Ion modification liquid as well as preparation method and application thereof

Abstract

The invention provides an ion modification liquid and a preparation method and application thereof, and relates to the technical field of purification, and the ion modification liquid comprises a nitrogen-containing heterocyclic compound, quaternary ammonium salt and phosphate. The ion modification liquid comprises the nitrogen-containing heterocyclic compound, the quaternary ammonium salt and the phosphate ester, the phosphate ester with the scale inhibition performance serves as a bridging intermediate substance, the quaternary ammonium salt with the antibacterial performance and the nitrogen-containing heterocyclic compound can be connected to form an ion mixture, and the nitrogen-containing heterocyclic compound can react with acyl chloride on the surface of the finished RO membrane. Therefore, the ionic mixture is grafted on the surface of the RO membrane. According to the ion modification liquid, the ion mixture can be grafted to the surface of the RO membrane through soaking and is not prone to falling off in the water washing process, and the water flux of the RO membrane can be improved through soaking of the ion modification liquid. Therefore, the problem that a conventional anti-pollution antibacterial RO membrane cannot give consideration to the filtering performance can be solved.

Description

Technical Field

[0001] The invention relates to the technical field of purification, and in particular to an ion-modified liquid and a preparation method and application thereof. Background Art

[0002] Reverse osmosis membrane (RO membrane) is a semi-permeable membrane that uses pressure difference as a driving force to separate and purify solutions. Due to differences in water quality conditions, RO membranes will produce membrane pollution during use. Membrane pollution refers to the process in which particles, colloidal particles, organic solute macromolecules, especially microorganisms in the water, react physically and chemically with the membrane surface to form adhesion layers such as scale and filter cake on the membrane surface. The deposition of pollutants will increase the permeation resistance of the membrane, resulting in a reversible or irreversible decrease in flux. On the other hand, it will cause irreversible damage to the interfacial polymer layer structure on the membrane surface, resulting in an irreversible decrease in the desalination rate.

[0003] The conventional solution is to modify the RO membrane to obtain an anti-fouling and antibacterial RO membrane. However, although the existing modification methods can reduce membrane pollution or improve the antibacterial properties of the RO membrane, they will lead to a decrease in the filtration performance of the RO membrane. Summary of the invention

[0004] In view of the above problems, the present invention proposes an ion-modified liquid and a preparation method and application thereof, aiming to improve the problem that conventional anti-pollution and antibacterial RO membranes cannot take into account both filtration performance.

[0005] In a first aspect, the present invention provides an ion-modified liquid comprising a nitrogen-containing heterocyclic compound, a quaternary ammonium salt and a phosphate ester.

[0006] In one embodiment, the molar ratio of the nitrogen-containing heterocyclic compound, the quaternary ammonium salt, and the phosphate ester is (0.5-1):(0.4-0.8):1.

[0007] In one embodiment, the nitrogen-containing heterocyclic compound is at least one selected from imidazole, imidazole derivatives, benzimidazole, benzimidazole derivatives, purine, and purine derivatives.

[0008] In one embodiment, the imidazole derivatives include compounds represented by formula (I), formula (II), and formula (III):

[0009] and / or,

[0010] Benzimidazole derivatives include compounds represented by formula (IV):

[0011] and / or,

[0012] Purine derivatives include compounds represented by formula (V);

[0013]

[0014] Among them, R 1 , R 2 , R 3 , R 4 , R 5 Each of them is selected from one of alkyl, halo, halogenated alkyl and hydroxylated alkyl.

[0015] In one embodiment, the imidazole derivatives include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-butyl-4-chloro-5-hydroxymethylimidazole; and / or,

[0016] Benzimidazole derivatives include 2-methylbenzimidazole, 2-hydroxymethylbenzimidazole; and / or,

[0017] Purine derivatives include 2-aminopurine.

[0018] In one embodiment, the quaternary ammonium salt is at least one selected from hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, hexyltrimethylammonium bromide, 2-bromoethyltrimethylammonium bromide, benzyltrimethylammonium bromide, and hexadecyldimethylethylammonium bromide.

[0019] In one embodiment, the phosphate ester is selected from at least one of trimethyl phosphate, triethyl phosphate, and tripropyl phosphate.

[0020] In a second aspect, the present invention provides a method for preparing an ion-modified liquid, comprising reacting a mixed liquid including a nitrogen-containing heterocyclic compound, a quaternary ammonium salt, and a phosphate ester at 140° C. to 165° C. for 8 to 15 hours; or,

[0021] The mixed solution including the nitrogen-containing heterocyclic compound and the phosphate ester is reacted at 140° C.-165° C. for 8-15 hours, and then the quaternary ammonium salt is added and reacted at 50° C.-80° C. for 6-10 hours.

[0022] In one embodiment, the steps of “reacting a mixture comprising a nitrogen-containing heterocyclic compound, a quaternary ammonium salt, and a phosphate ester at 140° C.-165° C. for 8-15 hours” and “reacting a mixture comprising a nitrogen-containing heterocyclic compound and a phosphate ester at 140° C.-165° C. for 8-15 hours” both include:

[0023] The mixed solution was heated to 140°C-165°C in an oil bath, and then subjected to a constant temperature reaction and condensation reflux during the reaction.

[0024] In one embodiment, the mixture further comprises a sodium salt.

[0025] In one embodiment, the method for preparing the ion-modified liquid further comprises:

[0026] An organic solvent is added to the reaction product and stirred, and then the mixture is allowed to stand for separation and the aqueous phase is collected.

[0027] In one embodiment, the organic solvent is selected from at least one of anhydrous ether, ethyl acetate and chloroform.

[0028] In one embodiment, the method for preparing the ion-modified liquid further comprises:

[0029] The aqueous phase liquid is vacuum baked at 50°C-70°C for 0.5-2h.

[0030] In a third aspect, the present invention provides the use of the above-mentioned ion-modified liquid or the ion-modified liquid prepared by the above-mentioned preparation method in the preparation of antiscaling and antibacterial RO membranes.

[0031] In one embodiment, the RO membrane is immersed in a treatment solution containing an ion-modifying solution, and then baked together, and finally rinsed with water and dried.

[0032] In one embodiment, the immersion time is 0.5 min-2 min; and / or the baking temperature is 50° C.-100° C., and the baking time is 2 min-5 min.

[0033] In one embodiment, the mass concentration of the ion-modified liquid in the treatment liquid is 15%-50%.

[0034] The ion-modified liquid of the present invention comprises a nitrogen-containing heterocyclic compound, a quaternary ammonium salt and a phosphate ester. The phosphate ester with scale inhibition performance can be used as a bridging intermediate substance to connect the quaternary ammonium salt with antibacterial performance with the nitrogen-containing heterocyclic compound to form an ion mixture, and the nitrogen-containing heterocyclic compound can react with the acyl chloride on the surface of the finished RO membrane, so that the ion mixture can be grafted on the surface of the RO membrane. The ion-modified liquid of the present invention can make the ion mixture grafted to the surface of the RO membrane by soaking, and it is not easy to fall off during the water flushing process, and the soaking of the ion-modified liquid can improve the water flux of the RO membrane. That is, the RO membrane treated with the ion-modified liquid of the present invention not only has antibacterial and scale inhibition performance, but also can improve the water flux of the RO membrane. Therefore, the present invention can improve the problem that the conventional anti-pollution and antibacterial RO membrane cannot take into account the filtering performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the principle of modification of RO membrane by ion-modified liquid in one embodiment of the present invention. DETAILED DESCRIPTION

[0036] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and are therefore only used as examples and are not intended to limit the protection scope of the present invention.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which the present invention belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" in the specification and claims of the present invention and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0038] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0039] In the description of the embodiments of the present invention, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this document generally indicates that the associated objects before and after are in an "or" relationship. The term "at least one" means one or more.

[0040] In order to obtain an anti-pollution and antibacterial RO membrane, the conventional solution is to modify the RO membrane. The modification method includes inserting a PVA coating on the RO membrane. The PVA coating can improve the hydrophilicity of the membrane surface and effectively reduce the contact between the membrane surface and the trapped molecules, thereby reducing membrane pollution. However, the PVA coating is physically combined with the RO membrane and is easily dissolved and detached during the rinsing process of the RO membrane, resulting in a decrease in membrane performance. There is also a method of coating nanosilver ions on the membrane surface to obtain an antibacterial RO membrane. The coating of nanosilver ions may increase the resistance of the membrane surface, thereby reducing water flux. Therefore, although the existing modification method can reduce membrane pollution or improve the antibacterial properties of the RO membrane, it will cause the filtration performance of the RO membrane to decrease.

[0041] Based on the above problems, the present invention provides an ion-modified liquid, comprising a nitrogen-containing heterocyclic compound, a quaternary ammonium salt and a phosphate ester.

[0042] The nitrogen-containing heterocyclic compound refers to a compound having a nitrogen-containing heterocyclic structure. The active site (nitrogen atom) on the nitrogen-containing heterocyclic compound can react with the acyl chloride, thereby reacting with the unreacted acyl chloride group on the polyamide layer on the surface of the RO membrane, thereby being grafted onto the surface of the RO membrane.

[0043] Quaternary ammonium salts are a class of cationic salt compounds formed by four organic groups connected to a nitrogen atom, with the general formula R 1 R 2 R3 R 4 N + X - , where R 1 , R 2 , R 3 , R 4 Usually alkyl or aryl, etc., X - It is an anion, common ones are chloride ions, bromide ions, etc. Quaternary ammonium salts have good bactericidal and disinfecting effects and can give RO membranes antibacterial properties.

[0044] Phosphate esters are a class of compounds containing phosphate bonds (-O-PO(OH)-O-) and have certain scale inhibition properties. Figure 1 As shown, phosphate ester, as a bridging structure, can rearrange with nitrogen-containing heterocyclic compounds, that is, the nitrogen atoms of the nitrogen-containing heterocyclic compounds rearrange to form covalent bonds, further forming nitrogen cations, which form ionic bonds with the negative oxygen ions on the phosphate ester; in addition, the phosphate ester hydrolyzes to form oxygen anions, which can combine with the nitrogen cations of the quaternary ammonium salt to form ionic bonds. Therefore, the phosphate ester can bridge the nitrogen-containing heterocyclic compound with the quaternary ammonium salt to form an ionic mixture.

[0045] The RO membrane treated with the ion-modified liquid of the present invention not only has antibacterial and anti-scaling properties, but also can improve the water flux of the RO membrane. This is because the ion-modified liquid can graft the ion mixture onto the surface of the RO membrane through immersion, which is not easy to fall off during water flushing, and the ion-modified liquid immersion can increase the water flux of the RO membrane. Therefore, the present invention can improve the problem that conventional anti-pollution and antibacterial RO membranes cannot take into account filtering performance.

[0046] According to some embodiments of the present invention, the molar ratio of the nitrogen-containing heterocyclic compound, the quaternary ammonium salt, and the phosphate ester is (0.5-1):(0.4-0.8):1.

[0047] The ideal reaction addition amount is a 1:1 molar ratio of nitrogen-containing heterocyclic compounds and phosphates. However, due to the problem of incomplete reaction, when the reaction is carried out at a molar ratio of 1:1, the content of unreacted monomers in the reaction product is high, which increases the number of cleaning times. Reducing the molar ratio to 0.5:1 can reduce the content of unreacted monomers in the reaction product.

[0048] The amount of quaternary ammonium salt added is less than one mole, which can prevent the quaternary ammonium salt from completely replacing it, so that it retains a part of the vacancies for ion exchange. At the same time, reducing the amount of quaternary ammonium salt added can reduce costs.

[0049] According to some embodiments of the present invention, the nitrogen-containing heterocyclic compound is selected from at least one of imidazole, imidazole derivatives, benzimidazole, benzimidazole derivatives, purine, and purine derivatives.

[0050] The structural formula of imidazole is Imidazole is aromatic, and the nitrogen atom on its ring can undergo a protonation reaction to form an imidazolium cation. The structural formula of benzimidazole is It is composed of a benzene ring and an imidazole ring fused together. The nitrogen atoms on the benzene ring and the imidazole ring can undergo electrophilic substitution reactions. The structural formula of purine is It is composed of a pyrimidine ring and an imidazole ring fused together, and can undergo a variety of chemical reactions such as substitution reaction and oxidation reaction. The nitrogen atom of the above compound has high activity and is conducive to the reaction.

[0051] According to some embodiments of the present invention, the imidazole derivatives include compounds represented by formula (I), formula (II), and formula (III):

[0052] and / or,

[0053] Benzimidazole derivatives include compounds represented by formula (IV):

[0054] and / or,

[0055] Purine derivatives include compounds represented by formula (V);

[0056]

[0057] Among them, R 1 , R 2 , R 3 , R 4 , R 5 Each of them is selected from one of alkyl, halogen, halogenated alkyl, hydroxylated alkyl and amino.

[0058] The term "halogen" refers to a halogen atom group; a haloalkyl group refers to a halogenated product formed by replacing a hydrogen atom on an alkyl group with a halogen atom; and a hydroxylated alkyl group refers to a product formed by introducing a hydroxyl group into an alkyl group.

[0059] According to some embodiments of the present invention, the imidazole derivatives include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-butyl-4-chloro-5-hydroxymethylimidazole; and / or,

[0060] Benzimidazole derivatives include 2-methylbenzimidazole, 2-hydroxymethylbenzimidazole; and / or,

[0061] Purine derivatives include 2-aminopurine.

[0062] According to some embodiments of the present invention, the quaternary ammonium salt is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, hexyltrimethylammonium bromide, 2-bromoethyltrimethylammonium bromide, benzyltrimethylammonium bromide, and hexadecyldimethylethylammonium bromide.

[0063] According to some embodiments of the present invention, the phosphate ester is selected from at least one of trimethyl phosphate, triethyl phosphate, and tripropyl phosphate.

[0064] According to some embodiments of the present invention, the present invention provides a method for preparing an ion-modified liquid, wherein a mixed liquid including a nitrogen-containing heterocyclic compound, a quaternary ammonium salt, and a phosphate ester is reacted at 140°C-165°C for 8-15 hours; or, a mixed liquid including a nitrogen-containing heterocyclic compound and a phosphate ester is reacted at 140°C-165°C for 8-15 hours, and then a quaternary ammonium salt is added and reacted at 50°C-80°C for 6-10 hours.

[0065] The present invention selects to carry out the reaction at 140° C.-165° C., which can provide energy for molecular rearrangement on the one hand, and on the other hand, this temperature range can increase the solubility of the nitrogen-containing heterocyclic compound, thereby increasing the reaction rate.

[0066] The preparation method of the present invention can directly heat the mixed solution including the nitrogen-containing heterocyclic compound, the quaternary ammonium salt and the phosphate ester for reaction, or can firstly react the nitrogen-containing heterocyclic compound with the phosphate ester, and then add the quaternary ammonium salt for reaction. The water-soluble nitrogen-containing heterocyclic compound can be mixed with the quaternary ammonium salt and the phosphate ester to react together to form an ion mixture; and the water-slightly soluble nitrogen-containing heterocyclic compound can first react with the phosphate ester to form an ion mixture, so that its water solubility is improved, and then the quaternary ammonium salt is added to react to replace the redundant ester bonds in the phosphate ester.

[0067] According to some embodiments of the present invention, the steps of “reacting a mixed solution including a nitrogen-containing heterocyclic compound, a quaternary ammonium salt, and a phosphate ester at 140° C.-165° C. for 8-15 hours” and “reacting a mixed solution including a nitrogen-containing heterocyclic compound and a phosphate ester at 140° C.-165° C. for 8-15 hours” both include:

[0068] The mixed solution was heated to 140°C-165°C in an oil bath, and then subjected to a constant temperature reaction and condensation reflux during the reaction.

[0069] Condensation reflux during the reaction can prevent the evaporation of solvent water and the volatilization and loss of reaction substances.

[0070] According to some embodiments of the present invention, the mixed solution further includes sodium salt. The sodium salt is added to catalyze the hydrolysis reaction of the phosphate ester. The hydrolysis reaction is a reversible equilibrium reaction. The addition of sodium salt can increase the forward reaction rate, thereby promoting the hydrolysis of the phosphate ester. The sodium salt can be sodium chloride or sodium sulfate.

[0071] According to some embodiments of the present invention, the method for preparing the ion-modified liquid further comprises:

[0072] An organic solvent is added to the reaction product and stirred, and then the mixture is allowed to stand for separation and the aqueous phase is collected.

[0073] The organic solvent should satisfy the conditions that the solubility of the reaction monomer in the organic solvent is greater than that in water, and the solubility of the reaction product in the organic solvent is less than that in water.

[0074] In the embodiment of the present invention, unreacted monomers can be removed by adding an organic solvent for extraction. To improve the removal effect, the organic solvent can be added for multiple extraction treatments.

[0075] According to some embodiments of the present invention, the organic solvent is selected from at least one of anhydrous ether, ethyl acetate, and chloroform.

[0076] According to some embodiments of the present invention, the method for preparing the ion-modified liquid further comprises: vacuum baking the aqueous phase liquid at 50° C.-70° C. for 0.5-2 h.

[0077] Since a small amount of organic liquid remains in the aqueous phase liquid after extraction and separation, baking in a vacuum environment can make the organic solvent evaporate quickly while retaining water, thereby purifying the aqueous phase liquid.

[0078] According to some embodiments of the present invention, the present invention provides use of the above-mentioned ion-modified liquid or the ion-modified liquid prepared by the above-mentioned preparation method in the preparation of antiscaling and antibacterial RO membranes.

[0079] According to some embodiments of the present invention, the RO membrane is immersed in a treatment solution containing an ion modification solution, and then baked together, and finally rinsed and dried with water. The modification treatment of the RO membrane can be completed by the immersion treatment, and the method is simple and easy to operate.

[0080] According to some embodiments of the present invention, the immersion time is 0.5 min-2 min; and / or the baking temperature is 50° C.-100° C., and the time is 2 min-5 min.

[0081] The immersion time, baking temperature and baking time will affect the desalination rate of the RO membrane. The longer the immersion time, the higher the temperature and the longer the baking time, the lower the desalination rate of the RO membrane. Controlling the above parameters within this range can keep the desalination rate of the RO membrane unaffected or minimize the impact on the desalination rate.

[0082] In the embodiment of the present invention, the RO membrane is immersed in the treatment solution for 0.5min-2min, so that the acyl chloride groups can be activated. If the time is too long, the polyamide structure of the RO membrane will be hydrolyzed. The baking treatment can promote the grafting reaction.

[0083] According to some embodiments of the present invention, the mass concentration of the ion-modified liquid in the treatment liquid is 15%-50%.

[0084] The higher the mass concentration of the ion-modified liquid in the treatment liquid, the better the anti-scaling and antibacterial properties of the modified RO membrane. However, when the concentration is high, the polyurethane desalination layer will be easily decomposed, thereby affecting the desalination rate of the RO membrane. In order to balance the anti-scaling and antibacterial properties and the desalination rate, the mass concentration of the ion-modified liquid in the treatment liquid can be limited to 15%-50%.

[0085] Next, the present invention will be described by means of specific embodiments.

[0086] Example 1

[0087] (1) Add 11.7 g of deionized water, 1.4 g of trimethyl phosphate, and 0.58 g of sodium chloride to a round-bottom flask and stir for 2 min; then add 0.4 g of 2-methylimidazole and 1.5 g of hexadecyltrimethylammonium bromide and stir until uniform;

[0088] (2) Place the round-bottom flask in an oil bath and heat it to 150°C. Turn on the condensation water to reflux and stir the reaction for 11 hours. When the solution turns orange-red and transparent, take it out and cool it naturally to room temperature.

[0089] (3) Add 12 ml of anhydrous ether to the reaction product in the round-bottom flask, stir for 5 min, pour into a separatory funnel, let stand for stratification, take the aqueous phase liquid at the lower end, and repeat three times; add 12 ml of chloroform to the aqueous phase liquid, stir for 5 min, pour into a separatory funnel, let stand for stratification, take the aqueous phase liquid at the upper end, and repeat three times; then put the obtained aqueous phase liquid into a vacuum oven, bake at 65° C. for 1 h, take out and let stand to room temperature, and seal and store to obtain an ion-modified liquid;

[0090] (4) Cut the finished RO membrane into a size of 120mm*57mm;

[0091] (5) Take 12 g of the ion-modified liquid, add 68 g of deionized water to dilute, and stir evenly to obtain a treated liquid;

[0092] (6) Pour the treatment solution into a culture dish, immerse the cut membrane in the treatment solution for 1 min, and then put them into an oven for baking at a temperature of 50°C for 2 min;

[0093] (7) After baking, take out the membrane, clean it with deionized water, and then blow dry it at 30°C.

[0094] Example 2

[0095] The difference from Example 1 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 1.

[0096] Example 3

[0097] The difference from Example 1 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 1.

[0098] Example 4

[0099] The difference from Example 1 is that in step (6), the present embodiment performs baking activation for 4 minutes. The remaining steps are the same as those in Example 1.

[0100] Example 5

[0101] The difference from Example 4 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 4.

[0102] Example 6

[0103] The difference from Example 4 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 4.

[0104] Example 7

[0105] The difference from Example 1 is that in step (5), 12 g of ion-modified liquid is taken, 48 g of deionized water is added to dilute, and the treated liquid is obtained after stirring evenly. The remaining steps are the same as those in Example 1.

[0106] Example 8

[0107] The difference from Example 7 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 7.

[0108] Example 9

[0109] The difference from Example 7 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 7.

[0110] Example 10

[0111] The difference from Example 7 is that in step (6), the present embodiment performs baking activation for 4 minutes. The remaining steps are the same as those in Example 7.

[0112] Embodiment 11

[0113] The difference from Example 10 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 10.

[0114] Example 12

[0115] The difference from Example 10 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 10.

[0116] Embodiment 13

[0117] The difference from Example 1 is that in step (5), 12 g of ion-modified liquid is taken, 12 g of deionized water is added to dilute, and the treated liquid is obtained after stirring evenly. The remaining steps are the same as those in Example 1.

[0118] Embodiment 14

[0119] The difference from Example 13 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 13.

[0120] Embodiment 15

[0121] The difference from Example 13 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 13.

[0122] Example 16

[0123] The difference from Example 13 is that in step (6), the present embodiment performs baking activation for 4 minutes. The remaining steps are the same as those of Example 13.

[0124] Embodiment 17

[0125] The difference from Example 16 is that the temperature for baking activation in step (6) is 75° C. The remaining steps are the same as those in Example 16.

[0126] Embodiment 18

[0127] The difference from Example 16 is that the temperature for baking activation in step (6) is 100° C. The remaining steps are the same as those in Example 16.

[0128] Embodiment 19

[0129] (1) Add 3 g of deionized water and 1.4 g of trimethyl phosphate to a round-bottom flask and stir for 2 min; then add 1.16 g of benzimidazole and stir until uniform;

[0130] (2) Place the round-bottom flask in an oil bath and heat it to 150°C. Turn on the condensation water to reflux and stir the reaction for 11 hours. When the solution turns orange-yellow and transparent, take it out and cool it naturally to room temperature.

[0131] (3) Add 5 ml of ethyl acetate to the reaction product in the round-bottom flask, stir for 5 min, pour into a separatory funnel, let stand for stratification, and take out the aqueous phase liquid at the bottom, repeat three times; then put the aqueous phase liquid into a vacuum oven, bake at 65° C. for 1 h, take out and let stand to room temperature to obtain solution A;

[0132] (4) Add 8 g of deionized water, 0.58 g of sodium chloride, and 3 g of hexadecyltrimethylammonium bromide to the above solution A, stir and react at a constant temperature of 60° C. for 8 h, and let stand to room temperature after the reaction is completed;

[0133] (5) Add 12 ml of chloroform to the reaction product in step (4), stir for 5 min, pour into a separatory funnel, let stand for stratification, and take the upper aqueous phase liquid, repeat three times; then put the obtained aqueous phase liquid into a vacuum oven, bake at 65° C. for 1 h, take out and let stand to room temperature, and seal and store to obtain an ion-modified liquid;

[0134] (6) Cut the finished RO membrane into a size of 120mm*57mm;

[0135] (7) Take 12 g of the ion-modified liquid, add 68 g of deionized water to dilute, and stir evenly to obtain a treated liquid;

[0136] (8) Pour the treatment solution into a culture dish, immerse the cut membrane in the treatment solution for 1 min, and then put them into an oven for baking at 75°C for 2 min;

[0137] (9) After baking, take out the membrane, clean it with deionized water, and then blow dry it at 30°C.

[0138] Embodiment 20

[0139] (1) Add 3 g of deionized water and 1.4 g of trimethyl phosphate to a round-bottom flask and stir for 2 min; then add 1.22 g of purine and stir until uniform;

[0140] (2) Place the round-bottom flask in an oil bath and heat it to 150°C. Turn on the condensation water to reflux and stir the reaction for 11 hours. When the solution turns orange-yellow and transparent, take it out and cool it naturally to room temperature.

[0141] (3) adding 8 g of deionized water, 0.58 g of sodium chloride, and 3 g of hexadecyltrimethylammonium bromide to the reaction product in step (2), stirring and reacting at a constant temperature of 60° C. for 8 h, and allowing to stand to room temperature after the reaction is completed;

[0142] (4) Add 12 ml of chloroform to the reaction product in step (3), stir for 5 min, pour into a separatory funnel, let stand for stratification, and take the upper aqueous phase liquid, repeat three times; then put the obtained aqueous phase liquid into a vacuum oven, bake at 65° C. for 1 h, take out and let stand to room temperature, and seal and store to obtain an ion-modified liquid;

[0143] (5) Cut the finished RO membrane into a size of 120mm*57mm;

[0144] (6) Take 12 g of the ion-modified liquid, add 68 g of deionized water to dilute, and stir evenly to obtain a treated liquid;

[0145] (7) Pour the treatment solution into a culture dish, immerse the cut membrane in the treatment solution for 1 min, and then put them into an oven for baking at 75°C for 2 min;

[0146] (8) After baking, take out the membrane, clean it with deionized water, and then blow dry it at 30°C.

[0147] Comparative Example

[0148] The comparative example is the original RO membrane without modification.

[0149] Performance Testing

[0150] (1) Flat membrane test:

[0151] The RO membranes in Examples 1-20 and Comparative Examples were straightened and fixed with flat membrane clamps (effective area of ​​about 42 cm 2 ), the flux and desalination rate were tested according to the flat membrane test method, the test parameters were: pure water spiked with 500±20ppm NaCl as influent, pH 7.0-7.5, water temperature 25℃, the pressure before the membrane was adjusted to 70psi, and the concentrate flow rate was 5±0.1L / min.

[0152] Desalination rate = (raw water conductivity - pure water conductivity) / raw water conductivity × 100%

[0153] (2)RO filter element test:

[0154] The RO membranes in Examples 1-20 and Comparative Examples were cut into 1050mm*270mm, and 8 membranes were rolled into RO filter elements according to conventional membrane rolling technology for water efficiency test and E. coli removal rate test. The water efficiency method refers to GB 34914-2021, and the E. coli removal rate test method refers to the Drinking Water Testing Specification.

[0155] Test Results

[0156] Table 1 Initial flux and initial desalination rate of RO membrane in Examples 1-20 and Comparative Examples

[0157]

[0158] As can be seen from Table 1, the initial flux of the RO membrane treated with the ion-modified liquid of the present invention is higher than that of the original RO membrane, and the initial flux can be increased by up to 56.3%. The initial desalination rate of the modified RO membrane in Example 1 and Example 7 is higher than that of the original RO membrane. Although the initial desalination rate of the modified RO membrane in other embodiments is lower than that of the original RO membrane, the difference is not large.

[0159] When the concentration of the treatment solution is 15%, it can be seen from the comparison of Examples 1-3 or 4-6 that when the baking activation temperature increases, the initial flux of the modified membrane also increases, but the initial desalination rate decreases. The same is true for treatment solutions of other concentrations.

[0160] When the concentration of the treatment solution is 15%, it can be seen from the comparison of Examples 1 and 4, 2 and 5, 3 and 6 that when the baking activation time increases, the initial flux of the modified membrane also increases, but the initial desalination rate decreases. The same is true for treatment solutions of other concentrations.

[0161] When the baking activation temperature is 50°C and the baking activation time is 2 minutes, it can be seen from the comparison of Examples 1, 7, and 13 that when the concentration of the treatment solution increases, the initial flux of the modified membrane also increases, but the initial desalination rate decreases. The same is true for other temperatures and times.

[0162] By comparing Examples 2, 19-20, it can be seen that the ion-modified liquids formed by different preparation methods have a certain influence on the initial water flux and initial desalination rate of the modified RO membrane. The initial flux of the modified RO membrane prepared by the preparation method of Example 19 is closest to the original RO membrane, that is, the water flux of the modified RO membrane prepared by Example 19 is not significantly improved, but its initial desalination rate is the highest.

[0163] Table 2 Water efficiency and E. coli removal rate data of RO membrane in Examples 2, 19-20 and Comparative Examples

[0164]

[0165] It can be seen from Table 2 that the initial flux, 1000L water flux and 2000L water flux of the modified RO membrane prepared in the embodiment of the present invention are higher than those of the original RO membrane in the comparative example; although the initial desalination rate of the modified RO membrane prepared in the embodiment of the present invention is lower than that of the original RO membrane in the comparative example, the 1000L desalination rate and the 2000L desalination rate are obviously better than those of the original RO membrane in the comparative example, indicating that the ion-modified liquid of the present invention can not only increase the water flux of the RO membrane, but also improve the long-term desalination rate of the RO membrane.

[0166] It can also be seen from Table 2 that the modified RO membrane prepared in the embodiment of the present invention has no odor after being immersed in the Escherichia coli spiked solution for 30 days, while the original RO membrane in the comparative example has an odor after being immersed for 3 days, indicating that the RO membrane treated with the ion-modified solution of the present invention has significant antibacterial properties.

[0167] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be included in the scope of the claims and specification of the present invention. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An ion-modified liquid, characterized in that: Including nitrogen-containing heterocyclic compounds, quaternary ammonium salts and phosphates.

2. The ion-modified liquid according to claim 1, characterized in that The molar ratio of the nitrogen-containing heterocyclic compound, the quaternary ammonium salt and the phosphate ester is (0.5-1):(0.4-0.8):

1.

3. The ion-modified liquid according to claim 1 or 2, characterized in that The nitrogen-containing heterocyclic compound is selected from at least one of imidazole, imidazole derivatives, benzimidazole, benzimidazole derivatives, purine, and purine derivatives.

4. The ion-modified liquid according to claim 3, characterized in that The imidazole derivatives include compounds represented by formula (I), formula (II) and formula (III): and / or, The benzimidazole derivatives include compounds represented by formula (IV): and / or, The purine derivatives include compounds represented by formula (V); Wherein, R1, R2, R3, R4 and R5 are all selected from one of alkyl, halo, halogenated alkyl and hydroxylated alkyl.

5. The ion-modified liquid according to claim 4, characterized in that The imidazole derivatives include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-butyl-4-chloro-5-hydroxymethylimidazole; and / or, The benzimidazole derivatives include 2-methylbenzimidazole and 2-hydroxymethylbenzimidazole; and / or, The purine derivatives include 2-aminopurine.

6. The ion-modified liquid according to claim 1 or 2, characterized in that: The quaternary ammonium salt is selected from at least one of hexadecyltrimethylammonium bromide, dodecyltrimethylammonium bromide, hexyltrimethylammonium bromide, 2-bromoethyltrimethylammonium bromide, benzyltrimethylammonium bromide and hexadecyldimethylethylammonium bromide.

7. The ion-modified liquid according to claim 1 or 2, characterized in that: The phosphate ester is selected from at least one of trimethyl phosphate, triethyl phosphate and tripropyl phosphate.

8. A method for preparing an ion-modified liquid, characterized in that: The mixed solution including the nitrogen-containing heterocyclic compound, the quaternary ammonium salt and the phosphate ester is reacted at 140°C-165°C for 8-15 hours; or, The mixed solution including the nitrogen-containing heterocyclic compound and the phosphate ester is reacted at 140° C.-165° C. for 8-15 hours, and then the quaternary ammonium salt is added and reacted at 50° C.-80° C. for 6-10 hours.

9. The method for preparing an ion-modified liquid according to claim 8, characterized in that: The steps of "reacting a mixed solution including a nitrogen-containing heterocyclic compound, a quaternary ammonium salt and a phosphate ester at 140° C.-165° C. for 8-15 hours" and "reacting a mixed solution including a nitrogen-containing heterocyclic compound and a phosphate ester at 140° C.-165° C. for 8-15 hours" both include: The mixed solution was heated to 140°C-165°C in an oil bath, and then subjected to a constant temperature reaction and condensation reflux during the reaction.

10. The method for preparing an ion-modified liquid according to claim 8 or 9, characterized in that: The mixture also includes sodium salt.

11. The method for preparing an ion-modified liquid according to claim 8 or 9, characterized in that: The preparation method further comprises: An organic solvent is added to the reaction product and stirred, and then the mixture is allowed to stand for separation and the aqueous phase is collected.

12. The method for preparing an ion-modified liquid according to claim 11, characterized in that: The organic solvent is selected from at least one of anhydrous ether, ethyl acetate and chloroform.

13. The method for preparing an ion-modified liquid according to claim 11, characterized in that: The preparation method further comprises: The aqueous phase liquid is vacuum baked at 50° C.-70° C. for 0.5-2 h.

14. Use of the ion-modified liquid according to any one of claims 1 to 7 or the ion-modified liquid prepared by the preparation method according to any one of claims 8 to 13 in the preparation of antiscaling and antibacterial RO membranes.

15. The use according to claim 14, characterized in that The RO membrane is immersed in a treatment solution containing an ion-modified solution, and then baked together, and finally rinsed and dried with water.

16. The use according to claim 15, characterized in that The immersion time is 0.5 min-2 min; and / or the baking temperature is 50° C.-100° C., and the time is 2 min-5 min.

17. The use according to claim 15, characterized in that The mass concentration of the ion-modified liquid in the treatment liquid is 15%-50%.

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