Water channel membrane capable of accurately regulating and controlling sub-nano aperture and preparation method of water channel membrane

Abstract

The invention discloses a water channel membrane with precisely regulated sub-nano aperture and a preparation method thereof, and belongs to the field of membrane separation. The preparation method comprises the following steps: firstly, preparing a hydroxyl artificial water channel colloidal solution by using octyl carbamido polyol, carrying out amino modification on a hydroxyl water channel to obtain an aminated water channel solution, infiltrating a base membrane with the amino modified water channel solution, removing redundant liquid on the surface of the membrane, covering the surface of the base membrane with n-hexane containing trimesoyl chloride, and carrying out vacuum drying to obtain the membrane. And carrying out interfacial polymerization reaction, and drying to obtain the water channel membrane with the sub-nano pore diameter accurately regulated and controlled. Compared with a traditional material reverse osmosis membrane, a hydroxyl artificial water channel is introduced into the polyamide layer to serve as a main mass transfer channel, the sub-nano aperture of the membrane can be precisely regulated and controlled according to the concentration of a water channel solution, selective regulation and control of performance (conversion from nanofiltration to reverse osmosis) are achieved, and therefore the membrane has good adaptability and flexibility. According to the preparation method, the amino-modified hydroxyl water channel solution is simple and convenient to prepare and environmentally friendly, the whole membrane preparation process does not need to be changed in the amplification process, and industrialization of a new membrane preparation formula is easy to achieve.

Description

Technical Field

[0001] The present invention belongs to the technical field of membrane separation, and specifically relates to a water channel membrane with sub-nanometer pore size precise control and a preparation method thereof. Background Art

[0002] Nanofiltration and reverse osmosis technologies are widely used in the fields of seawater desalination, wastewater treatment, and biomedicine. Nanofiltration and reverse osmosis membranes are composed of a porous support layer (base membrane) and an active separation layer. The morphology of the active separation layer (pore size and surface morphology of the separation layer, etc.) has an important influence on the macroscopic performance of reverse osmosis and nanofiltration membranes. Nanofiltration membranes can intercept nanoscale substances, and the molecular weight of organic matter they intercept is about 200 to 800. The ability to intercept dissolved salts is between 20% and 98%, and the removal rate of soluble monovalent ions is lower than that of high-valent ions; reverse osmosis membranes are the most sophisticated membrane separation products, with a desalination rate of more than 99%, and can effectively intercept organic matter with a molecular weight greater than 100, while allowing water molecules to pass through.

[0003] However, the water-phase monomers used in the preparation of nanofiltration membranes and reverse osmosis membranes by traditional interfacial polymerization are piperazine and m-phenylenediamine, respectively. It is difficult to achieve the conversion of nanofiltration and reverse osmosis membranes by adjusting the concentration of a single type of monomer, which restricts the controllability of the membrane preparation process and increases the complexity of the production line. Therefore, it is urgent to innovate membrane preparation methods and design new water-phase monomers to achieve selective regulation of membrane performance (mutual conversion between nanofiltration and reverse osmosis). The R&D team proposed using amino-modified hydroxyl water channels directly as water-phase monomers, and the pore size of the polyamide separation layer can be precisely controlled at the sub-nanometer scale by adjusting the concentration. Summary of the invention

[0004] The purpose of the present invention is to provide a water channel membrane with sub-nanometer pore size precise control and a preparation method thereof, which can realize precise control of the pore size of the membrane separation layer at the sub-nanometer scale, and realize selective control of the membrane performance from nanofiltration to reverse osmosis as the concentration of the water channel solution increases.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention proposes a method for preparing a water channel membrane with sub-nanometer pore size precise control, the method comprising: firstly preparing octyl urea octyl polyol by using aminopropylene glycol and isocyanic acid, then preparing a water / ethanol colloidal solution (water channel solution) of octyl urea octyl polyol, then aminoating the water channel solution, soaking a base membrane in the amino-modified water channel solution, removing excess liquid on the membrane surface, and then covering the surface of the base membrane with n-hexane containing trimesoyl chloride, causing an interfacial polymerization reaction, and drying to obtain the water channel membrane.

[0007] The water channel membrane preparation method, the amino-modified water channel solution is prepared by the following method: octylurea polyol is added to a water / ethanol mixed solution to obtain a polymer solution, the polymer solution and N,N′-carbonyldiimidazole are added to a dimethyl sulfoxide solution, and then ethylenediamine is added to obtain an amino-modified water channel solution.

[0008] The preparation method of the water channel membrane, the specific preparation process is as follows:

[0009] (1) Preparation of octylurea polyol: aminopropylene glycol and octyl isocyanate are mixed to obtain a white solid; the mixture is heated at 80° C. for 1 to 3 hours, and the white solid is dissolved in a mixed solution of tetrahydrofuran, ethyl acetate and acetonitrile; the mixture is evaporated to dryness, washed with methanol and hexane, and dried to obtain octylurea polyol.

[0010] (2) Preparation of hydroxyl artificial water channel colloidal solution: Octylurea polyol, ethanol and water are prepared in proportion to prepare a water / ethanol colloidal solution of hydroxyl artificial water channel.

[0011] (3) Amino modification of hydroxyl water channels: A water / ethanol colloidal solution of octylhydroxyl water channels and N,N′-carbonyldiimidazole are dissolved in a dimethyl sulfoxide solution in a certain proportion. After a certain period of time, ethylenediamine is added to obtain an amino-modified water channel solution. The amino-modified water channel solution and water are mixed in a certain proportion to prepare an aqueous solution with a mass concentration of 0.05 to 0.3 wt / v%.

[0012] (4) Basement membrane infiltration: The basement membrane is immersed in the amino-modified water channel solution for 1 to 5 minutes, and then the excess liquid on the membrane surface is removed.

[0013] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1-0.3 wt / v% hexane solution of trimesoyl chloride for 30-120 seconds, remove excess solution on the film surface, and then dry.

[0014] 5. The preparation method according to claim 4, characterized in that in step (1), the white solid is mixed by 5-15 mmol of aminopropylene glycol and octyl isocyanate in equal amounts, the amount of tetrahydrofuran in the mixed solution is 5-10 ml, and the amount of ethyl acetate and acetonitrile in equal volumes is 3-8 ml.

[0015] 6. The preparation method according to claim 4, characterized in that in step (1), the octylurea polyol is evaporated to dryness by rotary evaporation drying technology.

[0016] 7. The preparation method according to claim 4, characterized in that in step (2), the volume ratio of ethanol to water in the water / ethanol colloidal solution of the hydroxyl water channel is 1:1, the mass concentration of octylurea polyol is 5-15 mg / mL, and the ultrasonic time is 10-20 minutes.

[0017] 8. The preparation method according to claim 4, characterized in that in step (3), the mass concentration of N,N′-carbonyldiimidazole is 2-4 g / mL, the amount of water / ethanol colloid solution of octylhydroxyl water channel, the amount of dimethyl sulfoxide solution, and the amount of ethylenediamine are 15-20 mL.

[0018] 9. The preparation method according to any one of claims 4 to 7, characterized in that in step (4), the content of trimesoyl chloride in the n-hexane solution of trimesoyl chloride is 1 to 4 g / L.

[0019] The present invention has the following beneficial effects:

[0020] (1) The aminated water channel monomer is easy to prepare, does not require the synthesis of additional materials, is readily available, and the preparation process is green and environmentally friendly.

[0021] (2) By using amino water channels as aqueous phase monomers, the pore size of the polyamide separation layer can be precisely controlled at the sub-nanometer scale, allowing the membrane separation accuracy to be switched between nanofiltration and reverse osmosis.

[0022] (3) The present invention only needs to replace the traditional piperazine / m-phenylenediamine with an amino water channel, thereby simplifying the overall membrane-making process and facilitating the industrialization of the new membrane-making formula. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a scanning electron microscope image of the surface of the polyamide layer of the six water channel membranes prepared in Comparative Example 1 and Examples 1-5. Figure 2 It is a comparison chart of water permeability, sodium sulfate retention rate and sodium chloride retention rate of four water channel membranes prepared in Comparative Example 1 and Examples 1-5. DETAILED DESCRIPTION

[0024] The present invention is described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Comparative Example 1

[0026] (1) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole was added to 30 mL of dimethyl sulfoxide solution and stirred at 60° C. for 12 h, and then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aqueous phase solution.

[0027] (2) Basement membrane infiltration: The basement membrane is immersed in the above aqueous solution for 2 min, and then the excess liquid on the membrane surface is removed;

[0028] (3) Interfacial polymerization: The surface of the base film is treated with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, and the excess solution on the film surface is removed, followed by drying.

[0029] Example 1

[0030] (1) Preparation of octylurea polyol: 10 mmol of aminopropylene glycol and octyl isocyanate in equal molar amounts were mixed and ultrasonically treated to obtain a white solid; the white solid was dissolved in a mixed solution of 10 mL of tetrahydrofuran, 5 mL of ethyl acetate and 5 mL of acetonitrile under heating at 80° C. for 2 h; the solution was evaporated to dryness using a rotary evaporation drying technique to obtain a white powder, which was then washed with methanol and hexane and dried to obtain octylurea polyol.

[0031] (2) Preparation of hydroxyl artificial water channel colloidal solution: a water / ethanol mixed solution was prepared with a volume ratio of deionized water to ethanol of 1:1; a certain amount of octylurea polyol was then added to the water / ethanol mixed solution, and ultrasonicated for 15 min to obtain a 10 mg / mL water / ethanol colloidal solution of hydroxyl water channels.

[0032] (3) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole and 20 mL of the above hydroxyl water channel were added to 30 mL of dimethyl sulfoxide solution and stirred at 60°C for 12 h, then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aminated water channel solution. The aminated water channel solution and water were mixed in proportion to prepare an aqueous solution with a mass concentration of 0.07 wt / v%.

[0033] (4) Basement membrane infiltration: The basement membrane was immersed in the amino-modified water channel solution for 2 min, and then the excess liquid on the membrane surface was removed;

[0034] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, remove the excess solution on the film surface, and then dry it.

[0035] Example 2

[0036] (1) Preparation of octylurea polyol: 10 mmol of aminopropylene glycol and octyl isocyanate in equal molar amounts were mixed and ultrasonically treated to obtain a white solid; the white solid was dissolved in a mixed solution of 10 mL of tetrahydrofuran, 5 mL of ethyl acetate and 5 mL of acetonitrile under heating at 80° C. for 2 h; the solution was evaporated to dryness using a rotary evaporation drying technique to obtain a white powder, which was then washed with methanol and hexane and dried to obtain octylurea polyol.

[0037] (2) Preparation of hydroxyl artificial water channel colloidal solution: a water / ethanol mixed solution was prepared with a volume ratio of deionized water to ethanol of 1:1; a certain amount of octylurea polyol was then added to the water / ethanol mixed solution, and ultrasonicated for 15 min to obtain a 10 mg / mL water / ethanol colloidal solution of hydroxyl water channels.

[0038] (3) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole and 20 mL of the above hydroxyl water channel were added to 30 mL of dimethyl sulfoxide solution and stirred at 60° C. for 12 h, then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aminated water channel solution. The aminated water channel solution and water were mixed in proportion to prepare an aqueous solution with a mass concentration of 0.1 wt / v%.

[0039] (4) Basement membrane infiltration: The basement membrane was immersed in the amino-modified water channel solution for 2 min, and then the excess liquid on the membrane surface was removed;

[0040] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, remove the excess solution on the film surface, and then dry it.

[0041] Example 3

[0042] (1) Preparation of octylurea polyol: 10 mmol of aminopropylene glycol and octyl isocyanate in equal molar amounts were mixed and ultrasonically treated to obtain a white solid; the white solid was dissolved in a mixed solution of 10 mL of tetrahydrofuran, 5 mL of ethyl acetate and 5 mL of acetonitrile under heating at 80° C. for 2 h; the solution was evaporated to dryness using a rotary evaporation drying technique to obtain a white powder, which was then washed with methanol and hexane and dried to obtain octylurea polyol.

[0043] (2) Preparation of hydroxyl artificial water channel colloidal solution: a water / ethanol mixed solution was prepared with a volume ratio of deionized water to ethanol of 1:1; a certain amount of octylurea polyol was then added to the water / ethanol mixed solution, and ultrasonicated for 15 min to obtain a 10 mg / mL water / ethanol colloidal solution of hydroxyl water channels.

[0044] (3) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole and 20 mL of the above hydroxyl water channel were added to 30 mL of dimethyl sulfoxide solution and stirred at 60° C. for 12 h, then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aminated water channel solution. The aminated water channel solution and water were mixed in proportion to prepare an aqueous solution with a mass concentration of 0.6 wt / v%.

[0045] (4) Basement membrane infiltration: The basement membrane was immersed in the amino-modified water channel solution for 2 min, and then the excess liquid on the membrane surface was removed;

[0046] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, remove the excess solution on the film surface, and then dry it.

[0047] Example 4

[0048] (1) Preparation of octylurea polyol: 10 mmol of aminopropylene glycol and octyl isocyanate in equal molar amounts were mixed and ultrasonically treated to obtain a white solid; the white solid was dissolved in a mixed solution of 10 mL of tetrahydrofuran, 5 mL of ethyl acetate and 5 mL of acetonitrile under heating at 80° C. for 2 h; the solution was evaporated to dryness using a rotary evaporation drying technique to obtain a white powder, which was then washed with methanol and hexane and dried to obtain octylurea polyol.

[0049] (2) Preparation of hydroxyl artificial water channel colloidal solution: a water / ethanol mixed solution was prepared with a volume ratio of deionized water to ethanol of 1:1; a certain amount of octylurea polyol was then added to the water / ethanol mixed solution, and ultrasonicated for 15 min to obtain a 10 mg / mL water / ethanol colloidal solution of hydroxyl water channels.

[0050] (3) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole and 20 mL of the above hydroxyl water channel were added to 30 mL of dimethyl sulfoxide solution and stirred at 60° C. for 12 h, then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aminated water channel solution. The aminated water channel solution and water were mixed in proportion to prepare an aqueous solution with a mass concentration of 1.0 wt / v%.

[0051] (4) Basement membrane infiltration: The basement membrane was immersed in the amino-modified water channel solution for 2 min, and then the excess liquid on the membrane surface was removed;

[0052] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, remove the excess solution on the film surface, and then dry it.

[0053] Example 5

[0054] (1) Preparation of octylurea polyol: 10 mmol of aminopropylene glycol and octyl isocyanate in equal molar amounts were mixed and ultrasonically treated to obtain a white solid; the white solid was dissolved in a mixed solution of 10 mL of tetrahydrofuran, 5 mL of ethyl acetate and 5 mL of acetonitrile under heating at 80° C. for 2 h; the solution was evaporated to dryness using a rotary evaporation drying technique to obtain a white powder, which was then washed with methanol and hexane and dried to obtain octylurea polyol.

[0055] (2) Preparation of hydroxyl artificial water channel colloidal solution: a water / ethanol mixed solution was prepared with a volume ratio of deionized water to ethanol of 1:1; a certain amount of octylurea polyol was then added to the water / ethanol mixed solution, and ultrasonicated for 15 min to obtain a 10 mg / mL water / ethanol colloidal solution of hydroxyl water channels.

[0056] (3) Amino modification of hydroxyl water channel: 1.56 g of N,N′-carbonyldiimidazole and 20 mL of the above hydroxyl water channel were added to 30 mL of dimethyl sulfoxide solution and stirred at 60° C. for 12 h, then 10 mL of ethylenediamine was added and stirred for another 12 h to obtain an aminated water channel solution. The aminated water channel solution was mixed with water in a proportion to prepare an aqueous solution with a mass concentration of 1.5 wt / v%.

[0057] (4) Basement membrane infiltration: The basement membrane was immersed in the amino-modified water channel solution for 2 min, and then the excess liquid on the membrane surface was removed;

[0058] (5) Interfacial polymerization: Treat the surface of the base film with a 0.1 wt / v% hexane solution of trimesoyl chloride for 60 seconds, remove the excess solution on the film surface, and then dry it.

[0059] Test Example 1

[0060] Surface morphology: Figure 1 The scanning electron microscope observation shown in FIG. 1 shows that the surface of the polyamide layer of the comparative example 1 and the examples 1-5 all show a nodular morphology. Among them, the nodular density of the comparative example 1 is significantly higher than that of the examples, and as the NH 2 -OHAWCs concentration increases, and the nodular density of the examples gradually decreases. At the same time, Examples 3-5 show an increase in nodule diameter, which may be due to the fact that after the water channel concentration increases to a certain level, the concentration increases further, which will cause agglomeration between channel structures, and the resulting nodule diameter is also larger, and the degree of increase in its specific surface area decreases successively.

[0061] Test Example 2

[0062] Water permeability: Use pure water to pre-press each membrane sample at an operating pressure of 5 bar for 1 hour. The test is carried out under the cross-flow filtration conditions of an operating pressure of 5 bar, a water temperature of 25°C, and a cross-flow rate of 20 cm / s. In the same time, the volume of water discharged from each sample membrane is measured and the water permeability is calculated. The test results are shown in the figure. Figure 2 shown.

[0063] Na 2 SO 4 Retention rate: Use pure water to pre-press each membrane sample at 5 bar operating pressure for 1 hour, prepare 1000 mg / L Na 2 SO 4 Aqueous solution, the test was carried out under cross-flow filtration conditions with an operating pressure of 5 bar, a water temperature of 25°C, and a cross-flow rate of 20 cm / s. The inlet and outlet Na 2 SO 4 Concentration, calculated Na 2 SO 4 Retention rate, test results such as Figure 2 shown.

[0064] NaCl retention rate: Use pure water to pre-press each membrane sample at an operating pressure of 5 bar for 1 hour, prepare a 1000 mg / L NaCl aqueous solution, and test it under the cross-flow filtration conditions of an operating pressure of 5 bar, a water temperature of 25°C, and a cross-flow rate of 20 cm / s. The NaCl concentration of the inlet and outlet water is determined based on the conductivity, and the Na 2 SO 4 Retention rate, test results such as Figure 2 shown.

[0065] Depend on Figure 2 It can be seen that with the NH 2 As the concentration of -OHAWCs increased, the water permeability increased from 8.6 L m -2 h -1 bar -1 Down to 1.2L m -2 h -1 bar -1 Na 2 SO 4 The retention of N increased from ∼86.3% to ∼99.3%, and the retention of NaCl increased from ∼43.1% to ∼95% ( Figure 2 ), where Na 2 SO 4 When the retention of NaCl is 95%, the retention of NaCl is 50% (Example 1), which is consistent with the NF membrane properties; when the retention of NaCl is 95%, the retention of Na 2 SO 4 The retention rate is ~99% (Example 5), which is consistent with the RO membrane properties ( Figure 1), so the sub-nanopore size of the membrane prepared based on amino-modified hydroxyl water channels is adjustable, achieving selective performance regulation (from nanofiltration to reverse osmosis).

Claims

1. A water channel membrane with sub-nanometer pore size precision control and its preparation method, It is characterized in that Hydroxyl artificial water channels are introduced into the polyamide layer as the main mass transfer channels. The sub-nanopore size of the membrane can be precisely controlled. As the concentration of the water channel solution increases, the membrane performance can be selectively controlled from nanofiltration to reverse osmosis.

2. A method for preparing a water channel membrane with sub-nanometer pore size precision control, It is characterized in that The method comprises: firstly preparing octyl urea octyl alcohol by using aminopropylene glycol and isocyanic acid; then preparing a water / ethanol colloidal solution of hydroxyl water channels, then aminating the water channel solution, soaking a base membrane in the amino-modified water channel solution, removing excess liquid on the membrane surface, then covering the surface of the base membrane with n-hexane containing trimesoyl chloride, causing an interfacial polymerization reaction, and drying to obtain the water channel membrane.

3. The preparation method according to claim 2, It is characterized in that The amino-modified water channel solution is prepared by the following method: adding octylurea polyol to a water / ethanol mixed solution to obtain a polymer solution, then adding the polymer solution and N,N′-carbonyldiimidazole to a dimethyl sulfoxide solution, and then adding ethylenediamine to obtain an amino-modified water channel solution.

4. The preparation method according to claim 2 or 3, It is characterized in that The method specifically comprises the following steps: (1) Preparation of octylurea polyol: aminopropylene glycol and octyl isocyanate are mixed to obtain a white solid; the mixture is heated at 80° C. for 1 to 3 hours, and the white solid is dissolved in a mixed solution of tetrahydrofuran, ethyl acetate and acetonitrile; the mixture is evaporated to dryness, washed with methanol and hexane, and dried to obtain octylurea polyol. (2) Preparation of hydroxyl artificial water channel colloidal solution: Octylurea polyol, ethanol and water are prepared in proportion to prepare a water / ethanol colloidal solution of hydroxyl artificial water channel. (3) Amino modification of hydroxyl water channels: A water / ethanol colloidal solution of octylhydroxyl water channels and N,N′-carbonyldiimidazole are dissolved in a dimethyl sulfoxide solution in a certain proportion. After a certain period of time, ethylenediamine is added to obtain an amino-modified water channel solution. The amino-modified water channel solution and water are mixed in a certain proportion to prepare an aqueous solution with a mass concentration of 0.05 to 0.3 wt / v%. (4) Basement membrane infiltration: The basement membrane is immersed in the amino-modified water channel solution for 1 to 5 minutes, and then the excess liquid on the membrane surface is removed; (5) Interfacial polymerization: Treat the surface of the base film with a 0.1-0.3 wt / v% hexane solution of trimesoyl chloride for 30-120 seconds, remove excess solution on the film surface, and then dry.

5. The preparation method according to claim 4, It is characterized in that In step (1), the white solid is mixed with 5-15 mmol of aminopropylene glycol and octyl isocyanate in equal amounts, the amount of tetrahydrofuran in the mixed solution is 5-10 ml, and the amount of ethyl acetate and acetonitrile in equal volumes is 3-8 ml.

6. The preparation method according to claim 4, It is characterized in that In step (1), the octylurea polyol is evaporated to dryness by rotary evaporation drying technology.

7. The preparation method according to claim 4, It is characterized in that In step (2), the volume ratio of ethanol to water in the water / ethanol colloidal solution of the hydroxyl water channel is 1:1, the mass concentration of octylurea polyol is 5-15 mg / mL, and the ultrasonic time is 10-20 minutes.

8. The preparation method according to claim 4, It is characterized in that In step (3), the mass concentration of N,N′-carbonyldiimidazole is 2-4 g / mL, the amount of water / ethanol colloid solution of octylhydroxyl water channel, the amount of dimethyl sulfoxide solution, and the amount of ethylenediamine are 15-20 mL.

9. The preparation method according to any one of claims 4 to 7, It is characterized in that In step (4), the content of trimesoyl chloride in the n-hexane solution of trimesoyl chloride is 1-4 g / L.

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