Bionic graphene induced down fiber / chitosan uranium adsorbent, method and application

Abstract

The invention discloses a bionic graphene induced down fiber / chitosan uranium adsorbent, and a method and application thereof, and belongs to the technical field of material science. The preparation method comprises the following steps: firstly, carrying out cyano grafting subsequent oximation modification on crushed down feather fibers, and then reacting with chitosan / graphene oxide under different conditions to prepare the bionic graphene induced down feather fiber / chitosan uranium adsorbent. Graphene oxide with excellent photo-thermal conversion capacity is introduced into a system in a doping mode, so that the photo-thermal conversion capacity and adsorption capacity of the material are improved, and the uranium adsorbent with more excellent adsorption performance is prepared. The advantages of the porous structure and the rigid specific surface area of aerogel are combined, the preparation route is simple, the complexity of the system in design and processing is reduced, and an effective way is expected to be provided for solving the contradiction between the high adsorption performance and the excellent photo-thermal conversion capacity of the uranium adsorption material.

Description

Technical Field

[0001] The present invention belongs to the technical field of materials science, and particularly relates to a bionic graphene-induced down fiber / chitosan uranium adsorbent, a method and an application thereof. Background Art

[0002] With the continuous growth of global energy demand and the increasing awareness of environmental protection, nuclear energy, as a clean and efficient form of energy, has attracted much attention for its development prospects. However, the sustainable development of nuclear energy largely depends on the continuous and stable supply of uranium resources. Uranium is a radioactive nuclide with chemical toxicity and radiation effects. The harm caused by uranium to human health and the environment is receiving increasing attention. However, the known onshore uranium resource reserves globally are only 7.6 million tons, far from meeting the demand for nuclear energy development. The ocean contains approximately 4.5 billion tons of uranium, which is a huge source of this metal. Efficient extraction of uranium from seawater is considered the most feasible method to solve the shortage of uranium resources. Therefore, the technology for extracting uranium from solutions, especially seawater, is very important.

[0003] To extract uranium from seawater, researchers have developed various adsorption materials and technologies. Among them, down fiber, as a natural biomass material, has been widely used in the preparation of adsorption materials due to its rich surface functional groups and easy modification. Through chemical modification, such as grafting cyano and oximation, excellent adsorption ligand amidoxime groups can be introduced into down fiber, thereby improving its adsorption performance. In addition, graphene, as a new two-dimensional material, has also been introduced into adsorption materials due to its excellent photothermal conversion efficiency and mechanical properties, in order to achieve photothermal synergistic adsorption.

[0004] Although certain progress has been made in the prior art, there are still some problems. On the one hand, the marine environment is complex and changeable, and the adsorption performance of traditional adsorption materials in the marine environment is often poor, making it difficult to meet the demand for efficient uranium extraction. On the other hand, the existing methods for extracting uranium from seawater have high costs and complex preparation processes, which limit their large-scale application. Therefore, it is of great significance to develop a seawater uranium extraction method with low cost, high efficiency, and suitable for the marine environment. Summary of the Invention

[0005] In order to overcome the above-mentioned drawbacks of the prior art, the purpose of the present invention is to provide a bionic graphene-induced down fiber / chitosan uranium adsorbent, a method and an application thereof, so as to solve the technical problem that the existing uranium adsorbents have poor adsorption performance in the complex marine environment.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention discloses a preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Put the crushed and pretreated down fiber into a sodium carbonate solution, soak it in acrylonitrile, and heat and stir to graft cyano groups onto the down fiber; then add hydroxylamine hydrochloride and sodium hydroxide for cyano-oximation reaction, followed by washing with water and drying to obtain amidoximated down fiber. Subsequently, add a chitosan solution, a graphene oxide solution, and a glutaraldehyde solution in sequence, stir, age, and freeze-dry to obtain a biomimetic graphene-induced down fiber / chitosan uranium adsorbent material.

[0007] Preferably, the mass ratio of down fiber, sodium carbonate solution, acrylonitrile, hydroxylamine hydrochloride, sodium hydroxide, chitosan solution, graphene oxide solution, and glutaraldehyde solution is (1 - 2) g : (30 - 40) ml : (1.5 - 2.5) g : (7 - 9) g : (4 - 5) g : (0.2 - 0.4) g : (3 - 5) ml : (0.5 - 1) ml.

[0008] Preferably, the molar ratio of acrylonitrile to hydroxyl groups in the down fiber is (1.2 - 1.5) : 1.

[0009] Preferably, the temperature for heating and stirring is 35 - 40 °C; the time for heating and stirring is 3 - 4 h; the stirring rate is 80 - 100 r / min.

[0010] Preferably, the temperature for the cyano-oximation reaction is 70 - 75 °C, and the time is 4 - 5 h.

[0011] Preferably, the chitosan solution is prepared by dissolving chitosan powder in an acetic acid solution; the concentration of the chitosan solution is 2% - 2.5%.

[0012] Preferably, when washing with water, methanol is used as the cleaning liquid; the drying temperature is 40 - 60 °C; the time is 12 - 24 h.

[0013] Preferably, pre-freezing is carried out before freeze-drying, the temperature for freeze-drying is -50 - -60 °C; the vacuum degree is 1 - 1.3 Pa; the time is 24 - 36 h.

[0014] The present invention also discloses a biomimetic graphene-induced down fiber / chitosan uranium adsorbent, which is prepared by using the preparation method of the above-mentioned biomimetic graphene-induced down fiber / chitosan uranium adsorbent.

[0015] The present invention also discloses the application of the biomimetic graphene-induced down fiber / chitosan uranium adsorbent prepared by the preparation method of the above-mentioned biomimetic graphene-induced down fiber / chitosan uranium adsorbent in uranium extraction from seawater.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The invention discloses a preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, which comprises the following steps: firstly, pre-treating and crushing the down fiber to enlarge its specific surface area, then adding acrylonitrile to the aqueous solution under the condition that a sodium carbonate solution is used as a solvent, and appropriately increasing the temperature. Hydroxylamine hydrochloride and sodium hydroxide are used as oximation agents of cyano groups to realize cyano oximation, the purpose of which is to graft an adsorption ligand with high adsorption performance for uranium, and then the oximed down fiber, chitosan and graphene oxide are used to prepare a bionic bird's nest uranium adsorbent (GAM) precursor, which is then freeze-dried after pre-freezing to obtain a uranium adsorbent with better adsorption performance and photothermal conversion performance. Combined with the advantages that the surface of the down fiber has multiple functional groups such as amino groups and the fiber itself is light and easy to modify, the preparation route of the invention is simple, the complexity of the system in design and processing is reduced, and it is expected to provide an effective way to solve the contradiction between the uranium adsorption performance and excellent photothermal conversion of the down fiber material. The down fiber grafted with cyanide and oximated disclosed in the present invention is an effective method for introducing an excellent adsorption ligand amidoxime group into the fiber. The synthesis method is simple. The pulverized down fiber grafted and modified with cyanide can become an adsorbent with high adsorption capacity. Due to the introduction of graphene oxide, the material has excellent photothermal conversion efficiency, can utilize natural sunlight resources to efficiently promote uranium extraction from seawater, and the biomass materials in the raw materials have the characteristics of low price and environmental friendliness, which is very suitable for solving the current situation of difficult uranium mining. The present invention modifies the pulverized down fiber by oximation, and composites it with chitosan and graphene oxide to obtain a uranium adsorbent with excellent photothermal conversion efficiency and good adsorption capacity. The unique properties of graphene oxide and down fiber are used to make it have a special bionic structure, which is conducive to better allowing uranyl ions to be adsorbed through photothermal synergistic adsorption, and achieving excellent adsorption performance and good photothermal conversion performance of the uranium adsorbent.

[0017] The invention also discloses a bionic graphene-induced down fiber / chitosan uranium adsorbent prepared by the preparation method. The bird's nest structure contained in the structure has good mechanical properties and structural stability, and can better resist the impact of waves in seawater.

[0018] The present invention also discloses the use of the bionic graphene-induced down fiber / chitosan uranium adsorbent prepared by the preparation method in extracting uranium from seawater. The bionic graphene-induced down fiber / chitosan uranium adsorbent has high adsorption capacity and good selectivity when extracting uranium from real seawater, and can realize high-efficiency uranium extraction from seawater. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The synthetic route of the bionic graphene-induced down fiber / chitosan uranium adsorbent disclosed in Example 1 of the present invention; Figure 2Infrared absorption diagram of the bionic graphene-induced down fiber / chitosan uranium adsorbent disclosed in Example 1 of the present invention; Figure 3 EDS elemental analysis of the bionic graphene-induced down fiber / chitosan uranium adsorbent after adsorption disclosed in Example 1 of the present invention. Detailed implementation manners

[0020] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0021] In the present invention, if there is no special description, all the implementation manners and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution.

[0022] In the present invention, if there is no special description, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution.

[0023] In the present invention, if there is no special description, the percentage (%) or part refers to the weight percentage or weight part relative to the composition.

[0024] In the present invention, if there is no special description, the various components or their preferred components involved can be combined with each other to form a new technical solution.

[0025] In the present invention, unless otherwise specified, the numerical range "a~b" represents the abbreviated representation of any real number combination between a and b, where a and b are both real numbers. For example, the numerical range "6~22" means that all real numbers between "6~22" have been fully listed herein, and "6~22" is only the abbreviated representation of these numerical combinations.

[0026] The "range" disclosed in the present invention can be in the form of one or more lower limits and one or more upper limits respectively.

[0027] In the present invention, the term "and / or" used herein refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0028] In the present invention, unless otherwise specified, each reaction or operation step can be carried out sequentially or in order. Preferably, the reaction methods herein are carried out sequentially.

[0029] Unless otherwise specified, the technical and scientific terms used herein have the same meanings as those familiar to persons skilled in the art. In addition, any methods or materials similar or equivalent to those described herein can also be applied to the present invention.

[0030] A preparation method of a bionic graphene-induced down fiber / chitosan-based uranium adsorbent includes the following steps: 1) Put the crushed and pretreated down fiber into a sodium carbonate solution to expose its surface functional groups, add an appropriate amount of acrylonitrile to make it in a wetting state, and heat and stir simultaneously to graft cyano groups onto the down fiber; 2) Add hydroxylamine hydrochloride and sodium hydroxide to the fiber modified with acrylonitrile above for cyano-oximation. After the reaction, amidoximated down fiber is obtained. Wash and dry the modified feather fiber in sequence; 3) Dissolve an appropriate amount of chitosan powder in an acetic acid solution to obtain a chitosan solution. Put the prepared amidoximated down fiber (0.4 g) into the above chitosan solution, add a graphene oxide solution, then add a glutaraldehyde solution, stir and age, and then freeze-dry to obtain a bionic graphene-induced down fiber / chitosan-based uranium adsorbent.

[0031] In step 1), the sodium carbonate solution serves as the reaction solvent, and the ratio of the crushed fiber to the sodium carbonate solution is between 1:30 and 1:40.

[0032] In step 1), the dosage of acrylonitrile is calculated based on the hydroxyl group content on the surface of the crushed fiber; the molar ratio of hydroxyl groups to acrylonitrile in the down fiber is 1:(1.2 - 1.5).

[0033] In step 1), the contact time between acrylonitrile and the crushed down fiber is 3 - 4 h, the reaction temperature is 35 - 40 °C; the stirring rate is 80 - 100 r / min.

[0034] In step 2), cyano-oximation is to carry out oximation on the down fiber modified with cyano groups with a liquid prepared from hydroxylamine hydrochloride and sodium hydroxide. The reaction temperature is 70 - 75 °C, and the reaction time is 4 - 5 h; the fiber modified by oximation is washed with methanol and then placed in a drying oven to stand and dry for 12 - 24 h; the drying conditions are: forced-air drying; temperature 40 - 60 °C; time 12 - 24 h.

[0035] In step 3), chitosan needs to be dissolved in an acetic acid solution with a certain concentration. The dissolution conditions are: using the acetic acid solution as the solvent, dissolving chitosan with a 2% acetic acid solution, and controlling the concentration of the chitosan solution at 2% - 2.5%.

[0036] In step 3), the graphene-induced down fiber / chitosan aerogel precursor solution is pre-frozen to a certain extent to prevent the sample from splashing during freeze-drying. The conditions for freeze-drying are as follows: the temperature is -50~-60°C; the vacuum degree is 1~1.3 Pa; the time is 24~36 h.

[0037] The mass ratio of down fiber, sodium carbonate solution, acrylonitrile, hydroxylamine hydrochloride, sodium hydroxide, chitosan solution, graphene oxide solution and glutaraldehyde solution is (1~2) g : (30~40) ml : (1.5~2.5) g : (7~9) g : (4~5) g : (0.2~0.4) g : (3~5) ml : (0.5~1) ml.

[0038] The present invention also discloses a bionic graphene-induced down fiber / chitosan uranium adsorbent prepared by the above preparation method, which is used for the adsorption of uranium in seawater by photo-thermal synergy, so that it has excellent adsorption performance and good selectivity. It solves the problems of low adsorption efficiency and slow adsorption rate of traditional adsorbents, and enables high extraction efficiency, high selectivity and good recycling performance by using sunlight.

[0039] The present invention also discloses the application of the bionic graphene-induced down fiber / chitosan uranium adsorbent prepared by the above preparation method in uranium extraction from seawater. After modification, the crushed down fiber becomes an efficient adsorbent. Due to the introduction of graphene oxide, it has excellent photo-thermal conversion efficiency and can efficiently promote uranium extraction from seawater by using natural sunlight resources. The structure has a special bionic bird's nest structure, which is conducive to the photo-thermal synergistic adsorption of uranyl ions, realizing excellent adsorption performance and good photo-thermal conversion performance; the structure endows the adsorbent with good mechanical properties and structural stability, and can better resist the impact of sea waves in seawater.

[0040] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Usually, the components described and shown in the accompanying drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0041] In the examples, DF is down fiber; DF-AN is down fiber grafted with cyano groups; DF-AO is amidoximated down fiber; GAC is aerogel without graphene oxide added; GAM is aerogel with graphene oxide added; GO is graphene oxide; CS is chitosan.

[0042] Example 1 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps, and the synthesis route is as Figure 1 shown, Step 1: Grafting of cyano groups onto pulverized down fiber Graft cyanide groups onto down fiber to prepare cyano-modified down fiber. Clean and treat DF with a degreasing agent to remove impurities and grease on the surface of DF. Then, take 1 g of clean DF, add 30 ml of 10% Na2CO3 solution (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.) solution (W / W = 10%) into a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to hydroxyl groups in down fiber is 1.2:1. Then add 1.5 g of acrylonitrile, react at a stirring rate of 80 r / min at 35 °C for 3 h, and extract unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 40 °C for 12 h to constant weight to obtain DF-AN.

[0043] Step 2: Amidoximation of DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain amidoximated down fiber (DF-AO). Add 1 g of DF-AN, 7 g of NH2OH·HCl and 4 g of NaOH into 100 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 70 °C for 4 h, wash 3 times with methanol solution after the reaction, and finally dry in a blast drying oven at 40 °C for 12 h to constant weight to obtain amidoximated down fiber (DF-AO).

[0044] Step 3: Preparation of graphene-induced down fiber / chitosan aerogel (GAM) Dissolve 0.2 g of chitosan powder in 20 mL of 2% acetic acid solution to obtain a 2% chitosan solution. Put 0.2 g of the prepared DF-AO into 20 ml of chitosan solution, add 3 ml of 10 mg / L graphene oxide solution, add 0.5 ml of glutaraldehyde solution, stir and then age. Then carry out freeze-drying at -50 °C and 1 Pa for 24 h to obtain a bionic graphene-induced down fiber / chitosan uranium adsorbent.

[0045] Figure 1This is a synthetic route map of the bionic graphene-induced down fiber / chitosan uranium adsorbent disclosed in Example 1 of the present invention; it can be seen from the figure that the oxime groups on the down fiber interact with the groups in chitosan, and at the same time, there is a hydrogen bond interaction between graphene and chitosan.

[0046] Figure 2 This is the infrared absorption diagram of the bionic graphene-induced down fiber / chitosan uranium adsorbent disclosed in Example 1 of the present invention; it can be seen from the figure that the infrared absorption diagrams of DF, DF-AN, DF-AO, GAC, and GAM in Example 1; the successful synthesis of GAM aerogel was verified by FT-IR spectrum. In the FT-IR spectrum of DF-AN, at 2259 cm -1 A new stretching vibration peak appeared at 949 cm-1, which was attributed to -C≡N, indicating that DF-AN was successfully prepared. In the FT-IR spectrum of DF-AO, the stretching vibration peak of -C≡N disappeared, while the stretching vibration peak of NO in amidoxime appeared at 949 cm-1. -1 , proving that -C≡N in DF-AN was converted into amidoxime after modification. -1 and 1065 cm -1 In the GAC, the stretching vibration peaks of COC and CO belonging to the chitosan structure can be seen. At the same time, from the FT-IR spectrum of GAM, it can be seen that GO and CS have the same characteristics, and the stretching vibration of C=O and the deformation vibration of NH move to higher wavenumbers, which may be due to the GO-COO - and CS-NH3 + electrostatic interaction between them.

[0047] Figure 3 This is the EDS element analysis of the bionic graphene-induced down fiber / chitosan uranium adsorbent disclosed in Example 1 of the present invention after adsorption; as can be seen from the figure, through EDS energy spectrum scanning analysis, it can be seen that compared with the original aerogel, uranium elements appear in the aerogel after modified adsorption, which can prove that the adsorbent prepared this time can successfully adsorb uranium, and can also prove that the adsorbent is successfully prepared. This result shows that GAM aerogel has a good uranium adsorption capacity.

[0048] Example 2 A method for preparing a bionic graphene-induced down fiber / chitosan uranium adsorbent comprises the following steps: Step 1: Cyanide grafting of crushed down fibers Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.1 g of clean DF, add 31 ml of 10% Na2CO3 solution to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF and protonate them under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1:1. Then add 1.6 g of acrylonitrile, react at a stirring rate of 81 r / min at 36 °C for 3.5 h, and extract the unreacted acrylonitrile with ethanol. Finally, wash with ethanol and dry in a blast dryer at 42 °C for 13 h to constant weight to obtain DF-AN.

[0049] Step 2: Oximation of DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain DF-AO. Add 1.1 g of DF-AN, 7.2 g of NH2OH·HCl, and 4.1 g of NaOH successively to 105 ml of methanol-aqueous solution (1:7 vol / vol), react at 71 °C for 4.1 h, wash 4 times with methanol solution after the reaction, and finally dry in a blast dryer at 42 °C for 13 h to constant weight to obtain DF-AO.

[0050] Step 3: Preparation of GAM aerogel Dissolve 0.25 g of chitosan powder in 20 mL of 2.1% acetic acid solution to obtain a chitosan solution with a concentration of 2%. Put 0.22 g of the above-prepared DF-AO into 20 ml of chitosan solution, add 3.2 mL of 10 mg / L graphene oxide solution, add 0.5 mL of glutaraldehyde solution, stir and then age. Then, at -51 °C, 1 Pa, freeze-dry for 25 h.

[0051] Example 3 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.2 g of clean DF, add 32 ml of 10% Na2CO3 solution to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF and protonate them under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.3:1. Then add 1.7 g of acrylonitrile, react at a stirring rate of 82 r / min at 37 °C for 3 h, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 44 °C for 14 h to constant weight to obtain DF-AN.

[0052] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 1.2 g of DF-AN, 7.4 g of NH₂OH·HCl, and 4.2 g of NaOH to 110 ml of a methanol-aqueous solution (1:7 vol / vol) in sequence, react at 72 °C for 4.2 h, wash 5 times with a methanol solution after the reaction, and finally dry at 44 °C for 14 h to constant weight to obtain DF-AO.

[0053] Step 3: Preparation of GAM aerogel Dissolve 0.2 g of chitosan powder in 21 mL of 2.2% acetic acid solution to obtain a chitosan solution with a concentration of 2.1%. Put the prepared DF-AO (0.24 g) into 21 ml of the chitosan solution, add 3.4 mL of 10 mg / L graphene oxide solution, add 0.6 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -52 °C and 1.1 Pa for 26 h.

[0054] Example 4 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Grafting cyanide groups onto crushed down fibers Graft cyanide groups onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.3 g of clean DF, add 33 mL of 10% Na₂CO₃ to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1:1. Then add 1.8 g of acrylonitrile, react at 38 °C for 4 h at a stirring rate of 83 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 46 °C for 15 h to constant weight to obtain DF-AN.

[0055] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 1.3 g of DF-AN, 7.6 g of NH₂OH·HCl, and 4.3 g of NaOH to 115 ml of a methanol-aqueous solution (1:7 vol / vol) in sequence, react at 73 °C for 4.3 h, wash 3 times with a methanol solution after the reaction, and finally dry at 46 °C for 15 h to constant weight to obtain DF-AO.

[0056] Step 3: Preparation of GAM aerogel Dissolve 0.25 g of chitosan powder in 21 mL of 2.3% acetic acid solution to obtain a chitosan solution with a concentration of 2.1%. Put the prepared DF-AO (0.26 g) into 21 ml of the chitosan solution, add 3.6 mL of 10 mg / L graphene oxide solution, and add 0.6 mL of glutaraldehyde solution. Stir and then age. Then freeze-dry at -53°C and 1.1 Pa for 27 h.

[0057] Example 5 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft cyanide groups onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.4 g of clean DF, add 34 ml of Na2CO3 to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in the down fiber is 1.2:1. Then add 1.9 g of acrylonitrile, react at 39°C for 3 h at a stirring rate of 84 r / min, and extract the unreacted acrylonitrile with ethanol. Finally, wash with ethanol and dry at 48°C for 16 h to constant weight to obtain DF-AN.

[0058] Step 2: Oxime DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain DF-AO. Add 1.4 g of DF-AN, 7.8 g of NH2OH·HCl, and 4.4 g of NaOH to 120 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 74°C for 4.4 h, wash 3 times with methanol solution after the reaction, and finally dry at 48°C for 16 h to constant weight to obtain DF-AO.

[0059] Step 3: Preparation of GAM aerogel Dissolve 0.3 g of chitosan powder in 22 mL of 2.4% acetic acid solution to obtain a chitosan solution with a concentration of 2.2%. Put the prepared DF-AO (0.28 g) into 22 ml of the chitosan solution, add 3.8 mL of 10 mg / L graphene oxide solution, and add 0.7 mL of glutaraldehyde solution. Stir and then age. Then freeze-dry at -54°C and 1.2 Pa for 28 h.

[0060] Example 6 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.5 g of clean DF, add 35 ml of Na2CO3 into a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF and protonate them under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.4:1. Then add 2 g of acrylonitrile, react at a stirring rate of 85 r / min at 37 °C for 3.5 h, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 50 °C for 17 h to constant weight to obtain DF-AN.

[0061] Step 2: Oximation of DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain DF-AO. Add 1.5 g of DF-AN, 8 g of NH2OH·HCl, and 4.5 g of NaOH into 125 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 75 °C for 4.5 h, wash 3 times with methanol solution after the reaction, and finally dry at 50 °C for 17 h to constant weight to obtain DF-AO.

[0062] Step 3: Preparation of GAM aerogel Dissolve 0.35 g of chitosan powder in 22 mL of 2.5% acetic acid solution to obtain a chitosan solution with a concentration of 2.2%. Put the above-prepared DF-AO (0.3 g) into 22 ml of chitosan solution, add 4 mL of 10 mg / L graphene oxide solution, add 0.7 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -55 °C and 1.2 Pa for 29 h.

[0063] Example 7 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto crushed down fiber Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.6 g of clean DF, add 36 ml of Na2CO3 into a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF and protonate them under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.2:1. Then add 2.1 g of acrylonitrile, react at a stirring rate of 90 r / min at 37 °C for 4 h, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 52 °C for 18 h to constant weight to obtain DF-AN.

[0064] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 1.6 g of DF-AN, 8.2 g of NH₂OH·HCl, and 4.6 g of NaOH to 130 ml of a methanol-aqueous solution (1:7 vol / vol) in sequence, react at 72 °C for 4.6 h, wash 3 times with a methanol solution after the reaction, and finally dry at 52 °C for 18 h to constant weight to obtain DF-AO.

[0065] Step 3: Preparation of GAM aerogel Dissolve 0.3 g of chitosan powder in 23 mL of 2.6% acetic acid solution to obtain a chitosan solution with a concentration of 2.3%. Put the prepared DF-AO (0.32 g) into 23 ml of the chitosan solution, add 4.2 mL of 10 mg / L graphene oxide solution, add 0.8 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -56 °C and 1.2 Pa for 30 h.

[0066] Example 8 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Grafting cyanide groups onto the crushed down fiber Graft cyanide groups onto DF to prepare DF-AN. Clean and treat DF with a degreasing agent to remove impurities and grease on the surface of DF. Then, take 1.7 g of clean DF, add 37 ml of Na₂CO₃ to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in the down fiber is 1.2:1. Then add 2.2 g of acrylonitrile, react at 37 °C for 3.5 h at a stirring rate of 92 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 54 °C for 19 h to constant weight to obtain DF-AN.

[0067] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 1.7 g of DF-AN, 8.4 g of NH₂OH·HCl, and 4.7 g of NaOH to 135 ml of a methanol-aqueous solution (1:7 vol / vol) in sequence, react at 73 °C for 4.7 h, wash 3 times with a methanol solution after the reaction, and finally dry at 54 °C for 19 h to constant weight to obtain DF-AO.

[0068] Step 3: Preparation of GAM aerogel Dissolve 0.35 g of chitosan powder in 23 mL of 2.7% acetic acid solution to obtain a chitosan solution with a concentration of 2.3%. Put the prepared DF-AO (0.34 g) into 23 ml of the chitosan solution, add 4.4 mL of 10 mg / L graphene oxide solution, and add 0.8 mL of glutaraldehyde solution. Stir and then age. Then freeze-dry at -57°C and 1.2 Pa for 31 h.

[0069] Example 9 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft cyanide groups onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.8 g of clean DF, add 38 ml of Na2CO3 to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in the down fiber is 1.5:1. Then add 2.3 g of acrylonitrile, react at 37°C for 4 h at a stirring rate of 94 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 56°C for 20 h to constant weight to obtain DF-AN.

[0070] Step 2: Oximation of DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain DF-AO. Add 1.8 g of DF-AN, 8.6 g of NH2OH·HCl, and 4.8 g of NaOH to 140 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 74°C for 4.8 h, wash 3 times with methanol solution after the reaction, and finally dry at 56°C for 20 h to constant weight to obtain DF-AO.

[0071] Step 3: Preparation of GAM aerogel Dissolve 0.4 g of chitosan powder in 24 mL of 2.8% acetic acid solution to obtain a chitosan solution with a concentration of 2.4%. Put the prepared DF-AO (0.36 g) into 24 ml of the chitosan solution, add 4.6 mL of 10 mg / L graphene oxide solution, and add 0.9 mL of glutaraldehyde solution. Stir and then age. Then freeze-dry at -58°C and 1.3 Pa for 32 h.

[0072] Example 10 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 1.9 g of clean DF, add 39 mL of 10% Na2CO3 solution to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.5:1. Then add 2.4 g of acrylonitrile, react at 40 °C for 4 h at a stirring rate of 96 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 58 °C for 21 h to constant weight to obtain DF-AN.

[0073] Step 2: Oximation of DF-AN React the prepared DF-AN with NH2OH⋅HCl to obtain DF-AO. Add 1.9 g of DF-AN, 8.8 g of NH2OH·HCl, and 4.9 g of NaOH to 100 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 75 °C for 4 h, wash 3 times with methanol solution after the reaction, and finally dry at 58 °C for 21 h to constant weight to obtain DF-AO.

[0074] Step 3: Preparation of GAM aerogel Dissolve 0.2 g of chitosan powder in 24 mL of 2.9% acetic acid solution to obtain a chitosan solution with a concentration of 2.4%. Put 0.38 g of the above-prepared DF-AO into 24 ml of chitosan solution, add 4.8 mL of 10 mg / L graphene oxide solution, add 0.9 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -59 °C and 1.3 Pa for 33 h.

[0075] Example 11 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Graft cyanide groups onto the crushed down fiber Graft the cyanide group onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 2 g of clean DF, add 40 ml of Na2CO3 to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.2:1. Then add 2.5 g of acrylonitrile, react at 35 °C for 4 h at a stirring rate of 98 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 60 °C for 22 h to constant weight to obtain DF-AN.

[0076] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 2 g of DF-AN, 9 g of NH₂OH·HCl, and 5 g of NaOH to 120 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 70 °C for 4.5 h, wash with methanol solution 3 times after the reaction, and finally dry at 60 °C for 22 h to constant weight to obtain DF-AO.

[0077] Step 3: Preparation of GAM aerogel Dissolve 0.3 g of chitosan powder in 25 mL of 3% acetic acid solution to obtain a chitosan solution with a concentration of 2.5%. Put 0.4 g of the prepared DF-AO into 25 ml of the chitosan solution, add 5 mL of 10 mg / L graphene oxide solution, add 1 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -60 °C and 1.3 Pa for 35 h.

[0078] Example 12 A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, comprising the following steps: Step 1: Grafting cyanide groups onto the crushed down fiber Graft cyanide groups onto DF to prepare DF-AN. Clean and treat DF with a degreaser to remove impurities and grease on the surface of DF. Then, take 2 g of clean DF, add 40 ml of Na₂CO₃ to a 250 mL flask, soak at room temperature for 30 min to expose the active hydroxyl groups in DF, and protonate under alkaline conditions. The molar ratio of acrylonitrile to the hydroxyl groups in down fiber is 1.5:1. Then add 2.5 g of acrylonitrile, react at 35 °C for 3 h at a stirring rate of 100 r / min, and extract the unreacted acrylonitrile with ethanol (≥99%, Tianjin Tianli Chemical Reagent Co., Ltd.). Finally, wash with ethanol and dry at 60 °C for 24 h to constant weight to obtain DF-AN.

[0079] Step 2: Oximation of DF-AN React the prepared DF-AN with NH₂OH⋅HCl to obtain DF-AO. Add 2 g of DF-AN, 9 g of NH₂OH·HCl, and 5 g of NaOH to 140 ml of methanol-aqueous solution (1:7 vol / vol) in sequence, react at 75 °C for 5 h, wash with methanol solution 3 times after the reaction, and finally dry at 50 °C for 24 h to constant weight to obtain DF-AO.

[0080] Step 3: Preparation of GAM aerogel Dissolve 0.4 g of chitosan powder in 25 mL of 2.5% acetic acid solution to obtain a chitosan solution with a concentration of 2.5%. Put 0.2 g of DF-AO prepared above into the above 25 ml of chitosan solution, add 3 mL of 10 mg / L graphene oxide solution, add 1 mL of glutaraldehyde solution, stir and then age. Then freeze-dry at -50 °C and 1.3 Pa for 36 h.

[0081] In summary, in the present invention, the pulverized down fiber is first subjected to cyano grafting and subsequent oximation modification, and then reacted with chitosan / graphene oxide under different conditions to prepare a uranium adsorbent of bionic graphene-induced down fiber / chitosan. Graphene oxide with excellent photothermal conversion ability is introduced into the system by doping to improve the photothermal conversion ability and adsorption capacity of the material, and a uranium adsorbent with more excellent adsorption performance is prepared. Combining the advantages of the aerogel porous structure and the rigid specific surface area, the preparation route of the present invention is simple, reducing the complexity of the system in design and processing. The uranium adsorbent prepared by the method of the present invention has high adsorption performance, and the preparation method is simple and easy to implement, suitable for large-scale production, and is expected to provide an effective way to solve the contradiction between the high adsorption performance of uranium adsorption materials and the excellent photothermal conversion ability.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A preparation method of a bionic graphene-induced down fiber / chitosan uranium adsorbent, characterized in that, It includes the following steps: Put the crushed and pretreated down fiber into a sodium carbonate solution, soak it in acrylonitrile, and heat and stir to graft cyano groups onto the down fiber; then add hydroxylamine hydrochloride and sodium hydroxide for cyano-oximation reaction, followed by washing with water and drying to obtain amidoximated down fiber. Subsequently, add a chitosan solution, a graphene oxide solution, and a glutaraldehyde solution in sequence, stir, age, and freeze-dry to obtain a bionic graphene-induced down fiber / chitosan uranium adsorbent.

2. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, The mass ratio of the down fiber, sodium carbonate solution, acrylonitrile, hydroxylamine hydrochloride, sodium hydroxide, chitosan solution, graphene oxide solution, and glutaraldehyde solution is (1~2) g : (30~40) ml : (1.5~2.5) g : (7~9) g : (4~5) g : (0.2~0.4) g : (3~5) ml : (0.5~1) ml.

3. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, The molar ratio of acrylonitrile to the hydroxyl groups in the down fiber is (1.2~1.5) :

1.

4. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, The temperature of the heating and stirring is 35~40 °C; the time of the heating and stirring is 3~4 h; the stirring rate is 80~100 r / min.

5. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, The temperature of the cyano-oximation reaction is 70~75 °C, and the time is 4~5 h.

6. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, The chitosan solution is prepared by dissolving chitosan powder in an acetic acid solution; the concentration of the chitosan solution is 2%~2.5%.

7. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, wherein When washing with water, methanol is used as the cleaning liquid; the temperature of the drying is 40~60 °C; the time is 12~24 h.

8. The preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to claim 1, characterized in that, Pre-freezing is carried out before freeze-drying, the temperature of the freeze-drying is -50~-60 °C; the vacuum degree is 1~1.3 Pa; the time is 24~36 h.

9. A bionic graphene-induced down fiber / chitosan uranium adsorbent, characterized in that, It is prepared by using the preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to any one of claims 1~8.

10. Application of the bionic graphene-induced down fiber / chitosan uranium adsorbent prepared by the preparation method of the bionic graphene-induced down fiber / chitosan uranium adsorbent according to any one of claims 1~8 in uranium extraction from seawater.

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