Bifunctional separation membrane as well as synthesis method and application thereof

Abstract

The invention belongs to the technical field of membrane separation, and particularly relates to a bifunctional separation membrane as well as a synthesis method and application thereof. The bifunctional separation membrane provided by the invention comprises a supporting bottom membrane and a polyamide catalytic active layer compounded on the surface of one side of the supporting bottom membrane, the polyamide catalytic active layer is formed by carrying out interfacial polymerization reaction on a water-phase solution and an oil-phase solution and then carrying out metal salt loading and reducing by a reducing agent; the water phase solution contains an amine monomer and a sulfhydryl compound, and the oil phase solution contains an acyl chloride monomer. Metal atoms with catalytic activity are anchored on the polyamide separation membrane through interaction of sulfydryl and metal, the membrane is endowed with strong catalytic performance, various oxidants can be catalyzed to oxidize and remove pollutants and organic matters in water, and the safety of water is greatly improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of membrane separation technology, and particularly relates to a bifunctional separation membrane and a synthesis method and application thereof. BACKGROUND

[0002] Water safety is a basic requirement for human survival and health, and it is of great significance to protect public health, promote social and economic development, and maintain environmental health. Ensuring water safety is crucial to protecting public health. Organic pollutants in water pose a serious threat to human health and the environment. Long-term exposure to organic pollutants in water can lead to the occurrence of chronic diseases. These substances are often difficult to degrade and can accumulate in the human and biological body, causing long-term toxicity risks. In addition, they also interfere with the water ecosystem, affecting the reproduction, growth and normal life structure of aquatic organisms, and through the food chain, endangering the broader ecological balance. Because these pollutants are usually persistent, low in concentration and highly biologically active, they are difficult to be effectively removed by traditional water treatment processes, and even new pollutants such as disinfection by-products can pose a serious threat to human health. In the face of more severe organic pollution problems, it is urgent to develop water treatment processes that can efficiently control new pollutants.

[0003] In recent years, membrane separation technology has been widely used in seawater desalination, wastewater advanced treatment and reclaimed water reuse, etc. It is one of the core technologies of water treatment. Its application to water treatment processes is expected to achieve efficient removal of new pollutants in water and ensure water safety. Functional membranes can effectively intercept various organic pollutants such as perfluorinated compounds, antibiotics, endocrine disruptors and bacterial resistance genes. Using functional membranes to remove organic pollutants in water has a unique advantage. However, current commercial membranes are mainly designed for desalination, water softening, decolorization, etc. Their selectivity for pollutants is low, making it difficult to meet the requirements for organic pollutant removal. In particular, neutral small molecule pollutants such as disinfection by-products and industrial solvents have very limited removal efficiency on commercial nanofiltration and reverse osmosis membranes. It is urgent to develop new membrane materials to achieve efficient removal of pollutants in water. SUMMARY

[0004] Therefore, the purpose of the present application is to provide a bifunctional separation membrane and a synthesis method and application thereof. The bifunctional separation membrane provided by the present application can efficiently remove organic pollutants and total organic carbon in water in the presence of an oxidizing agent, while efficiently intercepting salt ions in water.

[0005] The present invention provides a dual-function separation membrane, comprising: a supporting base membrane, and a polyamide catalytic active layer composited on a single-side surface of the supporting base membrane; the polyamide catalytic active layer is formed by interfacial polymerization reaction between an aqueous solution and an oily solution, followed by metal salt loading and reduction with a reducing agent; the aqueous solution contains amine monomers and thiol compounds, and the oily solution contains acyl chloride monomers.

[0006] Preferably, the amine monomer is one or more of m-phenylenediamine, piperazine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine and ethylenediamine.

[0007] Preferably, the thiol compound is one or more of mercaptoethanol, cysteine, (3-mercaptopropyl)triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 2-mercaptoethylamine and dimercaptopropanol.

[0008] Preferably, the acyl chloride monomer is one or more of trimesoyl chloride, terephthaloyl chloride and phthaloyl chloride.

[0009] Preferably, the metal salt is one or more of cobalt chloride, cobalt chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, cobalt sulfate, cobalt sulfate hydrate, copper chloride, copper chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, copper sulfate and copper sulfate hydrate.

[0010] Preferably, the reducing agent is sodium borohydride and / or ascorbic acid.

[0011] Preferably, the supporting base membrane is made of polysulfone, polyethersulfone or polyvinylidene fluoride.

[0012] Preferably, the average pore size of the dual-function separation membrane is less than 0.6 nm, and the molecular weight cut-off is 200 to 400 Da.

[0013] The present invention provides a method for synthesizing the dual-function separation membrane described in the above technical solution, comprising the following steps:

[0014] a) contacting one side surface of the supporting base film with an aqueous solution to obtain a base film with an aqueous monomer attached thereto;

[0015] b) immersing the base membrane with the aqueous phase monomer attached thereto in an oil phase solution to perform interfacial polymerization to form a polyamide layer, thereby obtaining an unmodified polyamide separation membrane;

[0016] c) soaking the unmodified polyamide separation membrane in a metal salt solution to obtain a metal salt-loaded polyamide separation membrane;

[0017] d) immersing the metal salt-loaded polyamide separation membrane in a reducing agent solution to form a polyamide catalytic active layer through reduction, thereby obtaining a dual-function separation membrane.

[0018] The present invention provides a water treatment method, wherein the separation membrane used in the water treatment process comprises the bifunctional separation membrane described in the above technical solution or the bifunctional separation membrane prepared by the synthesis method described in the above technical solution.

[0019] Compared with the prior art, the present invention provides a dual-function separation membrane, its synthesis method and application. The dual-function separation membrane provided by the present invention includes: a supporting base membrane, and a polyamide catalytic active layer composited on a single-side surface of the supporting base membrane; the polyamide catalytic active layer is formed by interfacial polymerization reaction between an aqueous phase solution and an oil phase solution, and then loaded with a metal salt and reduced by a reducing agent; the aqueous phase solution contains amine monomers and thiol compounds, and the oil phase solution contains acyl chloride monomers. The present invention anchors catalytically active metal atoms on the polyamide separation membrane through the interaction between thiol groups and metals, giving the membrane strong catalytic properties, which can catalyze various oxidants to oxidize and remove pollutants and organic matter in water, greatly improving the safety of water. Experimental results show that the dual-function separation membrane provided by the present invention has a removal rate of more than 99% for pollutants in water in the presence of oxidants, and a removal rate of more than 95% for the total organic carbon content in water.

[0020] More specifically, the technical solution provided by the present invention has at least the following beneficial effects:

[0021] 1. In the present invention, mercapto groups are used to coordinate with metals, and the stability of the coordination ensures the stable catalytic activity of the membrane material and extremely low risk of metal dissolution.

[0022] 2. The present invention combines membrane separation technology with catalytic advanced oxidation technology. The two technologies complement each other to improve the removal performance of pollutants and organic matter in water bodies, which can make up for the insufficient removal performance of separation membranes for small molecule pollutants and greatly improve the safety of water.

[0023] 3. The separation membrane synthesis method provided by the present invention is simple, has low raw material cost, and can be produced on a large scale. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0025] Figure 1 Schematic diagram of the structure of the dual-function separation membrane provided by the present invention;

[0026] Figure 2 is a cross-sectional transmission electron micrograph of the dual-function separation membrane of Example 1 provided by the present invention;

[0027] Figure 3 It is a bar graph showing the pollutant 1,4-dioxane removal effect of the separation membranes of Examples 1 to 13 and Comparative Example 1 provided by the present invention;

[0028] Figure 4 It is a bar chart of the total organic carbon removal effect of the separation membranes of Examples 1 to 13 and Comparative Example 1 provided by the present invention.

[0029] Attachment Figures 1-2 Marking instructions: 1 is the supporting base membrane, 2 is the polyamide catalytic active layer. DETAILED DESCRIPTION

[0030] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0031] The present invention provides a dual-function separation membrane, comprising: a supporting base membrane, and a polyamide catalytic active layer composited on a single-side surface of the supporting base membrane; the polyamide catalytic active layer is formed by interfacial polymerization reaction between an aqueous solution and an oily solution, followed by metal salt loading and reduction with a reducing agent; the aqueous solution contains amine monomers and thiol compounds, and the oily solution contains acyl chloride monomers.

[0032] In the bifunctional separation membrane provided by the present invention, the material of the supporting base membrane includes but is not limited to polysulfone, polyethersulfone or polyvinylidene fluoride; the molecular weight cutoff of the supporting base membrane is preferably 20-200kDa, specifically 20kDa, 50kDa, 100kDa or 200kDa.

[0033] In the bifunctional separation membrane provided by the application, the amine monomer in the aqueous solution has at least two N-containing groups that can participate in interfacial polymerization, and the amine monomer is preferably one or more of m-phenylenediamine, piperazine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, and ethylenediamine; the content of the amine monomer in the aqueous solution is preferably 0.2-4 wt%, and can be specifically 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, or 4 wt%.

[0034] In the bifunctional separation membrane provided by the application, the thiol compound in the aqueous solution is preferably one or more of mercaptoethanol, cysteine, (3-mercaptopropyl)triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyl dimethoxymethylsilane, 2-mercaptoethylamine, and dimercapto propanol; the content of the thiol compound in the aqueous solution is preferably 0.2-4 wt%, and can be specifically 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt%, 2 wt%, 2.1 wt%, 2.2 wt%, 2.3 wt%, 2.4 wt%, 2.5 wt%, 2.6 wt%, 2.7 wt%, 2.8 wt%, 2.9 wt%, 3 wt%, 3.1 wt%, 3.2 wt%, 3.3 wt%, 3.4 wt%, 3.5 wt%, 3.6 wt%, 3.7 wt%, 3.8 wt%, 3.9 wt%, or 4 wt%.

[0035] In the bifunctional separation membrane provided by the present invention, the acyl chloride monomer in the oil phase solution has at least two acyl chloride groups that can participate in the interfacial polymerization reaction, and the acyl chloride monomer is preferably one or more of trimesoyl chloride, terephthaloyl chloride and phthaloyl chloride; the content of the acyl chloride monomer in the oil phase solution is preferably 0.05-0.5wt%, specifically 0.05wt%, 0.07wt%, 0.1wt%, 0.12wt%, 0.15wt%, 0.17wt%, 0.2wt%, 0.23wt%, 0.25wt%, 0.27wt%, 0.3wt%, 0.32wt%, 0.35wt%, 0.37wt%, 0.4wt%, 0.42wt%, 0.45wt%, 0.47wt% or 0.5wt%.

[0036] In the dual-function separation membrane provided by the present invention, the organic solvent in the oil phase solution includes, but is not limited to, one or more of n-hexane, isoparaffins and n-nonane.

[0037] In the bifunctional separation membrane provided by the present invention, the temperature for carrying out the interfacial polymerization reaction is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the time for carrying out the interfacial polymerization reaction is preferably 10-300s, specifically 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, 250s, 260s, 270s, 280s, 290s or 300s.

[0038] In the bifunctional separation membrane provided by the present invention, the metal salt is preferably one or more of cobalt chloride, cobalt chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, cobalt sulfate, cobalt sulfate hydrate, copper chloride, copper chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, copper sulfate and copper sulfate hydrate.

[0039] In the dual-function separation membrane provided by the present invention, the method of loading the metal salt is preferably to soak it in a metal salt solution. Wherein, the content of the metal salt in the metal salt solution is preferably 0.01 to 1 mol / L, specifically 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, 0.5 mol / L, 0.55 mol / L, 0.6 mol / L, 0.65 mol / L, 0.7 mol / L , 0.75mol / L, 0.8mol / L, 0.85mol / L, 0.9mol / L, 0.95mol / L or 1mol / L; the soaking temperature is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the soaking time is preferably 0.5-6h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h.

[0040] In the bifunctional separation membrane provided by the present invention, the reducing agent is preferably sodium borohydride and / or ascorbic acid.

[0041] In the dual-function separation membrane provided by the present invention, the reduction method is preferably soaking in a reducing agent solution. The content of the reducing agent in the reducing agent solution is preferably 0.01 to 0.5 mol / L, specifically 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.07 mol / L, 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.17 mol / L, 0.2 mol / L, 0.23 mol / L, 0.25 mol / L, 0.27 mol / L, 0.3 mol / L, 0.32 mol / L, 0.35 mol / L, 0.45 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, 0.9 mol / L, 0.10 mol / L, 0.11 mol / L, 0.12 mol / L, 0.15 mol / L, 0.17 mol / L, 0.2 mol / L, 0.23 mol / L, 0.25 mol / L, 0.27 mol / L, 0.3 mol / L, 0.32 mol / L, 0.35 mol / L, 0.5 ol / L, 0.37mol / L, 0.4mol / L, 0.42mol / L, 0.45mol / L, 0.47mol / L or 0.5mol / L; the soaking temperature is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the soaking time is preferably 2-24h, specifically 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h.

[0042] In the bifunctional separation membrane provided by the present invention, the average membrane pore size of the bifunctional separation membrane is preferably less than 0.6 nm; and the molecular weight cut-off of the bifunctional separation membrane is preferably 200 to 400 Da.

[0043] The present invention also provides a method for synthesizing a dual-function separation membrane, comprising the following steps:

[0044] a) contacting one side surface of the supporting base film with an aqueous solution to obtain a base film with an aqueous monomer attached thereto;

[0045] b) immersing the base membrane with the aqueous phase monomer attached thereto in an oil phase solution to perform interfacial polymerization to form a polyamide layer, thereby obtaining an unmodified polyamide separation membrane;

[0046] c) soaking the unmodified polyamide separation membrane in a metal salt solution to obtain a metal salt-loaded polyamide separation membrane;

[0047] d) immersing the metal salt-loaded polyamide separation membrane in a reducing agent solution to form a polyamide catalytic active layer through reduction, thereby obtaining a dual-function separation membrane.

[0048] In the synthesis method provided by the present invention, in step a), the material of the supporting base membrane includes but is not limited to polysulfone, polyethersulfone or polyvinylidene fluoride.

[0049] In the synthesis method provided by the present invention, in step a), the aqueous phase solution contains an amine monomer, a thiol compound and water.

[0050] In the synthesis method provided by the present invention, in step a), the amine monomer in the aqueous solution has at least two N-containing groups that can participate in the interfacial polymerization reaction, and the amine monomer is preferably one or more of m-phenylenediamine, piperazine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine and ethylenediamine; the content of the amine monomer in the aqueous solution is preferably 0.2-4wt%, specifically 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1 .1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.7wt%, 2.8wt%, 2.9wt%, 3wt%, 3.1wt%, 3.2wt%, 3.3wt%, 3.4wt%, 3.5wt%, 3.6wt%, 3.7wt%, 3.8wt%, 3.9wt% or 4wt%.

[0051] In the synthesis method provided by the present invention, in step a), the thiol compound in the aqueous solution is preferably one or more of mercaptoethanol, cysteine, (3-mercaptopropyl)triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 2-mercaptoethylamine and dimercaprol; the content of the thiol compound in the aqueous solution is preferably 0.2-4wt%, specifically 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1. 1wt%, 1.2wt%, 1.3wt%, 1.4wt%, 1.5wt%, 1.6wt%, 1.7wt%, 1.8wt%, 1.9wt%, 2wt%, 2.1wt%, 2.2wt%, 2.3wt%, 2.4wt%, 2.5wt%, 2.6wt%, 2.7wt%, 2.8wt%, 2.9wt%, 3wt%, 3.1wt%, 3.2wt%, 3.3wt%, 3.4wt%, 3.5wt%, 3.6wt%, 3.7wt%, 3.8wt%, 3.9wt% or 4wt%.

[0052] In the synthesis method provided by the present invention, in step b), the oil phase solution contains acyl chloride monomers and an organic solvent.

[0053] In the synthesis method provided by the present invention, in step b), the acyl chloride monomer in the oil phase solution has at least two acyl chloride groups that can participate in the interfacial polymerization reaction, and the acyl chloride monomer is preferably one or more of trimesoyl chloride, terephthaloyl chloride and phthaloyl chloride; the content of the acyl chloride monomer in the oil phase solution is preferably 0.05-0.5wt%, specifically 0.05wt%, 0.07wt%, 0.1wt%, 0.12wt%, 0.15wt%, 0.17wt%, 0.2wt%, 0.23wt%, 0.25wt%, 0.27wt%, 0.3wt%, 0.32wt%, 0.35wt%, 0.37wt%, 0.4wt%, 0.42wt%, 0.45wt%, 0.47wt% or 0.5wt%.

[0054] In the synthesis method provided by the present invention, in step b), the organic solvent in the oil phase solution includes but is not limited to one or more of n-hexane, isoparaffins and n-nonane.

[0055] In the synthesis method provided by the present invention, in step b), the temperature for carrying out the interfacial polymerization reaction is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the time for carrying out the interfacial polymerization reaction is preferably 10-300s, specifically 10s, 20s, 30s, 40s, 50s, 60s, 70s, 80s, 90s, 100s, 110s, 120s, 130s, 140s, 150s, 160s, 170s, 180s, 190s, 200s, 210s, 220s, 230s, 240s, 250s, 260s, 270s, 280s, 290s or 300s.

[0056] In the synthesis method provided by the present invention, in step c), the metal salt solution contains metal salt and water.

[0057] In the synthesis method provided by the present invention, in step c), the metal salt in the metal salt solution is preferably one or more of cobalt chloride, cobalt chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, cobalt sulfate, cobalt sulfate hydrate, copper chloride, copper chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, copper sulfate, and copper sulfate hydrate; the content of the metal salt in the metal salt solution is preferably 0.01 to 1 mol / L, specifically 0.01 mol / L, 0.05 mol / L, 0.1 mol / L , 0.15mol / L, 0.2mol / L, 0.25mol / L, 0.3mol / L, 0.35mol / L, 0.4mol / L, 0.45mol / L, 0.5mol / L, 0.55mol / L, 0.6mol / L, 0.65mol / L, 0.7mol / L, 0.75mol / L, 0.8mol / L, 0.85mol / L, 0.9mol / L, 0.95mol / L or 1mol / L.

[0058] In the synthesis method provided by the present invention, in step c), the soaking temperature is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the soaking time is preferably 0.5-6h, specifically 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h, 5h, 5.5h or 6h.

[0059] In the synthesis method provided by the present invention, in step d), the reducing agent solution contains a reducing agent and water.

[0060] In the synthesis method provided by the present invention, in step d), the reducing agent in the reducing agent solution is preferably sodium borohydride and / or ascorbic acid; the content of the reducing agent in the reducing agent solution is preferably 0.01-0.5 mol / L, specifically 0.01 mol / L, 0.03 mol / L, 0.05 mol / L, 0.07 mol / L, 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.17 mol / L, 0.2 mol / L, 0.23 mol / L, 0.25 mol / L, 0.27 mol / L, 0.3 mol / L, 0.32 mol / L, 0.35 mol / L, 0.37 mol / L, 0.4 mol / L, 0.42 mol / L, 0.45 mol / L, 0.47 mol / L or 0.5 mol / L.

[0061] In the synthesis method provided by the present invention, in step d), the soaking temperature is preferably 10-40°C, specifically 10°C, 15°C, 20°C, 25°C (room temperature), 30°C, 35°C or 40°C; the soaking time is preferably 2-24h, specifically 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h or 24h.

[0062] The present invention also provides a water treatment method, wherein the separation membrane used in the water treatment process includes the bifunctional separation membrane described in the above technical solution or the bifunctional separation membrane produced by the synthesis method described in the above technical solution. In the present invention, the bifunctional separation membrane can be used to simultaneously intercept, filter, and catalytically degrade pollutants in raw water in the presence of an oxidant; the oxidant includes, but is not limited to, potassium permonosulfate; and the organic pollutants in the raw water include, but are not limited to, 1,4-dioxane.

[0063] For the purpose of greater clarity, the present invention is described in detail with reference to the following examples and comparative examples.

[0064] Example 1

[0065] A dual-function separation membrane having a structure such as Figure 1 As shown, it includes: a supporting base membrane 1, and a polyamide catalytic active layer 2 composited on a single side surface of the supporting base membrane 1; the polyamide catalytic active layer 2 is formed by interfacial polymerization reaction between an aqueous solution and an oily solution, and then loaded with a metal salt and reduced with a reducing agent.

[0066] The synthesis method of the above-mentioned bifunctional separation membrane is as follows:

[0067] Step 1: dissolving an amine monomer (piperazine) and a thiol compound (cysteine) in water to obtain an aqueous solution; wherein the content of the amine monomer in the aqueous phase is 0.5 wt %, and the content of the thiol compound in the aqueous phase is 0.5 wt %;

[0068] Step 2: dissolving an acyl chloride monomer (trimellitoyl chloride) in an organic phase solvent (n-hexane) to obtain an oil phase solution; wherein the content of the acyl chloride monomer in the oil phase solution is 0.15 wt %;

[0069] Step 3: contacting the aqueous phase solution with one side of a supporting base membrane (material: polysulfone, molecular weight cut-off: 100 kDa) to obtain a base membrane with attached aqueous phase monomers;

[0070] Step 4: Immersing the base membrane with the aqueous phase monomer attached in the oil phase solution to perform interfacial polymerization to form a polyamide layer, thereby obtaining an unmodified polyamide separation membrane; wherein the interfacial polymerization reaction is performed at room temperature for 30 seconds;

[0071] Step 5: dissolving a metal salt (cobalt chloride) in water to obtain a metal salt solution; wherein the content of the metal salt in the water is 0.1 mol / L;

[0072] Step 6: Soaking the unmodified polyamide separation membrane obtained in step 4 in the metal salt solution obtained in step 5 to obtain a polyamide separation membrane loaded with metal salt; wherein the soaking temperature is room temperature and the soaking time is 1 hour;

[0073] Step 7: dissolving a reducing agent (ascorbic acid) in water to obtain a reducing agent solution; wherein the content of the reducing agent in the water is 0.1 mol / L;

[0074] Step 8: Soak the metal salt-loaded polyamide separation membrane obtained in step 6 in the reducing agent solution of step 7 to form a polyamide catalytic active layer through reduction, thereby obtaining a bifunctional separation membrane; wherein the soaking temperature is room temperature and the soaking time is 12 hours.

[0075] The cross section of the dual-function separation membrane prepared in this example was observed by transmission electron microscopy. Figure 2 shown.

[0076] Example 2

[0077] Refer to Example 1, the only difference is that the metal salt used in step 5 is cupric chloride.

[0078] Example 3

[0079] Refer to Example 1, the only difference is that the metal salt used in step 5 is cobalt nitrate.

[0080] Example 4

[0081] Refer to Example 1, the only difference is that the metal salt used in step 5 is cobalt sulfate.

[0082] Example 5

[0083] Refer to Example 1, the only difference is that the material of the supporting base membrane used in step 3 is polyethersulfone.

[0084] Example 6

[0085] Refer to Example 1, the only difference is that the material of the supporting base membrane used in step 3 is polyvinylidene fluoride, and the molecular weight cut-off is 200 kDa.

[0086] Example 7

[0087] Refer to Example 1, the only difference is that the sulfhydryl compound used in step 1 is mercaptoethanol.

[0088] Example 8

[0089] Refer to Example 1, the only difference is that the mercapto compound used in step 1 is (3-mercaptopropyl)triethoxysilane.

[0090] Example 9

[0091] Refer to Example 1, the only difference is that the sulfhydryl compound used in step 1 is 2-mercaptoethylamine.

[0092] Example 10

[0093] Refer to Example 1, the only difference is that the amine monomer used in step 1 is m-phenylenediamine.

[0094] Example 11

[0095] Refer to Example 1, the only difference is that the amine monomer used in step 1 is triethylenetetramine.

[0096] Example 12

[0097] Refer to Example 1, the only difference is that the acyl chloride monomer used in step 2 is terephthaloyl chloride.

[0098] Example 13

[0099] Refer to Example 1, the only difference is that the reducing agent used in step 7 is sodium borohydride.

[0100] Comparative Example 1

[0101] A polyamide separation membrane comprises: a supporting base membrane and a polyamide layer composited on one side surface of the supporting base membrane; the polyamide catalytic layer is formed by interfacial polymerization reaction between an aqueous solution and an oily solution.

[0102] The synthesis method of the above-mentioned polyamide separation membrane is as follows:

[0103] Step 1: dissolving an amine monomer (piperazine) in water to obtain an aqueous solution; wherein the content of the amine monomer in the aqueous solution is 1 wt %;

[0104] Step 2: dissolving an acyl chloride monomer (trimellitoyl chloride) in an organic phase solvent (n-hexane) to obtain an oil phase solution; wherein the content of the acyl chloride monomer in the oil phase solution is 0.15 wt %;

[0105] Step 3: contacting the aqueous phase solution with one side of a supporting base membrane (material: polysulfone, molecular weight cut-off: 100 kDa) to obtain a base membrane with attached aqueous phase monomers;

[0106] Step 4: Immerse the base membrane with the attached aqueous phase monomer in the oil phase solution to perform interfacial polymerization to form a polyamide layer, thereby obtaining a polyamide separation membrane; wherein the interfacial polymerization reaction is performed at room temperature for 30 seconds.

[0107] Performance evaluation

[0108] (1) Average membrane pore size and molecular weight cut-off

[0109] The membrane materials prepared in the above examples and comparative examples were tested for average membrane pore size and molecular weight cut-off, and the results are shown in the following table:

[0110]

[0111]

[0112] (2) Water flux and salt interception performance test

[0113] The water flux and salt rejection performance of the membrane materials prepared in the above embodiments and comparative examples were tested using a cross-flow nanofiltration device. The specific testing method was as follows: the membrane material was first compacted with deionized water until the flux was stable; a salt solution containing 10 mM sodium sulfate was prepared as the feed solution, and the pH was adjusted to 7.0 ± 0.1; the feed solution was thoroughly mixed for 1 hour without applying pressure; after equilibrium, in the circulation mode, the system pressure was adjusted to 6.9 bar at 25°C and a flow rate of 60 LPH, and the water flux and salt rejection rate were tested after equilibration for 1 hour.

[0114] The test results of Examples 1 to 13 and Comparative Example 1 are shown in the following table:

[0115] Water flux(LMH / Bar) Retention rate (%) Example 1 10.23 98.2 Example 2 9.83 99.1 Example 3 9.23 97.2 Example 4 8.98 98.4 Example 5 9.47 97.2 Example 6 10.11 97.8 Example 7 8.87 99.1 Example 8 9.78 96.9 Example 9 10.59 98.2 Example 10 8.42 97.9 Example 11 9.33 98.8 Example 12 9.58 99.4 Example 13 10.61 95.4 Comparative Example 1 9.99 97.9

[0116] As can be seen from the above table, the water flux and salt rejection rate of the separation membranes of Examples 1 to 13 and Comparative Example 1 are similar, indicating that immersion in the metal salt solution and the reducing solution has no adverse effect on the basic structure of the membrane. The separation membranes prepared in Examples 1 to 13 achieve a rejection rate of more than 90% for sodium sulfate, and can achieve efficient desalination of water.

[0117] (3) Pollutant removal performance test

[0118] The pollutant removal performance of the membrane materials prepared in the above examples and comparative examples was tested using a cross-flow nanofiltration device. The specific testing method was as follows: the membrane material was first compacted with deionized water until the flux was stable; 1 mg / L 1,4-dioxane and 1 mM potassium monopersulfate complex salt were prepared as the feed solution; after equilibration, the system pressure was adjusted to 6.9 bar at 25°C and a flow rate of 60 LPH in a circulation mode, and the 1,4-dioxane removal efficiency was tested after equilibration for 1 hour.

[0119] The test results of Examples 1 to 13 and Comparative Example 1 are as follows: Figure 3 As shown. Figure 3 It can be seen that the pollutant removal efficiency of Examples 1 to 13 is greatly improved compared with that of Comparative Example 1. The dual-function separation membrane can improve the removal efficiency of pollutants and improve water quality safety.

[0120] (4) Total organic carbon removal performance test

[0121] The total organic carbon removal performance of the membrane materials prepared in the above embodiments and comparative examples was tested using a cross-flow nanofiltration device. The specific testing method was as follows: the membrane material was first compacted with deionized water until the flux was stable; 1 mM potassium permonosulfate complex salt was prepared using municipal household water supply as the feed solution; after equilibration, the system pressure was adjusted to 6.9 bar at 25°C and a flow rate of 60 LPH in circulation mode, and the total organic carbon removal efficiency was tested after equilibration for 1 hour.

[0122] The test results of Examples 1 to 13 and Comparative Example 1 are as follows: Figure 4 As shown. Figure 4 It can be seen that the total organic carbon removal efficiency of Examples 1 to 13 is greatly improved compared with that of Comparative Example 1, thereby improving water quality safety.

[0123] (5) Long-term pollutant removal stability test

[0124] The membrane materials prepared in the above examples and comparative examples were tested for their long-term pollutant removal stability using a cross-flow nanofiltration device. The specific testing method was as follows: the membrane material was first compacted with deionized water until the flux was stable; 1 mg / L 1,4-dioxane and 1 mM potassium permonosulfate complex salt were prepared as the feed solution; after equilibration, the system pressure was adjusted to 6.9 bar at 25°C and a flow rate of 60 LPH in a circulation mode, the feed solution was replaced every 12 hours, and the 1,4-dioxane removal efficiency was tested after 240 hours of continuous operation.

[0125] After 240 hours of continuous operation, the removal efficiency of 1,4-dioxane in Examples 1 to 13 was still maintained above 98%, demonstrating its good long-term stability.

[0126] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A dual-function separation membrane, characterized in that: include: A supporting base membrane, and a polyamide catalytic active layer composited on a single side surface of the supporting base membrane; The polyamide catalytic active layer is formed by interfacial polymerization of an aqueous solution and an oily solution, followed by metal salt loading and reduction with a reducing agent; The aqueous phase solution contains amine monomers and mercapto compounds, and the oil phase solution contains acyl chloride monomers.

2. The dual-function separation membrane according to claim 1, characterized in that The amine monomer is one or more of m-phenylenediamine, piperazine, p-phenylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine and ethylenediamine.

3. The dual-function separation membrane according to claim 1, characterized in that The thiol compound is one or more of mercaptoethanol, cysteine, (3-mercaptopropyl)triethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyldimethoxymethylsilane, 2-mercaptoethylamine and dimercaptopropanol.

4. The dual-function separation membrane according to claim 1, characterized in that The acyl chloride monomer is one or more of trimesoyl chloride, terephthaloyl chloride and phthaloyl chloride.

5. The dual-function separation membrane according to claim 1, characterized in that The metal salt is one or more of cobalt chloride, cobalt chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, cobalt sulfate, cobalt sulfate hydrate, copper chloride, copper chloride hydrate, cobalt nitrate, cobalt nitrate hydrate, copper sulfate and copper sulfate hydrate.

6. The dual-function separation membrane according to claim 1, characterized in that The reducing agent is sodium borohydride and / or ascorbic acid.

7. The dual-function separation membrane according to claim 1, characterized in that The material of the supporting base membrane is polysulfone, polyethersulfone or polyvinylidene fluoride.

8. The dual-function separation membrane according to claim 1, characterized in that The average membrane pore size of the dual-function separation membrane is less than 0.6 nm, and the molecular weight cut-off is 200 to 400 Da.

9. A method for synthesizing a bifunctional separation membrane according to any one of claims 1 to 8, characterized in that: The following steps are involved: a) contacting one side surface of the supporting base film with an aqueous solution to obtain a base film with an aqueous monomer attached thereto; b) immersing the base membrane with the aqueous phase monomer attached thereto in an oil phase solution to perform interfacial polymerization to form a polyamide layer, thereby obtaining an unmodified polyamide separation membrane; c) soaking the unmodified polyamide separation membrane in a metal salt solution to obtain a metal salt-loaded polyamide separation membrane; d) immersing the metal salt-loaded polyamide separation membrane in a reducing agent solution to form a polyamide catalytic active layer through reduction, thereby obtaining a dual-function separation membrane.

10. A water treatment method, characterized in that: The separation membrane used in the water treatment process includes the bifunctional separation membrane according to any one of claims 1 to 8 or the bifunctional separation membrane prepared by the synthesis method according to claim 9.

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