Oxidation-resistant composite reverse osmosis membrane and preparation method thereof

Abstract

The invention belongs to the technical field of chemical membrane separation, and particularly relates to an oxidation-resistant composite reverse osmosis membrane and a preparation method thereof.The preparation method comprises the following steps that a m-phenylenediamine water-phase solution, a trimesoyl chloride oil-phase solution and a cyanuric chloride oil-phase solution are prepared; soaking the porous support body in a m-phenylenediamine water phase solution, then soaking the porous support body in a trimesoyl chloride oil phase solution, and carrying out interfacial polymerization reaction to prepare a nascent state reverse osmosis membrane; soaking the nascent state reverse osmosis membrane in a cyanuric chloride oil phase solution, then soaking the nascent state reverse osmosis membrane in a m-phenylenediamine water phase solution, and carrying out interfacial polymerization reaction again to prepare a polyamide and polytriazine composite membrane; and carrying out heat treatment on the polyamide and polytriazine composite membrane to prepare the oxidation-resistant composite reverse osmosis membrane. The preparation method is simple in process, the prepared composite reverse osmosis membrane is good in oxidation resistance and high in desalination performance, and the prepared oxidation-resistant composite reverse osmosis membrane is gt in desalination rate; the oxidation resistance is gt; and the reaction time is 20000ppmh.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical membrane separation, and particularly relates to an oxidation-resistant composite reverse osmosis membrane and a preparation method thereof. Background Technique

[0002] Reverse osmosis desalination technology relies on the interception function of reverse osmosis membranes for inorganic salts in aqueous solutions. Driven by a pressure difference higher than the osmotic pressure of the solution, water is promoted to permeate from the high-concentration solute side to the low-concentration solute side, thereby achieving the goal of removing inorganic salts and obtaining pure water. As a key product in the field of membrane separation, reverse osmosis membranes can effectively intercept dissolved salts in water and organic substances with a molecular weight greater than 100, while allowing water molecules to pass through smoothly. They have excellent separation characteristics and extremely high application value.

[0003] In the treatment of drinking water, reverse osmosis membranes can efficiently remove harmful substances such as bacteria, viruses, heavy metals, and organic substances in water, significantly improving the safety and taste of drinking water and ensuring the drinking health of residents. In the field of industrial wastewater treatment, the use of reverse osmosis membrane technology can achieve the recycling and reuse of water resources, reduce the production costs of enterprises, reduce environmental pollution, and contribute to the sustainable development of the industry. In the juice concentration process, compared with the traditional evaporation concentration method, the reverse osmosis concentration method has lower energy consumption and can better retain the aroma components and nutrients in the juice, producing high-quality concentrated juice.

[0004] Currently, the composite reverse osmosis membranes widely used in industry usually use polysulfone ultrafiltration membranes as porous supports. By sequentially coating an aqueous solution of m-phenylenediamine and an organic phase solution of trimesoyl chloride, a polyamide desalination functional layer with a thickness of dozens to hundreds of nanometers is formed through an interfacial polymerization reaction, and its desalination rate can be as high as over 99%. However, polyamide reverse osmosis membranes have obvious defects, namely poor oxidation resistance. When the membrane is exposed to strong oxidizing substances such as sodium hypochlorite solutions with a relatively high concentration, it is extremely prone to oxidative damage, resulting in the loss of desalination performance and restricting its application in some special environments.

[0005] Cyanuric chloride molecules contain three active chlorine atoms (similar to the acyl chloride structure) and have relatively high reactivity; the two amino groups in m-phenylenediamine molecules belong to nucleophilic groups and have lone pairs of electrons. The two can polymerize to form a triazine ring structure. Based on this, an interfacial polymerization method can be used to prepare a polytriazine composite porous membrane on a porous support. The polytriazine structure is mainly characterized by a triazine ring, which is a six-membered heterocycle composed of three nitrogen atoms and three carbon atoms, making it have good stability, capable of maintaining its structure and performance stable at relatively high temperatures, and also having good tolerance to acids, bases, and organic solvents. It can be used to prepare composite water treatment membranes resistant to chlorine, heat, acids, and bases. However, the chemical activity of cyanuric chloride is relatively low, resulting in the desalination rate of polytriazine composite membranes being difficult to meet the usage requirements of reverse osmosis membranes.

[0006] In the prior art, polyamide composite reverse osmosis membranes have poor oxidation resistance, and polyazine structure composite membranes have low desalination rates, unable to meet the actual application requirements. Developing a composite reverse osmosis membrane with both high desalination performance and good oxidation resistance and its preparation method has become an urgent problem to be solved in the current field of chemical membrane separation technology. Summary of the Invention

[0007] The purpose of the present invention is to provide an oxidation-resistant composite reverse osmosis membrane and its preparation method. The preparation method has a simple process, and the prepared composite reverse osmosis membrane has good oxidation resistance and high desalination performance.

[0008] To achieve the above purpose, the present invention provides a preparation method of an oxidation-resistant composite reverse osmosis membrane, including the following steps:

[0009] S1. Prepare an aqueous solution of m-phenylenediamine, an oil-phase solution of trimesoyl chloride, and an oil-phase solution of cyanuric chloride;

[0010] S2. Immerse the porous support in the aqueous solution of m-phenylenediamine, and then immerse it in the oil-phase solution of trimesoyl chloride, and prepare a nascent reverse osmosis membrane through interfacial polymerization reaction;

[0011] S3. Immerse the nascent reverse osmosis membrane in the oil-phase solution of cyanuric chloride, and then immerse it in the aqueous solution of m-phenylenediamine, and interfacial polymerization reaction occurs again to form a polyamide and polyazine composite membrane through covalent bonds;

[0012] S4. Heat-treat the polyamide and polyazine composite membrane to prepare the oxidation-resistant composite reverse osmosis membrane.

[0013] Preferably, in S1, the mass fraction of m-phenylenediamine in the aqueous solution of m-phenylenediamine is 1-3%, and a pH buffer aqueous solution is added to the aqueous solution of m-phenylenediamine to maintain its pH value at 9-10;

[0014] The pH buffer aqueous solution includes 2-4% camphorsulfonic acid and 1-2% triethylamine by mass fraction.

[0015] Preferably, in S1, the mass fraction of trimesoyl chloride in the oil-phase solution of trimesoyl chloride is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin.

[0016] Preferably, in S1, the mass fraction of cyanuric chloride in the oil-phase solution of cyanuric chloride is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin.

[0017] Preferably, in S2, the immersion time of the porous support in the aqueous solution of m-phenylenediamine and the oil-phase solution of trimesoyl chloride is both 1-3 min.

[0018] Preferably, in S2, the porous support is an ultrafiltration membrane, and the ultrafiltration membrane includes one of a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, and a polyvinylidene fluoride ultrafiltration membrane.

[0019] Preferably, in S3, the immersion time of the nascent reverse osmosis membrane in the cyanuric chloride oil-phase solution and the m-phenylenediamine water-phase solution is 1 - 3 min for both.

[0020] Preferably, in S4, the heat treatment is carried out in an oven, the temperature of the heat treatment is 60 - 90 °C, and the time of the heat treatment is 2 - 10 min.

[0021] By carrying out the heat treatment process, the present invention helps to enhance the intermolecular interaction within the membrane, make the polyamide and polytriazine structures more stable, further optimize the performance of the membrane, including improving the mechanical strength of the membrane, the pore size distribution of the membrane, etc., thereby enhancing the comprehensive performance of the composite reverse osmosis membrane.

[0022] The present invention also provides an oxidation-resistant composite reverse osmosis membrane, which is prepared by the preparation method of the above-mentioned oxidation-resistant composite reverse osmosis membrane.

[0023] Preferably, the salt rejection rate of the oxidation-resistant composite reverse osmosis membrane > 98%, and the oxidation resistance > 20000 ppmh.

[0024] The polyamide layer of the composite reverse osmosis of the present invention ensures a high rejection rate during the desalination process of the reverse osmosis membrane, and the polytriazine structure of the composite reverse osmosis membrane endows the reverse osmosis membrane with oxidation resistance.

[0025] The mechanism of the present invention: Using the ultrafiltration membrane as the porous support, it is successively immersed in the m-phenylenediamine water-phase solution and the trimesoyl chloride oil-phase solution. The amino group (-NH 2 ) in m-phenylenediamine and the acyl chloride group (-COCl) in trimesoyl chloride undergo a polymerization reaction at the interface of the water phase and the oil phase to form polyamide. This polyamide layer has a tight molecular structure and can effectively intercept dissolved salts and organic substances with a molecular weight greater than 100 in water, ensuring the high desalination performance of the reverse osmosis membrane. The nascent reverse osmosis membrane is first immersed in the cyanuric chloride oil-phase solution, allowing the cyanuric chloride molecules to diffuse into the membrane. Since there are three active chlorine atoms (similar to the acyl chloride structure) in the cyanuric chloride molecule and its chemical activity is relatively high, when it is then immersed in the m-phenylenediamine water-phase solution, the chlorine atoms of cyanuric chloride and the amino group of m-phenylenediamine undergo an interfacial polymerization reaction to form a polytriazine ring structure. The triazine ring in the polytriazine structure consists of three nitrogen atoms and three carbon atoms to form a six-membered heterocyclic ring. This special structure endows the membrane with good stability, making it have good tolerance to acids, alkalis, and organic solvents, especially significantly improving the oxidation resistance of the membrane.

[0026] The beneficial effects of the present invention:

[0027] (1) The present invention adopts the above-mentioned oxidation-resistant composite reverse osmosis membrane and its preparation method, overcoming the disadvantages of poor oxidation resistance of polyamide composite reverse osmosis membranes and low desalination rate of poly(triazine) structure composite membranes.

[0028] (2) The present invention adopts the above-mentioned oxidation-resistant composite reverse osmosis membrane and its preparation method. By using the method of secondary interfacial polymerization reaction, a composite material of polyamide and poly(triazine) structure is formed through covalent bonds, and a reverse osmosis membrane with high desalination rate and good oxidation resistance is prepared.

[0029] (3) The present invention adopts the above-mentioned oxidation-resistant composite reverse osmosis membrane and its preparation method. The polyamide layer of the prepared composite reverse osmosis ensures a high rejection rate during the desalination process, and the poly(triazine) structure imparts oxidation resistance to the reverse osmosis membrane.

[0030] (4) The desalination rate of the oxidation-resistant composite reverse osmosis of the present invention is > 98%, and the oxidation resistance is > 20000 ppmh.

[0031] The technical solution of the present invention will be further described in detail below through the drawings and examples. Description of the Drawings

[0032] Figure 1 It is a schematic diagram of the preparation process of the oxidation-resistant composite reverse osmosis membrane in Example 1 of the present invention;

[0033] Figure 2 It is the SEM and AFM diagrams of the oxidation-resistant composite reverse osmosis membrane prepared in Example 1 of the present invention; Figure 2 In which a is the SEM diagram, Figure 2 In which b is the AFM diagram. Detailed Embodiments

[0034] The present invention will be further described below in conjunction with the drawings and examples. Unless otherwise defined, the technical terms or scientific terms used in the present invention should have the ordinary meaning understood by those of ordinary skill in the field to which the present invention belongs. The features mentioned above in the present invention or the features mentioned in the specific examples can be combined arbitrarily. These specific embodiments are only used to illustrate the present invention and not to limit the scope of the present invention.

[0035] The present invention provides a method for preparing an oxidation-resistant composite reverse osmosis membrane, comprising the following steps:

[0036] S1. Prepare an aqueous solution of m-phenylenediamine, an organic phase solution of trimesoyl chloride, and an organic phase solution of cyanuric chloride;

[0037] S2. Immerse the porous support in the aqueous solution of m-phenylenediamine, and then immerse it in the organic phase solution of trimesoyl chloride, and prepare a nascent reverse osmosis membrane through interfacial polymerization reaction.

[0038] S3. Immerse the nascent reverse osmosis membrane in a cyanuric chloride oil-phase solution, and then immerse it in a m-phenylenediamine aqueous solution to undergo an interfacial polymerization reaction again to form a polyamide and polytriazine composite membrane through covalent bonds;

[0039] S4. Heat-treat the polyamide and polytriazine composite membrane to prepare an oxidation-resistant composite reverse osmosis membrane.

[0040] Preferably, in S1, the mass fraction of m-phenylenediamine in the m-phenylenediamine aqueous solution is 1-3%, and a pH buffer aqueous solution is added to the m-phenylenediamine aqueous solution to keep its pH value at 9-10; in the present invention, by controlling the mass fraction of m-phenylenediamine to be 1-3%, a reverse osmosis membrane with high flux and high salt rejection rate can be ensured.

[0041] The pH buffer aqueous solution includes 2-4% camphorsulfonic acid and 1-2% triethylamine by mass fraction.

[0042] Preferably, in S1, the mass fraction of trimesoyl chloride in the trimesoyl chloride oil-phase solution is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin. In the present invention, by controlling the mass fraction of trimesoyl chloride to be 0.1-0.3%, a reverse osmosis membrane with high flux and high salt rejection rate can be prepared.

[0043] Preferably, in S1, the mass fraction of cyanuric chloride in the cyanuric chloride oil-phase solution is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin. In the present invention, by controlling the mass fraction of cyanuric chloride to be 0.1-0.3%, a reverse osmosis membrane with high flux and high salt rejection rate can be ensured.

[0044] Preferably, in S2, the soaking time of the porous support in the m-phenylenediamine aqueous solution and the trimesoyl chloride oil-phase solution is 1-3 min.

[0045] Preferably, in S2, the porous support is an ultrafiltration membrane, and the ultrafiltration membrane includes one of a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, and a polyvinylidene fluoride ultrafiltration membrane.

[0046] Preferably, in S3, the soaking time of the nascent reverse osmosis membrane in the cyanuric chloride oil-phase solution and the m-phenylenediamine aqueous solution is 1-3 min.

[0047] Preferably, in S4, the heat treatment is carried out in an oven, the temperature of the heat treatment is 60-90 °C, and the time of the heat treatment is 2-10 min. In the present invention, through the heat treatment process, it helps to enhance the intermolecular interaction in the membrane, make the polyamide and polytriazine structures more stable, further optimize the performance of the membrane, including improving the mechanical strength of the membrane and the pore size distribution of the membrane, etc., so as to improve the comprehensive performance of the composite reverse osmosis membrane.

[0048] The present invention also provides an oxidation-resistant composite reverse osmosis membrane, which is prepared by the preparation method of the oxidation-resistant composite reverse osmosis membrane described above.

[0049] Preferably, the salt rejection rate of the oxidation-resistant composite reverse osmosis membrane is > 98%, and the oxidation resistance is > 20000 ppmh.

[0050] The polyamide layer of the composite reverse osmosis of the present invention ensures a high rejection rate during the desalination process of the reverse osmosis membrane, and the polyazine structure of the composite reverse osmosis membrane endows the reverse osmosis membrane with oxidation resistance.

[0051] In some embodiments of the present invention, performance tests are carried out on the composite reverse osmosis membrane.

[0052] Using a cross-flow membrane cell, with an aqueous sodium chloride solution with a mass fraction of 0.1% as the feed solution, the flux and salt rejection rate of the composite reverse osmosis are tested under a pressure of 0.8 MPa. The permeation flux of the oxidation-resistant composite reverse osmosis membrane is calculated by formula (1):

[0053]

[0054] In formula (1): J is the water flux, L / m 2 hbar; V is the permeation volume, L; A is the membrane surface area, m 2 ; Δt is the membrane filtration operation time, h; P is the operating pressure, bar.

[0055] The conductivity of the permeate of the reverse osmosis membrane is measured using a conductivity meter, and the sodium chloride concentration is measured by the conductivity of the aqueous solution. The sodium chloride salt rejection rate of the oxidation-resistant composite reverse osmosis membrane is calculated by formula (2):

[0056]

[0057] In formula (2): R is the salt rejection rate of the reverse osmosis membrane, %; C p is the sodium chloride concentration of the permeate solution; C f is the sodium chloride concentration of the retentate solution.

[0058] Soak the composite reverse osmosis membrane in an aqueous sodium hypochlorite solution with a mass fraction of 0.1% (1000 ppm) for 20 h, and then test the flux and salt rejection rate of the composite reverse osmosis membrane. Based on the change in the salt rejection rate, the oxidation resistance of the composite reverse osmosis membrane is judged. If the change range of the salt rejection rate is not more than 2%, it is determined that the oxidation resistance of the composite reverse osmosis membrane is > 20000 ppmh.

[0059] Example 1

[0060] As Figure 1 shown, the present invention provides a preparation method of an oxidation-resistant composite reverse osmosis membrane, comprising the following steps:

[0061] S1. Prepare an aqueous solution of m-phenylenediamine with a mass fraction of 2%. In the aqueous solution, add camphorsulfonic acid with a mass fraction of 2% and triethylamine with a mass fraction of 1%, and maintain the pH value of the aqueous solution at 9 - 10. Prepare a heptane oil-phase solution of trimesoyl chloride with a mass fraction of 0.15%, and prepare a heptane oil-phase solution of cyanuric chloride with a mass fraction of 0.1%.

[0062] S2. Using a polysulfone ultrafiltration membrane as the porous support, immerse the porous support in the aqueous solution of m-phenylenediamine for 1 min, and then immerse it in the heptane oil-phase solution of trimesoyl chloride for 1 min to obtain a nascent reverse osmosis membrane through interfacial polymerization reaction.

[0063] S3. Immerse the nascent reverse osmosis membrane in the heptane oil-phase solution of cyanuric chloride for 1 min, and then immerse it in the aqueous solution of m-phenylenediamine for 1 min, and interfacial polymerization reaction occurs again to form a polyamide and polytriazine composite membrane through covalent bonds.

[0064] S4. Place the polyamide and polytriazine composite membrane in an oven and heat-treat it at a temperature of 60 °C for 5 min to prepare an oxidation-resistant composite reverse osmosis membrane.

[0065] Using an aqueous sodium chloride solution with a mass fraction of 0.1% as the feed solution, test the performance of the composite reverse osmosis membrane. The water flux is 3.2 L / m 2 hbar, and the salt rejection rate is 99.2%. Using an aqueous sodium hypochlorite solution with a mass fraction of 0.1% as the feed solution, test the oxidation resistance of the composite reverse osmosis membrane, and the oxidation resistance > 20000 ppmh.

[0066] Example 2

[0067] The difference from Example 1 is that in S1, the mass fraction of m-phenylenediamine in the aqueous solution of m-phenylenediamine is 1.5%, and the others are the same as in Example 1. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.5 L / m 2 hbar, and the salt rejection rate is 98.7%. The oxidation resistance > 20000 ppmh.

[0068] Example 3

[0069] The difference from Example 1 is that in S1, the mass fraction of m-phenylenediamine in the aqueous solution of m-phenylenediamine is 2.5%, and the others are the same as in Example 1. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 2.4 L / m 2 hbar, and the salt rejection rate is 99.0%. The oxidation resistance > 20000 ppmh.

[0070] Example 4

[0071] The difference from Example 1 is that in S1, the mass fraction of m-phenylenediamine in the aqueous m-phenylenediamine solution is 1.0%, and the others are the same as in Example 1. The water flux of the oxidation-resistant composite reverse osmosis membrane prepared is 3.8 L / m 2 hbar, and the salt rejection rate is 98.3%. The oxidation resistance performance > 20000 ppmh.

[0072] Example 5

[0073] The difference from Example 1 is that in S2, the porous support is immersed in the aqueous m-phenylenediamine solution for 2 min and in the oil-phase solution of trimellitic acid chloride for 2 min. In S3, the nascent reverse osmosis membrane is immersed in the oil-phase solution of cyanuric chloride for 2 min and in the aqueous m-phenylenediamine solution for 2 min. The others are the same as in Example 1. The water flux of the oxidation-resistant composite reverse osmosis membrane prepared is 2.2 L / m 2 hbar, and the salt rejection rate is 99.4%. The oxidation resistance performance > 20000 ppmh.

[0074] Example 6

[0075] The difference from Example 5 is that in S2, the porous support is immersed in the aqueous m-phenylenediamine solution for 0.5 min, and the others are the same as in Example 5. The water flux of the oxidation-resistant composite reverse osmosis membrane prepared is 4.2 L / m 2 hbar, and the salt rejection rate is 98.4%. The oxidation resistance performance > 20000 ppmh.

[0076] Example 7

[0077] The difference from Example 5 is that in S2, the porous support is immersed in the aqueous m-phenylenediamine solution for 2.5 min, and the others are the same as in Example 5. The water flux of the oxidation-resistant composite reverse osmosis membrane prepared is 3.0 L / m 2 hbar, and the salt rejection rate is 99.2%. The oxidation resistance performance > 20000 ppmh.

[0078] Example 8

[0079] The difference from Example 5 is that in S2, the porous support is immersed in the aqueous m-phenylenediamine solution for 3.0 min, and the others are the same as in Example 5. The water flux of the oxidation-resistant composite reverse osmosis membrane prepared is 2.6 L / m 2 hbar, and the salt rejection rate is 99.3%. The oxidation resistance performance > 20000 ppmh.

[0080] Example 9

[0081] S1. Prepare an aqueous solution of m-phenylenediamine with a mass fraction of 2%. Add camphorsulfonic acid with a mass fraction of 2% and triethylamine with a mass fraction of 1% to the aqueous solution of m-phenylenediamine, and maintain the pH value of the aqueous solution of m-phenylenediamine at 9 - 10. Prepare an organic phase solution of trimesoyl chloride in n-heptane with a mass fraction of 0.1%, and prepare an organic phase solution of cyanuric chloride in n-heptane with a mass fraction of 0.05%.

[0082] S2. Use a polysulfone ultrafiltration membrane as a porous support. Immerse the porous support in the aqueous solution of m-phenylenediamine for 2 min, and then immerse it in the organic phase solution of trimesoyl chloride for 2 min. An as-formed reverse osmosis membrane is obtained through interfacial polymerization reaction.

[0083] S3. Immerse the as-formed reverse osmosis membrane in the organic phase solution of cyanuric chloride for 2 min, and then immerse it in the aqueous solution of m-phenylenediamine for 2 min. Interfacial polymerization reaction occurs again to form a polyamide and polytriazine composite membrane through covalent bonds.

[0084] S4. Place the polyamide and polytriazine composite membrane in an oven, and under the condition of a temperature of 60 °C, perform heat treatment for 5 min to prepare an oxidation-resistant composite reverse osmosis membrane.

[0085] Use an aqueous solution of sodium chloride with a mass fraction of 0.1% as the feed liquid to test the performance of the composite reverse osmosis membrane. The water flux is 3.6 L / m 2 hbar, and the salt rejection rate is 98.6%. Use an aqueous solution of sodium hypochlorite with a mass fraction of 0.1% as the feed liquid to test the oxidation resistance of the composite reverse osmosis membrane. The oxidation resistance > 20000 ppmh.

[0086] Example 10

[0087] The difference from Example 9 is that in S4, the heat treatment temperature in the oven is 70 °C, and the heat treatment time is 3 min. Others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.7 L / m 2 hbar, and the salt rejection rate is 99.0%. The oxidation resistance > 20000 ppmh.

[0088] Example 11

[0089] The difference from Example 9 is that in S4, the heat treatment temperature in the oven is 80 °C, and the heat treatment time is 3 min. Others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.3 L / m 2 hbar, and the salt rejection rate is 98.0%. The oxidation resistance > 20000 ppmh.

[0090] Example 12

[0091] The difference from Example 9 is that in S4, the oven heat treatment temperature is 90 °C and the heat treatment time is 2 min. Others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.1 L / m 2 hbar, and the salt rejection rate is 99.2%. The oxidation resistance performance > 20000 ppmh.

[0092] Example 13

[0093] The difference from Example 9 is that in S1, the oil phase in the trimesoyl chloride oil phase solution and the cyanuric chloride oil phase solution is n-hexane, and others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.5 L / m 2 hbar, and the salt rejection rate is 99.2%. The oxidation resistance performance > 20000 ppmh.

[0094] Example 14

[0095] The difference from Example 9 is that in S1, the oil phase in the trimesoyl chloride oil phase solution and the cyanuric chloride oil phase solution is isoparaffin, and others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 2.6 L / m 2 hbar, and the salt rejection rate is 99.4%. The oxidation resistance performance > 20000 ppmh.

[0096] Example 15

[0097] The difference from Example 9 is that in S2, a polyethersulfone ultrafiltration membrane is used as the porous support, and others are the same as in Example 9. The water flux of the prepared oxidation-resistant composite reverse osmosis membrane is 3.8 L / m 2 hbar, and the salt rejection rate is 98.3%. The oxidation resistance performance > 20000 ppmh.

[0098] Example 16

[0099] The difference from Example 9 is that in S2, a polyacrylonitrile ultrafiltration membrane is used as the porous support, and others are the same as in Example 9. The reverse osmosis permeation flux of the prepared oxidation-resistant composite is 1.6 L / m 2 hbar, and the salt rejection rate is 98.3%. The oxidation resistance performance > 20000 ppmh.

[0100] Comparative Example 1

[0101] S1. Prepare an aqueous solution of m-phenylenediamine with a mass fraction of 2%. Add camphorsulfonic acid with a mass fraction of 2% and triethylamine with a mass fraction of 1% to the aqueous solution of m-phenylenediamine, and maintain the pH value of the aqueous solution of m-phenylenediamine at 9 - 10. Prepare an n-heptane oil phase solution of trimesoyl chloride with a mass fraction of 0.1%.

[0102] S2. Using a polysulfone ultrafiltration membrane as the porous support, soak the porous support in an aqueous solution of m-phenylenediamine for 2 min, and then soak it in an organic solution of trimesoyl chloride for 2 min. An interfacial polymerization reaction is carried out to obtain a nascent reverse osmosis membrane.

[0103] S3. Place the nascent composite reverse osmosis membrane in an oven and heat-treat it at a temperature of 60 °C for 5 min to prepare a composite reverse osmosis membrane.

[0104] Using an aqueous sodium chloride solution with a mass fraction of 0.1% as the feed solution, the performance of the composite reverse osmosis membrane is tested. The water flux is 3.9 L / m 2 hbar, and the salt rejection rate is 98.7%. Using an aqueous sodium hypochlorite solution with a mass fraction of 0.1% as the feed solution, the oxidation resistance of the composite reverse osmosis membrane is tested, and the oxidation resistance is <5000 ppmh. It shows that there is no antioxidant performance.

[0105] Comparative Example 2

[0106] S1. Prepare an aqueous solution of m-phenylenediamine with a mass fraction of 2%. Add camphorsulfonic acid with a mass fraction of 2% and triethylamine with a mass fraction of 1% to the aqueous solution of m-phenylenediamine, and keep the pH value of the aqueous solution of m-phenylenediamine at 9-10. Prepare an organic solution of cyanuric chloride in n-heptane with a mass fraction of 0.2%.

[0107] S2. Using a polysulfone ultrafiltration membrane as the porous support, soak the porous support in the aqueous solution of m-phenylenediamine for 2 min, and then soak it in the organic solution of cyanuric chloride for 2 min. An interfacial polymerization reaction is carried out to obtain a nascent reverse osmosis membrane.

[0108] S3. Place the nascent composite membrane in an oven and heat-treat it at a temperature of 60 °C for 5 min to prepare a composite membrane.

[0109] Using an aqueous sodium chloride solution with a mass fraction of 0.1% as the feed solution, the performance of the composite membrane is tested. The water flux is 5.2 L / m 2 hbar, and the salt rejection rate is only 58.2%. It shows that the salt rejection rate is low and it cannot be used as a reverse osmosis membrane.

[0110] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that they can still modify or equivalently replace the technical solutions of the present invention, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an oxidation-resistant composite reverse osmosis membrane, characterized in that: The following steps are involved: S1, preparing a m-phenylenediamine aqueous solution, a trimesoyl chloride oil solution and a cyanuric chloride oil solution; S2, immersing the porous support in an aqueous solution of m-phenylenediamine, and then immersing it in an oil solution of trimesoyl chloride, and producing a nascent reverse osmosis membrane by interfacial polymerization reaction; S3, immersing the nascent reverse osmosis membrane in a cyanuric chloride oil phase solution, and then immersing it in a meta-phenylenediamine aqueous phase solution, and causing interfacial polymerization reaction again to obtain a polyamide and polytriazine composite membrane; S4. Heat-treating the polyamide and polytriazine composite membrane to prepare an oxidation-resistant composite reverse osmosis membrane.

2. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S1, the mass fraction of m-phenylenediamine in the m-phenylenediamine aqueous phase solution is 1-3%, and a pH buffer solution is added to the m-phenylenediamine aqueous phase solution to maintain its pH value at 9-10; The pH buffer aqueous solution comprises 2-4% camphorsulfonic acid and 1-2% triethylamine by mass fraction.

3. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S1, the mass fraction of trimesoyl chloride in the trimesoyl chloride oil phase solution is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin.

4. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S1, the mass fraction of cyanuric chloride in the cyanuric chloride oil phase solution is 0.1-0.3%, and the oil phase includes one or more of n-hexane, n-heptane, and isoparaffin.

5. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S2, the immersion time of the porous support in the m-phenylenediamine aqueous solution and the trimesoyl chloride oil solution is 1-3 min.

6. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S2, the porous support is an ultrafiltration membrane, and the ultrafiltration membrane includes one of a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, a polyacrylonitrile ultrafiltration membrane, and a polyvinylidene fluoride ultrafiltration membrane.

7. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S3, the nascent reverse osmosis membrane is immersed in the cyanuric chloride oil phase solution and the m-phenylenediamine water phase solution for 1-3 minutes.

8. The method for preparing an oxidation-resistant composite reverse osmosis membrane according to claim 1, characterized in that: In S4, the heat treatment is carried out in an oven at a temperature of 60-90° C. and a time of 2-10 min.

9. An oxidation-resistant composite reverse osmosis membrane, characterized in that: The membrane is prepared by the method for preparing an oxidation-resistant composite reverse osmosis membrane according to any one of claims 1 to 8.

10. The oxidation-resistant composite reverse osmosis membrane according to claim 9, characterized in that: The desalination rate of the oxidation-resistant composite reverse osmosis membrane is >98%, and the oxidation resistance is >20000ppmh.

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