A carbon-based adsorbent with high adsorption performance for uranium, a preparation method and application thereof

Abstract

The application relates to a carbon-based adsorbent with high adsorption performance for uranium and a preparation method and application thereof, and relates to the field of uranium adsorption materials. The carbon-based adsorbent with high adsorption performance for uranium is prepared by the following method: a dispersant PBI is synthesized, nano-carbon material is added into the dispersant PBI for ultrasonic treatment, a nano-carbon dispersion liquid is added into an alkali solution, and after stirring, centrifugal separation and washing, PBI functionalized nano-carbon is obtained; acrylonitrile and triethylamine are added into a water dispersion liquid of the PBI functionalized nano-carbon to carry out a cyanoethylation reaction to obtain a cyanoethylation product; hydroxylamine hydrochloride and triethylamine are added into an ethanol dispersion liquid of the obtained cyanoethylation product to carry out an amine oxime reaction, and the carbon-based adsorbent with high adsorption performance for uranium is obtained. The material exhibits excellent adsorption performance for uranyl ions, and the saturated adsorption capacity for uranium can reach 489 mg.g ‑1 The method has the advantages of simple operation, low cost, mild reaction condition and wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of adsorption materials, in particular to a carbon-based adsorbent with high adsorption performance for uranium and a preparation method and application thereof. BACKGROUND

[0002] Uranium has important applications and status in the fields of energy, military and nuclear science. For a long time, uranium is the most important nuclear energy fuel used by human beings, which can greatly reduce the dependence on traditional fossil energy and reduce carbon dioxide emissions, providing sustainable and efficient energy for human beings.

[0003] From the reserves, the land uranium resources are limited, while the uranium reserves in seawater are abundant. The total reserves are about 4.5 billion tons, which is more than 1000 times the content of land uranium ore. Therefore, it is of great significance to efficiently extract uranium from seawater. However, due to the very low concentration of uranium in seawater, general separation methods such as precipitation, membrane separation, solvent extraction, electrochemical purification, ion exchange and the like are difficult to meet the requirements. In contrast, the adsorption method is suitable for the enrichment of low-concentration ions and has the advantages of economy, simplicity and high efficiency, and has the most application potential in seawater uranium extraction.

[0004] The adsorption performance of the adsorbent is the key to seawater uranium extraction. The concentration of uranium in seawater is low, and there are many competitive ions competing for adsorption sites, so it is necessary to design an adsorbent with high adsorption selectivity and high adsorption capacity for uranyl ions. Uranium usually exists in the form of positive tetravalent or hexavalent complex, and the lone pair electrons of the O atom and N atom of the amidoamine functional group can form a stable coordination bond with the uranyl ion, which can specifically and efficiently capture and fix uranium, and the adsorption efficiency of uranyl ion is very high. However, the adsorption effect of the material containing such functional groups at present is far from the expected, the main reason is that the active functional groups are not exposed enough, and the effective utilization rate of the material is low.

[0005] In view of the above problems, the present application combines amidoamine functional groups with nanocarbon materials to prepare a new type of adsorbent, which utilizes the large specific surface area and stability of graphene, carbon nanotubes, carbon aerogel, carbon black and other nanocarbon materials to improve the adsorption capacity and long-term durability of the composite material for uranyl ions. A perylene imide dispersant containing multiple amino groups is used as a medium, and then acrylonitrile and hydroxylamine hydrochloride are added in turn, and finally the amidoamine group is introduced onto the surface of the carbon material to improve the uranium adsorption rate. The present application provides a new idea for developing new uranium adsorption materials. SUMMARY

[0006] The present application aims at the problems of complicated preparation process and low adsorption capacity of existing materials for adsorbing uranium, and develops a simple and efficient carbon-based adsorbent material. First, the perylene imide dispersant is used to realize the uniform dispersion of nano-carbon materials such as graphene, so that the specific surface area of the carbon material is fully utilized. Then, the multiple amino groups on the molecule are used as reaction sites, and the addition of acrylonitrile and the reduction of hydroxylamine are used to obtain the amidoxime group. The present application effectively combines the high specific surface area of nano-carbon materials and the amidoxime functional group, so that the active groups of the adsorbent are fully exposed, thereby obtaining an amidoxime functionalized carbon-based adsorbent composite material with high adsorption capacity, and realizing efficient adsorption of uranium.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a carbon-based adsorbent with high efficient adsorption performance for uranium, the preparation method comprising the following steps:

[0008] Step one: synthesize a perylene imide dispersant PBI containing multiple amino groups, add the nano-carbon material into the dispersant PBI, and obtain a uniform dispersion liquid by ultrasonic treatment;

[0009] Step two: add the nano-carbon dispersion liquid obtained in step one into an alkaline solution with a certain concentration, fully stir to deprotonate, and then centrifuge and wash to obtain PBI functionalized nano-carbon;

[0010] Step three: add acrylonitrile and a catalyst triethylamine into the water dispersion liquid of the PBI functionalized nano-carbon obtained in step two to perform a cyanoethylation reaction, centrifuge and wash the product after the reaction is completed, and obtain a cyanoethylation product;

[0011] Step four: add hydroxylamine hydrochloride and triethylamine into the ethanol dispersion liquid of the cyanoethylation product obtained in step three to perform an amidoxime reaction, centrifuge and wash the product after the reaction is completed, and dry to obtain a carbon-based adsorbent with high efficient adsorption performance for uranium.

[0012] The above-mentioned carbon-based adsorbent with high efficient adsorption performance for uranium, in step one, the dispersant PBI is obtained by the reaction of perylene anhydride and polyamine, and the polyamine can be ethylenediamine, diethylenetriamine, triethylenetetramine, polyethylenepolyamine or polyethylenimine.

[0013] The above-mentioned carbon-based adsorbent with high efficient adsorption performance for uranium, in step one, the nano-carbon material is one or more of graphene, carbon nanotube, carbon black, graphite, biomass carbon and carbon aerogel.

[0014] The above-mentioned carbon-based adsorbent with high efficient adsorption performance for uranium, in step one, the mass ratio of PBI to nano-carbon material is 1:2 to 2:1.

[0015] The carbon-based adsorbent with high adsorption performance for uranium in the above has the following steps: the alkali solution in step two is sodium hydroxide solution or potassium hydroxide solution, and the concentration is 1-5 wt.%.

[0016] The carbon-based adsorbent with high adsorption performance for uranium in the above has the following steps: in step three, the molar ratio of acrylonitrile to PBI is 10:1-40:1, the reaction temperature of cyanoethylation is 75-85 DEG C, and the reaction time is 20-36 h.

[0017] The carbon-based adsorbent with high adsorption performance for uranium in the above has the following steps: in step four, the molar ratio of hydroxylamine hydrochloride to PBI is 20:1-40:1, the reaction temperature of amidoxime is 65-75 DEG C, and the reaction time is 18-24 h.

[0018] The carbon-based adsorbent with high adsorption performance for uranium in the above has the following steps: in step four, the molar ratio of hydroxylamine hydrochloride to triethylamine is 0.5:1-1.5:1.

[0019] The carbon-based adsorbent with high adsorption performance for uranium in the above has the following steps: in step four, the drying method is freeze drying.

[0020] The application of the carbon-based adsorbent with high adsorption performance for uranium in the above to adsorption and recovery of uranium in water.

[0021] The beneficial effects of the application are as follows:

[0022] The adsorbent prepared by the application effectively combines the large specific surface area of the nanocarbon material with the amidoxime functional group, greatly improving the adsorption capacity of the composite material for uranyl ions. The use of the perylene imide dispersant can make the carbon material combine with the carbon material through π-π interaction and be uniformly adsorbed on the surface of the graphene nanocarbon material, so that the carbon material is uniformly dispersed in the liquid phase. The amino group in the perylene imide molecule can be used as a reaction site and finally converted into an amidoxime group with specific adsorption capacity for uranyl ions. The use of the dispersant makes the amidoxime uniformly distributed on the surface of the carbon material, providing sufficient adsorption sites for the composite material. In addition, the preparation method described in the application has the advantages of low raw material cost, simple operation and mild preparation conditions. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 The FT-IR spectra of GR-PBI-CN and GR-PBI-AO are shown in the following figure;

[0024] Figure 2 The adsorption effect of the adsorbent sample synthesized in Example 2 under different pH conditions is shown in the following figure;

[0025] Figure 3In the figure, A is the adsorption isotherm of the adsorbent sample synthesized in Example 1; B is the adsorption isotherm of the adsorbent sample synthesized in Example 2; C is the adsorption isotherm of the adsorbent sample synthesized in Example 3; D is the adsorption isotherm of the adsorbent sample synthesized in Example 4;

[0026] Figure 4 The kinetic curve of the adsorption of uranium by the adsorbent sample synthesized in Example 2 in uranium solutions with different concentrations; DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the present application, the technical solutions of the present application will be described more fully below with reference to specific embodiments. The described embodiments are only a part of the embodiments of the present application, and the present application can be implemented in other different forms. The following embodiments do not limit the present application in any way.

[0028] Example 1

[0029] A preparation method of a carbon-based adsorbent with high adsorption performance for uranium, the steps are as follows:

[0030] 1) Synthesis of polyamino perylene imide dispersant PBI. Take 5 mmol 3,4,9,10-pyrene tetracarboxylic dianhydride in 40 mL toluene reagent, add 50 mmol triethylenetetramine to it, ultrasonic for a period of time, then reflux at 120℃ for 24h to obtain the crude product. The obtained crude product is added to a 1wt. % potassium hydroxide solution and stirred for 6h to remove unreacted anhydride, then the solid product is dissolved in an appropriate amount of formic acid, the product is precipitated with isopropyl alcohol, and the dispersant PBI solution is obtained by dissolving in water.

[0031] 2) Preparation of non-covalently modified graphene PBI composite intermediate. Add PBI solution to 100mg graphene powder to make the solid content of PBI 50mg. Add water to make the mass ratio of graphene, PBI and water 1:0.5:1500, and ultrasonic for 30min to obtain a graphene aqueous dispersion. The obtained graphene dispersion is added to a 1wt. % potassium hydroxide solution, and deprotonated by stirring, then centrifuged and washed to obtain PBI functionalized graphene.

[0032] 3) Cyanoethylation reaction. Add 1g acrylonitrile and 1mL triethylamine to the aqueous dispersion obtained in step 2), and react at 80℃ for 20h. After cooling to room temperature, the product is centrifuged and washed to obtain the cyanoethylation product GR-PBI-CN. Figure 1 In the figure, the upper line is the infrared spectrum of the product, and the absorption peak at 2242cm -1 indicates the presence of cyano group in the molecule, which proves the successful synthesis of the product GR-PBI-CN.

[0033] 4) Amine oximation reaction. 0.7 g of hydroxylamine hydrochloride and 1 g of triethylamine were added to the ethanol dispersion of the product obtained in step 3) to carry out the oximation reaction. After reacting at 70 °C for 18 h, the mixture was cooled to room temperature. The product was centrifuged, washed, and freeze-dried to obtain the graphene-based composite material GR-PBI-AO, which has high adsorption capacity for uranium. Figure 1 The lower line is its infrared spectrum, 2242 cm⁻¹. -1 The disappearance of the cyano peak and the 3448 cm⁻¹ -1 hydroxyl peak and 1652cm -1 The appearance of the C=N absorption peak proves the successful synthesis of the target adsorbent GR-PBI-AO.

[0034] Example 2

[0035] The preparation method is the same as described in Example 1, except that:

[0036] In step 2), the solid content of the dispersant PBI added is 100 mg, and the rest of the operation and dosage are exactly the same as in Example 1.

[0037] Example 3

[0038] The preparation method is the same as described in Example 1, except that:

[0039] In step 2), the solid content of the dispersant PBI added is 150 mg, and the rest of the operation and dosage are exactly the same as in Example 1.

[0040] Example 4

[0041] The preparation method is the same as described in Example 1, except that:

[0042] In step 2), the solid content of the dispersant PBI added is 200 mg, and the rest of the operation and dosage are exactly the same as in Example 1.

[0043] Example 5

[0044] Weigh 5.0 mg of the adsorbent material prepared in Example 2 into a vial, and add 10 mL of a 50 mg·L⁻¹ solution. -1 U(VI) solutions with pH values ​​of 3.0, 4.0, 5.0, 6.0, and 7.0 were prepared, shaken, and placed in a constant temperature shaking incubator. Adsorption was carried out at 303 K for 24 hours, followed by filtration. The uranium ion concentration before and after adsorption was determined using inductively coupled plasma mass spectrometry (ICP-MS). The concentration was calculated using the formula A% = [(C0 - C...]. e The adsorption capacity of the above material is calculated by multiplying C0 by 100%. Where: C0 (mg·L⁻¹) -1 ) represents the initial concentration of uranyl ions; C e (mg·L-1 The concentration of uranyl ions in the solution at equilibrium is shown below. Figure 2 As shown, the adsorbent exhibits the highest adsorption rate for uranium at pH 6, reaching 95.4%.

[0045] Example 6

[0046] Weigh 5.0 mg of the adsorbent material prepared in Examples 1, 2, 3, and 4 into a vial, and add 10 mL of 20 mg·L⁻¹ to each vial. -1 50 mg·L -1 100 mg·L -1 150 mg·L -1 200 mg·L -1 300mg·L -1 350 mg·L -1 and 400 mg·L -1 A uranium solution with a pH of 6.0 was prepared, shaken well, and placed in a constant temperature shaking incubator. Adsorption was carried out at 303 K for 24 hours. After filtration, the uranium ion concentration before and after adsorption was determined using inductively coupled plasma mass spectrometry (ICP-MS). The concentration was calculated using the formula q. e =(C0-C e The adsorption capacity of the above material is calculated using C0 / m. Where: C0 (mg·L-m) -1 ) represents the initial concentration of uranyl ions; V(L) represents the solution volume; C e (mg·L -1 ) represents the concentration of uranyl ions in the solution at equilibrium; q e Let m(g) represent the adsorption capacity, and m(g) represent the adsorbent mass. A dotted-line plot was generated, and the results were analyzed using three different isothermal adsorption models: Langmuir, Freundlich, and Temkin. The results are shown below. Figure 3 As shown. The material in Example 3 exhibits higher adsorption performance, with a saturated adsorption capacity reaching 489 mg·g⁻¹. -1 ( Figure 3 (C). The saturated adsorption capacities of Examples 1, 2, and 4 were 400 mg·g⁻¹, respectively. -1 ( Figure 3 (A), 436 mg·g -1 ( Figure 3 (B) and 437 mg·g -1 ( Figure 3 (D).

[0047] Example 7

[0048] Weigh 5.0 mg of the adsorbent material prepared in Example 3 into a vial, and add 10 mL of a 50 mg·L⁻¹ solution. -1 100 mg·L -1 150 mg·L-1 U(VI) solution with pH 6.0, oscillation adsorption for 5 min, 10 min, 20 min, 30 min, 1 h, 2 h, 4 h, 6 h, 8 h, 12 h, 24 h at 303 K, filtration to collect the adsorption solution, determination of uranium ion concentration before and after adsorption by inductively coupled plasma mass spectrometer (ICP-MS), calculation of the adsorption capacity of the above material by the formula q e =(C0-C e )V / m. In the formula, C0(mg·L -1 ) is the initial concentration of uranyl ion; V(L) is the volume of solution; C e (mg·L -1 ) is the concentration of uranyl ion in the solution when reaching equilibrium; q e is the adsorption capacity, m(g) is the mass of adsorbent. The results are shown in Table 1. Figure 4 With the increase of adsorption time, the adsorption capacity of the adsorbent is first rapidly increased in a short time, then slowly increased, and then reaches equilibrium at 12 h.

[0049] The raw materials and equipment used in the present application are commonly used in the art, unless otherwise specified.

[0050] The above examples only express several embodiments of the present application, and the description is more specific and detailed, but it cannot be understood as the limitation of the scope of the patent. Any modification, deformation and equivalent transformation of the above examples without departing from the concept of the present application still belong to the protection scope of the technical scheme of the present application.

Claims

1. A carbon-based adsorbent with high adsorption capacity for uranium, characterized in that, The preparation method includes the following steps: Step 1: Synthesize a perylene imide (PBI) dispersant solution containing multiple amino groups, add the PBI solution to the carbon nanomaterial, and sonicate to obtain a uniform dispersion; the carbon nanomaterial is one or more of graphene, carbon nanotubes, carbon black, graphite, biomass carbon, and carbon aerogel. Step 2: Add the nano-carbon dispersion obtained in Step 1 to an alkaline solution of a certain concentration, stir thoroughly to deprotonate, centrifuge and wash to obtain PBI-functionalized nano-carbon; Step 3: Add acrylonitrile and triethylamine catalyst to the aqueous dispersion of PBI-functionalized carbon nanotubes obtained in Step 2 to carry out cyanoethylation reaction. After the reaction is complete, centrifuge and wash the product to obtain the cyanoethylated product. Step 4: Add hydroxylamine hydrochloride and triethylamine to the ethanol dispersion of the cyanoethylated product obtained in Step 3 to carry out the oxime reaction. After the reaction is complete, centrifuge, wash and dry the product to obtain a carbon-based adsorbent with high adsorption performance for uranium.

2. The carbon-based adsorbent with high uranium adsorption performance according to claim 1, characterized in that, In step one, the dispersant PBI is obtained by reacting perylene anhydride with a polyamine, which is ethylenediamine, diethylenetriamine, triethylenetetramine, or polyethyleneimine.

3. The carbon-based adsorbent with high uranium adsorption performance according to claim 1, characterized in that, In step one, the ratio of PBI to nano-carbon materials by mass is 1:2 to 2:

1.

4. The carbon-based adsorbent with high uranium adsorption performance according to claim 1, characterized in that, In step two, the alkaline solution is a sodium hydroxide solution or a potassium hydroxide solution with a concentration of 1~5 wt.%.

5. A carbon-based adsorbent with high uranium adsorption performance according to claim 1, characterized in that, In step three, the molar ratio of acrylonitrile to PBI is 10:1 to 40:1, the reaction temperature of the cyanoethylation reaction is 75 to 85°C, and the reaction time is 20 to 36 hours.

6. The carbon-based adsorbent with high adsorption performance for uranium according to claim 1, characterized in that, In step four, the molar ratio of hydroxylamine hydrochloride to PBI is 20:1 to 40:1, the reaction temperature of the oxime reaction is 65 to 75°C, and the reaction time is 18 to 24 hours.

7. The carbon-based adsorbent with high adsorption capacity for uranium according to claim 1, characterized in that, In step four, the molar ratio of hydroxylamine hydrochloride to triethylamine is 0.5:1 to 1.5:

1.

8. A carbon-based adsorbent with high uranium adsorption performance according to claim 1, characterized in that, In step four, the drying method is freeze drying.

9. The application of the carbon-based adsorbent with high uranium adsorption performance as described in any one of claims 1 to 8 for the adsorption and recovery of uranium in water.

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