Rhenium ion engraved chitosan adsorption material based on organic covalent crosslinking grafting as well as preparation method and application of rhenium ion engraved chitosan adsorption material

Abstract

The invention belongs to the field of effective extraction of scattered metals and preparation of green adsorbents, and particularly relates to a rhenium ion imprinted chitosan adsorption material based on organic covalent crosslinking grafting and a preparation method and application thereof. The preparation method of the organic covalent cross-linked grafted nitrogen-rich rhenium ion imprinted chitosan adsorption material provided by the invention comprises the following steps: sequentially carrying out cross-linking, methyl acrylate grafting chain extension and nitrogen-rich branched chain reagent grafting chain extension on a chitosan molding material; and carrying out ReO4-imprinting and fixing an imprinting space by using a second organic covalent cross-linking agent. The method is simple in preparation condition and mild in condition. The prepared organic covalent cross-linked grafted nitrogen-rich rhenium ion imprinted chitosan adsorption material shows good stability in an acid solution and shows outstanding selective capture performance on ReO4 <-> in an acid leaching solution.

Description

Technical Field

[0001] This application belongs to the field of effective extraction of rare metals and preparation of green adsorbents. More specifically, it relates to a rhenium ion-imprinted chitosan adsorbent material based on organic covalent cross-linking grafting, its preparation method and application. Background Art

[0002] As a rare metal, rhenium has an extremely low content in the earth's crust. Due to its excellent physical and chemical properties, it is widely used in national defense, aerospace and emerging technology fields. The extraction of rhenium mainly comes from ores of primary resources and waste rhenium alloys and rhenium-platinum catalysts in secondary resources. Compared with the hydrometallurgy process, the pyrometallurgy process has high energy consumption, large dust pollution and large mineral losses, and has been gradually replaced by the all-wet process in recent years.

[0003] As a selective recovery reserve technology for rhenium in rhenium-containing leaching solution, the adsorption technology has great application prospects due to its high efficiency and simple operation. The core of the adsorption technology lies in the development of adsorbent materials with stable structure, high performance, renewable use, low price and environmental friendliness.

[0004] From the analysis of the source of rhenium-containing waste liquid and the water quality characteristics of the waste liquid, it can be seen that the composition of rhenium-containing wastewater is very complex, with extremely high acidity and accompanied by a large number of interfering ions. Rhenium mainly exists in the form of perrhenate (ReO4 - ) in the solution. Therefore, the key technical difficulty in the recovery of rhenium in aqueous solution at present lies in the efficient and selective recovery of rhenium. Summary of the Invention

[0005] Aiming at the defects of the prior art, the purpose of this application is to provide a rhenium ion-imprinted chitosan adsorbent material based on organic covalent cross-linking grafting, its preparation method and application, aiming to solve the technical problem that the chitosan adsorbent material in the prior art has poor adsorption performance, especially poor adsorption selectivity for perrhenate.

[0006] To achieve the above purpose, in the first aspect, this application provides a preparation method of a rhenium ion-imprinted chitosan adsorbent material based on organic covalent cross-linking grafting, including the following steps: (1) Mix the chitosan molding material with an aqueous solution of a first organic covalent cross-linking agent, so that the amino or hydroxyl group contained in the chitosan molding material reacts with the first organic covalent cross-linking agent to obtain a preliminarily cross-linked chitosan molding material, so as to improve the acid resistance stability of the chitosan molding material; (2) The preliminarily cross-linked chitosan molding material obtained in step (1) is successively mixed with an organic solvent of methyl acrylate and an organic solution of a nitrogen-rich branched chain reagent, and then an organic covalent grafting reaction occurs to extend the length of the amino branched chain on the chitosan molding material, and a nitrogen-rich branched chain functionalized chitosan molding material is obtained; (3) Mix the nitrogen-rich branched-chain functionalized chitosan molding material obtained in step (2) with an acidic aqueous solution containing ReO4 - so that ReO4 - is adsorbed by the chitosan molding material to obtain a nitrogen-rich branched-chain functionalized chitosan molding material loaded with ReO4 - ; (4) Mix the nitrogen-rich branched-chain functionalized chitosan molding material loaded with ReO4 - obtained in step (3) with an aqueous solution of a second organic covalent crosslinking agent to carry out a crosslinking reaction to fix the ReO4 - recognition-adsorption sites, and then immerse the adsorbed material after the crosslinking reaction in a desorbing solution of ReO4 - to remove ReO4 - ions on the ReO4 - recognition-adsorption sites, and prepare a rhenium ion imprinted chitosan adsorbent based on organic covalent crosslinking / grafting.

[0007] According to another aspect of the present invention, there is provided a rhenium ion imprinted chitosan adsorbent based on organic covalent crosslinking grafting prepared by the preparation method described above.

[0008] According to another aspect of the present invention, there is provided an application of the rhenium ion imprinted chitosan adsorbent based on organic covalent crosslinking grafting in selectively adsorbing ReO4 - in an acidic aqueous solution.

[0009] Generally speaking, compared with the prior art through the above technical solutions conceived by the present application, the following beneficial effects are obtained: (1) The preparation of the organic covalent crosslinking grafting nitrogen-rich rhenium ion imprinted chitosan adsorbent provided by the present invention is obtained by crosslinking a chitosan molding material with a first organic covalent crosslinking agent, grafting and chain extending with methyl acrylate, grafting and chain extending with a nitrogen-rich branched-chain reagent, ReO4 - imprinting, and fixing the imprinting space with a second organic covalent crosslinking agent. The preparation method has simple preparation conditions and mild conditions. The prepared organic covalent crosslinking grafting nitrogen-rich rhenium ion imprinted chitosan adsorbent shows good stability in acidic solutions and excellent selective capture performance for ReO4 - in acidic leachates.

[0010] (2) In the preferred embodiment of the present invention, the adsorption selectivity coefficient of the nitrogen-rich rhenium ion imprinted chitosan adsorbent for rhenate in a mixed acidic aqueous solution of rhenate and sulfate with a molar ratio of 1:1 is as high as 11.43. Description of the Drawings

[0011] Figure 1It is the synthesis route diagram of the adsorbent material in Example 1 of this application; Figure 2 It is the comparison diagram of the selectivity coefficients of the adsorbent materials prepared in Example 1 of this application and the comparative example; Figure 3 It is the comparison diagram of the selectivity coefficients of the adsorbent materials prepared in Examples 1 to 6 of this application. Detailed implementation manners

[0012] In order to make the objectives, technical solutions and advantages of this application more clear and understandable, the following further details this application in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not used to limit this application.

[0013] The embodiments of the present invention are implemented on the premise of the technical solutions of the present invention, and the detailed implementation manners and processes are given. However, the protection scope of the present invention is not limited to the following embodiments. For the process parameters without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions.

[0014] At the endpoints and any values within the ranges disclosed in the present invention, these ranges or values are not limited to the exact ranges or values. These ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values and individual point values of each range, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in the present invention.

[0015] For the process parameters without specific conditions noted in the following embodiments, they are usually in accordance with conventional conditions.

[0016] The wastewater containing perrhenate ions is usually acidic wastewater, and the sulfate ion concentration in it is high. When using an adsorbent material to adsorb perrhenate ions, the adsorption capacity is very high. However, due to the competitive effect of sulfate ions, the adsorption selectivity of rhenium is very poor. Aiming at the problem of poor adsorption performance, especially poor selectivity, of the existing adsorbent materials for ReO4 in the leaching solution - In view of the problem of poor adsorption performance, especially poor selectivity, of the existing adsorbent materials for ReO4 in the leaching solution, the present invention provides a chitosan adsorbent material with nitrogen-rich rhenium ion imprinting based on organic covalent cross-linking grafting, its preparation method and application. Taking the microsphere-shaped adsorbent material as an example, in some embodiments, the preparation of the chitosan adsorbent material with nitrogen-rich rhenium ion imprinting based on organic covalent cross-linking grafting is to prepare chitosan microspheres by dropping chitosan acetate gel into an alkaline ethanol solution through microfluidic cutting; then successively through epichlorohydrin cross-linking, nitrogen-rich branch grafting, ReO4 - Imprinting and glutaraldehyde fixing of the imprinting space are obtained. The preparation method has simple conditions and mild conditions. The prepared chitosan microspheres with nitrogen-rich rhenium ion imprinting based on organic covalent cross-linking grafting show good stability in acidic solutions and have good adsorption performance for ReO4 in acidic leaching solutions- Exhibits outstanding selective capture performance.

[0017] A preparation method of a rhenium ion imprinted chitosan adsorbent material based on organic covalent cross-linking grafting provided by the present invention includes the following steps: (1) Mix a chitosan molding material with an aqueous solution of a first organic covalent cross-linking agent, so that the amino or hydroxyl group contained in the chitosan molding material reacts with the first organic covalent cross-linking agent to obtain a preliminarily cross-linked chitosan molding material, so as to improve the acid resistance stability of the chitosan molding material; (2) Sequentially mix the preliminarily cross-linked chitosan molding material obtained in step (1) with an organic solvent of methyl acrylate and an organic solution of a nitrogen-rich branched chain reagent, and then carry out an organic covalent grafting reaction to extend the length of the amino branched chain on the chitosan molding material to obtain a nitrogen-rich branched chain functionalized chitosan molding material; (3) Mix the nitrogen-rich branched chain functionalized chitosan molding material obtained in step (2) with an acidic aqueous solution containing ReO4 - so that ReO4 - is adsorbed by the chitosan molding material to obtain a nitrogen-rich branched chain functionalized chitosan molding material loaded with ReO4 - ; (4) Mix the nitrogen-rich branched chain functionalized chitosan molding material loaded with ReO4 - obtained in step (3) with an aqueous solution of a second organic covalent cross-linking agent to carry out a cross-linking reaction to fix the "recognition-adsorption" site of ReO4 - , and then immerse the cross-linked adsorbent material in a desorbing solution of ReO4 - to remove ReO4 - ions on the "recognition-adsorption" site, and prepare a rhenium ion imprinted chitosan adsorbent material based on organic covalent cross-linking grafting. -

[0018] The shape and size of the chitosan molding material described in the present invention are not limited, and can be chitosan microspheres, chitosan fibers, chitosan aerogels or chitosan films, which can be adjusted according to actual application requirements.

[0019] In some embodiments, the chitosan molding material is chitosan microspheres with a diameter of 0.1-3 mm; in other embodiments, the chitosan molding material is chitosan fibers, which can be prepared by conventional preparation methods or purchased commercially.

[0020] The source or preparation method of the chitosan molding material of the present invention is not limited. It can be purchased on the market or prepared by oneself. When preparing, generally, chitosan powder is placed in an acetic acid solution and stirred overnight to obtain chitosan gel. In some embodiments, the mass percentage of chitosan in the chitosan gel is 1%-5%. Subsequently, the chitosan gel is dropped directly into an alkaline ethanol solution or extruded into an alkaline ethanol solution with a syringe to obtain chitosan microspheres or chitosan fibers; in order to obtain chitosan microspheres with a smaller diameter, the chitosan gel can also be dropped into an alkaline ethanol solution through microfluidic cutting technology to prepare chitosan microspheres.

[0021] In some embodiments, the chitosan molding material is chitosan microspheres, and the chitosan microspheres are prepared by microfluidic cutting technology. The mobile phase used in the preparation process is chitosan gel, and the dispersed phase (cutting phase) is a n-octanol solution of Span 80. The concentration (mass percentage) of Span 80 in the dispersed phase is 1%-5%. The pressure ratio of the mobile phase to the dispersed phase (cutting phase) is 500-2000 Mpa:50-2000 Mpa.

[0022] In some embodiments, during the preparation of chitosan microspheres by microfluidic cutting technology, the alkaline ethanol solution is a mixed solution of an aqueous solution of sodium hydroxide and ethanol. The concentration of the aqueous solution of sodium hydroxide is 0.5-1 mol / L, and the ethanol concentration (volume ratio) is 30-70%.

[0023] The main reaction occurring in step (1) is the cross-linking reaction of the amino or hydroxyl group contained in chitosan with the ring-opening of epichlorohydrin. After the cross-linking reaction, the acid resistance of the chitosan molding material is improved. In some embodiments, the first organic covalent cross-linking agent in step (1) is one or more of epichlorohydrin (ECH), glutaraldehyde (GA), and ethylene glycol diglycidyl ether (EGDE); among them, the concentration of the first organic covalent cross-linking agent is 0.01-1% (v / v) (low-concentration cross-linking), more preferably 0.05-0.5% (v / v), and this concentration range ensures moderate cross-linking of chitosan; the dosage ratio of the chitosan molding material to the aqueous solution of the first organic covalent cross-linking agent is 5 g:10-20 mL.

[0024] In step (2), the preliminarily cross-linked chitosan molding material is first chain-extended with methyl acrylate to extend the length of the amino side chains in the chitosan structure; then it is further cross-linked with a nitrogen-rich side chain reagent to further extend the length of the amino side chains, attempting to improve the selectivity of the adsorbent material for perrhenate in this way. In some embodiments, the organic solution of methyl acrylate in step (2) is an organic solution obtained by dissolving methyl acrylate in an organic solvent, and the organic solvent is one or more of ethanol or methanol; the volume percentage of methyl acrylate in the organic solution of methyl acrylate is 20-60% (v / v), and the dosage ratio of the chitosan molding material (wet weight) to the organic solution of methyl acrylate is 5 g: 20-50 mL; the nitrogen-rich side chain reagent in step (2) is one or more of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), tetraethylenepentamine (TEPA), 1,3-propanediamine (TMEDA), and 3,3'-diaminodipropylamine (IBPA); the organic solution of the nitrogen-rich side chain reagent is an organic solution obtained by dissolving the nitrogen-rich side chain reagent in an organic solvent, and the organic solvent is one or more of ethanol or methanol; the volume percentage of the nitrogen-rich side chain reagent in the organic solution of the nitrogen-rich side chain reagent is 20-60% (v / v), and the dosage ratio of the chitosan molding material (wet weight) to the organic solution of the nitrogen-rich side chain reagent is 5 g: 20-50 mL.

[0025] In some embodiments, the concentration of rhenium in the acidic aqueous solution containing ReO4 - in step (3) is 1-20 g / L; the pH is 1-5; the dosage ratio of the nitrogen-rich side chain-functionalized chitosan molding material to the acidic aqueous solution containing ReO4 - is 5 g: 10-20 mL.

[0026] The second organic covalent cross-linking agent in step (4) is one or more of epichlorohydrin (ECH), glutaraldehyde (GA), and ethylene glycol diglycidyl ether (EGDE); the dosage ratio of the nitrogen-rich side chain-functionalized chitosan molding material loaded with ReO4 - to the aqueous solution of the second organic covalent cross-linking agent is 5 g: 10-20 mL, and the volume concentration of the second organic covalent cross-linking agent in the aqueous solution of the second organic covalent cross-linking agent is 2%-10% (v / v).

[0027] In some embodiments, the desorbing solution of ReO4 - in step (4) is one or more of dilute hydrochloric acid and aqueous sodium chloride solution, and the concentration of the analytical solution (also called the eluent of ReO4 - is 0.5-2 mol / L.

[0028] The rhenium ion-printed chitosan adsorbent material based on organic covalent cross-linking grafting prepared by the preparation method of the present invention can be microspherical, fibrous, etc. according to different initial chitosan forming materials. This adsorbent material can be used for selectively adsorbing ReO4 in acidic aqueous solutions - .

[0029] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0030] Example 1 A preparation method of nitrogen-rich rhenium ion-printed chitosan microspheres with organic covalent cross-linking grafting, the synthesis route is as Figure 1 shown, and the method includes the following steps: (1) Stir and mix 2 g of chitosan powder with 98 mL of 2% (v / v) acetic acid aqueous solution to obtain chitosan gel; (2) Drop the chitosan gel microfluidic cutting device obtained in step (1) drop by drop into an aqueous solution of sodium hydroxide in ethanol to obtain chitosan microspheres (CBs). During the preparation process, the concentration of sodium hydroxide is 1 mol / L, and the concentration of ethanol is 50% (v / v); the used dispersed phase (cutting phase) (n-octanol solution of span 80), the concentration of span 80 is 2% (v / v); the pressure ratio of the mobile phase (chitosan gel) to the cutting phase (n-octanol solution of span 80) is 1500 Mpa: 300 Mpa.

[0031] (3) Add 5 g (wet weight) of the chitosan microspheres obtained in step (2) into 15 mL of ECH (epichlorohydrin 0.1% (v / v) solution, and carry out a cross-linking reaction at pH 11, 40 °C, and 160 rpm for 24 h to improve the physical and chemical stability of the chitosan microspheres. The prepared chitosan microspheres are ECH-cross-linked chitosan microspheres (ECBs).

[0032] (4) Add 5 g (wet weight) of the ECBs obtained in step (3) into 30 mL of 50% (v / v) methyl acrylate ethanol solution, and carry out a cross-linking reaction at 50 °C and 160 rpm for 24 h to obtain methyl acrylate-functionalized chitosan microspheres (MECBs).

[0033] (5) Add 5 g (wet weight) of the MECBs obtained in step (4) into 30 mL of 50% (v / v) triethylenetetramine ethanol solution, and carry out a cross-linking reaction at 60 °C, 160 rpm, and under a N2 atmosphere for 24 h to obtain triethylenetetramine-functionalized chitosan microspheres (TETA-MECBs).

[0034] (6) Add 5 g (wet weight) of the TETA-MECBs described in step (5) into 15 mL of an aqueous solution of sodium perrhenate (with a rhenium concentration of about 14 mg / ml), and adsorb for 24 h at pH 3, 25 °C, and 160 rpm to obtain rhenium-loaded triethylenetetramine-functionalized chitosan microspheres.

[0035] (7) Add the rhenium-loaded triethylenetetramine-functionalized chitosan microspheres obtained in step (6) into 15 mL of a glutaraldehyde solution with a concentration of 2.5% (v / v), and react for 24 h at 25 °C and 160 rpm to achieve the fixation of the "recognition-adsorption" sites. Subsequently, the synthesized adsorbent material was immersed in 1 mol / L NaCl solution to remove ReO4 - ions on the "recognition-adsorption" sites. - ReO4 on the "recognition-adsorption" sites - ions, and prepare rhenium perrhenate - ion-imprinted triethylenetetramine-functionalized chitosan microspheres (IP-TETA-MECBs) (8) The IP-TETA-MECBs prepared in step (6) were used for the selective recovery of rhenium ions in an acidic rhenium-containing solution (the molar ratio of ReO4 - ions to SO4 - ions is 1:1). The adsorption conditions are as follows: the adsorbent dosage is 0.1 g, the solution volume is 100 mL, pH 2, 160 rpm, 25 °C, 24 h.

[0036] The selectivity coefficient is calculated as shown in formula (1)

[0037] —— The adsorption amount of the target metal (mg); —— The adsorption equilibrium concentration of the target metal (mg / L); —— The adsorption amount of the interfering metal (mg); —— The adsorption equilibrium concentration of the interfering metal (mg / L); —— The adsorption selectivity coefficient of the adsorbent.

[0038] Comparative Example 1 Other conditions are the same as in Example 1, except that steps (4), (5), (6), and (7) of Example 1 are omitted, and the ECBs obtained in step (3) of Example 1 are directly used as the adsorbent material to explore its selective capture performance for rhenium, and the adsorption conditions are the same as those described in step (8) of Example 1.

[0039] Comparative Example 2 Other conditions were the same as those in Example 1, except that steps (4) and (5) in Example 1 were omitted. 5 g of ECBs obtained in step (3) of Example 1 were added to 15 mL of an aqueous solution of sodium perrhenate (with a rhenium concentration of about 14 mg / ml), and adsorbed for 24 h at pH 3, 25 °C, and 160 rpm to obtain rhenium-loaded chitosan microspheres. Subsequently, ReO4 was processed according to step (7) of Example 1 - Fixation of the "recognition-adsorption" site and ReO4 - ion elution to prepare rhenium ion-imprinted chitosan microspheres (GIECBs). GIECBs were used as an adsorbent material to explore their selective capture performance for rhenium, and the adsorption conditions were the same as those described in step (8) of Example 1.

[0040] Comparative Example 3 Other conditions were the same as those in Example 1, except that steps (5), (6), and (7) in Example 1 were omitted. The MECBs obtained in step (4) of Example 1 were used as an adsorbent material to explore their selective capture performance for rhenium, and the adsorption conditions were the same as those described in step (8) of Example 1.

[0041] Comparative Example 4 Other conditions were the same as those in Example 1, except that steps (6) and (7) in Example 1 were omitted. The TETA-MECBs obtained in step (5) of Example 1 were used as an adsorbent material to explore their selective capture performance for rhenium, and the adsorption conditions were the same as those described in step (8) of Example 1.

[0042] Comparative Example 5 Other conditions were the same as those in Example 1, except that step (6) in Example 1 was omitted. The preparation process of the adsorbent material (NIP-TETA-MECBs) used in Comparative Example 5 was basically the same as the steps described in Example 1, except that the rhenium adsorption process described in step (6) of Example 1 was not performed on NIP-TETA-MECBs. The adsorption conditions were the same as those described in step (8) of Example 1.

[0043] Example 2 The preparation process of the adsorbent material (IP-EDA-MECBs) used in Example 2 was basically the same as the steps described in Example 1, except that triethylenetetramine used in step (5) of Example 1 was replaced with ethylenediamine (EDA). The adsorption conditions were the same as those described in step (8) of Example 1.

[0044] Example 3 The preparation process of the adsorbent material (IP-DETA-MECBs) used in Example 3 was basically the same as the steps described in Example 1, except that triethylenetetramine used in step (5) of Example 1 was replaced with diethylenetriamine (DETA). The adsorption conditions were the same as those described in step (8) of Example 1.

[0045] Example 4 The preparation process of the adsorbent material (IP-TEPA-MECBs) used in Example 4 was basically the same as the steps described in Example 1, except that triethylenetetramine used in step (5) of Example 1 was replaced with tetraethylenepentamine (TEPA). The adsorption conditions were the same as those described in step (8) of Example 1.

[0046] Example 5 The preparation process of the adsorbent material (IP-TMEDA-MECBs) used in Example 5 was basically the same as the steps described in Example 1, except that triethylenetetramine used in step (5) of Example 1 was replaced with 1,3-propanediamine (TMEDA). The adsorption conditions were the same as those described in step (8) of Example 1.

[0047] Example 6 The preparation process of the adsorbent material (IP-IBPA-MECBs) used in Example 6 was basically the same as the steps described in Example 1, except that triethylenetetramine used in step (5) of Example 1 was replaced with 3,3'-diaminodipropylamine (IBPA). The adsorption conditions were the same as those described in step (8) of Example 1.

[0048] For the adsorbent materials prepared in the above examples and comparative examples, the selectivity coefficients were measured according to formula (1), and the list is as Figure 2 and Figure 3 . From Figure 2 it can be seen that the chitosan adsorbent material prepared in Example 1 has a significantly excellent rhenium adsorption selectivity coefficient compared with the adsorbent materials of other comparative examples, up to 11.43; thus, it can be seen that each step of the preparation process of the chitosan adsorbent material with organic covalent cross-linked grafted nitrogen-rich rhenium ion imprinting of the present invention is essential. Figure 3 By comparing Examples 1 to 6, in which chitosan adsorbent materials were prepared using different nitrogen-rich branched chain reagents, it was found that using triethylenetetramine in Example 1 had the best selectivity coefficient compared with other reagents.

[0049] Example 7 A method for preparing chitosan microspheres with organic covalent cross-linked grafted nitrogen-rich rhenium ion imprinting includes the following steps: (1) Stir and mix 2 g of chitosan powder with 98 mL of 2% (v / v) acetic acid aqueous solution to obtain chitosan gel; (2) The chitosan gel microfluidic cutting device described in step (1) was dropped into an aqueous ethanol solution of sodium hydroxide drop by drop to obtain chitosan microspheres (CBs). During the preparation process, the concentration of sodium hydroxide was 1 mol / L, and the ethanol concentration was 50% (v / v); the used dispersed phase (cutting phase) (n-octanol solution of span 80), the concentration of span 80 was 2% (v / v); the pressure ratio of the mobile phase (chitosan gel) to the cutting phase (n-octanol solution of span 80) was 1500 Mpa: 500 Mpa.

[0050] (3) 5 g (wet weight) of the chitosan microspheres described in step (2) were added to 15 mL of ECH (epichlorohydrin 0.2% (v / v) solution), and cross-linked at pH 11, 40 °C, and 160 rpm for 24 h to improve the physical and chemical stability of the chitosan microspheres. The prepared chitosan microspheres were ECH-cross-linked chitosan microspheres (ECBs).

[0051] (4) 5 g (wet weight) of the ECBs described in step (3) were added to 40 mL of a 40% (v / v) methyl acrylate ethanol solution, and cross-linked at 50 °C and 160 rpm for 24 h to obtain methyl acrylate-functionalized chitosan microspheres (MECBs).

[0052] (5) 5 g (wet weight) of the MECBs described in step (4) were added to 40 mL of a 40% (v / v) triethylenetetramine ethanol solution, and cross-linked at 60 °C, 160 rpm, and in an N2 atmosphere for 24 h to obtain triethylenetetramine-functionalized chitosan microspheres (TETA-MECBs).

[0053] (6) 5 g (wet weight) of the TETA-MECBs described in step (5) were added to 15 mL of an aqueous sodium perrhenate solution (rhenium concentration about 14 mg / ml), and adsorbed at pH 3, 25 °C, and 160 rpm for 24 h to obtain rhenium-loaded triethylenetetramine-functionalized chitosan microspheres.

[0054] (7) The rhenium-loaded triethylenetetramine-functionalized chitosan microspheres obtained in step (6) were added to 15 mL of a 5% (v / v) glutaraldehyde solution, and reacted at 25 °C and 160 rpm for 24 h to achieve the fixation of the "recognition-adsorption" site. Subsequently, the synthesized adsorbent material was immersed in a 1 mol / L NaCl solution to remove ReO4 - the ReO4 on the "recognition-adsorption" site - ions, and the ReO4 - was prepared. -Ion-imprinted triethylenetetramine-functionalized chitosan microspheres (IP-TETA-MECBs) (8) The IP-TETA-MECBs prepared in step (6) were used for the selective recovery of rhenium ions from acidic rhenium-containing solutions (where the molar ratio of ReO4 - ions to SO4 - ions was 1:1). The adsorption conditions were as follows: the adsorbent dosage was 0.1 g, the solution volume was 100 mL, pH 2, 160 rpm, 25 °C, and 24 h. The chitosan adsorbent material prepared in this example also had excellent rhenium adsorption selectivity.

[0055] As described above, only the specific embodiments of the present application are provided, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A preparation method of a rhenium ion imprinted chitosan adsorbent based on organic covalent cross-linking grafting, characterized in that, It includes the following steps: (1) Mix the chitosan molding material with an aqueous solution of a first organic covalent crosslinking agent, so that the amino or hydroxyl group contained in the chitosan molding material reacts with the first organic covalent crosslinking agent to obtain a preliminarily crosslinked chitosan molding material, so as to improve the acid resistance stability of the chitosan molding material; (2) Sequentially mix the preliminarily crosslinked chitosan molding material obtained in step (1) with an organic solution of methyl acrylate and an organic solution of a nitrogen-rich branched chain reagent, and then carry out an organic covalent grafting reaction to extend the length of the amino branched chain on the chitosan molding material to obtain a nitrogen-rich branched chain functionalized chitosan molding material; (3) Mix the nitrogen-rich branched-chain functionalized chitosan molding material obtained in step (2) with an acidic aqueous solution containing ReO4 - so that ReO4 - is adsorbed by the chitosan molding material to obtain a nitrogen-rich branched-chain functionalized chitosan molding material loaded with ReO4 - ; (4) Load ReO4 obtained in step (3) - The nitrogen-rich branched functionalized chitosan molding material is mixed with an aqueous solution of a second organic covalent crosslinking agent to undergo a crosslinking reaction to achieve ReO4 - Identify and fix the adsorption sites, and then immerse the adsorbent material after the cross-linking reaction in ReO4 - Remove ReO4 from the desorption solution - Identification - Adsorption sites on ReO4 - ions, and a rhenium ion-imprinted chitosan adsorption material based on organic covalent cross-linking grafting was prepared.

2. The preparation method according to claim 1, characterized in that, The chitosan molding material is a chitosan microsphere, a chitosan fiber, a chitosan aerogel or a chitosan film.

3. The preparation method according to claim 1, characterized in that, The first organic covalent crosslinking agent in step (1) is one or more of epichlorohydrin, glutaraldehyde and ethylene glycol diglycidyl ether; Among them, the volume percentage concentration of the first organic covalent crosslinking agent is 0.01-1%; the dosage ratio of the chitosan molding material to the aqueous solution of the first organic covalent crosslinking agent is 5 g:10-20 mL.

4. The preparation method according to claim 1, wherein The organic solution of methyl acrylate in step (2) is an organic solution obtained by dissolving methyl acrylate in an organic solvent, and the organic solvent is one or more of ethanol or methanol; the volume percentage of methyl acrylate in the organic solution of methyl acrylate is 20-60%, and the dosage ratio of the chitosan molding material to the organic solution of methyl acrylate is 5 g:20-50 mL.

5. The preparation method according to claim 1, wherein, The nitrogen-rich branched chain reagent in step (2) is one or more of ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, 1,3-propanediamine and 3,3'-diaminodipropylamine; and / or, The organic solution of the nitrogen-rich branched chain reagent is an organic solution obtained by dissolving the nitrogen-rich branched chain reagent in an organic solvent, and the organic solvent is one or more of ethanol or methanol; the volume percentage of the nitrogen-rich branched chain reagent in the organic solution of the nitrogen-rich branched chain reagent is 20-60%, and the dosage ratio of the chitosan molding material to the organic solution of the nitrogen-rich branched chain reagent is 5 g:20-50 mL.

6. The preparation method according to claim 1, wherein The concentration of rhenium in the acidic aqueous solution containing ReO4 described in step (3) is 1-20 g / L; the dosage ratio of the nitrogen-rich branched-chain functionalized chitosan molding material to the acidic aqueous solution containing ReO4 - is 5 g: 10-20 mL. - ​ 7. The preparation method according to claim 1, wherein The second organic covalent crosslinking agent in step (4) is one or more of epichlorohydrin, glutaraldehyde and ethylene glycol diglycidyl ether; The loaded ReO4 - The dosage ratio of the nitrogen-rich branched chain-functionalized chitosan molding material to the aqueous solution of the second organic covalent crosslinking agent is 5 g: 10-20 mL, and the volume concentration of the second organic covalent crosslinking agent in the aqueous solution of the second organic covalent crosslinking agent is 2%-10%.

8. The preparation method according to claim 1, characterized in that, The desorbing solution of ReO4 described in step (4) - is one or more of dilute hydrochloric acid and aqueous sodium chloride solution, and the concentration of the desorbing solution is 0.5-2 mol / L.

9. A rhenium ion imprinted chitosan adsorbent based on organic covalent crosslinking grafting prepared by the preparation method according to any one of claims 1 to 8.

10. Application of the rhenium ion imprinted chitosan adsorbent material based on organic covalent cross-linking grafting in selectively adsorbing ReO4 in acidic aqueous solution - as described in claim 9

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