Causticity material separation membrane and preparation method thereof

Abstract

The invention relates to the field of separation membranes, and discloses a caustic material separation membrane and a preparation method thereof, the caustic material separation membrane comprises a porous carrier and a cross-linking layer on the surface of the porous carrier; the cross-linking layer is prepared by cross-linking a pre-cross-linking product of a polyol compound and an anionic polymer with a cross-linking agent; the hydroxyl value of the polyhydric alcohol compound is 400 to 2000 mgKOH / g; the anionic polymer at least comprises one acidic group; the cross-linking agent at least comprises one reactive group; the reactive group is one of carboxyl, aldehyde group and amido. According to the invention, an adjustable semi-interpenetrating network cross-linking layer is formed on the surface of the porous carrier through the cross-linking reaction of the polyol compound and the anionic polymer with the cross-linking agent, so that the separation membrane can be used in caustic feed liquid for a long time, the separation precision is adjustable, and the scale inhibition performance is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of separation membranes, in particular to a caustic material separation membrane and a preparation method thereof. BACKGROUND

[0002] In the production and processing processes of food, electronics, textiles, metallurgy and papermaking industries, a large amount of caustic wastewater is generated. Due to the complex composition of industrial wastewater and the high concentration of alkali, traditional separation membranes are prone to hydrolysis and scaling in caustic alkali solution, resulting in poor running stability, limited service life and reduced mechanical strength, which limits their application and increases the cost. Therefore, it is of great practical significance to prepare a caustic material separation membrane.

[0003] At present, there have been many studies on improving the alkali resistance of separation membranes. Patent CN115105967A obtains an alkali-resistant separation layer by interfacial Mannich reaction polymerization of polyamines, aldehyde compounds and fatty ketones containing alpha hydrogen, which can resist the damage of harsh alkali environment to the membrane sheet. The shortcomings are that the salt rejection rate is low and the separation performance is poor. Patent CN114130220A uses a multifunctional crosslinking agent and an amine-based compound to generate an initial membrane through interfacial polymerization, and then generates a composite membrane through crosslinking, effectively improving the alkali resistance of the membrane. However, the membrane selected in this patent is only soaked in 0.2wt% sodium hydroxide solution for 20h, the soaking time is short, and the alkali concentration is low, which is insufficient for long-term high-concentration alkali resistance. Patent CN117414712A adds an epoxy monomer to the oil phase solvent and reacts with the primary amine substance in the water phase solvent to generate an epoxy amine functional layer, which has good adhesion and alkali resistance. However, the separation precision of the nanofiltration membrane prepared is poor, and the application field is limited. Literature (Journal of Membrane Science 637 (2021) 119631) prepared a nanofiltration membrane for treating lignin alkali solution (pH = 7-14) by crosslinking polyethyleneimine and isocyanuric acid triglycidyl ester, which can be used for wastewater treatment in the papermaking industry. However, the membrane separation precision is poor, and the flux is low, which limits its application. The above methods improve the alkali resistance of the separation membrane to some extent, but cannot guarantee the separation precision of the membrane at the same time, and the scaling of the separation membrane is not mentioned. SUMMARY

[0004] The present application is to overcome the above-mentioned problems of the prior art separation membrane, and to provide a caustic material separation membrane and a preparation method thereof. Through the crosslinking reaction of polyol compounds and anionic polymers with crosslinking agents, a semi-interpenetrating network crosslinking layer is formed on the surface of the porous carrier, which makes the separation membrane can be used in caustic material for a long time, and the separation precision is adjustable and the scale inhibition performance is good.

[0005] In order to achieve the above-mentioned purposes, the present application adopts the following technical solutions: In a first aspect, the present application provides a caustic material separation membrane, comprising a porous carrier and a crosslinked layer on the surface of the porous carrier; the crosslinked layer is prepared by crosslinking a pre-crosslinked product of a polyol compound and an anionic polymer with a crosslinking agent; the polyol compound has a hydroxyl value of 400-2000 mgKOH / g; the anionic polymer contains at least one acidic group; the crosslinking agent contains at least one reactive group; and the reactive group is one of carboxyl, aldehyde and amine groups.

[0006] The polyol compound and the anionic polymer in the present application can be pre-crosslinked to form a branched polyol, and the branched polyol can be post-crosslinked with the crosslinking agent. The branched polyol has a high degree of branching, and the reaction is controllable. Finally, a crosslinked layer with an adjustable semi-interpenetrating network structure is formed. The crosslinked layer can significantly improve the alkali resistance of the separation membrane, so that it can be used in caustic liquor for a long time. In addition, by selecting polyol compounds with different hydroxyl values, the separation precision can be fine-tuned, and the separation membrane with different precision can be prepared, so that the separation membrane has good separation effect. The addition of the anionic polymer in the reaction can inhibit the growth of crystal nucleus and alleviate fouling, thereby improving the anti-fouling performance of the separation membrane. Therefore, the separation membrane in the present application has high flux, good separation precision and is not easy to foul, and can be used in high-concentration alkali liquor for a long time.

[0007] Preferably, the mass ratio of the polyol compound, the anionic polymer and the crosslinking agent is 0.05-10:0.01-0.1:0.01-5.

[0008] Preferably, the polyol compound comprises polyvinyl alcohol and other polyol compounds, and the other polyol compounds are selected from one or more of butanediol, butylene glycol, neopentyl glycol, hexanediol, glycerol, pentaerythritol, trimethylolpropane, sorbitol, mannitol, polyethylene glycol, bisphenol A and its homologues or derivatives. A small amount of polyvinyl alcohol is added to the polyol compound as a chain extension crosslinking agent to assist the reaction, which helps to build a crosslinked layer with complete crosslinked structure, so as to ensure the uniformity and toughness of the crosslinked structure, and further improve the alkali resistance of the separation membrane.

[0009] Preferably, the mass ratio of the polyvinyl alcohol and the other polyol compounds is 1:0.05-0.5.

[0010] Preferably, the anionic polymer is selected from one or more of hydrolyzed polymaleic anhydride, polyepoxysuccinic acid, polyaspartic acid, polyacrylic acid, polymethylene succinic acid, sodium polystyrene sulfonate, sodium poly-2-acryloyl-2-methylpropane sulfonate, S-carboxyethyl thioglycolate, hydroxyethylidene diphosphonic acid, acrylic acid copolymer, maleic anhydride copolymer and itaconic acid copolymer.

[0011] Preferably, the cross-linking agent is selected from one or more of boric acid, tannic acid, tartaric acid, malic acid, phytic acid, citric acid, succinic acid, maleic acid, polyacrylic acid, formaldehyde, glyoxal, glutaraldehyde, furfural, citral, cinnamaldehyde, dimethylol urea, melamine, carbodiimide, N,N'-methylene bisacrylamide, polyvinylamine, transglutaminase, 1,2,3-propanetriol diglycidyl ether, and homologues or derivatives of the above.

[0012] Preferably, the porous support is one of a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane, and a reverse osmosis membrane.

[0013] Preferably, the microfiltration membrane, the ultrafiltration membrane, the nanofiltration membrane, and the reverse osmosis membrane are flat-plate type or hollow-fiber type.

[0014] In a second aspect, the present application provides a method for preparing the caustic material separation membrane described above, comprising the following steps: (1) reacting a polyol compound and an anionic polymer in a solvent to obtain a homogeneous pre-crosslinking solution; (2) applying the homogeneous pre-crosslinking solution to the surface of a porous support, discarding after a certain period of time, and obtaining a pre-crosslinking membrane after air drying; (3) dissolving a cross-linking agent in a solvent, then applying it to the surface of the pre-crosslinking membrane, discarding after a certain period of time, and obtaining the caustic material separation membrane after heat treatment and solidification.

[0015] Preferably, discarding after a certain period of time in steps (2) and (3) is 30-300 seconds.

[0016] Therefore, the present application has the following beneficial effects: (1) The polyol compound and the anionic polymer can react with the cross-linking agent to form a cross-linking layer with an adjustable semi-interpenetrating network structure, which can significantly improve the alkali resistance of the separation membrane, allowing it to be used in caustic solutions for a long time; (2) By selecting polyol compounds with different hydroxyl values, the separation precision can be fine-tuned, and the preparation of separation membranes with different precision can be achieved; (3) Adding an anionic polymer to participate in the reaction can inhibit crystal nucleus growth and alleviate fouling, improving the anti-fouling performance of the separation membrane. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a physical map of the separation membrane after the scale inhibition test of Example 3 and Comparative Example 1 of the present application; wherein (a) is Example 3; and (b) is Comparative Example 1. DETAILED DESCRIPTION

[0018] The specific embodiments of the present application are further described below, but are not limited to these embodiments.

[0019] The polyvinyl alcohol used in the following examples is all type 2499, and the ultrafiltration membrane material is polyether sulfone with a molecular weight cutoff of 50000 Da.

[0020] Example 1 A preparation method of a caustic material separation membrane, the specific steps are as follows: (1) 1 part of glycerol polyether (Hongbaoli H304, hydroxyl value 405-435 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 80 parts of anhydrous ethanol, 20 parts of water are uniformly mixed, then 0.01 parts of FeCl 3· 6H2O is added, and stirring is continued at 70°C for 2 hours until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) 0.1 parts of glutaraldehyde and 100 parts of water are uniformly mixed and applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, it is poured off and heat treated at 60°C for 10 min to obtain a separation membrane.

[0021] Example 2 A preparation method of a caustic material separation membrane, the specific steps are as follows: (1) 1 part of glycerol polyether (Hongbaoli H304, hydroxyl value 405-435 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 80 parts of anhydrous ethanol, 20 parts of water are uniformly mixed, then 0.01 parts of FeCl 3· 6H2O is added, and stirring is continued at 70°C for 2 hours until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) 0.1 parts of glutaraldehyde and 100 parts of water are uniformly mixed and applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, it is poured off and heat treated at 60°C for 10 min to obtain a separation membrane.

[0022] Example 3 A preparation method of a caustic material separation membrane, the specific steps are as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Hongbaoli H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, then 0.01 parts of H2SO4 is added, and stirring is continued at 95°C for 1 hour until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the mixture is heat treated at 60°C for 10 min to obtain a separation membrane.

[0023] Example 4 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) After 1 part of chitosan, 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 80 parts of acetic acid, and 20 parts of water are uniformly mixed, 0.01 parts of H2SO4 is added, and the mixture is continuously stirred at 70°C for 2 hours until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the mixture is heat treated at 60°C for 10 min to obtain a separation membrane.

[0024] Example 5 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) After 1 part of sorbitol polyether (Hongbaoli H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyaspartic acid (MW: 1000-5000 Da), and 100 parts of water are uniformly mixed, 0.01 parts of H2SO4 is added, and the mixture is continuously stirred at 95°C for 1 hour until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the mixture is heat treated at 60°C for 10 min to obtain a separation membrane.

[0025] Example 6 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) After 1 part of sorbitol polyether (Hongbaoli H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyaspartic acid (MW: 1000-5000 Da), and 100 parts of water are uniformly mixed, 0.01 parts of H2SO4 is added, and the mixture is continuously stirred at 95°C for 1 hour until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300 s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300 s, they are poured off, and the pre-crosslinked membrane is heat treated at 60°C for 10 min to obtain a separation membrane.

[0026] Example 7 A preparation method of a caustic material separation membrane is as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Bee H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300 s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of tannic acid and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300 s, they are poured off, and the pre-crosslinked membrane is heat treated at 60°C for 10 min to obtain a separation membrane.

[0027] Example 8 A preparation method of a caustic material separation membrane is as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Bee H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300 s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of N, N'-methylene bisacrylamide and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300 s, they are poured off, and the pre-crosslinked membrane is heat treated at 60°C for 10 min to obtain a separation membrane.

[0028] Comparative Example 1 A preparation method of a caustic material separation membrane is as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Bee H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the separation membrane is obtained by heat treatment at 60°C for 10 min.

[0029] Comparative Example 2 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Pearl H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyvinyl alcohol, 0.2 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the separation membrane is obtained by heat treatment at 60°C for 10 min.

[0030] Comparative Example 3 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Pearl H635SG, hydroxyl value 485-515 mgKOH / g), 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied to the surface of the ultrafiltration membrane, and after 300s, it is poured off to obtain a pre-crosslinked membrane; (3) After 0.1 part of glutaraldehyde and 100 parts of water are uniformly mixed, they are applied to the surface of the pre-crosslinked membrane obtained in step (2), and after 300s, they are poured off, and the separation membrane is obtained by heat treatment at 60°C for 10 min.

[0031] Comparative Example 4 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Pearl H635SG, hydroxyl value 485-515 mgKOH / g), 0.2 parts of polyvinyl alcohol, 0.05 parts of polyepoxysuccinic acid (MW: 400-1500 Da), 100 parts of water are uniformly mixed, and then 0.01 parts of H2SO4 is added, and continuously stirred at 95°C for 1 hour, until a homogeneous pre-crosslinking solution is formed; (2) The pre-crosslinking solution is applied on the surface of the ultrafiltration membrane, and then discarded after 300 seconds, to obtain a pre-crosslinked membrane; (3) The 0.1 part of glutaraldehyde and 100 parts of water are mixed uniformly, and then applied on the surface of the pre-crosslinked membrane obtained in step (2), and then discarded after 300 seconds, and then heat treated at 60°C for 10 minutes to obtain a separation membrane.

[0032] Comparative Example 5 A preparation method of a caustic material separation membrane, and the specific steps are as follows: (1) In a nitrogen atmosphere, 1 part of sorbitol polyether (Red Pearl H635SG, hydroxyl value 485-515 mgKOH / g), 0.2 part of polyvinyl alcohol, 0.05 part of polyepoxysuccinic acid (MW: 400-1500 Da), 0.1 part of glutaraldehyde, 100 parts of water are mixed uniformly, and then 0.01 part of H2SO4 is added, and then continuously stirred at 95°C for 1 hour to obtain a crosslinking solution; (2) The crosslinking solution is applied on the surface of the ultrafiltration membrane, and then discarded after 300 seconds, and then heat treated at 60°C for 10 minutes to obtain a separation membrane.

[0033] The alkali resistance of the separation membranes prepared in the above examples and comparative examples is tested, and the test method is as follows: The separation membranes prepared in the examples and comparative examples are soaked in 1 mol / L sodium hydroxide solution for 360 hours, and the solution temperature is 25°C, and the membrane is taken out every 72 hours, and then tested on a cross-flow membrane testing platform. The test conditions are: 100 ppm polyethylene glycol PEG600 aqueous solution, operating pressure is 0.5 MPa, test temperature is 25°C, and pH value is 6.5-7.5. The specific test results are shown in Table 1.

[0034] Table 1: Test results of flux and PEG600 rejection rate of each example and comparative example during alkali soaking process As can be seen from Table 1, the separation membranes prepared in Examples 1-8 have good alkali resistance, and the separation performance does not decrease significantly after soaking in high-concentration alkali liquor for 360 h. The number of hydroxyl groups of the polyol compound selected in Examples 1-4 gradually increases, and the branching degree increases, so that the crosslinking degree of the separation membrane increases, and the alkali resistance and separation precision increase. Compared with the separation membrane of Comparative Example 3 without adding polyvinyl alcohol, the separation membrane in Example 3 shows stronger alkali resistance in a caustic environment, indicating that the addition of a small amount of polyvinyl alcohol helps to build a crosslinked layer with complete crosslinking structure. However, in Comparative Example 4, the addition of excessive polyvinyl alcohol leads to the reaction of polyvinyl alcohol and crosslinking agent playing a dominant role, and polyvinyl alcohol is a long-chain linear polymer with low branching degree, resulting in low separation precision and hydrophobicity of the separation membrane. The types of anionic polymer (Examples 3, 5, 6) and crosslinking agent (Examples 3, 7, 8) all have an effect on the alkali resistance of the separation membrane, and suitable anionic polymer and crosslinking agent can be selected according to the application scenario of the separation membrane.

[0035] Compared with Comparative Example 1 without adding anionic polymer and Comparative Example 2 with excessive addition of anionic polymer, the alkali resistance of the separation membrane in Example 3 is improved, indicating that a proper amount of anionic polymer and polyol compound pre-crosslinking to form branched polyol is beneficial to improve the crosslinking degree of the crosslinked layer; but excessive addition of anionic polymer will cause the crosslinking degree of the crosslinked layer to decrease. Compared with Comparative Example 5 in which the crosslinking agent is directly mixed with the polyol compound and the anionic polymer for reaction, the separation membrane in Example 3 has higher initial separation precision and slightly smaller flux, which is due to the uncontrollable crosslinking reaction in Comparative Example 5, resulting in the precipitation of crosslinked material in the crosslinking solution, which cannot spread uniformly on the porous carrier.

[0036] The scale inhibition performance of the separation membranes prepared in Example 3 and Comparative Example 1 was tested, and the test method was as follows: According to GB / T 16632-2019 "Determination of Scale Inhibition Performance of Water Treatment Agent by Calcium Carbonate Deposition Method", the separation membranes prepared in Example 3 and Comparative Example 1 were placed in a cross-flow filtration device, the test pressure was 0.75 MPa, the device liquid was a mixed solution of 240 ppm calcium chloride, 732 ppm sodium bicarbonate and 152 ppm sodium tetraborate decahydrate, the produced water was returned to the liquid, and the test was continued for 360 h. The flux of the separation membrane and the calcium ion content in the liquid were recorded every 72 h, and the surface condition of the membrane sheet was observed after the test. The specific test results are shown in Table 2 and Figure 1 .

[0037] Table 2: Test results of scale inhibition performance of the separation membranes of Example 3 and Comparative Example 1 From Table 2, it can be seen that the flux change of Example 3 is smaller (10.5%, compared with 40.0% of Comparative Example 1), the calcium ion change is smaller (11.1%, compared with 26.3% of Comparative Example 1), and from Figure 1 It can be seen that the film surface of Comparative Example 1 appears grayish white calcium carbonate deposition, while Example 3 does not appear deposition, which indicates that the addition of anionic polymer scale inhibitor can improve the scale inhibition performance of the separation membrane.

[0038] The above is only the preferred embodiment of the present application, based on the above-mentioned principles, including the support system of the membrane applicable to the present patent, also including the membrane support layer and the separation layer, without departing from the method of the present application, a number of improvements and supplements can also be made, which improvements and supplements should also be considered as the protection scope of the present application.

Claims

1. A caustic material separation membrane, characterized in that, It includes a porous carrier and a cross-linked layer on the surface of the porous carrier; the cross-linked layer is prepared by cross-linking a pre-cross-linked product of a polyol compound and an anionic polymer with a cross-linking agent; The hydroxyl value of the polyol compound is 400-2000 mgKOH / g; the anionic polymer contains at least one acidic group; the crosslinking agent contains at least one reactive group; the reactive group is one of carboxyl, aldehyde, and amine groups.

2. The caustic material separation membrane according to claim 1, characterized in that, The mass ratio of polyol compound, anionic polymer and crosslinking agent is 0.05-10:0.01-0.1:0.01-5.

3. The caustic material separation membrane according to claim 1 or 2, characterized in that, The polyol compounds mentioned include polyvinyl alcohol and other polyol compounds, which are selected from one or more of butanediol, butenediol, neopentyl glycol, hexanediol, glycerol, pentaerythritol, trimethylolpropane, sorbitol, mannitol, polyethylene glycol, bisphenol A and their homologues or derivatives.

4. The caustic material separation membrane according to claim 3, characterized in that, The mass ratio of polyvinyl alcohol to other polyol compounds is 1:0.05 to 0.

5.

5. The caustic material separation membrane according to claim 1 or 2, characterized in that, The anionic polymer is selected from one or more of the following: hydrolyzed polymaleic anhydride, polyepoxysuccinic acid, polyaspartic acid, polyacrylic acid, polymethylene succinic acid, sodium polystyrene sulfonate, sodium poly-2-acryloyl-2-methylpropanesulfonate, S-carboxyethyl thiosuccinic acid, hydroxyethylidene diphosphonic acid, acrylic copolymers, maleic anhydride copolymers, and itaconic acid copolymers.

6. The caustic material separation membrane according to claim 1 or 2, characterized in that, The crosslinking agent is selected from one or more of the following: boric acid, tannic acid, tartaric acid, malic acid, phytic acid, citric acid, succinic acid, maleic acid, polyacrylic acid, formaldehyde, glyoxal, glutaraldehyde, furfural, citral, cinnamaldehyde, dimethylol urea, melamine, carbodiimide, N,N'-methylenebisacrylamide, polyethyleneamine, transglutaminase, 1,2,3-propanetriol diglycidyl ether, and homologues or derivatives thereof.

7. The caustic material separation membrane according to claim 1, characterized in that, The porous carrier is one of microfiltration membrane, ultrafiltration membrane, nanofiltration membrane, and reverse osmosis membrane.

8. The caustic material separation membrane according to claim 7, characterized in that, The microfiltration membrane, ultrafiltration membrane, nanofiltration membrane, and reverse osmosis membrane mentioned are either flat sheet type or hollow fiber type.

9. A method for preparing a caustic material separation membrane as described in any one of claims 1 to 8, characterized in that, Includes the following steps: (1) A homogeneous pre-crosslinked solution is obtained by reacting a polyol compound with an anionic polymer in a solvent; (2) Apply the homogeneous pre-crosslinking solution to the surface of the porous carrier, keep it and then pour it off. After air drying, a pre-crosslinking membrane is obtained. (3) Dissolve the crosslinking agent in a solvent, then apply it to the surface of the pre-crosslinked membrane, keep it and then pour it off. After heat treatment and curing, the caustic material separation membrane is obtained.

10. The preparation method according to claim 9, characterized in that, Discard after holding for 30–300 seconds in steps (2) and (3).

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