Supramolecular polymer membrane based on pillararene as well as preparation method and application of supramolecular polymer membrane

Abstract

The invention discloses a pillararene-based supramolecular polymer membrane, a preparation method thereof and application of the pillararene-based supramolecular polymer membrane in dye separation. The preparation method utilizes interfacial polymerization, and comprises the following steps: mixing a CH2Cl2 solution containing MeP5Bpy with an aqueous solution containing tetra (4-aminophenyl) methane and acetic acid, and standing to obtain the pillararene-based supramolecular polymer membrane at the interface of CH2Cl2 and the aqueous solution. The dye separation process is simple to operate and low in equipment requirement; rectification operation is not needed in the separation process, energy consumption is low, energy is saved, and the production cost is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of membrane separation, and in particular to a supramolecular polymer membrane based on pillar aromatics, and a preparation method and application thereof. Background Art

[0002] In the chemical and industrial fields, the separation of dyes has always been a vital task. With the increasingly stringent environmental protection requirements and the increasing demand for industrial production, efficient and environmentally friendly dye separation technology has become a hot topic of research. At the same time, membrane separation technology has become an important part of modern separation technology due to its advantages such as high efficiency, selectivity and low energy consumption. Membrane separation technology has been widely used in many fields such as water treatment, gas separation, food processing and pharmaceutical separation. However, how to further improve the efficiency and selectivity of membrane separation technology is still a major challenge facing scientists.

[0003] Pillar[5]arene, as a typical representative of macrocyclic molecules, has attracted much attention due to its unique structural characteristics. Pillar[5]arene has complex molecular structures, flexible spatial configurations, and internal cavities, which give it significant advantages in dye separation. Its internal cavity can enclose dye molecules and enhance the selectivity and efficiency of the separation process by forming stable complexes. In addition, the chiral recognition sites of pillar[5]arene can specifically interact with dye molecules through non-covalent interactions (such as hydrogen bonds, π-π stacking, and electrostatic interactions), thereby achieving efficient dye separation.

[0004] Pillarene can be cross-linked with special guest molecules to form multifunctional and multi-responsive nanosponge polymers for dyes and heavy metal ions (Fe 3+ ) adsorption. Guan et al. (Guan XW, Lin Q, Zhang YM, et al. Soft Matter, 2019, 15(15): 3241.) designed and constructed a multifunctional sponge-like supramolecular polymer gel (SHG) by using a tripod guest molecule (TA) and a naphthalene diimide-functionalized pillar [5] aromatic hydrocarbon host (AP5). The study found that the HG dry gel also showed an adsorption capacity of Fe 3+, methyl orange, methylene blue and Sudan red I dyes with high separation performance (dye adsorption rate can reach 99.8%). Zhang et al. (Zhang H, Wu JR, Wang X, et al. Dyes Pigments, 2019, 162: 512.) successfully prepared the column [5] aromatic modified Fe3O4 magnetic nanoparticles (CP5-MNPs) with highly controllable pore size distribution by a one-step solvothermal method for the first time; the study found that CP5-MNPs with an average diameter of (446 ± 57) nm had the best adsorption efficiency, with the maximum adsorption rates of methylene blue and crystal violet being 98.6% and 98.9%, respectively. Yuan et al. (Yuan B, Xu JF, Sun CL, et al. ACS Appl MaterInter) assembled the macrocyclic main molecule - pillar[6]arene into a multilayer membrane to improve the mechanical strength of the membrane. The study found that the multilayer membrane containing the rigid structure of pillar[6]arene has good specificity and binding and release reversibility for methyl viologen derivatives of appropriate size. It can be foreseen that this multilayer membrane will be used in the field of dye enrichment and purification of methyl viologen-contaminated water in the future.

[0005] Introducing column[5]arene into membrane materials can give full play to its unique structural advantages and further improve the separation performance of membrane materials. In this way, the membrane material not only inherits the chiral recognition and inclusion effect of column[5]arene, but also significantly improves the mechanical strength and chemical stability of the membrane material. This new column[5]arene-based membrane material shows broad application prospects in the field of dye separation. It can not only improve the efficiency and selectivity of dye separation, but also reduce the environmental pollution in traditional separation methods, which is in line with the concept of green chemistry and sustainable development.

[0006] In conclusion, dye separation and membrane separation are both important topics in modern chemistry and industry. Pillar[5]arene, as a macrocyclic molecule with unique structural characteristics, shows unique advantages in dye separation. The development of this new material not only promotes the development of membrane separation technology, but also provides strong support for solving the difficulties in dye separation. It has important research value and application prospects. With the deepening of research, pillar[5]arene-based membrane materials will play an increasingly important role in dye separation and other separation technology fields. Summary of the invention

[0007] The invention provides a supramolecular polymer membrane based on pillar aromatics, a preparation method thereof and application of the membrane in dye separation.

[0008] The present invention uses the aldehyde-column [5] aromatic hydrocarbon material MeP5Bpy as one of the raw materials to synthesize a supramolecular polymer film for separating dyes such as Congo red. The supramolecular polymer film material exhibits significant advantages of high selectivity, high efficiency, simple operation, good stability, strong controllability and environmental friendliness in separating dyes such as Congo red. These advantages improve the efficiency and effect of separating dyes such as Congo red, and provide new tools and methods for the development of the field of dye separation.

[0009] [1] A method for preparing a supramolecular polymer membrane based on pillar aromatic hydrocarbons by interfacial polymerization, comprising: mixing a CH2Cl2 solution containing MeP5Bpy with an aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid and allowing the mixture to stand, thereby obtaining the supramolecular polymer membrane based on pillar aromatic hydrocarbons at the interface between the CH2Cl2 and the aqueous solution;

[0010] The MeP5Bpy has the structure shown below:

[0011]

[0012] The tetrakis(4-aminophenyl)methane has the structure shown below:

[0013]

[0014] The pillararene-based supramolecular polymer membrane contains C═N bonds generated by the aldehyde-amine condensation reaction between the MeP5Bpy and the tetrakis(4-aminophenyl)methane.

[0015] In the method for preparing the supramolecular polymer membrane based on pillar aromatic hydrocarbons described in [1], in the CH2Cl2 solution containing MeP5Bpy, the ratio of the mass of MeP5Bpy to the volume of CH2Cl2 can be 20 to 30 mg:5 mL.

[0016] In the method for preparing the supramolecular polymer membrane based on pillararenes described in [1], in the aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid, the ratio of the mass of tetrakis(4-aminophenyl)methane to the volume of water can be 4 to 6 mg:5 mL.

[0017] In the method for preparing a supramolecular polymer membrane based on pillararene described in [1], the concentration of acetic acid in the aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid may be 0.05 to 0.07 mol / L.

[0018] In the method for preparing the supramolecular polymer membrane based on pillar aromatics described in [1], the volume ratio of the CH2Cl2 solution containing MeP5Bpy to the aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid can be 1:1 to 1.1.

[0019] In the method for preparing the pillararene-based supramolecular polymer membrane described in [1], the molar ratio of the MeP5Bpy to the tetrakis(4-aminophenyl)methane can be 1.9 to 2.1:1, such as 2:1.

[0020] In the method for preparing a pillararene-based supramolecular polymer film described in [1], the mixing and standing can be performed in a sealed container.

[0021] [2] A pillararene-based supramolecular polymer membrane prepared according to the preparation method described in [1].

[0022] The thickness of the pillararene-based supramolecular polymer film can be as thin as 1 to 1.5 micrometers, such as 1.32±0.03 micrometers.

[0023] [3] Use of the pillararene-based supramolecular polymer membrane according to [2] in dye separation. Further, the dye may include one or more of methyl red, Ronny red, methylene blue, methyl orange, Safranine O, Rhodamine B, Orange G, acid-washed fuchsin, Congo red, etc.

[0024] [4] A dye separation method, comprising: using the pillar aromatic hydrocarbon-based supramolecular polymer membrane described in [2] to filter a mixed liquid containing the dye to achieve dye retention.

[0025] [4] In the dye separation method described in claim 4, the dye may include one or more of methyl red, Ronnie red, methylene blue, methyl orange, Safranine O, Rhodamine B, Orange G, acid-washed fuchsin, Congo red, etc.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The present invention uses aldehyde-based pillar[5]arene and tetrakis(4-aminophenyl)methane to prepare a pillararene-based supramolecular polymer membrane material through aldehyde-ammonia condensation, which is used to separate dyes. The aldehyde-based pillar[5]arene is dissolved in CH2Cl2, the tetrakis(4-aminophenyl)methane is dissolved in water, and then an acetic acid aqueous solution is added, and the two are mixed in a sealed container and allowed to stand for a period of time, and a pillararene-based supramolecular polymer membrane can be obtained at the interface between dichloromethane and the aqueous solution.

[0028] The effective molecular weight cutoff threshold of the target dye molecule of the pillararene-based supramolecular polymer membrane material of the present invention is about 350 g / mol.

[0029] The dye separation process of the present invention is simple to operate and has low equipment requirements; the separation process does not require distillation operation, has low energy consumption, saves energy, and reduces production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1The hydrogen nuclear magnetic resonance (HNMR) of the aldehyde column [5] aromatic material MeP5Bpy in Example 1 1 H NMR) spectrum.

[0031] Figure 2 It is a schematic diagram of mixing and standing of a method for preparing a supramolecular polymer membrane based on pillar aromatics of the present invention and a schematic diagram of the molecular structure of the obtained supramolecular polymer membrane based on pillar aromatics.

[0032] Figure 3 The figure shows the characterization results of the polymer film material of Example 2, including X-ray diffraction (XRD), infrared spectrum, and scanning electron microscope (SEM) photos.

[0033] Figure 4 The ultraviolet spectra of Congo red dye before and after separation in Example 3 (left figure) and the retention rate results of dye molecules with different molecular weights (right figure) are shown. DETAILED DESCRIPTION

[0034] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0035] Example 1

[0036] Preparation of aldehyde-column [5]arene MeP5Bpy:

[0037] (1) Synthesis of MeP4Q1: MeP5 (7.50 g, 10.0 mmol) was dissolved in 250 mL of dichloromethane (CH2Cl2), cerium (IV) diammonium nitrate (CAN, 10.9 g, 20.0 mmol) was dissolved in 20 mL of water, and then an aqueous solution of cerium diammonium nitrate was added dropwise to the dichloromethane. The mixture was stirred at room temperature for 30 minutes. The reaction was terminated by adding 200 mL of water. The organic layer was separated, washed three times with water, and then concentrated to obtain a dark red solid (6.80 g). The mixture was used in the next step without further purification.

[0038] (2) Synthesis of MeP5(OH)2: The dark red solid obtained in (1) was dissolved in 200 mL of tetrahydrofuran (THF), and a solution of sodium thiosulfate (NaBH4, 1.90 g, 50.0 mmol) dissolved in 200 mL of methanol was added. The mixture was stirred at room temperature under an argon atmosphere, and the red solution almost immediately turned pale yellow. The reaction was quenched with water, and the organic layer was separated and washed three times with water. After removing the volatiles, a pale yellow solid (5.23 g) was obtained, which was immediately used in the next step without further purification.

[0039] (3) Synthesis of MeP5(OTf)2: Trifluoromethanesulfonic anhydride (Tf2O, 20 mL) was added dropwise to a mixture of MeP5(OH)2 (5.02 g, 6.90 mmol) and pyridine (dried, 10 mL) in CH2Cl2 (dried, 200 mL) at 0°C under argon atmosphere. The mixture was then stirred at room temperature for 24 hours and then quenched with water. After washing the organic phase three times with water, the organic layer was concentrated under vacuum and subjected to silica gel chromatography (petroleum ether / CH2Cl2=1:1) to obtain MeP5(OTf)2 (5.31 g, 78%) in the form of a white powder.

[0040] (4) Synthesis of column [5] arene containing aldehyde group (MeP5BPy): Tetrakis(triphenylphosphine)palladium (266 mg, 230 μmol), MeP5(OTf)2 (1.00 g, 1.00 mmol), 4-pyridineboronic acid pinacol ester (1.20 g, 6.00 mmol) and potassium carbonate (K2CO3, 2.50 g, 1.80 mmol) were added to 80 mL of mixed solvent (THF / H2O, 3:1 v / v). The mixture was stirred at 100°C for 24 h. After cooling to room temperature, the excess solvent was removed on a rotary evaporator under reduced pressure. After adding 200 mL of CH2Cl2, the solution was washed with deionized water (2×100 mL) and brine (100 mL), dried (Na2SO4), concentrated under vacuum, and finally recrystallized (CHCl3 / petroleum ether) to obtain MeP5BPy (621 mg, 73%) in the form of pale red crystals.

[0041] The product MeP5BPy prepared in this example is characterized by hydrogen nuclear magnetic resonance. Figure 1 The specific data are as follows:

[0042] 1 H NMR (400MHz, CDCl3, 298K) δ (ppm): 10.02 (s, 2H), 7.63 (d, J = 8.1Hz, 4H), 7.08 (d, J = 7.8Hz, 4H), 6.87 (s, 2H), 6.75 (s, 2H), 6.71(s,2H),6.55(s,2H),5.92(s,2H),3.93–3.73(m,10H),3.69(d,J=5.9Hz,6H),3.57(s,6H),3.38(s,6H),3.30(s,6H).

[0043] The synthetic route of the above preparation process can be expressed as follows:

[0044]

[0045] Example 2

[0046] Preparation of supramolecular polymer membrane based on pillar aromatics: 23.4 mg of MeP5BPy (or MeP5-CHO) was dissolved in 5 mL of CH2Cl2; 5 mg of tetrakis(4-aminophenyl)methane was dissolved in 5 mL of water, and then 60 μL of 5 mol / L acetic acid aqueous solution was added; the above two solutions were mixed in a sealed bottle and allowed to stand for a period of time. Figure 2 As shown, a supramolecular polymer membrane based on pillararenes can be obtained at the interface between dichloromethane and aqueous solution.

[0047] Figure 3 The XRD, IR and SEM characterization results of the polymer film material (Membrane) prepared as described above are shown. XRD spectrum ( Figure 3 a) shows that the film material is not the ideal COF material. Infrared spectrum ( Figure 3 b) Displayed at 1601cm -1 A new C=N bond appears at the position of the aldehyde column [5] aromatic hydrocarbon and tetrakis (4-aminophenyl) methane react through aldehyde-ammonia condensation. SEM image ( Figure 3 c. Figure 3 d) shows that a traditional ridge-valley structure appears on the membrane surface, which is consistent with the common membrane structure reported in the literature and can effectively accelerate the diffusion rate of the solvent. The thickness of the membrane is 1.295 μm to 1.344 μm.

[0048] Example 3

[0049] Separation of dyes:

[0050] (1) Prepare standard solutions of different dye molecules:

[0051] The dye molecules are methyl red, Ronnie red, methylene blue, methyl orange, safranin O, rhodamine B, orange G, acid-washed fuchsin, and Congo red;

[0052] For each dye molecule, (10, 20, 30, 40, 50) mg of dye was weighed and dissolved in 1 L of water to prepare concentrations of (10, 20, 30, 40, 50) mg / L, respectively.

[0053] (2) Establish a standard curve:

[0054] Test the UV spectra of solutions of different concentrations respectively, record the chromatographic peak areas, and draw standard curves.

[0055] (3) Determination of samples:

[0056] The polymer film prepared in Example 2 was laid flat on a hydrophilic PES polyethersulfone filter membrane, which was then fixed on a membrane analyzer. The separation performance was determined by filtering aqueous dye solutions of different molecular weights and analyzing the filtrate. Figure 4 The left-center figure shows the ultraviolet spectra of Congo red dye before and after separation. Through calculation, it can be obtained that the retention rate of Congo red by the membrane is 91%, showing a significant retention efficiency. Figure 4 The middle right figure shows the retention rate of dye molecules with different molecular weights, indicating that the effective retention molecular weight threshold of the target molecule of the membrane is 350 g / mol.

[0057] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A method for preparing a supramolecular polymer membrane based on pillararene, characterized in that: Using interfacial polymerization, including: mixing a CH2Cl2 solution containing MeP5Bpy with an aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid and standing the mixture, to obtain the pillararene-based supramolecular polymer film at the interface between the CH2Cl2 and the aqueous solution; The MeP5Bpy has the structure shown below: The tetrakis(4-aminophenyl)methane has the structure shown below: The pillararene-based supramolecular polymer membrane contains C═N bonds generated by the aldehyde-amine condensation reaction between the MeP5Bpy and the tetrakis(4-aminophenyl)methane.

2. The preparation method according to claim 1, characterized in that: In the CH2Cl2 solution containing MeP5Bpy, the ratio of the mass of MeP5Bpy to the volume of CH2Cl2 is 20-30 mg:5 mL.

3. The preparation method according to claim 1, characterized in that: In the aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid: The ratio of the mass of tetrakis(4-aminophenyl)methane to the volume of water is 4-6 mg:5 mL; and / or, The acetic acid concentration is 0.05~0.07mol / L.

4. The preparation method according to claim 1, characterized in that: The volume ratio of the CH2Cl2 solution containing MeP5Bpy to the aqueous solution containing tetrakis(4-aminophenyl)methane and acetic acid is 1:1 to 1.

1.

5. The preparation method according to claim 1, characterized in that: The molar ratio of the MeP5Bpy to the tetrakis(4-aminophenyl)methane is 1.9-2.1:

1. 6 . The pillararene-based supramolecular polymer membrane prepared according to the preparation method according to claim 1 .

7. Use of the pillararene-based supramolecular polymer membrane according to claim 6 in dye separation.

8. The use according to claim 7, characterized in that: The dye comprises one or more of methyl red, Ronnie red, methylene blue, methyl orange, safranine O, rhodamine B, orange G, acid-washed fuchsin, and Congo red.

9. A dye separation method, characterized in that: include: The pillararene-based supramolecular polymer membrane of claim 6 is used to filter a mixed solution containing a dye to achieve dye retention.

10. The dye separation method according to claim 9, characterized in that: The dye comprises one or more of methyl red, Ronnie red, methylene blue, methyl orange, safranine O, rhodamine B, orange G, acid-washed fuchsin, and Congo red.

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