阅读说明：本技术 图灵结构共价有机框架膜材料及其用途 (Tuoling structure covalent organic framework membrane material and application thereof ) 是由 马利建 张洁 周立宏 于 2021-10-15 设计创作，主要内容包括：本发明属于有机脱酸材料领域,具体涉及图灵结构共价有机框架膜材料及其用途。本发明提供了一种图灵结构共价有机框架膜材料,采用有机-有机溶剂界面法,以2,4,6-三羟基-1,3,5-苯三甲醛为节点单体与间苯二胺通过醛胺缩合反应,合成得到图灵结构共价有机框架(t-TpMa-COF)膜材料。本发明提供的t-TpMa-COF材料拥有良好的热稳定性和酸碱稳定性,可有效实现高酸度料液的高效脱酸处理。本发明为新型图灵结构膜材料的设计和制备提供了新的思路,同时为乏燃料后处理料液等高酸度工业废水的脱酸减容和处理流程简化提供了新的解决途径。(The invention belongs to the field of organic deacidification materials, and particularly relates to a Turing structure covalent organic framework film material and application thereof. The invention provides a Turing structure covalent organic framework (t-TpMa-COF) film material which is synthesized by adopting an organic-organic solvent interface method and taking 2,4, 6-trihydroxy-1, 3, 5-benzenetricarboxylic aldehyde as a node monomer to carry out an aldehyde-amine condensation reaction with m-phenylenediamine. The t-TpMa-COF material provided by the invention has good thermal stability and acid-base stability, and can effectively realize efficient deacidification treatment of high-acidity feed liquid. The invention provides a new idea for the design and preparation of a novel Tuling structure membrane material, and simultaneously provides a new solution for deacidification volume reduction and treatment process simplification of high-acidity industrial wastewater such as spent fuel post-treatment feed liquid and the like.)

1. the Tuling structure covalent organic framework film material is synthesized by adopting an organic-organic solvent interface method and taking 2,4, 6-trihydroxy-1, 3, 5-benzene triformal as a node monomer to react with m-phenylenediamine through aldehyde-amine condensation.

2. The Turing-structured covalent organic framework membrane material of claim 1, wherein: the preparation method comprises the following steps: dissolving 2,4, 6-trihydroxy-1, 3, 5-benzene trimethyl aldehyde in a lower layer solvent, and adding a buffer layer; dissolving m-phenylenediamine in the upper layer solvent, and continuously and slowly adding the m-phenylenediamine to the top of the buffer layer; standing at room temperature without interference for 7 days; the buffer layer disappears, and the Turing structure covalent organic framework membrane material is obtained at the interface of the upper layer and the lower layer and washed by water and dichloromethane respectively.

3. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the concentration of the 2,4, 6-trihydroxy-1, 3, 5-benzene trimethyl aldehyde dissolved in the lower layer solvent is 0.5-2 mmol/L.

4. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the lower layer solvent is dichloromethane.

5. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the buffer layer is acetic acid, Sc (OTf)₃、Eu(OTf)₃Or water; the concentration of the acetic acid is 2-6M.

6. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the upper layer solvent is a mixed solvent of ethanol, water or dichloromethane and N, N-dimethylformamide; the volume ratio of the dichloromethane to the N, N-dimethylformamide is 6: 1-4.

7. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the concentration of the m-phenylenediamine dissolved in the upper layer solvent is 0.5-2 mmol/L.

8. The Turing-structured covalent organic framework membrane material of claim 2, wherein: the volume ratio of the lower-layer solvent to the buffer layer to the upper-layer solvent is 2: 1-1.5: 1.5-3.

9. Use of the Turing-structured covalent organic framework membrane material of any one of claims 1 to 7 in the preparation of deacidification agents.

10. Use of the Turing-structured covalent organic framework membrane material according to claim 9, characterized in that: the deacidification agent is used for deacidification treatment of spent fuel post-treatment feed liquid.

Technical Field

The invention belongs to the field of organic deacidification materials, and particularly relates to a Turing structure covalent organic framework film material and application thereof.

Background

Complex and delicate patterns and forms can be seen everywhere in nature, such as animal patches, plant rota-leaf sequences, etc., and scientists' charts disclose the chemical nature of these forms by using a "reaction-diffusion" equation, i.e., some repeated natural patterns may be generated by the interaction or interaction of two specific substances (molecules, cells, etc.)¹. Later, scientists called the "Tuoling" structure by forming patches, stripes, rings, spirals, or mottled spots of spontaneous organization of two components "^2-4. The generation of the Turing structure generally needs to be carried out in a reaction-diffusion system, and the interfacial polymerization reaction system is the reaction-diffusion system under a non-thermodynamic equilibrium state^5-7. The membrane with the Tuoling structure prepared by interfacial polymerization has excellent transmission performance in the aspects of water permeability and water-salt selectivity, and the characteristic enables the membrane material to have great application potential in the field of membrane separation^8-11. However, the related research on the material of the Tuoling structure membrane is still very rare at present. Therefore, the research on the novel Turing structure membrane material and the development of the huge application value thereof in the membrane separation field have important scientific significance.

The membrane separation technology is a method for selectively separating and purifying components by utilizing the difference of selective permeability of different components on a membrane and taking external conditions (pressure, electric field, heat and the like) or component concentration difference as a driving force^12-18. The emerging membrane separation technology has been widely applied in many fields due to its unique characteristics of low energy consumption, simple separation process, material reusability, etc^19-22. Especially, when the feed liquid generated in the spent fuel post-treatment process is faced, the membrane separation method can be more fully exertedTechnical advantages thereof^23-25. The acidity of the feed liquid generated by post-treatment is generally above 3mol/L, and a method of calcination denitration, dilution or neutralization is generally needed to reduce the acidity of the solution^26,27. The calcination needs very high temperature, and in the calcination process, the nitric acid volatilized at high temperature has very strong corrosion to tail gas equipment, and fission products such as Ru, Tc and the like in the feed liquid are also easily volatilized in a solution with high acidity, so that great adverse effects are caused^28-30. Dilution increases the volume of the waste stream, while neutralization increases the salt content of the solution, which can add significant difficulty, throughput, and disposal cost to waste treatment³¹. The membrane separation method changes the traditional deacidification thinking, directly reduces the acidity of the feed liquid through proton transmission, breaks through the limits of sensitivity to heavy metals, high energy consumption, volatile gas generation in the deacidification process and the like, and provides a simple, convenient and flexible new method for the deacidification of the feed liquid in the extreme environment of the post-treatment process of the spent fuel. However, many membrane materials are difficult to exert their advantages in separation when faced with feed liquids having high radioactivity levels, high decay heat power and biotoxicity, complex chemical compositions, strong acidity, high corrosivity, and the like³². Therefore, research and development of membrane separation materials suitable for the spent fuel post-processing real feed liquid environment are still the focus of attention of researchers.

Disclosure of Invention

In order to solve the problems, the invention provides a Turing structure covalent organic framework membrane material.

The Turing-structured covalent organic framework (t-TpMa-COF) film material is synthesized by adopting an organic-organic solvent interface method and taking 2,4, 6-trihydroxy-1, 3, 5-benzene triformal as a node monomer to carry out an aldehyde-amine condensation reaction with m-phenylenediamine.

The preparation method of the covalent organic framework membrane material with Tuoling structure is shown in figure 1.

The preparation method of the Turing structure covalent organic framework membrane material comprises the following steps: dissolving Tp (2,4, 6-trihydroxy-1, 3, 5-benzenetricarboxylic acid) in a lower layer solvent, and adding a buffer layer; then adding Ma (m-phenylenediamine)) Dissolving in the upper solvent, and continuously and slowly adding the solution on the top of the buffer layer; standing at room temperature without interference for 7 days; the buffer layer disappears, t-TpMa-COF film material is obtained at the interface of the upper layer and the lower layer, and water and CH are respectively used₂Cl₂(dichloromethane) wash.

In the preparation method of the covalent organic framework membrane material with the Tuoling structure, the lower layer solvent is CH₂Cl₂。

In the preparation method of the covalent organic framework film material with the Tuoling structure, the buffer layer is acetic acid, Sc (OTf)₃(scandium trifluoromethanesulfonate), Eu (OTf)₃(europium trifluoromethanesulfonate) or water. The concentration of the acetic acid is 2-6M.

In the preparation method of the covalent organic framework membrane material with the Tuoling structure, the upper layer solvent is ethanol, water or CH₂Cl₂Mixed solvent with DMF (N, N-dimethylformamide). The CH₂Cl₂The volume ratio of the DMF to the DMF is 6: 1-4.

In the preparation method of the Turing structure covalent organic framework membrane material, the concentration of the Ma dissolved in the upper layer solvent is 0.5-2 mmol/L.

In the preparation method of the Tuoling structure covalent organic framework film material, the volume ratio of the lower layer solvent to the buffer layer to the upper layer solvent is 2: 1-1.5: 1.5-3.

The invention also provides application of the Tuoling structure covalent organic framework membrane material in preparation of deacidification agents. The deacidification agent is used for deacidification treatment of spent fuel post-treatment feed liquid.

The t-TpMa-COF material provided by the invention has good thermal stability and acid-base stability. In the microstructure, the t-TpMa-COF has two different-shaped turing structures, one linear turing structure and the other porous turing structure. Surprisingly, the two structures possess distinct properties, the side of the line pattern exhibiting hydrophobic properties, and the side of the hole pattern exhibiting superhydrophilic properties. In an ion sieving experiment, the t-TpMa-COF nanofiltration membrane shows excellent metal ion interception and proton permeationHigh performance, up to 5M HNO in acidity₃Can still keep on H under the condition⁺The selective permeability of the film enables the t-TpMa-COF to be easily adapted to the harsh environment of spent fuel post-treatment feed liquid, and the film is used for deacidifying the feed liquid. Meanwhile, t-TpMa-COF also has excellent performance in dye screening. the successful synthesis and application of t-TpMa-COF provide a selectable approach for designing a novel turing-structure membrane material, and broaden the application field of the turing-structure membrane material.

Drawings

FIG. 1 is a schematic diagram of the synthesis of a Tulip structure t-TpMa-COF membrane material.

FIG. 2A representation map of Tuoling structure t-TpMa-COF membrane material: (a) an infrared spectrum of t-TpMa-COF and the monomer; (b) 13C solid nuclear magnetic spectrum of t-TpMa-COF; (c) a PXRD pattern; (d) nitrogen adsorption desorption isotherms (inset is experimental and simulated pore diameter values for t-TpMa-COF).

FIG. 3 microstructure of Tuoling structure t-TpMa-COF film material: (a-c) spherical aberration correction electron microscopy of t-TpMa-COF (inset is structural diagram of t-TpMa-COF simulation); (c) (d) is a selected area electron diffraction pattern; (e) simulated layer spacing for t-TpMa-COF.

FIG. 4 scanning electron micrograph of Tulip structure t-TpMa-COF film material: (a) a cross-sectional scanning electron micrograph of t-TpMa-COF; (b) scanning electron microscope images of the upper surface of the t-TpMa-COF film; (c) the contact angle of the upper surface of the t-TpMa-COF film; (d) atomic force microscopy images of the upper surface of the t-TpMa-COF film; (e) scanning electron micrograph of the lower surface of the t-TpMa-COF film; (f) the contact angle of the lower surface of the t-TpMa-COF film; (g) atomic force microscopy of the lower surface of the t-TpMa-COF film.

FIG. 5 two water-facing permeability properties of Tuoling-structure t-TpMa-COF membrane materials: (a) the water permeability of the hydrophilic surface and the hydrophobic surface of the t-TpMa-COF membrane is high; (b)1M HNO₃H in the system⁺The permeate flux.

Fig. 614 permeation flux of competing ions through COF membranes in acidic systems: (a)1M HNO₃A system; (b)3M HNO₃A system; (c)5M HNO₃A system; (d)1M HCl system; (e)3M HCl system; (f)5M HCl system.

Fig. 714 shows the permeation flux of competing ions across the membrane at (a) pH 1.8 and (b)5M in a nitric acid system with a filtration time of 192 hours.

FIG. 8 is a schematic diagram of the filtration mechanism of deacidification and metal ion interception of Tuoling structure t-TpMa-COF membrane material.

FIG. 9(a) thermogravimetric curves of t-TpMa-COF; (b) an infrared spectrogram before and after t-TpMa-COF irradiation (c) an infrared spectrogram before and after t-TpMa-COF nitric acid soaking.

Detailed Description

The preparation method of the Turing structure covalent organic framework membrane material comprises the following steps:

a. dissolving Tp in CH₂Cl₂Adding a buffer layer; the concentration of Tp dissolved in the lower layer solvent is 0.5-2 mmol/L;

b. dissolving Ma in the upper layer solvent, and continuously and slowly adding Ma on the top of the buffer layer; the concentration of the Ma dissolved in the upper layer solvent is 0.5-2 mmol/L;

c. standing at room temperature without interference for 7 days; the buffer layer disappears, and t-TpMa-COF film materials are obtained at the interface of the upper layer and the lower layer and respectively take H as the material₂O and CH₂Cl₂And (6) washing.

The volume ratio of the lower-layer solvent to the buffer layer to the upper-layer solvent is 2: 1-1.5: 1.5-3.

In the preparation method of the covalent organic framework film material with the Tuoling structure, the buffer layer is acetic acid, Sc (OTf)₃、Eu(OTf)₃Or water. The concentration of the acetic acid is 2-6M.

In the preparation method of the covalent organic framework membrane material with the Tuoling structure, the upper layer solvent is ethanol, water or CH₂Cl₂Mixed solvent with DMF. The CH₂Cl₂The volume ratio of the DMF to the DMF is 6: 1-4.

Example 1 preparation of t-TpMa-COF films

t-TpMa-COF membranes were synthesized in a beaker: first, Tp is dissolved in the lower solvent and the buffer layer is added. Ma was then dissolved in the upper solvent and added slowly on top of the buffer layer. The mixture was left undisturbed at room temperature for 7 days. The buffer layer disappears and t-TpM is obtained at the interface of the upper and lower layersa-COF film with H₂O and CH₂Cl₂And (6) washing. The selection and the amount of the solvent are shown in the following table 1:

TABLE 1

Characterization of the t-TpMa-COF prepared in Table 1: from the IR spectrum (FIG. 2a), it can be seen that Tp in t-TpMa-COF has a length of C ═ O (1644 cm)^-1) Characteristic absorption peaks and-NH of Ma₂(～3200-3430cm^-1) The characteristic absorption peak disappears, C ═ C (1574 cm)^-1) The occurrence of characteristic absorption peaks of (a) demonstrates the successful performance of the aldol condensation reaction. Consistent with the results in the infrared, of t-TpMa-COF¹³C solid nuclear magnetic spectrum (¹³C solid-state nuclear magnetic resonance,¹³C SSNMR) pattern (fig. 2b) also exhibited C — N characteristic peak at 102 ppm. Next, the present invention investigated the way of stacking t-TpMa-COF sheets by means of Materials Studio (MS) simulation based on Powder X-ray (PXRD) data (FIG. 2 c). MS simulation shows that the simulation value of the AA stacking mode is better matched with the experimental value, and diffraction peaks of t-TpMa-COF at 9.25 degrees and 26.82 degrees can respectively correspond to the 100,001 crystal plane. In general, the pore size of materials varies significantly depending on the manner in which they are stacked. If AA stacking is adopted, the corresponding pore diameter of the material isLeft and right; if AB stacking is used, the pores of the material will be greatly reduced by the staggered barrier, ofIn order to further determine the stacking mode of the t-TpMa-COF, the invention carries out N on the t-TpMa-COF₂And (5) adsorption and desorption characterization. The results are shown in the figure (FIG. 2d), where the adsorption isotherm of t-TpMa-COF is in the form of an I-type adsorption isotherm, indicating that the pores of the material belong to micropores. The average pore diameter of the t-TpMa-COF can be obtained by calculation according to a non-local density functional methodThis matched the pore size of the AA stack, confirming that t-TpMa-COF was stacked with AA.

An electron microscope for spherical aberration correction was used to deeply reveal the regular ordered microstructure of t-TpMa-COF film material (FIG. 3), from which it can be observed that t-TpMa-COF film material resembles a honeycomb COF structural framework, in which bright spots and black correspond to structural units and 1D channels, consistent with the simulated structural type. The lattice grain spacing in the electron micrograph was measured to be about 0.33nm, which is consistent with the presence of a diffraction peak at 26.82 ° in XRD, which corresponds to the 001 plane of t-TpMa-COF. In addition, the Selected Area Electron Diffraction (SAED) pattern (FIG. 3d) shows that t-TpMa-COF has distinct electron diffraction points. In addition, the content of each element in the t-TpMa-COF is determined by element analysis, and the measurement result is closer to the theoretical calculation value.

The t-TpMa-COF film material prepared by adopting the liquid-liquid interfacial polymerization method forms different film surface appearances at the interface of two solvents. A poriform turing structure is formed on the water side of the interface of the two phases, and the water contact angle test shows that the side is super-hydrophilic (fig. 4b, c). On the dichloromethane side, a dense linear turing structure resembling the lotus leaf surface is formed. The contact angle on this side was measured to be 100 deg., indicating that it was hydrophobic (fig. 4e, f). And observing the surface morphology of the t-TpMa-COF film material by adopting a Scanning Electron Microscope (SEM). From the SEM images it can be seen that the hydrophilic pore-shaped turing structures consist of spherical aggregates (fig. 4b) and the hydrophobic linear turing structures consist of filamentous aggregates (fig. 4 e). In addition, the different morphological characteristics of the upper and lower sides of the t-TpMa-COF film can be clearly observed by the cross-section SEM test (FIG. 4 a). In order to more intuitively display the hydrophilic and hydrophobic properties directly related to different morphologies of two surfaces of the membrane, a simple solvent-driven ups and downs floating experiment is carried out on the t-TpMa-COF membrane. The t-TpMa-COF film material is placed in water with the super-hydrophilic surface facing upwards, the t-TpMa-COF film material can quickly sink to the water bottom, then the t-TpMa-COF film material is turned over to change the t-TpMa-COF film material into a t-TpMa-COF film material with the hydrophobic surface facing upwards, and at the moment, the t-TpMa-COF film material can quickly float to the water surface. The experiment clearly shows that the prepared t-TpMa-COF film material has the amphiprotic property that one surface is super-hydrophilic and the other surface is hydrophobic, the high affinity of the hydrophilic surface and water molecules and the repulsion characteristic of the hydrophobic surface to the water molecules cause the rapid sinking and floating of the film. In addition, the surface morphology of the t-TpMa-COF film material is further observed by using an Atomic Force Microscope (AFM). From AFM it can be seen (FIG. 4d, g) that the hydrophobic side is smoother, less wrinkled and undulating, with an average surface roughness (Ra) of 215nm, since it is mainly composed of dense linear structures, while the hydrophilic side is mainly composed of loose flocculent structures, with extremely pronounced undulations, with an average surface roughness (Ra) of 900nm, from which it can be seen that there is a large difference in average surface roughness of the two sides of the t-TpMa-COF.

Example 2 stability of t-TpMa-COF film Material

The physical and chemical stability of the membrane is one of the important indexes for ensuring the effective application of the membrane in the actual environment. In consideration of severe application conditions such as high temperature, strong irradiation, strong acidity and the like in a real feed liquid environment in the spent fuel post-treatment process, the invention tests the thermal stability, the acid stability and the irradiation stability of the t-TpMa-COF film material.

1) Thermal stability: by N₂Thermogravimetric analysis in an atmosphere measures the thermal stability of t-TpMa-COF film material.

The measurement results show (fig. 9a) that the weight loss before 100 ℃ is due to evaporation of the water physically absorbed by the material. Slight mass loss (t-TpMa-COF-4.08%) occurs between 100 and 400 ℃, and the mass loss is probably caused by the decomposition of small molecules in the material. The mass loss above 400 ℃ is significantly faster, probably because the structure itself starts to decompose. 66.8% remains up to 500 ℃, indicating that the material has good thermal stability.

2) Irradiation stability: the research on the irradiation stability of the t-TpMa-COF film material shows that (figure 9b) the infrared spectrum of the t-TpMa-COF before and after irradiation has almost no obvious change, which indicates that the t-TpMa-COF has good irradiation stability and can tolerate 10⁵Gamma irradiation of Gy.

The research shows that the t-TpMa-COF film material has higher acid stability, thermal stability and irradiation stability, so that the t-TpMa-COF film material is expected to be applied to ion screening in extreme environments such as spent fuel post-treatment feed liquid and the like.

3) Acid stability: and (3) respectively soaking the t-TpMa-COF film material in 1M, 3M and 5M nitric acid solutions for 72 hours, and then carrying out infrared test on the film material.

As can be seen from the infrared image (FIG. 9c), the characteristic peak position and intensity of the t-TpMa-COF film material have no obvious change, which proves that the t-TpMa-COF film material has stronger acid stability.

Example 3 filtration experiment of t-TpMa-COF Membrane Material

The filtration experiment of the prepared t-TpMa-COF membrane material is carried out by a customized U-shaped glass filter device. The filter device is divided into two parts of stock solution and filtrate by t-TpMa-COF membrane material. When a filtration experiment is carried out, a prepared t-TpMa-COF membrane material is clamped in the middle of the device, and a certain amount of HNO is filled in the stock solution part₃Polyionic solutions having the same ion concentration at (HCl) concentration, the filtrate fractions being filled with the same volume of aqueous solution to equalize the osmotic pressure, while monitoring the H of the aqueous solution using a pH meter⁺And (4) concentration. After the two parts are filled with the solution, ions start to permeate from the stock solution part, and the filtration experiment starts. Both parts were stirred electromagnetically to facilitate the penetration. At one hour intervals, 10mL of each solution was taken out of each of the two parts, and the ion concentration was measured by ICP-OES. Multiplexing experiment after the first filtration experiment, the two parts of solution were directly poured out without disassembling the filtration apparatus, and then 1M HNO was filled in both parts₃The solution was washed with electromagnetic agitation for 2 days to remove ions that may remain on the inner walls or membranes of the device. Subsequently, 1M HNO for cleaning₃Pouring out the solution, respectively filling the two parts with new polyion solution and aqueous solution, starting a second multiplexing experiment of the same membrane, and cleaning again according to the steps after each filtration experiment is finished. The maximum volume of a custom-made U-shaped glass filter device is 1000mL, and a stock solution part and a filtrate part are respectively filled with 400mL of solution when a filtration experiment is carried out.

In order to test the permeability of the hydrophilic surface and the hydrophobic surface of the prepared t-TpMa-COF membrane material to water, an aqueous solution is added into a filter cup on one side of the device, the volume of the filtered water is measured every 30min, and the filtration rate of the water is obtained through conversion.

1) Permeability of water

As two surfaces of the t-TpMa-COF filter membrane respectively have hydrophilic and hydrophobic properties, the two surfaces of the t-TpMa-COF filter membrane respectively have the water permeability. The research shows that (figure 5a), the permeability of the hydrophilic surface to water can reach 2.809L m^-2h^-1And the permeability of the hydrophobic surface to water is only 0.061L m^-2h^-1. This may be caused by the different turing structures on both sides of the t-TpMa-COF. According to the invention, the porous Turing structure of the hydrophilic surface and the super-hydrophilic characteristic thereof enable water molecules to enter more easily and smoothly pass through the longitudinal flow guide channel built by the structure, so that the water permeability of the membrane is greatly increased; the linear pattern structure of the hydrophobic surface is distributed in a plane shape and is very dense, and a longitudinal flow guide channel cannot be constructed, so that water molecules cannot easily penetrate through the surface of the membrane.

2) Permeability of cation

Then, the invention also explores the sieving capability of the hydrophilic surface and the hydrophobic surface of the t-TpMa-COF membrane on metal ions respectively. In order to systematically evaluate the ion sieving performance of t-TpMa-COF, the polyionic solutions selected for the experiments contained 14 cations, including H⁺Alkali metal, alkaline earth metal, transition metal, lanthanide and actinide metal ions, the valency of which includes monovalent, divalent and trivalent.

Preparing a polyion and dye solution: contains (Na)⁺、UO₂ ²⁺、Nd³⁺、Gd³⁺、Sm³⁺、La³⁺、Ce³⁺、Mn²⁺、Sr²⁺、Ba²⁺、Ni²⁺、Co²⁺、Zn²⁺) Polyionic solutions of 13 coexisting ions were prepared according to typical nuclear industry effluent compositions reported in the literature. In the preparation process, a certain mass of corresponding metal oxide or metal oxysalt is weighed and dissolved in concentrated nitric acid, and then diluted to a constant volume, so that the concentration of each metal ion in the multi-ion solution is 5.0mmol L^-1. At different pH values used in the experimentThe multi-ion solution is prepared by transferring multi-ion solution with a certain volume, diluting with water, adding HNO₃Or adjusting the pH value with NaOH, and then fixing the volume to obtain the product.

In the experiment, water and polyion solution are respectively added to two sides of a filter, and the filtering performance of the membrane is researched through the change of the solution concentration along with time. Firstly, the invention adds 1M HNO on one side of the hydrophobic surface of the filter₃The other side of the polyionic solution was added with the same volume of water, and the H content of the aqueous solution was monitored by means of a pH meter⁺The concentration changes, and the occurrence and concentration change of metal ions in the water are monitored by an ICP test. The experimental result shows that 13 metal ions can not pass through the t-TpMa-COF membrane under the experimental condition, but H⁺The membrane can be easily penetrated. The pH of the aqueous solution was reduced from 6.25 to 1.28 with a permeate flux of 54.5mol L^-1m². In the ion screening process, due to the existence of osmotic pressure, water can pass through the membrane to be subjected to reverse osmosis to one side containing the multi-ion solution, so that the volume of the multi-ion solution is increased, and the application of the multi-ion solution in a real spent fuel post-treatment environment is not facilitated. When containing 1M HNO₃When the polyionic solution of (2) was added to the hydrophilic side of the filter, none of the 14 metal ions could pass through the t-TpMa-COF membrane under the same experimental conditions. However, H in the filtrate was clearly observed compared to when the polyionic solution was on the hydrophobic side⁺The concentration increase rate of (A) was greatly improved, the pH was lowered from 6.40 to 0.94 in the same time, and the permeation flux was 119.3mol L^-1m²(see fig. 5b, 6 a). In the process, no obvious volume change is observed on one side of the solution containing the polyions, which shows that when the polyions are in the hydrophilic surface, the specific linear turing structure of the hydrophobic surface effectively blocks the reverse osmosis behavior of water molecules through the membrane, and plays a role in relieving osmotic pressure. In conclusion, when the polyion solution is added to one side of the hydrophilic surface of the filter, the ion screening efficiency is higher, and therefore the polyion solution is added to one side of the hydrophilic surface for experiment in subsequent experiments.

Concentrated nitric acid is widely used as a reactant-solvent in several chemical transformations of nuclear fuel reprocessing. Thus, the liquid waste is finally concentratedDenitration is essential before condensation and storage. The above experiment shows that t-TpMa-COF membrane material has the characteristic of allowing only H⁺The property of not allowing other metals to pass through and the excellent acid stability of the t-TpMa-COF film material provide an important basis for the deacidification treatment of the high-acid waste liquid, so that the increase of the capacity increase and the treatment difficulty caused by the dilution of the high-acid waste liquid in the traditional treatment method can be effectively avoided. The harsh conditions of strong acidity during spent fuel reprocessing render most membrane materials generally ineffective. Therefore, the invention firstly explores the influence of acidity on the filtration performance of the t-TpMa-COF membrane material. The research finds that the product is in 3M HNO₃Under the conditions, the pH of the aqueous solution is reduced from 6.20 to 0.45, and the permeation flux is 368.8mol L^-1m^-2(see fig. 6 b). More surprisingly, in 5M HNO₃(see FIG. 6c), the t-TpMa-COF film material still maintains high-efficiency metal ion blocking capability and still only allows H⁺And (4) passing. The pH of the aqueous solution is reduced from 6.21 to 0.14, and the permeation flux reaches 1015.7mol L^-1m^-2(see fig. 6 c). The research results show that the t-TpMa-COF film material can easily adapt to the harsh conditions of high acidity in the post-treatment process of spent fuel, and can effectively realize the deacidification treatment of the high acidity waste liquid. In addition, t-TpMa-COF membrane is in HNO₃Shows better metal ion interception and H in the system⁺The invention continuously explores the screening capacity of the t-TpMa-COF film material in a hydrochloric acid system. As can be seen from FIGS. 6d and e, under 1M and 3M HCl conditions, t-TpMa-COF effectively blocks the passage of metal ions and only allows H⁺Through, and H⁺Has higher concentration change rate and the permeation flux reaches 108.8 and 299.8mol L^-1m^-2. Also, in the 5M HCl system, the t-TpMa-COF membrane material still remains against H⁺The high-efficiency permeability is realized, the pH value of the aqueous solution is reduced from 6.10 to 0.03, and the permeation flux reaches 970.1mol L^-1m^-2(see fig. 6 f).

Next, the present inventors investigated the effect of time on filtration, taking a nitric acid system with pH 1.8 and a 5M nitric acid system as examples, extending the filtration time to 192 hours. Experiment knotIt was found that both systems were able to achieve H within 24 hours⁺The permeation rate after 24 hours is relatively slow. Importantly, after 192 hours, the t-TpMa-COF film material still maintains high-efficiency metal ion blocking capacity and only allows H⁺Through (fig. 7a, b).

Based on the above experimental results, the present invention provides a possible deacidification mechanism. As shown in fig. 8, in the filtration experiment, the electron-rich group (e.g. n/O) on the t-TpMa-COF membrane material first interacts with the metal cation in the solution and fixes it in the pore channel of the membrane. At this time, metal ions in a high valence state and a large ion diameter are more easily bound and fixed to these electron-rich groups, and thus the original ion transport channel becomes smaller due to the fixation of these metal ions. When other cations want to pass through, the cations are subjected to the charge repulsion effect of the fixed metal cations, so that the cations are difficult to pass through smoothly. And the hydrogen ions have the lowest valence state and the smallest ion diameter, and the charge repulsion action is the smallest, so the hydrogen ions can easily pass through the t-TpMa-COF membrane material under the concentration difference driving action. For anions in solution, the charge repulsion generated by the immobilized metal cations will not work. Therefore, anions also smoothly passed through the t-TpMa-COF membrane material to maintain charge balance, which was confirmed by ion chromatography (FIG. 7c, d).

The invention is based on excellent physical and chemical stability and unique structural characteristics of COFs (Covalent Organic framework) Materials, adopts an interface method to grow a t-TpMa-COF film material with a bidirectional anisotropic Turing structure for the first time, and is applied to the deacidification field. The membrane material has obvious two-sided anisotropy, one side has a linear Turing structure and hydrophobic property, and the other side has a porous Turing structure and super-hydrophilic property. The unique structure improves the permeability of the hydrophilic surface to water by 45 times compared with the hydrophobic surface, and can effectively inhibit the reverse osmosis of water while ensuring the water permeability of the membrane. In addition, the membrane material has excellent acid stability, thermal stability and irradiation stability, and can easily adapt to high-temperature high-acid and strong-radiation extreme rings of spent fuel post-treatment feed liquidAnd (4) environmental conditions. Permeation experiments show that the complex polyion system of the t-TpMa-COF film material has extremely high metal ion retention capacity and HNO with acidity up to 5M₃The filtration experiment is carried out in a simulated feed liquid for more than 192 hours, the metal ion interception rate is 100 percent, hydrogen ions can easily permeate the membrane, and the permeation flux is up to 1015.7mol L^-1m^-2And the efficient deacidification treatment of the high-acidity feed liquid can be effectively realized. The invention provides a new idea for the design and preparation of a novel Tuling structure membrane material, and simultaneously provides a new solution for deacidification volume reduction and treatment process simplification of high-acidity industrial wastewater such as spent fuel post-treatment feed liquid and the like.

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