Post-treatment method of reverse osmosis membrane and reverse osmosis membrane

Abstract

The present application relates to a reverse osmosis membrane post-processing method and a reverse osmosis membrane, wherein the reverse osmosis membrane post-processing method comprises the following steps: sequentially placing a reverse osmosis membrane prepared by an interfacial polymerization method in an acid solution containing a dialdehyde, water, an alkaline solution and a hydroxyl polyethylene glycol mercapto aqueous solution for cleaning treatment, wherein the hydroxyl polyethylene glycol mercapto aqueous solution is acidic. The reverse osmosis membrane post-processing method can effectively reduce the content of amino groups and polyamines on the reverse osmosis membrane while still having the performance of high retention and high water flux.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment membrane, in particular to a post-processing method of reverse osmosis membrane and the reverse osmosis membrane. BACKGROUND

[0002] Reverse osmosis membrane is one of the important types of separation membranes used in water treatment process, which has been widely used in drinking water treatment, seawater desalination, brackish water desalination, water reuse, etc. However, a large amount of amino groups and polyamines, such as m-phenylenediamine, will usually remain on the reverse osmosis membrane prepared by interfacial polymerization. Excessive residual polyamines not only affect the water quality, but also cause the reverse osmosis membrane to be oxidized and turned yellow and black during long-term storage, affecting the appearance and performance of the reverse osmosis membrane.

[0003] In order to reduce the amount of residual amino groups and polyamines on the reverse osmosis membrane, the existing technology usually uses pure water, alkali solution, acid solution, etc. for cleaning treatment after the reverse osmosis membrane is formed. However, the above treatment method will not only remove the residual polyamines, but also destroy the hydrogen bond network structure formed in the polyamide layer, causing the rejection performance of the reverse osmosis membrane to decrease, resulting in the reverse osmosis membrane being difficult to have both high rejection and high water flux performance. SUMMARY

[0004] Therefore, it is necessary to provide a post-processing method of reverse osmosis membrane and the reverse osmosis membrane, which can effectively reduce the content of amino groups and polyamines on the reverse osmosis membrane while still having both high rejection and high water flux performance.

[0005] A post-processing method of reverse osmosis membrane, comprising the following steps:

[0006] The reverse osmosis membrane prepared by interfacial polymerization is sequentially placed in an acid solution containing a dialdehyde, water, an alkaline solution, and a hydroxyl polyethylene glycol mercapto aqueous solution for cleaning treatment, wherein the hydroxyl polyethylene glycol mercapto aqueous solution is acidic.

[0007] In one embodiment, the temperature of the acid solution is T1, the temperature of the water is T2, the temperature of the alkaline solution is T3, and the temperature of the hydroxyl polyethylene glycol mercapto aqueous solution is T4, wherein the difference between any two of T1, T2, T3, and T4 is less than 5℃.

[0008] In one embodiment, T1, T2, T3, and T4 are independently selected from 70℃-90℃.

[0009] In one embodiment, the mass fraction of the dialdehyde in the acid solution is 0.1%-5%;

[0010] And / or, the acidic solution contains an acidic compound, and the mass fraction of the acidic compound in the acidic solution is 0.2%-2%.

[0011] In one of the embodiments, the acidic compound is selected from at least one of hydrochloric acid, sulfuric acid, and citric acid.

[0012] In one of the embodiments, the mass fraction of the basic compound in the basic solution is 0.2%-2.5%.

[0013] In one of the embodiments, the basic compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium hypochlorite, and sodium carbonate.

[0014] In one of the embodiments, the mass fraction of the hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-2%.

[0015] And / or, the hydroxyl polyethylene glycol thiol aqueous solution contains an acidic compound, and the mass fraction of the acidic compound in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-0.15%.

[0016] In one of the embodiments, the dialdehyde is selected from at least one of glutaraldehyde, glyoxal, and malondialdehyde.

[0017] A post-processing method for the reverse osmosis membrane obtained by the method.

[0018] In the post-processing method for the reverse osmosis membrane of the present application, when the reverse osmosis membrane prepared by the interfacial polymerization method is cleaned in the acidic solution containing the dialdehyde, part of the dialdehyde will react with the polyamine (such as m-phenylenediamine) not involved in the reaction, and part of the dialdehyde will react with the amino group remaining on the polyamide molecular chain and introduce an aldehyde group; when cleaned in the basic solution, the aldehyde group on the reverse osmosis membrane will continue to react with the residual polyamine, and then introduce an imine group (-C=N-) on the reverse osmosis membrane while further removing the residual polyamine, thereby improving the water flux of the reverse osmosis membrane; when cleaned in the acid polyethylene glycol thiol solution, the imine group (-C=N-) on the surface of the reverse osmosis membrane will react with the hydroxyl polyethylene glycol thiol, and then introduce a hydroxyl group and a polyethylene glycol chain with a terminal hydroxyl group on the reverse osmosis membrane. The introduction of the hydroxyl group and the polyethylene glycol chain can form a hydrogen bond network with the carboxyl group on the polyamide layer on one hand, so that the reverse osmosis membrane still maintains high rejection performance, and on the other hand, can significantly improve the hydrophilicity of the surface of the reverse osmosis membrane, further improving the water flux of the reverse osmosis membrane. Moreover, the improvement of the hydrophilicity can reduce the concentration polarization on the surface of the reverse osmosis membrane to a certain extent when the reverse osmosis membrane is applied to water treatment, thereby further ensuring the stability of the rejection performance of the reverse osmosis membrane.

[0019] Therefore, the post-treatment method of the reverse osmosis membrane can effectively reduce the content of amino groups and polyamines on the reverse osmosis membrane while maintaining the high rejection and high water flux performance of the reverse osmosis membrane. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present application, the present application will be described in more detail below. However, it should be understood that the present application can be implemented in many different forms and is not limited to the embodiments or examples described herein. On the contrary, the purpose of providing these embodiments or examples is to make the disclosure of the present application more thorough and comprehensive.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments or examples only and is not intended to be limiting of the present application. As used herein, the term "and / or" is intended to include any and all combinations of one or more of the associated listed items and can be used in lieu of "and / or" in any application or claim containing such term.

[0022] The post-treatment method of the reverse osmosis membrane provided by the present application comprises the following steps: sequentially placing a reverse osmosis membrane prepared by an interfacial polymerization method in an acid solution containing a dialdehyde, water, an alkaline solution, and a hydroxyl polyethylene glycol thiol aqueous solution for cleaning treatment, wherein the hydroxyl polyethylene glycol thiol aqueous solution is acidic.

[0023] In the present application, the specific steps of preparing the reverse osmosis membrane by the interfacial polymerization method are as follows: sequentially placing an aqueous solution containing a polyamine and an oil phase solution containing a polyacyl chloride on the same surface of a support membrane, and performing heat treatment to form a polyamide layer to obtain a reverse osmosis membrane, wherein the polyamine is preferably m-phenylenediamine, and the polyacyl chloride is preferably trimesoyl chloride. It can be understood that a large amount of amino groups and polyamines (such as m-phenylenediamine) that do not participate in the reaction remain on the polyamide layer formed by the interfacial polymerization, so that a large amount of amino groups and polyamines remain on the reverse osmosis membrane.

[0024] Specifically, when the reverse osmosis membrane prepared by the interfacial polymerization method is placed in the acidic solution containing the dialdehyde for cleaning, under the acidic condition, part of the dialdehyde reacts with the polyamine not involved in the reaction to remove the residual polyamine on the reverse osmosis membrane, at the same time, part of the dialdehyde reacts with the residual amino group on the polyamide molecular chain to introduce the aldehyde group on the reverse osmosis membrane while removing a large number of residual amino groups on the polyamide molecular chain, thereby removing a large number of residual polyamines and amino groups on the reverse osmosis membrane, leaving water channels, and further improving the water flux of the reverse osmosis membrane; moreover, the acidic solution is acidic, and can also neutralize the residual free amino groups and polyamines on the surface of the reverse osmosis membrane.

[0025] When the reverse osmosis membrane cleaned by the acidic solution is placed in water for cleaning, the residual amino groups and polyamines on the reverse osmosis membrane can be further removed while the excess acidic solution on the surface of the reverse osmosis membrane is removed, effectively avoiding the influence of the higher concentration of the acidic solution on the surface of the reverse osmosis membrane on the effect of subsequent cleaning by the alkaline solution.

[0026] When the reverse osmosis membrane cleaned by water is placed in the alkaline solution for cleaning, on the one hand, the alkaline solution neutralizes the residual acidic solution on the surface of the reverse osmosis membrane, further removes the residual polyamines and other impurities such as organic matter on the surface of the reverse osmosis membrane, and on the other hand, provides an alkaline environment, so that the aldehyde group on the reverse osmosis membrane can continue to react with the residual polyamine to introduce an imine group (-C=N-) on the reverse osmosis membrane, and further remove the residual polyamine.

[0027] When the reverse osmosis membrane cleaned by the alkaline solution is placed in the hydroxyl polyethylene glycol mercapto aqueous solution for cleaning, since the hydroxyl polyethylene glycol mercapto aqueous solution is acidic, an acidic condition is provided, so that the imine group (-C=N-) on the reverse osmosis membrane can react with the mercapto group in the hydroxyl polyethylene glycol mercapto to form a stable thioether bond, and then introduce a hydroxyl group and a polyethylene glycol chain with a terminal hydroxyl group on the reverse osmosis membrane, and the introduction of the hydroxyl group and the polyethylene glycol chain, on the one hand, can form a hydrogen bond network with the carboxyl group on the polyamide layer, repair the hydrogen bond network in the polyamide layer damaged when a large number of amino groups and polyamines are removed, and ensure the integrity of the entire polyamide layer, so that the reverse osmosis membrane still maintains high rejection performance, and on the other hand, can significantly improve the hydrophilicity of the surface of the reverse osmosis membrane, and further improve the water flux of the reverse osmosis membrane; moreover, the improvement of the hydrophilicity enables the reverse osmosis membrane to reduce the concentration polarization on the surface of the reverse osmosis membrane to a certain extent when the reverse osmosis membrane is applied to water treatment, and further ensures the stability of the rejection performance of the reverse osmosis membrane.

[0028] Therefore, compared with the post-processing method of the conventional reverse osmosis membrane, the post-processing method of the reverse osmosis membrane of the present application can effectively reduce the content of amino groups and polyamines on the reverse osmosis membrane while still maintaining the performance of high rejection and high water flux.

[0029] It should be noted that in the present application, the acidic solution refers to a solution with a pH less than 7, and the basic solution refers to a solution with a pH greater than 7. At the same time, when the binary aldehyde in the acidic solution reacts with the residual amino group on the polyamide molecular chain, a large steric hindrance will be formed due to the presence of the polyamide molecular chain, so the residual amino group on the polyamide molecular chain can usually only react with one of the aldehyde groups of the binary aldehyde.

[0030] In view of the fact that the temperature change between the acidic solution, water, basic solution and hydroxyl polyethylene glycol mercapto aqueous solution will affect the tension of the reverse osmosis membrane, and in turn affect the flatness of the reverse osmosis membrane, therefore, in the present application, the temperature of the acidic solution is T1, the temperature of the water is T2, the temperature of the basic solution is T3, and the temperature of the hydroxyl polyethylene glycol mercapto aqueous solution is T4, wherein the difference between any two of T1, T2, T3 and T4 is less than 5℃. It can be understood that the difference between T1 and T2, T1 and T3, T1 and T4, T2 and T3, T2 and T4, T3 and T4 is less than 5℃, and preferably T1, T2, T3 and T4 are the same. In this way, the tension of the reverse osmosis membrane can be effectively ensured to remain basically consistent throughout the entire post-processing step, avoiding the occurrence of membrane rolling phenomenon due to excessive tension change, and ensuring the flatness of the reverse osmosis membrane.

[0031] Further, in order to remove the residual polyamine on the surface of the reverse osmosis membrane more quickly, in the present application, T1, T2, T3 and T4 are all greater than or equal to 60℃, and preferably T1, T2, T3 and T4 are independently selected from 70-90℃. It can be understood that T1, T2, T3 and T4 can be partially the same, completely different or completely the same.

[0032] Alternatively, the mass fraction of the binary aldehyde in the acidic solution is 0.1-5%. In this way, the residual polyamine and amino group on the surface of the reverse osmosis membrane can be better removed, and at the same time, a suitable amount of aldehyde group can be introduced on the surface of the reverse osmosis membrane.

[0033] Further, the binary aldehyde is selected from at least one of glutaraldehyde, glyoxal and malondialdehyde, and preferably glutaraldehyde.

[0034] Alternatively, the acidic solution contains an acidic compound, and the mass fraction of the acidic compound in the acidic solution is 0.2-2%. In this way, by adjusting the amount of the acidic compound, on the one hand, the free amino group and the polyamine not involved in the reaction remaining on the reverse osmosis membrane can be effectively neutralized, and on the other hand, the corresponding acidic conditions can be provided, so that the binary aldehyde can better react with the polyamine not involved in the reaction and the residual amino group on the polyamide molecular chain, and the aldehyde group can be introduced on the reverse osmosis membrane.

[0035] Further, the acid compound is at least one selected from hydrochloric acid, sulfuric acid, and citric acid.

[0036] It can be understood that in the present application, the acid solution containing dialdehyde can be prepared by mixing an acid compound, a dialdehyde, and water.

[0037] In an embodiment, the reverse osmosis membrane prepared by the interfacial polymerization method is placed in the step of cleaning treatment in water, and the water is preferably pure water.

[0038] In the present application, the pH of the alkaline solution is 12-14, which is beneficial to neutralize the concentration of the acid solution on the reverse osmosis membrane and provide an alkaline condition, which is beneficial to the reaction of the aldehyde group on the reverse osmosis membrane with the polyamine, introducing an imine group and further removing the residual polyamine.

[0039] Further, the mass fraction of the alkaline compound in the alkaline solution is 0.2%-2.5%. It can be understood that in the present application, the pH of the alkaline solution is adjusted by adjusting the content of the alkaline compound, so as to better remove the residual polyamine on the reverse osmosis membrane.

[0040] Further, the alkaline compound is at least one selected from sodium hydroxide, potassium hydroxide, sodium hypochlorite, and sodium carbonate.

[0041] It can be understood that in the present application, the alkaline solution can be prepared by mixing an alkaline compound and water.

[0042] Alternatively, the mass fraction of the hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-2%. In this way, by controlling the mass fraction of the hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution, the amount of hydroxyl groups and polyethylene glycol segments introduced on the reverse osmosis membrane can be controlled, the hydrogen bond network in the polyamide layer can be better repaired, the hydrophilicity of the surface of the reverse osmosis membrane can be improved, the reverse osmosis membrane can still maintain high rejection performance, and the water flux of the reverse osmosis membrane can be further improved.

[0043] Alternatively, the hydroxyl polyethylene glycol thiol aqueous solution contains an acid compound, and the mass fraction of the acid compound in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-0.15%. It can be understood that in the present application, the acid compound is used to adjust the acidity of the hydroxyl polyethylene glycol thiol aqueous solution, so that the hydroxyl polyethylene glycol thiol can better react with the imine group, a specific content of polyethylene glycol chains and hydroxyl groups can be introduced, the hydrophilicity of the reverse osmosis membrane can be better improved, and the water flux and the stability of the rejection performance of the reverse osmosis membrane can be further improved.

[0044] In an embodiment, the acid compound in the hydroxyl polyethylene glycol thiol aqueous solution is preferably sulfuric acid.

[0045] It can be understood that in the present application, the hydroxyl polyethylene glycol mercapto aqueous solution can be prepared by mixing an acidic compound, hydroxyl polyethylene glycol mercapto and water.

[0046] In an embodiment, the reverse osmosis membrane prepared by the interfacial polymerization method is sequentially placed in an acidic solution containing a dialdehyde, water, an alkaline solution and a hydroxyl polyethylene glycol mercapto aqueous solution for cleaning treatment, and the time of each solution is 3-5 min, 3-5 min, 1-3 min and 1-3 min, respectively.

[0047] Meanwhile, the present application also provides a reverse osmosis membrane treated by the post-treatment method of the reverse osmosis membrane. The reverse osmosis membrane can have the performance of high rejection and high water flux, and can effectively avoid the phenomenon of oxidation, yellowing and blackening during long-term storage, and has good appearance performance.

[0048] In the following, the post-treatment method of the reverse osmosis membrane and the reverse osmosis membrane will be further described by the following specific examples. However, those skilled in the art will understand that the following examples are only used to illustrate the present application, and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be obtained by purchase.

[0049] Meanwhile, it should be noted that the reverse osmosis membranes to be post-treated used in examples 1 to 9 and comparative examples 1 to 4 in the present application are prepared by the following method: a water phase solution containing m-phenylenediamine is applied to the surface of a polysulfone support membrane, the excess water phase solution is poured off after 60 s, the membrane surface is blown dry with cold air, then an oil phase solution containing trimesoyl chloride is applied to the same surface of the polysulfone support membrane, the excess oil phase solution is poured off after 30 s, and then the membrane is placed in an 80℃ oven for 3 min to obtain the reverse osmosis membrane to be post-treated. In the water phase solution, the mass fraction of m-phenylenediamine is 2%, and in the oil phase solution, the mass fraction of trimesoyl chloride is 0.18%.

[0050] Example 1

[0051] Sulfuric acid, glutaraldehyde and water are mixed to prepare an acidic solution containing glutaraldehyde with a temperature of 80℃, wherein in the acidic solution containing glutaraldehyde, the mass fraction of glutaraldehyde is 2.5% and the mass fraction of sulfuric acid is 1%; sodium hydroxide and water are mixed to prepare an alkaline solution with a temperature of 80℃, wherein the mass fraction of sodium hydroxide in the alkaline solution is 1%; hydroxyl polyethylene glycol mercapto, sulfuric acid and water are mixed to prepare a hydroxyl polyethylene glycol mercapto aqueous solution with a temperature of 80℃, wherein in the hydroxyl polyethylene glycol mercapto aqueous solution, the mass fraction of hydroxyl polyethylene glycol mercapto is 1% and the mass fraction of sulfuric acid is 0.1%.

[0052] The reverse osmosis membrane to be post-processed is soaked in the acid solution containing glutaraldehyde for cleaning for 4 min, then soaked in pure water at a temperature of 80°C for cleaning for 4 min, then soaked in the alkaline solution for cleaning for 2 min, and then soaked in the hydroxyl polyethylene glycol mercapto aqueous solution for cleaning for 2 min, and then taken out, to obtain the post-processed reverse osmosis membrane.

[0053] Example 2

[0054] Hydrochloric acid, glyoxal and water are mixed to prepare an acid solution containing glyoxal at a temperature of 70°C, wherein the mass fraction of glyoxal in the acid solution containing glyoxal is 0.1%, and the mass fraction of hydrochloric acid is 0.2%; sodium hypochlorite and water are mixed to prepare an alkaline solution at a temperature of 72°C, wherein the mass fraction of sodium hypochlorite in the alkaline solution is 0.2%; hydroxyl polyethylene glycol mercapto, sulfuric acid and water are mixed to prepare a hydroxyl polyethylene glycol mercapto aqueous solution at a temperature of 70°C, wherein the mass fraction of hydroxyl polyethylene glycol mercapto in the hydroxyl polyethylene glycol mercapto aqueous solution is 0.05%, and the mass fraction of sulfuric acid is 0.05%.

[0055] The reverse osmosis membrane to be post-processed is soaked in the acid solution containing glutaraldehyde for cleaning for 4 min, then soaked in pure water at a temperature of 70°C for cleaning for 4 min, then soaked in the alkaline solution for cleaning for 2 min, and then soaked in the hydroxyl polyethylene glycol mercapto aqueous solution for cleaning for 2 min, and then taken out, to obtain the post-processed reverse osmosis membrane.

[0056] Example 3

[0057] Citric acid, malondialdehyde and water are mixed to prepare an acid solution containing malondialdehyde at a temperature of 90°C, wherein the mass fraction of malondialdehyde in the acid solution containing malondialdehyde is 5%, and the mass fraction of citric acid is 2%; potassium hydroxide and water are mixed to prepare an alkaline solution at a temperature of 90°C, wherein the mass fraction of potassium hydroxide in the alkaline solution is 2.5%; hydroxyl polyethylene glycol mercapto, hydrochloric acid and water are mixed to prepare a hydroxyl polyethylene glycol mercapto aqueous solution at a temperature of 90°C, wherein the mass fraction of hydroxyl polyethylene glycol mercapto in the hydroxyl polyethylene glycol mercapto aqueous solution is 2%, and the mass fraction of sulfuric acid is 0.15%.

[0058] The reverse osmosis membrane to be post-processed is soaked in the acid solution containing glutaraldehyde for cleaning for 4 min, then soaked in pure water at a temperature of 90°C for cleaning for 4 min, then soaked in the alkaline solution for cleaning for 2 min, and then soaked in the hydroxyl polyethylene glycol mercapto aqueous solution for cleaning for 2 min, and then taken out, to obtain the post-processed reverse osmosis membrane.

[0059] Example 4

[0060] Example 4 is the same as Example 1 except that the temperature of the acidic solution containing glutaraldehyde is 85℃, the temperature of the pure water is 82℃, the temperature of the basic solution is 80℃, and the temperature of the hydroxyl polyethylene glycol thiol aqueous solution is 75℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0061] It is observed that in the process of cleaning the post-processed reverse osmosis membrane in this example, the temperature difference in any two cleaning steps is not all less than 5℃, resulting in a relatively large temperature difference in the middle, leading to a large difference in tension in each step, and thus a micro-rolled membrane occurs.

[0062] Example 5

[0063] Example 5 is the same as Example 1 except that the temperature of the acidic solution containing glutaraldehyde is 65℃, the temperature of the pure water is 62℃, the temperature of the basic solution is 62℃, and the temperature of the hydroxyl polyethylene glycol thiol aqueous solution is 65℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0064] Example 6

[0065] Example 6 is the same as Example 1 except that the mass fraction of glutaraldehyde in the acidic solution containing glutaraldehyde is 0.05%; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0066] Example 7

[0067] Example 7 is the same as Example 1 except that the mass fraction of glutaraldehyde in the acidic solution containing glutaraldehyde is 6%; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0068] Example 8

[0069] Example 8 is the same as Example 1 except that the mass fraction of hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution is 0.02%; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0070] Example 9

[0071] Example 9 is the same as Example 1 except that the mass fraction of hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution is 2.5%; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0072] Comparative Example 1

[0073] Comparative Example 1 is the same as Example 1 except that a sulfuric acid solution is used instead of the acidic solution containing glutaraldehyde, wherein the mass fraction of sulfuric acid in the sulfuric acid solution is 1% and the temperature is 80℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0074] Comparative Example 2

[0075] Comparative Example 2 is the same as Example 1 except that the pH of the hydroxyl polyethylene glycol mercapto aqueous solution is 6.8 and the temperature of the hydroxyl polyethylene glycol mercapto aqueous solution is 80℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0076] Comparative Example 3

[0077] Comparative Example 3 is the same as Example 1 except that the hydroxyl polyethylene glycol mercapto aqueous solution is replaced by a sulfuric acid solution, wherein the mass fraction of sulfuric acid in the sulfuric acid solution is 0.1%, and the temperature of the sulfuric acid solution is 80℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0078] Comparative Example 4

[0079] Comparative Example 4 is the same as Example 1 except that the acid solution containing glutaraldehyde is replaced by a sulfuric acid solution, wherein the mass fraction of sulfuric acid in the sulfuric acid solution is 1%, and the temperature of the sulfuric acid solution is 80℃; the hydroxyl polyethylene glycol mercapto aqueous solution is replaced by pure water, and the temperature of the pure water is 80℃; the rest of the conditions are the same, and a post-processed reverse osmosis membrane is obtained.

[0080] The reverse osmosis membranes to be post-processed used in Examples 1 to 9 and Comparative Examples 1 to 4 and the post-processed reverse osmosis membranes prepared are respectively subjected to performance tests, and the test conditions are: the test pressure is 1.55 MPa, the concentrated water flow is 1.0 GPM, the ambient temperature is 25℃, the pH of the concentrated water is 6.5-7.5, the concentrated water is a 2000 ppm sodium chloride aqueous solution, and the test results are shown in Table 1.

[0081] Table 1

[0082]

[0083] It should be noted that in Table 1, the membrane water flux (F) is calculated from the volume of water passing through the reverse osmosis membrane in a certain time, and the formula is: F=V / (A×T), wherein V is the volume of water passing through the reverse osmosis membrane per unit time, A is the effective membrane area, and T is the time.

[0084] The rejection rate (R) is calculated by the concentration of the feed liquid and the concentration of the permeate, and the calculation formula is: R=(1-C1 / C0)×100%, wherein C1 is the concentration of the permeate, and C0 is the concentration of the feed liquid.

[0085] Any combination of the technical features in the above-described embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, as long as the combination of the technical features does not exist in contradiction, it shall be considered within the scope of the present disclosure.

[0086] The above-described embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it shall not be understood as a limitation on the patent scope of the present application. It shall be pointed out that, for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these shall be within the protection scope of the present application. Therefore, the protection scope of the present application patent shall be subject to the appended claims.

Claims

1. A method of post-treatment of a reverse osmosis membrane, characterized by, The method comprises the following steps: The reverse osmosis membrane prepared by using polyamine and polyacyl chloride and by adopting the interfacial polymerization method is sequentially placed in an acid solution containing a dialdehyde, water, an alkaline solution and a hydroxyl polyethylene glycol thiol aqueous solution for cleaning treatment, wherein the hydroxyl polyethylene glycol thiol aqueous solution is acidic.

2. The post-treatment method of a reverse osmosis membrane according to claim 1, characterized by, The temperature of the acid solution is T1, the temperature of the water is T2, the temperature of the alkaline solution is T3, and the temperature of the hydroxyl polyethylene glycol thiol aqueous solution is T4, wherein the difference between any two of T1, T2, T3 and T4 is less than 5℃.

3. The post-treatment method of a reverse osmosis membrane according to claim 2, characterized by, T1, T2, T3 and T4 are independently selected from 70-90℃.

4. The post-treatment method of a reverse osmosis membrane according to any one of claims 1 to 3, characterized in that, The mass fraction of the dialdehyde in the acid solution is 0.1%-5%. And / or, the acid solution contains an acidic compound, and the mass fraction of the acidic compound in the acid solution is 0.2%-2%.

5. The post-treatment method of a reverse osmosis membrane according to claim 4, characterized by, The acidic compound is selected from at least one of hydrochloric acid, sulfuric acid and citric acid.

6. The post-treatment method of a reverse osmosis membrane according to any one of claims 1 to 3, characterized in that, The mass fraction of the alkaline compound in the alkaline solution is 0.2%-2.5%.

7. The post-treatment method of a reverse osmosis membrane according to claim 6, characterized by, The alkaline compound is selected from at least one of sodium hydroxide, potassium hydroxide, sodium hypochlorite and sodium carbonate.

8. The post-treatment method of a reverse osmosis membrane according to any one of claims 1 to 3, characterized in that, The mass fraction of the hydroxyl polyethylene glycol thiol in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-2%. And / or, the hydroxyl polyethylene glycol thiol aqueous solution contains an acidic compound, and the mass fraction of the acidic compound in the hydroxyl polyethylene glycol thiol aqueous solution is 0.05%-0.15%.

9. The post-treatment method of a reverse osmosis membrane according to any one of claims 1 to 3, characterized in that, The dialdehyde is selected from at least one of glutaraldehyde, glyoxal and malondialdehyde.

10. A reverse osmosis membrane treated by a post-treatment method using the reverse osmosis membrane according to any one of claims 1-9.

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