Preparation method of phosphonate-modified acylhydrazone covalent organic polymer and application of phosphonate-modified acylhydrazone covalent organic polymer in adsorption and separation of heavy rare earth ions

Abstract

The invention discloses a preparation method of a phosphonate-modified acylhydrazone covalent organic polymer and application of the phosphonate-modified acylhydrazone covalent organic polymer to adsorption and separation of heavy rare earth ions, and belongs to the field of environmental protection. According to the invention, 2, 4, 6-tri (4-formyl phenyl)-1, 3, 5-triazine and tetraethyl ((2, 5-bis (hydrazino carbonyl)-1, 4-phenylene) bis (oxy) bis (ethane-2, 1-disubunit)) bis (phosphonate) are subjected to a Schiff base reaction to prepare a phosphonate modified acylhydrazone covalent organic polymer; a phosphonate functional group is modified on a framework of the acylhydrazone covalent organic polymer, and the acylhydrazone covalent organic polymer can be used for high-efficiency adsorption separation of heavy rare earth ions in a water phase; the phosphonate-modified acylhydrazone covalent organic polymer is simple in preparation method, has excellent adsorption separation performance on heavy rare earth ions, and is expected to be used as an efficient adsorbent for southern ion adsorption type rare earth ore low-concentration wastewater.

Description

Technical Field

[0001] The invention belongs to the technical field of environmental protection, and in particular relates to a preparation method of a phosphonate-modified acylhydrazone covalent organic polymer and an application of the polymer in adsorbing and separating heavy rare earth ions. Background Art

[0002] As the main source of medium and heavy rare earths in my country, the southern ion adsorption rare earth mines are affected by rainwater leaching and other effects. Such mining areas will produce a large amount of low-concentration rare earth wastewater. The content of rare earth ions in these low-concentration wastewaters can reach 50 mg / L. If they are discharged directly into the environment without treatment, it will not only cause a waste of precious rare earth resources, but also cause serious harm to the surrounding ecological environment. The current common methods for treating low-concentration rare earth wastewater mainly include solvent extraction, ion exchange, chemical precipitation, membrane separation, microbial method, adsorption method, etc. Among them, adsorption method is a very promising treatment method because of its low cost, simple and convenient operation, high efficiency and other advantages.

[0003] Covalent organic polymers (COPs) are organic polymers formed by strong covalent bonds between carbon and other heteroatoms such as boron, oxygen, nitrogen, sulfur, phosphorus, etc. Their unique physical and chemical properties have made them widely used in many fields. At the same time, the coordination ability of the functional groups in the material with the target metal ions has always been the key characteristic of nanomaterials in metal ion adsorption applications. According to the HSAB theory, phosphonate functional groups have higher affinity and selectivity for heavy rare earth ions than carboxyl, amino, hydroxyl, sulfonic acid and other functional groups.

[0004] Therefore, this study introduced phosphonate functional groups into COPs materials and prepared a phosphonate-modified acylhydrazone covalent organic polymer for the adsorption and separation of rare earth ions. The experimental results show that the prepared covalent organic polymer has a high distribution coefficient for heavy rare earth ions and is expected to be used as an efficient adsorbent for low-concentration wastewater from southern ion-adsorption rare earth mines. Summary of the invention

[0005] The purpose of the present invention is to provide a preparation method of a phosphonate-modified acylhydrazone covalent organic polymer and its application in adsorbing and separating heavy rare earth ions. The present invention prepares a phosphonate-modified acylhydrazone covalent organic polymer through a Schiff base reaction between 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and tetraethyl((2,5-di(hydrazinecarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate). The skeleton of the acylhydrazone covalent organic polymer is modified with a phosphonate functional group, which can be used for efficient adsorption and separation of heavy rare earth ions in an aqueous phase; the acylhydrazone covalent organic polymer prepared by the present invention has a simple preparation method, has excellent adsorption and separation performance for heavy rare earth ions, and can be used as an efficient adsorbent for low-concentration tail water of southern ionic rare earth mines.

[0006] The present invention provides a method for preparing a phosphonate-modified acylhydrazone covalent organic polymer, comprising the following steps: 1) using 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and tetraethyl((2,5-di(hydrazinocarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate) as reaction raw materials, adding a solvent and performing ultrasonic treatment to obtain a reaction mixture; 2) The container containing the reaction mixture is degassed through a freeze-thaw cycle, flame-sealed and heated at 100-200° C. for 3-7 days, cooled and filtered to collect the precipitate, and dried and washed to obtain the phosphonate-modified acylhydrazone covalent organic polymer.

[0007] Furthermore, in step 1), the mass ratio of tetraethyl ((2,5-di(hydrazinocarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate) to 2,4,6-tris(4-formylphenyl)-1,3,5-triazine is (1-2):1.

[0008] Furthermore, in step 1), the solvent comprises 1,4-dioxane, 1,3,5-mesitylene and acetic acid, and the volume ratio of the three is (1-5):(5-15):1; the concentration of the acetic acid is 6 M.

[0009] The present invention also provides the use of the phosphonate-modified acylhydrazone covalent organic polymer obtained by the preparation method in the adsorption and separation of heavy rare earth ions.

[0010] Furthermore, the heavy rare earth ion is Ho 3+ , Er 3+ 、Tm 3+ , Yb 3+ 、Lu 3+ , Y 3+ At least one of .

[0011] Furthermore, the phosphonate-modified acylhydrazone covalent organic polymer has the highest distribution coefficient for lutetium ions during the process of adsorption and separation of heavy rare earth ions.

[0012] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a one-step method to synthesize the phosphonate-modified acylhydrazone covalent organic polymer, the preparation method is simple, and it can be used for adsorption and separation of rare earth ions without post-treatment.

[0013] 2. The acylhydrazone covalent organic polymer prepared by the present invention introduces phosphonate functional groups into COPs materials for the first time.

[0014] 3. The acylhydrazone covalent organic polymer prepared by the present invention introduces a phosphonate functional group having a high affinity for rare earth ions through a monomer, thereby improving the affinity for rare earth ions.

[0015] 4. The acylhydrazone covalent organic polymer prepared by the present invention has a very high distribution coefficient for heavy rare earth ions during the process of adsorbing and separating rare earth ions.

[0016] 5. The acylhydrazone covalent organic polymer prepared by the present invention realizes efficient adsorption and separation of rare earth ions, and can be used as an efficient adsorbent for low-concentration tail water of southern ionic rare earth mines. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic diagram of the preparation process of COP-TFPT-TBBP.

[0018] Figure 2 It is the infrared spectra of TFPT, TBBP and COP-TFPT-TBBP.

[0019] Figure 3 This is the full XPS spectrum of COP-TFPT-TBBP.

[0020] Figure 4 This is the distribution coefficient diagram of COP-TFPT-TBBP for heavy rare earth ions.

[0021] Figure 5 This is the full XPS spectrum of COP-TFPT-TBBP after adsorbing lutetium ions. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the embodiments. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0024] Example 1: Preparation and characterization of phosphonate-modified acylhydrazone covalent organic polymers Tetraethyl((2,5-di(hydrazinocarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate) (TBBP, 41.5 mg), 2,4,6-tris(4-formylphenyl)-1,3,5-triazine (TFPT, 8 mg), 1,4-dioxane (0.5 mL) and 1,3,5-mesitylene (1.5 mL) were placed in a Pyrex tube and ultrasonicated for 10 min. Then, 6 M acetic acid solution (0.2 mL) was added to obtain a reaction mixture. The Pyrex tube containing the reaction mixture was degassed through three freeze pump-thaw cycles, flame sealed and incubated at 120 The mixture was heated in an oven at ℃ for 3 days, filtered after cooling, and the obtained light yellow solid product was washed three times with N,N-dimethylformamide (DMF), 1,4-dioxane (Diox), and acetone (Acetone). The solid was collected and vacuum dried at 80℃ for 12 hours to obtain a phosphonate-modified acylhydrazone covalent organic polymer (COP-TFPT-TBBP).

[0025] Figure 1 Schematic diagram of the preparation process of phosphonate-modified acylhydrazone covalent organic polymer COP-TFPT-TBBP.

[0026] Figure 2 is the infrared spectra of TFPT, TBBP and COP-TFPT-TBBP, Figure 2 It can be seen that the aldehyde group HC=O in TFPT is located at 1702 cm -1 The carbonyl C=O in TBBP is located at 1682 cm -1 After the Schiff base reaction, the newly generated C=N double bond is located at 1658 cm -1 , demonstrating the successful preparation of COP-TFPT-TBBP.

[0027] Figure 3 is the full XPS spectrum of COP-TFPT-TBBP, Figure 3 It can be seen that the C 1s, N 1s, O 1s, P2s, and P 2p peaks are clearly visible in the full XPS spectrum, further proving the successful preparation of COP-TFPT-TBBP.

[0028] Example 2: Efficient adsorption and separation of heavy rare earth ions by phosphonate-modified acylhydrazone covalent organic polymers Using COP-TFPT-TBBP as an adsorbent for heavy rare earth ions (Ho 3+ , Er 3+ 、Tm 3+ , Yb 3+ 、Lu 3+ , Y 3+ ) was investigated for its adsorption and separation performance. 5 mg COP-TFPT-TBBP was added to 5 mL of heavy rare earth mixed solution, stirred for 12 h, filtered with a 0.22 μm microporous filter membrane, and the content of rare earth ions in the filtrate was measured by inductively coupled plasma emission spectrometry. The distribution coefficient of COP-TFPT-TBBP for rare earth ions was calculated, and the affinity of the material for rare earth ions was studied. Figure 4 is the distribution coefficient diagram of COP-TFPT-TBBP for heavy rare earth ions. Figure 4 It can be seen that COP-TFPT-TBBP has a strong affinity for heavy rare earth ions (Ho 3+ , Er 3+ 、Tm 3+ , Yb 3+ 、Lu 3+ , Y 3+ ) have higher partition coefficients, among which COP-TFPT-TBBP has a higher partition coefficient for Lu 3+ Has the highest affinity.

[0029] Example 3: Efficient adsorption of lutetium ions by phosphonate-modified acylhydrazone covalent organic polymers Figure 5 This is the full XPS spectrum of COP-TFPT-TBBP after adsorption of lutetium ions. Figure 5 It can be seen that after COP-TFPT-TBBP adsorbed lutetium ions, Lu 4d peak appeared in the material. This is mainly attributed to the fact that COP-TFPT-TBBP introduced phosphate functional groups with high selectivity for heavy rare earth ions into the material, which can construct efficient heavy rare earth ion capture nanochannels in the material, greatly improving the material's adsorption performance for heavy rare earth ions.

[0030] The embodiments described above only express several preferred embodiments of the present invention, and the descriptions thereof are relatively specific and detailed, but are not intended to limit the present invention. It should be noted that for those skilled in the art, the present invention may also have various changes and modifications, and any modifications, equivalent substitutions, improvements, etc. made within the concept and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a phosphonate-modified acylhydrazone covalent organic polymer, characterized in that: The steps include: 1) using 2,4,6-tris(4-formylphenyl)-1,3,5-triazine and tetraethyl((2,5-di(hydrazinocarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate) as reaction raw materials, adding a solvent and performing ultrasonic treatment to obtain a reaction mixture; 2) The container containing the reaction mixture is degassed through a freeze-thaw cycle, flame-sealed and heated at 100-200° C. for 3-7 days, cooled and filtered to collect the precipitate, and dried and washed to obtain the phosphonate-modified acylhydrazone covalent organic polymer.

2. The method for preparing a phosphonate-modified acylhydrazone covalent organic polymer according to claim 1, characterized in that: In step 1), the mass ratio of tetraethyl ((2,5-di(hydrazinocarbonyl)-1,4-phenylene)bis(oxy)bis(ethane-2,1-diylidene))bis(phosphonate) to 2,4,6-tris(4-formylphenyl)-1,3,5-triazine is (1-2):

1.

3. The method for preparing a phosphonate-modified acylhydrazone covalent organic polymer according to claim 1, characterized in that: Step 1) The solvent includes 1,4-dioxane, 1,3,5-mesitylene and acetic acid, and the volume ratio of the three is (1-5):(5-15):1; the concentration of the acetic acid is 6 M.

4. Use of the phosphonate-modified acylhydrazone covalent organic polymer obtained by the preparation method according to any one of claims 1 to 3 in the adsorption and separation of heavy rare earth ions.

5. The application according to claim 4, characterized in that: The heavy rare earth ion is Ho 3+ , Er 3+ 、Tm 3+ , Yb 3+ 、Lu 3+ , Y 3+ At least one of .

6. The use according to claim 4, characterized in that: The phosphonate-modified acylhydrazone covalent organic polymer has the highest distribution coefficient for lutetium ions in the process of adsorbing and separating heavy rare earth ions.

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