A method for preparing an organic solvent nanofiltration membrane by interfacial polymerization of a polyphosphazene / amine compound

Abstract

This invention discloses a method for preparing organic solvent nanofiltration membranes via interfacial polymerization of polyphosphazene / amine compounds, belonging to the field of membrane separation technology. Addressing the problems of insufficient separation performance and solvent resistance in organic solvent nanofiltration membranes, the method includes: preparing a polyetherimide ultrafiltration membrane using a phase inversion method, and obtaining a polyetherimide-based membrane through a crosslinking reaction; depositing a polydopamine interlayer on the surface of the base membrane; preparing a selective layer through interfacial polymerization using an amine compound as an aqueous monomer, triethylamine as an acid-binding agent, a surfactant as an aqueous additive, and hexachlorotriphosphazene as an organic monomer; and obtaining the polyphosphazene / amine compound organic solvent nanofiltration membrane through heat treatment. The membrane obtained by this invention exhibits good separation performance and solvent resistance, and has promising applications in organic solvent recovery or solvent-solute separation.

Description

[Technical Field]

[0001] This invention relates to a method for preparing organic solvent nanofiltration membranes by interfacial polymerization of polyphosphazene / amine compounds, belonging to the field of membrane separation technology. [Background Technology]

[0002] Organic solvent nanofiltration (OSN) is a pressure-driven membrane separation technology for organic solvent systems, capable of separating solutes and solvents with molecular weights ranging from 200 to 2000 Da. It offers advantages such as high separation efficiency, low energy consumption, and mild operating conditions. Thin-film composite (TFC) membranes are the mainstream type of OSN membrane. Their selective layers are typically prepared via interfacial polymerization (IP), a simple and controllable method that is currently one of the most commonly used techniques for preparing high-performance OSN membranes. Improving the separation performance of TFC membranes involves controlling the microstructure and surface properties of the selective layer by changing the types of reactants, introducing functional intermediate layers, and adding surfactants.

[0003] Polyphosphazenes (PPz) are a class of polymers containing an inorganic-like backbone, whose main chain consists of alternating nitrogen and phosphorus atoms, with each phosphorus atom bonded to two active chlorine groups. Due to their tunable structure, they exhibit excellent chemical stability and adjustable physicochemical properties, making them widely used in the preparation of various functional materials. The two main monomers for preparing PPz are hexachlorotriphosphazene (HCCP) and polydichlorophosphazene (PDCP). The chlorine groups in these monomers are readily replaced by compounds containing amino or hydroxyl groups through nucleophilic substitution reactions, thereby constructing various topologies such as linear, star-shaped, and cyclic matrix polyphosphazenes. Among these, cyclic matrix polyphosphazenes exhibit excellent chemical stability and solvent resistance. Radmanesh et al. used alumina and polyacrylonitrile membranes as supports and 1,1,1-tris(4-hydroxyphenyl)ethane and hexachlorotriphosphazene as monomers to prepare cyclic matrix polyphosphazene membranes via interfacial polymerization, demonstrating the potential of alumina-supported thin-film composite membranes as nanofiltration membranes for organic solvents. However, the selective layer of the thin-film composite membrane prepared using polyacrylonitrile membranes as supports had defects, with an acetone permeation flux of 2.6 L·m⁻¹. -2 ·h -1 ·bar -1 The rejection rate for Na2SO4 was 71.1%, indicating a relatively low solute rejection rate [Journal of Membrane Science, 2023, 668: 121215]. Therefore, the preparation of high-performance OSN membranes using flexible polymers as carriers and HCCP remains a key challenge in this field.

[0004] Dopamine hydrochloride readily undergoes oxidative self-polymerization to form polydopamine (PDA). This polymer exhibits excellent interfacial adhesion, forming coatings on various organic and inorganic materials, and possesses both good antifouling properties and structural stability. Sharafat Ali et al. prepared an OSN membrane using a polybenzimidazole ultrafiltration membrane as the base membrane, forming a polydopamine selective layer on its surface, and using dibromo-p-xylene as a crosslinking agent. This membrane achieved a 99% rejection rate for methyl orange in ethanol [ACS Applied Materials & Interfaces, 2024, 16: 65517-65528]. Peng et al. prepared an OSN membrane using polydopamine / polyethyleneimine (PEI) as the intermediate layer. The hydrophilicity of this intermediate layer promotes the permeation of polar solvents, while its good adhesion ensures a tight bond between the support layer and the selective layer. The resulting nanofiltration membrane had a methanol permeation flux of 14.05 L·m⁻¹. - 2·h -1 • bar-1, with a rejection rate of over 99.42% for Evans blue [Separation and Purification Technology, 2025, 355: 129503]. Li et al. co-deposited polydopamine and the metal-organic framework HKUST-1 on the surface of a cross-linked polyetherimide ultrafiltration membrane as an intermediate layer, and then prepared an OSN membrane through interfacial polymerization, which significantly reduced the thickness of the selective layer and achieved a rejection rate of 92.8% for Congo red [Journal of Environmental Sciences, 2024, 141: 182-193]. The above studies show that polydopamine can be used directly as a selective layer for separation, or as an intermediate layer to improve interfacial bonding and separation performance. Combining the polydopamine intermediate layer with a polyphosphazene / amine compound interfacial polymerization system is expected to provide a new strategy for preparing high-performance OSN membranes. [Summary of the Invention]

[0005] To address the shortcomings of existing organic solvent nanofiltration membranes in terms of separation performance and solvent resistance, this invention provides a method for preparing organic solvent nanofiltration membranes through interfacial polymerization of polyphosphazene / amine compounds, characterized by the following steps:

[0006] a) Preparation of the base membrane: 15g-20g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 1g-4g of polyvinylpyrrolidone, and 76g-84g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric and a film was scraped using a doctor blade with a gap of 50μm-500μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in an 8wt%-15wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane;

[0007] b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.5. Add 0.1 wt% to 0.5 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a constant temperature water bath shaker at 25℃ to 60℃. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 0.5 h to 2 h. After removal, ultrasonically clean with deionized water for 5 min and then heat treat at 60℃ for 10 min to obtain a polydopamine deposition membrane.

[0008] c) Preparation of the selective layer: Dissolve 1 wt% to 8 wt% of amine compounds, 1 wt% to 3 wt% of triethylamine, and surfactants at a concentration of 0.1 to 2 times the critical micelle concentration of each surfactant in deionized water to prepare an aqueous phase solution; dissolve 0.1 wt% to 3 wt% of hexachlorotriphosphazene in n-hexane to prepare an organic phase solution; fix the polydopamine deposited film obtained in step b), let it air dry naturally, pour it into the aqueous phase solution, let it stand for 10 min, pour off the excess aqueous phase solution, and after there are no obvious droplets on the film surface, pour it into the organic phase solution to carry out the interfacial polymerization reaction for 10 min to 60 min. After the reaction is completed, rinse the film surface with n-hexane to obtain the nascent composite film;

[0009] d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 60℃~120℃ for 5min~60min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

[0010] Preferably, the surfactant in step c) is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, dodecyl dimethyl benzyl ammonium chloride, polysorbate 80, and fatty alcohol polyoxyethylene ether.

[0011] Preferably, the amine compound in step c) is one or more of polyethyleneimine, terminal amino hyperbranched polyamide, piperazine, m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, ethylenediamine, benzidine, diethylenetriamine, and triethylenetetramine, used alone or in blends, with a total mass fraction of 1 wt% to 8 wt% when blended.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0013] (1) The polydopamine intermediate layer enhances the bonding between the base membrane and the selective layer by utilizing its excellent interfacial adhesion, and the separation performance of the composite membrane remains stable after continuous operation.

[0014] (2) The introduction of surfactants regulates the interfacial polymerization process, optimizes the selective layer structure, and enables the composite membrane to exhibit high retention performance for solutes in organic solvents.

[0015] (3) The polyphosphazene / amine compound selective layer gives the composite membrane good chemical stability. After long-term immersion in organic solvents, the separation performance of the membrane does not decrease significantly. Detailed Implementation

[0016] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art. Unless otherwise specified, the chemical reagents used in the following embodiments are commercially available analytical grade or chemically pure products; the experimental methods described are conventional methods.

[0017] The separation performance of the polyphosphazene / amine compound organic solvent nanofiltration membrane prepared in this invention was determined using a cross-flow filtration device, namely the membrane's permeate flux (J) and rejection ratio (R):

[0018] J = V / (A × t × ΔP)

[0019] R = (1-C) p / C f )×100

[0020] Where: J is the permeation flux (L·m - 2·h -1 ·bar -1 V is the permeate volume (L); A is the effective membrane area (m²). 2 ); t is the running time (h); ΔP is the transmembrane pressure (bar); R is the rejection rate (%); C f and C p These represent the solute concentrations (mg / L) in the feed solution and permeate, respectively.

[0021] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited by the embodiments.

[0022] Example 1.

[0023] a) Preparation of the base membrane: 17g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 2g of polyvinylpyrrolidone, and 81g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric and a film was scraped using a doctor blade with a gap of 120μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in a 10wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane;

[0024] b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.5. Add 0.2 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a 40°C constant temperature water bath shaker. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 1 hour. After removal, ultrasonically clean it with deionized water for 5 minutes and then heat treat it at 60°C for 10 minutes to obtain a polydopamine deposition membrane.

[0025] c) Preparation of the selective layer: 1.5 wt% polyethyleneimine, 1.5 wt% piperazine, 2 wt% triethylamine, and sodium dodecyl sulfate at 1 times the critical micelle concentration were dissolved in deionized water to prepare an aqueous phase solution; 0.5 wt% hexachlorotriphosphazene was dissolved in n-hexane to prepare an organic phase solution; the polydopamine deposited membrane obtained in step b) was fixed, air-dried, and then poured into the aqueous phase solution. After standing for 10 min, excess aqueous phase solution was poured off. After the membrane surface was free of obvious droplets, the organic phase solution was poured in for interfacial polymerization reaction for 30 min. After the reaction was completed, the membrane surface was rinsed with n-hexane to obtain the nascent composite membrane.

[0026] d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 80°C for 10 min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

[0027] e) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was tested for separation performance of a 50 mg / L dye / ethanol solution using a cross-flow filtration device at room temperature and an operating pressure of 0.4 MPa. The results showed that the membrane's permeation flux for ethanol was 3.2 L·m - 2·h -1 ·bar -1The rejection rates for methylene blue, methyl orange, Congo red, and direct black 38 were 87%, 95%, 98%, and 99%, respectively.

[0028] f) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was continuously operated for 72 h, achieving a Congo red rejection rate of 98% and an ethanol permeation flux of 3.0 L·m - 2·h -1 ·bar -1 ;

[0029] g) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was immersed in N,N-dimethylformamide for 91 days and in acetone for 60 days. Its Congo red rejection rates were 97% and 98%, respectively, and its ethanol permeation flux was 2.5 L·m⁻¹. - 2·h -1 .bar -1 2.8L·m - 2·h -1 ·bar -1 .

[0030] Example 2.

[0031] a) Preparation of the base membrane: 20g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 3g of polyvinylpyrrolidone, and 77g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric and a film was scraped using a doctor blade with a gap of 90μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in a 12wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane;

[0032] b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.5. Add 0.2 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a 60°C constant temperature water bath shaker. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 1 hour. After removal, ultrasonically clean it with deionized water for 5 minutes and then heat treat it at 60°C for 10 minutes to obtain a polydopamine deposition membrane.

[0033] c) Preparation of the selective layer: 3 wt% polyethyleneimine, 2 wt% triethylamine, and hexadecyltrimethylammonium bromide at 1 times the critical micelle concentration were dissolved in deionized water to prepare an aqueous phase solution; 1 wt% hexachlorotriphosphazene was dissolved in n-hexane to prepare an organic phase solution; the polydopamine deposited membrane obtained in step b) was fixed, air-dried, and then poured into the aqueous phase solution. After standing for 10 min, the excess aqueous phase solution was poured off. After the membrane surface was free of obvious droplets, the organic phase solution was poured in for interfacial polymerization reaction for 20 min. After the reaction was completed, the membrane surface was rinsed with n-hexane to obtain the nascent composite membrane;

[0034] d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 90°C for 10 min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

[0035] e) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was tested for separation performance of a 50 mg / L dye / ethanol solution using a cross-flow filtration device at room temperature and an operating pressure of 0.4 MPa. The results showed that the membrane's permeation flux for ethanol was 2.5 L·m -2· h -1 .bar -1 The rejection rates for methylene blue, methyl orange, Congo red and direct black 38 were 90%, 95%, 97% and 98%, respectively.

[0036] f) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was continuously operated for 72 h, achieving a Congo red rejection rate of 96% and an ethanol permeation flux of 2.4 L·m - 2·h -1 ·bar -1 ;

[0037] g) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was immersed in N,N-dimethylformamide for 91 days and in acetone for 60 days. Its Congo red rejection rates were 94% and 95%, respectively, and its ethanol permeation flux was 2.2 L·m⁻¹. -2 ·h -1 ·bar -1 2.3 L·m -2. h -1 ·bar -1 .

[0038] Example 3.

[0039] a) Preparation of the base membrane: 15g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 2g of polyvinylpyrrolidone, and 83g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric and a film was scraped using a doctor blade with a gap of 120μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in a 10wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane;

[0040] b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.5. Add 0.3 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a 40°C constant temperature water bath shaker. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 1 hour. After removal, ultrasonically clean it with deionized water for 5 minutes and then heat treat it at 60°C for 10 minutes to obtain a polydopamine deposition membrane.

[0041] c) Preparation of the selective layer: 2 wt% terminal amino hyperbranched polyamide, 1.5 wt% triethylamine, and fatty alcohol polyoxyethylene ether at 1.5 times the critical micelle concentration were dissolved in deionized water to prepare an aqueous phase solution; 0.3 wt% hexachlorotriphosphazene was dissolved in n-hexane to prepare an organic phase solution; the polydopamine deposited membrane obtained in step b) was fixed, air-dried, and then poured into the aqueous phase solution. After standing for 10 min, the excess aqueous phase solution was poured off. After the membrane surface was free of obvious droplets, the organic phase solution was poured in for interfacial polymerization reaction for 60 min. After the reaction was completed, the membrane surface was rinsed with n-hexane to obtain the nascent composite membrane.

[0042] d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 70°C for 7 min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

[0043] e) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was tested for separation performance of a 50 mg / L dye / ethanol solution using a cross-flow filtration device at room temperature and an operating pressure of 0.4 MPa. The results showed that the membrane's permeation flux for ethanol was 4.3 L·m - 2·h -1 ·bar -1 The rejection rates for methylene blue, methyl orange, Congo red, and direct black 38 were 80%, 90%, 94%, and 95%, respectively.

[0044] f) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was continuously operated for 72 h, achieving a Congo red rejection rate of 93% and an ethanol permeation flux of 4.2 L·m -2 ·h -1 ·bar -1 ;

[0045] g) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was immersed in N,N-dimethylformamide for 91 days and in acetone for 60 days. Its Congo red rejection rates were 90% and 91%, respectively, and its ethanol permeation flux was 4.5 L·m⁻¹. -2 ·h -1 ·bar -1 4.4 L·m -2 ·h -1 ·bar -1 .

[0046] Example 4.

[0047] a) Preparation of the base membrane: 18g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 2g of polyvinylpyrrolidone, and 80g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric, and a film was scraped using a doctor blade with a gap of 250μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in a 15wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane;

[0048] b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.5. Add 0.2 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a 35°C constant temperature water bath shaker. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 1.5 h. After removal, ultrasonically clean with deionized water for 5 min and then heat treat at 60°C for 10 min to obtain a polydopamine deposition membrane.

[0049] c) Preparation of the selective layer: 5 wt% polyethyleneimine, 2 wt% triethylamine, and sodium dodecyl sulfate at 0.5 times the critical micelle concentration were dissolved in deionized water to prepare an aqueous phase solution; 2 wt% hexachlorotriphosphazene was dissolved in n-hexane to prepare an organic phase solution; the polydopamine deposited membrane obtained in step b) was fixed, air-dried, and then poured into the aqueous phase solution. After standing for 10 min, excess aqueous phase solution was poured off. After the membrane surface was free of obvious droplets, the organic phase solution was poured in for interfacial polymerization reaction for 30 min. After the reaction was completed, the membrane surface was rinsed with n-hexane to obtain the nascent composite membrane.

[0050] d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 110°C for 10 min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

[0051] e) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was tested for separation performance of a 50 mg / L dye / ethanol solution using a cross-flow filtration device at room temperature and an operating pressure of 0.4 MPa. The results showed that the membrane's permeation flux for ethanol was 1.5 L·m -2 .h -1 ·bar -1 The rejection rates for methylene blue, methyl orange, Congo red, and direct black 38 were 92%, 95%, 98%, and 99%, respectively.

[0052] f) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was continuously operated for 72 h, achieving a Congo red rejection rate of 98% and an ethanol permeation flux of 1.4 L·m -2 ·h -1 ·bar -1 ;

[0053] g) The polyphosphazene / amine compound organic solvent nanofiltration membrane obtained in step d) was immersed in N,N-dimethylformamide for 91 days and in acetone for 60 days. Its Congo red rejection rates were 96% and 97%, respectively, and its ethanol permeation flux was 1.2 L·m⁻¹. -2 ·h -1 .bar -1 1.3 L·m -2 ·h -1 ·bar -1 .

Claims

1. A method for preparing an organic solvent nanofiltration membrane by interfacial polymerization of a polyphosphazene / amine compound, characterized in that, Includes the following steps: a) Preparation of the base membrane: 15g-20g of polyetherimide particles were placed in an oven and dried at 80℃ for 12h; the dried polyetherimide particles were mixed with 1g-4g of polyvinylpyrrolidone, and 76g-84g of N,N-dimethylacetamide were added. The mixture was magnetically stirred at 60℃ for 8h and allowed to stand for degassing for 12h to obtain a polyetherimide casting solution; the polyetherimide casting solution was poured onto a nonwoven fabric and a film was scraped using a doctor blade with a gap of 50μm-500μm. The film was then immersed in deionized water for phase inversion. After the film was completely cured, it was removed and soaked in deionized water for 24h to obtain a polyetherimide ultrafiltration membrane; the polyetherimide ultrafiltration membrane was immersed in an 8wt%-15wt% hexamethylenediamine isopropanol solution and crosslinked at 60℃ for 30min to obtain a polyetherimide base membrane; b) Preparation of the intermediate layer: Prepare a 0.01 mol / L tris(hydroxymethyl)aminomethane-hydrochloric acid buffer solution with a pH of 8.

5. Add 0.1 wt% to 0.5 wt% dopamine hydrochloride to the buffer solution and stir until completely dissolved to form a dopamine hydrochloride deposition solution. Fix the polyetherimide-based membrane obtained in step a) and place it in a constant temperature water bath shaker at 25℃ to 60℃. Pour in the dopamine hydrochloride deposition solution until the base membrane is submerged and shake for 0.5 h to 2 h. After removal, ultrasonically clean with deionized water for 5 min and then heat treat at 60℃ for 10 min to obtain a polydopamine deposition membrane. c) Preparation of the selective layer: Dissolve 1 wt% to 8 wt% of amine compounds, 1 wt% to 3 wt% of triethylamine, and surfactants at a concentration of 0.1 to 2 times the critical micelle concentration of each surfactant in deionized water to prepare an aqueous phase solution; dissolve 0.1 wt% to 3 wt% of hexachlorotriphosphazene in n-hexane to prepare an organic phase solution; fix the polydopamine deposited film obtained in step b), let it air dry naturally, pour it into the aqueous phase solution, let it stand for 10 min, pour off the excess aqueous phase solution, and after there are no obvious droplets on the film surface, pour it into the organic phase solution to carry out the interfacial polymerization reaction for 10 min to 60 min. After the reaction is completed, rinse the film surface with n-hexane to obtain the nascent composite film; d) Heat treatment: The nascent composite membrane obtained in step c) is heat-treated in an oven at 60℃~120℃ for 5min~60min to obtain a polyphosphazene / amine compound organic solvent nanofiltration membrane.

2. The method for preparing an organic solvent nanofiltration membrane by interfacial polycondensation of a polyphosphazene / amine compound according to claim 1, characterized in that, The surfactant mentioned in step c) is one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, hexadecyltrimethylammonium bromide, dodecyl dimethyl benzyl ammonium chloride, polysorbate 80, and fatty alcohol polyoxyethylene ether.

3. The method for preparing an organic solvent nanofiltration membrane by interfacial polycondensation of a polyphosphazene / amine compound according to claim 1, characterized in that, The amine compound mentioned in step c) is one or more of the following: polyethyleneimine, terminal amino hyperbranched polyamide, piperazine, m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, ethylenediamine, benzidine, diethylenetriamine, and triethylenetetramine.

4. A polyphosphazene / amine compound organic solvent nanofiltration membrane, characterized by, It is prepared by the method described in any one of claims 1 to 3.

5. The application of the polyphosphazene / amine compound organic solvent nanofiltration membrane according to claim 4 in organic solvent recovery or solvent-solute separation.