime polyacrylonitrile nanofibers;

wherein, the electrostatic spinning process conditions further comprise: the anode voltage is 10-14 KV, the cathode voltage is 2-3 KV, the distance between the spray hole and the receiving roller is 15-18 cm, the rotating speed of the roller is 100-110 r/min, and the sample introduction speed is 0.3-1.1 mL/h.

9. Amino and amidoxime polyacrylonitrile nanofibers prepared by the preparation method of any one of claims 1 to 8, having a diameter of 240 to 390 nm.

10. Use of amine-based and amidoxime-based polyacrylonitrile nanofibres in uranium extraction from sea water according to claim 9, wherein the adsorption capacity of the amine-based and amidoxime-based polyacrylonitrile nanofibres to uranium is greater than 25 mg/g.

Technical Field

The invention relates to amino and amidoxime group polyacrylonitrile nano-fibers and a preparation method and application thereof.

Background

Natural uranium is both a raw material for nuclear weapons nuclear charge and a nuclear power fuel. The uranium ore resource has low uranium grade, small deposit scale, complex rock mineral components, and the leaching and recovery technology difficulty and cost of uranium are more and more increased along with the continuous development of resources. The contradiction between supply and demand of natural uranium in China is prominent year by year, and the gap part still needs to be guaranteed by overseas development and international market purchase. In the long run, the search and exploitation of unconventional uranium resources would be a necessary choice.

The seawater in the unconventional uranium resources is one of important resources with application prospects, but the concentration of uranium in the seawater is low, and proper materials must be selected to effectively extract the uranium resources in the seawater. Currently, amidoxime adsorbing materials are recognized as adsorbing materials with better performance. CN111118884A discloses an amidoximated polyacrylonitrile fiber prepared by grafting hydroxylamine hydrochloride on a polyacrylonitrile fiber; CN105080509A discloses that a polyacrylonitrile fiber membrane is prepared by applying electrostatic spinning, and then amidoximation is carried out on the fiber to prepare amidoximated polyacrylonitrile fiber. The fiber materials prepared by the above patents still have the following defects: because polyacrylonitrile fibre fluffy degree is high, and functional reaction efficiency is lower relatively, and polyacrylonitrile fibre's functional reaction homogeneity is relatively poor simultaneously, leads to less to the adsorption capacity of sea water uranium, and it is lower to carry uranium efficiency.

Disclosure of Invention

The invention aims to provide a preparation method of amino and amidoxime polyacrylonitrile nanofibers. The amino and amidoxime group polyacrylonitrile nano-fiber prepared by the preparation method can be used for extracting uranium from seawater, has large adsorption capacity to the seawater uranium, improves uranium extraction efficiency, or can be used for removing uranium from wastewater. The invention also aims to provide the amidogen-amidoxime-based polyacrylonitrile nanofiber. Still another object of the present invention is to provide a use of the amino and amidoxime group polyacrylonitrile nanofibers. The purpose of the invention is realized by the following technical scheme.

The invention provides a preparation method of amino and amidoxime polyacrylonitrile nano-fibers, which comprises the following steps:

(1) mixing a polyacrylonitrile solution I and a polyamine solution containing more than two ethylene groups, and reacting at 100-120 ℃ for 1.5-5 h to obtain an amino polyacrylonitrile spinning solution;

(2) mixing the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution, adding carbonate, reacting at 65-85 ℃ for 20-40 h, cooling, centrifuging, and taking the upper layer liquid to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) and (3) performing electrostatic spinning on the amino polyacrylonitrile spinning solution obtained in the step (1) and the amidoxime group polyacrylonitrile spinning solution obtained in the step (2) by using a double-nozzle electrostatic spinning machine, and then performing vacuum drying to obtain the amino and amidoxime group polyacrylonitrile nano-fibers.

The preparation method of the invention takes polyacrylonitrile as a raw material, designs a material functional group into a bifunctional form, carries out two kinds of functional modification on the polyacrylonitrile, and respectively prepares spinning solutions to improve the production efficiency and the reaction uniformity of the functional modification of the polyacrylonitrile.

According to one embodiment of the present invention, the polyacrylonitrile solution I is prepared by the steps including: adding the dried polyacrylonitrile powder into dimethyl sulfoxide, and stirring for 1-3 h at 50-70 ℃ to obtain a polyacrylonitrile solution I. The number average molecular weight of polyacrylonitrile can be 30000-85000; preferably 50000-85000.

The polyamine solution containing more than two ethylene groups is prepared by the following steps: adding polyamine containing more than two ethylene groups into dimethyl sulfoxide, and stirring for 1-2 h to prepare a polyamine solution containing more than two ethylene groups.

In the step (1), the reaction temperature of the polyacrylonitrile solution I and the polyamine solution containing more than two ethylene groups can be 100-120 ℃, preferably, the reaction temperature is 110-120 ℃; the reaction time can be 1.5-5 h, preferably 2-4 h. Thus being beneficial to amination of polyacrylonitrile and obtaining proper polyacrylonitrile spinning solution.

In the step (2), the reaction temperature of the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution can be 65-85 ℃, and preferably 70-80 ℃; the reaction time can be 20-40 h, preferably 24-36 h.

In the present invention, cooling to room temperature is possible. The rotating speed during centrifugation can be 10000-15000 r/min, and the centrifugation time can be 30 min.

According to the preparation method of the amidogen and amidoxime polyacrylonitrile nano-fiber, preferably:

in the polyacrylonitrile solution I, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of polyacrylonitrile is 15-22 wt%;

in the polyamine solution containing more than two ethylene groups, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of the polyamine containing more than two ethylene groups is 35-55 wt%.

In the polyacrylonitrile solution I of the present invention, the solvent used is dimethyl sulfoxide or dimethylformamide, preferably dimethyl sulfoxide. The mass concentration of polyacrylonitrile can be 15-22 wt%, preferably 16-21 wt%. The number average molecular weight of polyacrylonitrile can be 30000-85000; preferably 50000-85000.

In the polyamine solution containing two or more ethylene groups of the present invention, the solvent used is dimethyl sulfoxide or dimethylformamide, and dimethyl sulfoxide is preferred. The mass concentration of the polyamine containing two or more ethylene groups may be 35 to 55 wt%, preferably 40 to 55 wt%. Thus being beneficial to obtaining proper amino polyacrylonitrile spinning solution and further being beneficial to extracting uranium from seawater.

According to the preparation method of the amidoxime-based polyacrylonitrile nanofiber, preferably, the polyamine containing more than two ethylene groups is selected from one or more of diethylenetriamine, triethylene tetramine and tetraethylene pentamine.

In certain embodiments, the polyamine containing two or more ethylene groups is triethylene tetramine. In other embodiments, the polyamine containing two or more ethylene groups is tetraethylenepentamine.

According to the preparation method of the amino and amidoxime polyacrylonitrile nanofibers, preferably, the polyamine containing more than two ethylene groups is triethylene tetramine or tetraethylene pentamine.

According to the preparation method of the amino-and amidoxime-based polyacrylonitrile nanofiber, preferably, in the step (1), the mass ratio of polyacrylonitrile in the polyacrylonitrile solution I to polyamine containing more than two ethylene groups is 1: 1.5-5, and preferably 1: 2.5-4. Therefore, the method is favorable for obtaining proper amino polyacrylonitrile, and is favorable for improving the uranium extraction efficiency of the seawater.

According to the preparation method of the amidogen and amidoxime polyacrylonitrile nano-fiber, preferably:

in the polyacrylonitrile solution II, the used solvent is dimethyl sulfoxide or dimethyl formamide, and the mass concentration of polyacrylonitrile is 12-17 wt%;

in the hydroxylamine hydrochloride solution, the solvent is dimethyl sulfoxide or dimethyl formamide, and the mass percentage concentration of the hydroxylamine hydrochloride is 7-11 wt%.

In the polyacrylonitrile solution II, the solvent used is dimethyl sulfoxide or dimethylformamide, preferably dimethyl sulfoxide. The mass concentration of polyacrylonitrile can be 12-17 wt%, and is preferably 13-16 wt%.

In the hydroxylamine hydrochloride solution, the solvent used is dimethyl sulfoxide or dimethylformamide, and dimethyl sulfoxide is preferred. The mass percentage concentration of the hydroxylamine hydrochloride can be 7-11 wt%, and is preferably 8-12 wt%.

According to the preparation method of the amino and amidoxime group polyacrylonitrile nanofiber, preferably, in the step (2), the mass ratio of polyacrylonitrile to hydroxylamine hydrochloride in the polyacrylonitrile solution II is 1.5-3: 1, preferably 1.7-2.2: 1;

in the step (2), the carbonate is an alkali metal carbonate, and the molar ratio of the carbonate to the hydroxylamine hydrochloride is 1: 1.8-2.3, preferably 1: 1.9-2.2.

According to one embodiment of the invention, the carbonate is sodium carbonate.

According to the preparation method of amino and amidoxime group polyacrylonitrile nanofibers, preferably, in the step (3), the amino polyacrylonitrile spinning solution and amidoxime group polyacrylonitrile spinning solution are respectively added into a spraying device with the inner diameter of a spray orifice of a double-nozzle electrostatic spinning machine being 0.6-0.72 mm, electrostatic spinning is carried out at 40-50 ℃, and then vacuum drying is carried out at 50-60 ℃ to obtain amino and amidoxime group polyacrylonitrile fibers; wherein, the electrostatic spinning process conditions further comprise: the anode voltage is 10-14 KV, the cathode voltage is 2-3 KV, the distance between the spray hole and the receiving roller is 15-18 cm, the rotating speed of the roller is 100-110 r/min, and the sample introduction speed is 0.3-1.1 mL/h. According to one embodiment of the invention, the injection device is an injector.

In the invention, the feeding speed of the amino polyacrylonitrile spinning solution is preferably 0.3-0.6 mL/h, and more preferably 0.3-0.5 mL/h. The sample injection speed of the amidoxime polyacrylonitrile spinning solution is preferably 0.6-1.1 mL/h, and more preferably 0.9-1.1 mL/h.

The invention also provides amino and amidoxime polyacrylonitrile nano-fibers which are prepared by the preparation method, and the diameter of the amino and amidoxime polyacrylonitrile nano-fibers is 240-390 nm, preferably 250-320 nm.

The invention also provides the application of the amino and amidoxime polyacrylonitrile nano-fiber in extracting uranium from seawater, wherein the adsorption capacity of the amino and amidoxime polyacrylonitrile nano-fiber to uranium is greater than 25mg/g, preferably greater than or equal to 25.9mg/g, and more preferably greater than or equal to 29.5 mg/g. The adsorption capacity is based on the weight of the dry material of the amidoxime-based polyacrylonitrile nanofiber.

The preparation method provided by the invention is characterized in that polyacrylonitrile is used as a raw material, two kinds of functional modification are carried out on the polyacrylonitrile to respectively obtain amino polyacrylonitrile fiber spinning solution and amidoxime group polyacrylonitrile fiber spinning solution, and electrostatic spinning is carried out by adopting a double-nozzle electrostatic spinning method, so that the prepared amino group and amidoxime group polyacrylonitrile nano-fibers have large adsorption capacity on seawater uranium, and the uranium extraction efficiency is improved. In addition, the preparation method is simple to operate and is beneficial to industrial production.

Drawings

FIG. 1 is an electron microscope scanning image of the amino and amidoxime polyacrylonitrile nanofibers obtained in example 1.

Detailed Description

The present invention will be further described with reference to the following specific examples, but the scope of the present invention is not limited thereto.

In the following examples and comparative examples, some of the raw materials used were as follows:

polyacrylonitrile: purchased from Suzhou Huihuang fluoroplasticity Co Ltd, and the number average molecular weight is 50000;

diethylenetriamine, triethylene tetramine and tetraethylenepentamine are all purchased from national medicine group chemical reagent limited, and the specification is 500 mL;

and (3) hydroxylamine hydrochloride: purchased from Shanghai Michelin Biochemical technology, Inc., and having a specification of 500 g.

Example 1

(1) Adding 4.0 parts by weight of dried polyacrylonitrile powder into 21.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 3 hours to prepare a polyacrylonitrile solution I; adding 16.0 parts by weight of triethylene tetramine into 21.0 parts by weight of dimethyl sulfoxide, and stirring for 1 hour to prepare a triethylene tetramine solution; mixing the polyacrylonitrile solution I and the triethylene tetramine solution, and stirring and reacting for 4 hours at 110 ℃ to obtain amino polyacrylonitrile spinning solution;

(2) adding 4.0 parts by weight of polyacrylonitrile powder into 23.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 3 hours to prepare a polyacrylonitrile solution II; adding 2.0 parts by weight of hydroxylamine hydrochloride into 23.0 parts by weight of dimethyl sulfoxide, and stirring at 70 ℃ for 2 hours to prepare a hydroxylamine hydrochloride solution; mixing the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution, adding 1.5 parts by weight of sodium carbonate, stirring and reacting at 70 ℃ for 36 hours, cooling to room temperature, and centrifuging at the rotating speed of 13000r/min to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) spinning fibers by adopting a double-nozzle electrostatic spinning machine, respectively adding amino polyacrylonitrile spinning solution and amidoxime polyacrylonitrile spinning solution into injectors with the inner diameters of 0.6mm and 0.72mm of spray holes of the double-nozzle electrostatic spinning machine, fixing the injectors on the spinning machine, performing electrostatic spinning at 40 ℃, and setting electrostatic spinning parameters: the anode voltage is 14KV, the cathode voltage is 2KV, the distance between a spray hole and a receiving roller is 15cm, the rotating speed of the roller is 110r/min, the sample injection speed of the amino polyacrylonitrile spinning solution is 0.3mL/h, the sample injection speed of the amidoxime polyacrylonitrile spinning solution is 1.1mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at the temperature of 60 ℃ to obtain the amino and amidoxime polyacrylonitrile nanofibers.

Example 2

(1) Adding 4.0 parts by weight of dried polyacrylonitrile powder into 15.0 parts by weight of dimethylformamide, and stirring at 70 ℃ for 1 hour to prepare a polyacrylonitrile solution I; adding 10.0 parts by weight of tetraethylenepentamine into 15.0 parts by weight of dimethyl sulfoxide, and stirring for 2 hours to prepare a tetraethylenepentamine solution; mixing the polyacrylonitrile solution I and the tetraethylenepentamine solution, and stirring and reacting for 2 hours at 120 ℃ to obtain amino polyacrylonitrile spinning solution;

(2) adding 3.0 parts by weight of polyacrylonitrile powder into 20.0 parts by weight of dimethylformamide, and stirring at 50 ℃ for 2 hours to prepare a polyacrylonitrile solution II; adding 2.0 parts by weight of hydroxylamine hydrochloride into 20.0 parts by weight of dimethyl sulfoxide, and stirring at 75 ℃ for 1h to prepare a hydroxylamine hydrochloride solution; mixing the polyacrylonitrile solution II and hydroxylamine hydrochloride solution, adding 1.5 parts by weight of sodium carbonate, stirring and reacting at 80 ℃ for 36 hours, cooling to room temperature, and centrifuging at the rotating speed of 11000r/min to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) spinning fibers by adopting a double-nozzle electrostatic spinning machine, respectively adding amino polyacrylonitrile spinning solution and amidoxime polyacrylonitrile spinning solution into injectors with the inner diameters of 0.6mm and 0.72mm of spray holes of the double-nozzle electrostatic spinning machine, fixing the injectors on the spinning machine, performing electrostatic spinning at 45 ℃, and setting electrostatic spinning parameters: the anode voltage is 13KV, the cathode voltage is 3KV, the distance between a spray hole and a receiving roller is 16cm, the rotating speed of the roller is 106r/min, the sample injection speed of the amino polyacrylonitrile spinning solution is 0.3mL/h, the sample injection speed of the amidoxime polyacrylonitrile spinning solution is 0.8mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at 50 ℃ to obtain the amino and amidoxime polyacrylonitrile nanofibers.

Example 3

(1) Adding 4.5 parts by weight of dried polyacrylonitrile powder into 20.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 2 hours to prepare a polyacrylonitrile solution I; adding 17.0 parts by weight of triethylene tetramine into 20.0 parts by weight of dimethyl sulfoxide, and stirring for 2 hours to prepare a triethylene tetramine solution; mixing the polyacrylonitrile solution I and the triethylene tetramine solution, and stirring and reacting for 2 hours at 120 ℃ to obtain amino polyacrylonitrile spinning solution;

(2) adding 4.5 parts by weight of polyacrylonitrile powder into 23.5 parts by weight of dimethyl sulfoxide, and stirring at 70 ℃ for 1 hour to prepare a polyacrylonitrile solution II; adding 2.5 parts by weight of hydroxylamine hydrochloride into 23.5 parts by weight of dimethyl sulfoxide, and stirring at 80 ℃ for 1h to prepare a hydroxylamine hydrochloride solution; mixing the polyacrylonitrile solution II and hydroxylamine hydrochloride solution, adding 1.9 parts by weight of sodium carbonate, stirring and reacting at 70 ℃ for 30 hours, cooling to room temperature, and centrifuging at the rotating speed of 15000r/min to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) spinning fibers by adopting a double-nozzle electrostatic spinning machine, respectively adding an amino polyacrylonitrile spinning solution and an amidoxime polyacrylonitrile spinning solution into injectors with the inner diameters of 0.67mm and 0.72mm of spray holes of the double-nozzle electrostatic spinning machine, fixing the injectors on the spinning machine, performing electrostatic spinning at 45 ℃, and setting electrostatic spinning parameters: the anode voltage is 12KV, the cathode voltage is 2.5KV, the distance between a spray hole and a receiving roller is 17cm, the rotating speed of the roller is 105r/min, the sample injection speed of the amino polyacrylonitrile spinning solution is 0.5mL/h, the sample injection speed of the amidoxime polyacrylonitrile spinning solution is 1.0mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at 55 ℃ to obtain the amino and amidoxime polyacrylonitrile nanofibers.

Example 4

(1) Adding 4.5 parts by weight of dried polyacrylonitrile powder into 20.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 2 hours to prepare a polyacrylonitrile solution I; adding 17.0 parts by weight of diethylenetriamine into 20.0 parts by weight of dimethyl sulfoxide, and stirring for 2 hours to prepare a diethylenetriamine solution; mixing the polyacrylonitrile solution I and the diethylenetriamine solution, and stirring and reacting for 5 hours at 100 ℃ to obtain amino polyacrylonitrile spinning solution;

(2) adding 3.0 parts by weight of polyacrylonitrile powder into 18.0 parts by weight of dimethyl sulfoxide, and stirring at 60 ℃ for 2 hours to prepare a polyacrylonitrile solution II; adding 2.0 parts by weight of hydroxylamine hydrochloride into 18.0 parts by weight of dimethyl sulfoxide, and stirring at 70 ℃ for 2 hours to prepare a hydroxylamine hydrochloride solution; mixing the polyacrylonitrile solution II and hydroxylamine hydrochloride solution, adding 1.5 parts by weight of sodium carbonate, stirring and reacting at 75 ℃ for 30 hours, cooling to room temperature, and centrifuging at the rotating speed of 10000r/min to obtain amidoxime-based polyacrylonitrile spinning solution;

(3) spinning fibers by adopting a double-nozzle electrostatic spinning machine, respectively adding an amino polyacrylonitrile spinning solution and an amidoxime polyacrylonitrile spinning solution into injectors with the inner diameters of 0.6mm and 0.67mm of spray holes of the double-nozzle electrostatic spinning machine, fixing the injectors on the spinning machine, performing electrostatic spinning at 50 ℃, and setting electrostatic spinning parameters: the anode voltage is 10KV, the cathode voltage is 3KV, the distance between a spray hole and a receiving roller is 18cm, the rotating speed of the roller is 100r/min, the sample injection speed of the amino polyacrylonitrile spinning solution is 0.4mL/h, the sample injection speed of the amidoxime polyacrylonitrile spinning solution is 1.0mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at 50 ℃ to obtain the amino and amidoxime polyacrylonitrile nanofibers.

Comparative example 1

Adding 4.0 parts by weight of polyacrylonitrile powder into 23.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 3 hours to prepare a polyacrylonitrile solution II; adding 2.0 parts by weight of hydroxylamine hydrochloride into 23.0 parts by weight of dimethyl sulfoxide, and stirring at 70 ℃ for 2 hours to prepare a hydroxylamine hydrochloride solution; mixing the polyacrylonitrile solution II and the hydroxylamine hydrochloride solution, adding 1.5 parts by weight of sodium carbonate, stirring and reacting at 70 ℃ for 36 hours, cooling to room temperature, and centrifuging at the rotating speed of 13000r/min to obtain amidoxime-based polyacrylonitrile spinning solution;

carrying out electrostatic spinning on amidoxime-based polyacrylonitrile spinning solution at 40 ℃, and setting electrostatic spinning parameters: the anode voltage is 14KV, the cathode voltage is 2KV, the distance between a spray hole and a receiving roller is 15cm, the rotating speed of the roller is 110r/min, the sample injection speed of the amidoxime polyacrylonitrile spinning solution is 1.1mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at 60 ℃ to obtain the amidoxime polyacrylonitrile fiber.

Comparative example 2

Adding 4.0 parts by weight of dried polyacrylonitrile powder into 21.0 parts by weight of dimethyl sulfoxide, and stirring at 50 ℃ for 3 hours to prepare a polyacrylonitrile solution I; adding 16.0 parts by weight of triethylene tetramine into 21.0 parts by weight of dimethyl sulfoxide, and stirring for 1 hour to prepare a triethylene tetramine solution; mixing the polyacrylonitrile solution I and the triethylene tetramine solution, and stirring and reacting for 4 hours at 110 ℃ to obtain amino polyacrylonitrile spinning solution;

carrying out electrostatic spinning on the amino polyacrylonitrile spinning solution at 40 ℃, and setting electrostatic spinning parameters: the anode voltage is 14KV, the cathode voltage is 2KV, the distance between the spray hole and the receiving roller is 15cm, the rotating speed of the roller is 110r/min, the sample injection speed of the amino polyacrylonitrile spinning solution is 0.3mL/h, and after electrostatic spinning is finished, vacuum drying is carried out at 60 ℃ to obtain the amino polyacrylonitrile fiber.

The amino-and amidoxime-based polyacrylonitrile nanofibers obtained in example 1 were subjected to electron microscope scanning, and the results are shown in fig. 1. As shown in FIG. 1, the diameter range of the amino-group and amidoxime-group polyacrylonitrile nano-fiber is 240-390 nm, the fiber surface is smooth and flat, and no rough fracture phenomenon occurs.

The results of uranium adsorption tests performed on the products obtained in examples 1 to 4 and comparative examples 1 to 2 are shown in table 1 below. The analytical test method is as follows: firstly, preparing simulated seawater (supplementing uranyl tricarbonate in natural seawater until the uranium concentration in the solution is 0.3mg/L), wherein the pH value of the simulated seawater is 8.1, and then respectively carrying out simulated adsorption on the products of the examples and the comparative examples at an adsorption temperature of 25 ℃; the uranyl ion concentration was measured by HJ700-2014 (inductively coupled plasma mass spectrometry for measuring 65 elements in water).

TABLE 1

As can be seen from the comparison between the examples and the comparative examples, the amidogen and amidoxime polyacrylonitrile nano-fibers prepared by the preparation method have large adsorption capacity on seawater uranium.

The present invention is not limited to the above-described embodiments, and any variations, modifications, and substitutions which may occur to those skilled in the art may be made without departing from the spirit of the invention.