CN112844046A - Positively charged nanofiltration membrane and preparation method thereof - Google Patents
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- B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
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Abstract
The invention discloses a positively charged nanofiltration membrane and a preparation method thereof. Preparation: (1) dissolving a polymer, and standing to obtain a polymer solution; (2) coating the polymer solution on a support material, carrying out phase separation in a coagulation bath, and curing to form a base film; (3) dissolving a multi-amino compound in water, adding a pH regulator, and stirring to obtain an aqueous phase liquid; (4) dissolving a polybasic acyl chloride compound in an organic solvent and stirring to obtain an oil phase liquid; (5) soaking the basement membrane in aqueous phase liquid, and drying in the air; then placing the substrate in oil phase liquid for polymerization and drying to form a polyamide selection layer on the base film; (6) and (3) placing the base membrane with the polyamide selective layer formed on the surface in a mixed solution containing a polyfunctional amine compound and a cross-linking agent for soaking, rinsing and drying to obtain the positively-charged nanofiltration membrane. The nanofiltration membrane prepared by the method has different removal rates of univalent ions and bivalent ions, and is characterized by high removal rate of calcium chloride in a test solution and low removal rate of sodium chloride.
Description
Technical Field
The invention relates to the technical field of separation membranes, in particular to a positively charged nanofiltration membrane and a preparation method thereof.
Background
Nanofiltration, which is one of the membrane separation techniques, is generally a polymeric membrane having a pore size of about 1nm, and is called a nanofiltration membrane. The nanofiltration has special separation performance, compared with a seawater brackish water reverse osmosis membrane which needs high pressure driving, the nanofiltration can be partially desalted but not completely desalted, simultaneously the divalent ion interception condition can be basically comparable with the reverse osmosis, and organic matters and colloids with the relative molecular mass of 200-500 can be completely removed; the reverse osmosis seawater membrane also requires high operating pressure for low salinity water, while the nanofiltration membrane can normally operate at substantially low pressure; in view of potable water hardness removal and due to the charge on the surface of the nanofiltration membrane, nanofiltration can differentially trap high-valence and low-valence salt ions and partially retain beneficial ions in water.
Most of the current commercial nanofiltration membranes are polyamide composite membrane structures and are formed by interfacial polymerization of amino-containing compounds and acyl chloride compounds on a porous support layer. Most of the nanofiltration membranes in the market have high desalination rate of 95-98% for magnesium sulfate and removal rate of 40-50% for sodium chloride, and the factors influencing the desalination performance of the nanofiltration membranes mainly assume that the permeation form of the membrane is diffusion or pore flow, while the charged nanofiltration membranes are always negatively charged, and electrostatic effect must be considered.
Generally, the water-phase monomer adopted by most nanofiltration membranes is piperazine, the organic phase is trimesoyl chloride, and a large amount of unreacted acyl chloride groups are hydrolyzed into carboxylic acid after polymerization reaction, so that the surface of the nanofiltration membrane is negatively charged. Therefore, most of the existing nanofiltration membranes do not have the capacity of removing high-valence cations, and the acyl chloride which is not reacted after the interfacial polymerization reacts with amino compounds again in the preparation process of the positively charged nanofiltration membranes, so that a positively charged coating is deposited on the surface of the membrane, the amination degree of acyl chloride groups is improved, the degree of hydrolysis into carboxyl groups is reduced, and the surface of the membrane is positively charged.
Nowadays, there are increasingly high demands on the quality of life, in particular with regard to hardness removal of drinking water. The market reports about positively charged nanofiltration membranes removed by calcium chloride, so the preparation method of the positively charged nanofiltration membrane provided by the invention has great commercial potential.
Disclosure of Invention
The invention aims to provide a preparation method of a positively charged nanofiltration membrane, and the nanofiltration membrane prepared by the method has the characteristics of good desalting performance, high water flux and continuous production.
The invention is realized by the following technical scheme:
a preparation method of a positively charged nanofiltration membrane comprises the following steps:
(1) preparing a polymer solution: dissolving and stirring a polymer, and then standing and defoaming to obtain a polymer solution;
(2) preparing a base film: coating the polymer solution on a support material, then carrying out phase separation in a coagulation bath, and curing to form a base film;
(3) preparing a water phase liquid: dissolving a multi-amino compound in water, adding a pH regulator, and stirring to obtain an aqueous phase liquid; the pH regulator is triethylamine or trisodium phosphate;
(4) preparing an oil phase liquid: dissolving a polybasic acyl chloride compound in an organic solvent and stirring to obtain an oil phase liquid;
(5) preparation of polyamide selection layer: placing the basement membrane in the aqueous phase liquid for soaking, and then airing; then placing the film in the oil phase liquid for polymerization, and drying the film to form a polyamide selection layer on the base film;
(6) film surface electrical property transformation: placing the base membrane with the polyamide selective layer formed on the surface into a mixed solution containing a polyfunctional amine compound and a cross-linking agent for soaking, then rinsing and drying to obtain a positively charged nanofiltration membrane; the polyfunctional amine compound is at least one selected from polyethyleneimine, polyvinylamine and polypropyleneamine. Specifically, the positively charged nanofiltration membrane prepared by the method comprises a support layer and a polyamide selection layer, wherein one surface of the polyamide selection layer is attached to the surface of the support layer (namely a base membrane), and the other surface of the polyamide selection layer is obtained by crosslinking reaction with an amine compound containing multiple functional groups. The preparation method provided by the invention can be completely finished on a production line, the production process is easy to control, the membrane surface uniformity is good, and the preparation method has the characteristics of continuous and stable production. The support layer is formed by dissolving a polymer to form a polymer solution, and the polymer solution is subjected to phase separation reaction on the support material to form the support layer. The polyamide selective layer is obtained by carrying out interfacial polymerization on a compound containing polyamino and a compound containing polyacyl chloride and then soaking the polyamide selective layer in a compound aqueous solution containing polyfunctional amine, wherein a large amount of-NH exists in the polyfunctional amine compound solution2Cross-linking with unreacted acid chloride groups while part of amide bonds are exposed to H+Hydrolysis after attack makes the electric charge of the membrane surface change to positive charge.
Further, step (1) preparing a polymer solution: dissolving a polymer in a polymer solvent, stirring for 4-6 hours at 50-60 ℃, standing and defoaming for 18-24 hours after stirring is finished, and obtaining a polymer solution; the polymer is selected from at least one of polysulfone, polyethersulfone, polyarylsulfone and polytetrafluoroethylene; the polymer solvent is selected from any one of N, N-dimethylacetamide and N, N-dimethylformamide; and the polymer accounts for 15-18 wt% of the polymer solution.
Further, preparing the base film in the step (2): coating the polymer solution on a supporting material, then carrying out phase separation in a coagulating bath at 15-35 ℃ for 5-15 seconds, and curing to form a base film; the supporting material is non-woven fabric. Specifically, the invention adopts a liquid-liquid phase conversion method to form the basement membrane, the water bath temperature is 15-35 ℃, and the phase separation time is 5-15s, thus obtaining the basement membrane.
Further, preparing a water phase liquid in the step (3): dissolving a multi-amino compound in water, adding a pH regulator, and stirring for 20-40 minutes to obtain an aqueous phase liquid; the pH regulator is triethylamine or trisodium phosphate; the polybasic amino compound accounts for 0.1 to 0.5 weight percent of the aqueous phase liquid; the pH regulator accounts for 1.0-3.0 wt% of the aqueous phase liquid; and the water is deionized water.
Further, the polyamine compound is selected from at least one of piperazine, homopiperazine, m-phenylenediamine and o-phenylenediamine.
Further, preparing an oil phase liquid in the step (4): dissolving a polybasic acyl chloride compound in an organic solvent and stirring for 20-30 minutes to obtain an oil phase liquid; and the polybasic acyl chloride compound accounts for 0.1 to 0.3 weight percent of the oil phase liquid.
Further, the polybasic acyl chloride compound is selected from any one of trimesoyl chloride and paraphthaloyl chloride; the organic solvent is Isopar L or Isopar G.
Further, step (5) preparation of a polyamide selective layer: placing the basement membrane in the aqueous phase liquid, soaking for 30-60 seconds, and then airing; then placing the mixture in the oil phase liquid to generate interfacial polymerization reaction for 15-30 seconds; and after the reaction, drying the substrate in an oven at 70-100 ℃ for 10-30 seconds to form a polyamide selective layer on the base film. Sequentially applying a water phase solution and an oil phase solution on the base film to form a nascent state polyamide selection layer; then drying to obtain the polyamide selective layer.
Further, the film surface electrical property transformation in the step (6): placing the basal membrane with the polyamide selection layer formed on the surface in a mixed solution containing a polyfunctional amine compound and a cross-linking agent for soaking for 60-90 seconds, so that the charge property of the surface of the membrane is changed to show positive charge after the cross-linking reaction of the polyamide selection layer; rinsing in hot water at 50-60 ℃ after soaking, drying at 70-80 ℃, and removing redundant organic solvent on the surface to obtain the positively charged nanofiltration membrane; the polyfunctional amine compound is at least one selected from polyethyleneimine, polyvinylamine and polypropyleneamine; the polyfunctional amine compound accounts for 1.0-2.0 wt% of the mixed solution; the cross-linking agent accounts for 5.0-8.0 wt% of the mixed solution; the cross-linking agent is glutaraldehyde. Preferably, the soaking temperature of the basement membrane in the mixed solution is not lower than 25 ℃.
A positively charged nanofiltration membrane is characterized by being prepared by the preparation method.
The invention has the beneficial effects that:
the preparation method of the positively charged nanofiltration membrane provided by the invention is simple, and the nanofiltration membrane prepared by the method has different removal rates of univalent ions and bivalent ions, and is characterized by high removal rate of calcium chloride in a test solution and low removal rate of sodium chloride. Meanwhile, the nanofiltration membrane prepared by the method has the characteristics of high water flux, high desalination rate, strong responsiveness to the pH value of liquid to be treated, and strong treatment performance particularly on acidic wastewater. The positively charged nanofiltration membrane prepared by the invention can realize that the removal rate of 500ppm calcium chloride is more than 98 percent, the removal rate of 2000ppm sodium chloride is 30 to 50 percent, and the water flux range of the membrane is 25 to 30GFD under the environment of 25 ℃; can realize the removal of calcium ions in high-hardness drinking water, and simultaneously preserve part of sodium ions and potassium ions in the water which are beneficial to human bodies. Meanwhile, the nanofiltration membrane prepared by the method has the capacity of industrial continuous production.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a photograph of a nanofiltration electron microscope without membrane surface charge modification in example 1;
fig. 2 is an electron micrograph of the positively charged nanofiltration membrane described in example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
A preparation method of a positively charged nanofiltration membrane comprises the following specific steps:
(1) preparing a polymer solution: adding 100.0g of polysulfone into 525.0g of N, N-Dimethylformamide (DMF), stirring for 6 hours at 60 ℃, and standing for defoaming for 24 hours to obtain a polymer solution;
(2) preparing a base film: coating the polymer solution on non-woven fabrics, then carrying out phase separation for 10 seconds in a coagulating bath at 25 ℃, and curing to form a base film;
(3) preparing a water phase liquid: dissolving 4.0g of piperazine in 2000.0g of deionized water, adding 25.0g of triethylamine, and stirring for 30 minutes to obtain an aqueous phase;
(4) preparing an oil phase liquid: dissolving 0.4g of trimesoyl chloride in 200.0g of Isopar L and stirring for 30 minutes to obtain an oil phase liquid;
(5) preparation of polyamide selection layer: soaking the base film in the aqueous phase liquid for 60 seconds, and then draining the surface water of the base film; then placing the base film soaked by the aqueous phase liquid into the oil phase liquid for polymerization to generate interfacial polymerization reaction for 30 seconds, and drying the base film in a drying oven at 70 ℃ for 30 seconds after the polymerization reaction to form a polyamide selection layer on the base film; the nanofiltration membrane which is not subjected to the surface charge modification of the soaking membrane is obtained;
(6) film surface electrical property transformation: dissolving 40.0g of polyethyleneimine and 160.0g of glutaraldehyde in 1800.0g of deionized water to obtain a mixed solution containing a polyfunctional amine compound and a crosslinking agent, wherein the temperature of the mixed solution is 25 ℃; and then placing the base membrane with the polyamide selection layer formed on the surface in the mixed solution at the temperature of 25 ℃ for soaking for 60 seconds (after the polyamide selection layer is subjected to a crosslinking reaction, the charge property of the membrane surface is changed to show positive charge), rinsing in hot water at the temperature of 50 ℃ after soaking, and drying at the temperature of 80 ℃ to obtain the positively charged nanofiltration membrane.
Example 2
A preparation method of a positively charged nanofiltration membrane comprises the following specific steps:
(1) preparing a polymer solution: adding 110.0g of polyether sulfone into 525.0g of N, N-dimethylacetamide (DMAc), stirring for 5 hours at 50 ℃, and standing and defoaming for 20 hours to obtain a polymer solution;
(2) preparing a base film: coating the polymer solution on non-woven fabrics, then carrying out phase separation for 5 seconds in a coagulating bath at 35 ℃, and curing to form a base film;
(3) preparing a water phase liquid: dissolving 10.0g of m-phenylenediamine in 2000.0g of deionized water, adding 40.0g of trisodium phosphate, and stirring for 40 minutes to obtain an aqueous phase liquid;
(4) preparing an oil phase liquid: dissolving 0.2G of terephthaloyl chloride in 200.0G of Isopar G and stirring for 20 minutes to obtain an oil phase liquid;
(5) preparation of polyamide selection layer: soaking the basement membrane in the aqueous phase solution for 30 seconds, and then draining the surface water of the basement membrane; then placing the base film soaked by the aqueous phase liquid into the oil phase liquid for polymerization to generate interfacial polymerization reaction for 20 seconds, and drying the base film in a drying oven at 100 ℃ for 15 seconds after the polymerization reaction to form a polyamide selection layer on the base film;
(6) film surface electrical property transformation: dissolving 20.0g of polyvinylamine and 140.0g of glutaraldehyde in 1840.0g of deionized water to obtain a mixed solution containing a polyfunctional amine compound and a crosslinking agent, wherein the temperature of the mixed solution is 25 ℃; and then placing the base membrane with the polyamide selection layer formed on the surface in the mixed solution at the temperature of 25 ℃ for soaking for 70 seconds (after the polyamide selection layer is subjected to a crosslinking reaction, the charge property of the surface of the membrane is changed to show positive charge), rinsing in hot water at the temperature of 60 ℃ after soaking, and drying at the temperature of 75 ℃ to obtain the positively charged nanofiltration membrane.
Example 3
A preparation method of a positively charged nanofiltration membrane comprises the following specific steps:
(1) preparing a polymer solution: adding 95.0g of polytetrafluoroethylene into 525.0g of N, N-Dimethylformamide (DMF), stirring for 4 hours at 55 ℃, and then standing and defoaming for 18 hours to obtain a polymer solution;
(2) preparing a base film: coating the polymer solution on non-woven fabrics, then carrying out phase separation for 15 seconds in a coagulating bath at the temperature of 20 ℃, and curing to form a base film;
(3) preparing a water phase liquid: dissolving 6.0g of o-phenylenediamine in 2000.0g of deionized water, adding 60.0g of triethylamine, and stirring for 20 minutes to obtain an aqueous phase liquid;
(4) preparing an oil phase liquid: dissolving 0.6g of trimesoyl chloride in 200.0g of Isopar L and stirring for 25 minutes to obtain an oil phase liquid;
(5) preparation of polyamide selection layer: soaking the base film in the aqueous phase liquid for 45 seconds, and then draining the surface water of the base film; then placing the base film soaked by the aqueous phase liquid into the oil phase liquid for polymerization to generate interfacial polymerization reaction for 25 seconds, and drying the base film in a drying oven at the temperature of 80 ℃ for 25 seconds after the polymerization reaction to form a polyamide selection layer on the base film;
(6) film surface electrical property transformation: dissolving 30.0g of polyacrylamide and 100.0g of glutaraldehyde in 1870.0g of deionized water to obtain a mixed solution containing a polyfunctional amine compound and a crosslinking agent, wherein the temperature of the mixed solution is 25 ℃; and then placing the base membrane with the polyamide selection layer formed on the surface in the mixed solution at the temperature of 25 ℃ for soaking for 90 seconds (after the polyamide selection layer is subjected to a crosslinking reaction, the charge property of the surface of the membrane is changed to show positive charge), rinsing in hot water at the temperature of 55 ℃ after soaking, and drying at the temperature of 70 ℃ to obtain the positively charged nanofiltration membrane.
Comparative example 1
Comparative example 1 is different from example 1 in that comparative example 1 is prepared by dissolving 60.0g of polyethyleneimine and 160.0g of glutaraldehyde in 1780.0g of deionized water to obtain a mixed solution, and otherwise referring to example 1.
Comparative example 2
Comparative example 2 is different from example 1 in that comparative example 2 is prepared by dissolving 80.0g of polyethyleneimine and 160.0g of glutaraldehyde in 1760.0g of deionized water to obtain a mixed solution, and the rest of the preparation conditions are as in example 1 to obtain a nanofiltration membrane.
Comparative example 3
Comparative example 3 is different from example 1 in that comparative example 3 prepares a nanofiltration membrane by dissolving 100.0g of polyethyleneimine and 160.0g of glutaraldehyde in 1740.0g of deionized water to obtain a mixed solution, and referring to example 1 for the rest of the preparation conditions.
Comparative example 4
Comparative example 4 is different from example 1 in that comparative example 4 is prepared by dissolving 120.0g of polyethyleneimine and 160.0g of glutaraldehyde in 1720.0g of deionized water to obtain a mixed solution, and the rest of the preparation conditions are the same as those of example 1 to prepare a nanofiltration membrane.
Comparative example 5
Comparative example 5 differs from example 1 in that a 30 ℃ mixed solution was prepared, and the nanofiltration membrane was obtained under the same conditions as in example 1.
Comparative example 6
Comparative example 6 differs from example 1 in that a 35 ℃ mixed solution was prepared, and the nanofiltration membrane was obtained under the same conditions as in example 1.
Comparative example 7
Comparative example 7 is different from example 1 in that a mixed solution of 40 ℃ is prepared, and a nanofiltration membrane is obtained by referring to example 1 under the other conditions.
Test example 1
The nanofiltration membranes obtained in example 1 and comparative examples 1 to 4 were tested for water flux and calcium chloride rejection: the test is carried out on a cross-flow membrane test bench, and the test solutions are respectively 500ppm of CaCl2And 2000ppm NaCl solution, regulating pH of the test solution to 7.5 +/-0.5 with hydrochloric acid or sodium hydroxide, soaking the membrane in deionized water for 30 min, cutting to corresponding size, and testingAnd (3) adjusting the testing pressure to be 0.5MPa and the testing temperature to be 25 ℃, enabling the nanofiltration membrane diaphragm to stably operate for 30 minutes at constant temperature and constant pressure, collecting a permeate water sample within a certain time after stable operation, testing the conductivity and volume of the solution, calculating the water flux and desalination rate of the nanofiltration membrane diaphragm according to the following formula, pre-flushing for 15-20 minutes before replacing the testing solution, and then switching the target testing solution, wherein the specific results are shown in table 1.
The nanofiltration membrane desalination rate calculation formula is as follows:
in the formula:
r-salt rejection rate;
kp-permeant conductivity in microsiemens per centimeter (μ S/cm);
kf-measuring the conductivity of the fluid in microsiemens per centimeter (. mu.S/cm).
The water flux calculation formula of the nanofiltration membrane is as follows:
in the formula:
f-water flux in liters per square meter hour [ L/(m)2.h)]；
The volume of permeate collected over time V-t, in liters (L);
a-effective membrane area in square meters (m)2)；
t-the time taken to collect V volumes of permeate in hours (h).
Table 1 shows the water flux and calcium chloride desalination rate results of the nanofiltration membranes of example 1 and comparative examples 1 to 4
As shown in the test results in Table 1, with the increase of the concentration of polyethyleneimine, more amino groups and acyl chloride form covalent bonds, so that the electric property of the membrane surface tends to be more towards the decrease trend of water flux after positive charge, and the membrane becomes more hydrophobic.
Test example 2
The nanofiltration membranes obtained in example 1 and comparative examples 5 to 7 were tested for water flux and calcium chloride rejection, and the specific results are shown in table 2.
Table 2 shows the water flux and calcium chloride desalination rate results of the nanofiltration membranes of example 1 and comparative examples 5 to 7
From the test results in table 2, it can be seen that the higher the temperature of the soaking solution (mixed solution), the better the crosslinking effect, and the higher the membrane water flux and the calcium chloride salt rejection rate.
Test example 3
The nanofiltration membrane obtained in the step (5) of example 1 and the nanofiltration membrane obtained in the step (6) of example 1 and subjected to surface charge modification of the submerged membrane (i.e., the prepared positively charged nanofiltration) were observed by a Scanning Electron Microscope (SEM), and the results are shown in fig. 1 and fig. 2, respectively.
The above-mentioned preferred embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention. Obvious variations or modifications of the present invention are within the scope of the present invention.
Claims (10)
1. A preparation method of a positively charged nanofiltration membrane is characterized by comprising the following steps:
(1) preparing a polymer solution: dissolving and stirring a polymer, and then standing and defoaming to obtain a polymer solution;
(2) preparing a base film: coating the polymer solution on a support material, then carrying out phase separation in a coagulation bath, and curing to form a base film;
(3) preparing a water phase liquid: dissolving a multi-amino compound in water, adding a pH regulator, and stirring to obtain an aqueous phase liquid; the pH regulator is triethylamine or trisodium phosphate;
(4) preparing an oil phase liquid: dissolving a polybasic acyl chloride compound in an organic solvent and stirring to obtain an oil phase liquid;
(5) preparation of polyamide selection layer: placing the basement membrane in the aqueous phase liquid for soaking, and then airing; then placing the film in the oil phase liquid for polymerization, and drying the film to form a polyamide selection layer on the base film;
(6) film surface electrical property transformation: placing the base membrane with the polyamide selective layer formed on the surface into a mixed solution containing a polyfunctional amine compound and a cross-linking agent for soaking, then rinsing and drying to obtain a positively charged nanofiltration membrane; the polyfunctional amine compound is at least one selected from polyethyleneimine, polyvinylamine and polypropyleneamine.
2. The method for preparing a positively charged nanofiltration membrane according to claim 1, wherein the step (1) of preparing a polymer solution comprises: dissolving a polymer in a polymer solvent, stirring for 4-6 hours at 50-60 ℃, standing and defoaming for 18-24 hours after stirring is finished, and obtaining a polymer solution; the polymer is selected from at least one of polysulfone, polyethersulfone, polyarylsulfone and polytetrafluoroethylene; the polymer solvent is selected from any one of N, N-dimethylacetamide and N, N-dimethylformamide; and the polymer accounts for 15-18 wt% of the polymer solution.
3. The method for preparing a positively charged nanofiltration membrane according to claim 1, wherein the preparation of the base membrane in the step (2): coating the polymer solution on a supporting material, then carrying out phase separation in a coagulating bath at 15-35 ℃ for 5-15 seconds, and curing to form a base film; the supporting material is non-woven fabric.
4. The method for preparing a positively charged nanofiltration membrane according to claim 1, wherein the step (3) comprises the following steps: dissolving a multi-amino compound in water, adding a pH regulator, and stirring for 20-40 minutes to obtain an aqueous phase liquid; the pH regulator is triethylamine or trisodium phosphate; the polybasic amino compound accounts for 0.1 to 0.5 weight percent of the aqueous phase liquid; the pH regulator accounts for 1.0-3.0 wt% of the aqueous phase liquid; the water is deionized water.
5. The method of claim 4, wherein the polyamino compound is at least one selected from the group consisting of piperazine, homopiperazine, m-phenylenediamine, and o-phenylenediamine.
6. The method for preparing a positively charged nanofiltration membrane according to claim 1, wherein the step (4) of preparing an oil phase liquid: dissolving a polybasic acyl chloride compound in an organic solvent and stirring for 20-30 minutes to obtain an oil phase liquid; and the polybasic acyl chloride compound accounts for 0.1 to 0.3 weight percent of the oil phase liquid.
7. The method for preparing a positively-charged nanofiltration membrane according to claim 6, wherein the poly-acyl chloride compound is selected from any one of trimesoyl chloride and terephthaloyl chloride; the organic solvent is Isopar L or Isopar G.
8. The method for preparing a positively charged nanofiltration membrane according to claim 1, wherein the step (5) of preparing the polyamide selective layer comprises: placing the basement membrane in the aqueous phase liquid, soaking for 30-60 seconds, and then airing; then placing the mixture in the oil phase liquid to generate interfacial polymerization reaction for 15-30 seconds; and after the reaction, drying the substrate in an oven at 70-100 ℃ for 10-30 seconds to form a polyamide selective layer on the base film.
9. The method for preparing a positively-charged nanofiltration membrane according to claim 1, wherein the electrical property of the membrane surface in the step (6) is changed: placing the base membrane with the polyamide selective layer formed on the surface in a mixed solution containing a polyfunctional amine compound and a cross-linking agent, soaking for 60-90 seconds, rinsing in hot water at 50-60 ℃ after soaking, and drying at 70-80 ℃ to obtain the positively-charged nanofiltration membrane; the polyfunctional amine compound is at least one selected from polyethyleneimine, polyvinylamine and polypropyleneamine; the polyfunctional amine compound accounts for 1.0-2.0 wt% of the mixed solution; the cross-linking agent accounts for 5.0-8.0 wt% of the mixed solution; the cross-linking agent is glutaraldehyde.
10. A positively charged nanofiltration membrane, characterized in that it is produced by the process according to any one of claims 1 to 9.
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| CN (1) | CN112844046A (en) |
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| CN113441020A (en) * | 2021-08-05 | 2021-09-28 | 江西省科学院能源研究所 | Composite nanofiltration membrane and preparation method and application thereof |
| CN113457449A (en) * | 2021-07-26 | 2021-10-01 | 中国海洋大学 | Polyamide nanofiltration membrane with multivalent/monovalent salt selectivity and preparation method thereof |
| CN114471157A (en) * | 2022-01-24 | 2022-05-13 | 烟台金正环保科技有限公司 | Preparation method of positively charged acid-resistant nanofiltration membrane and positively charged acid-resistant nanofiltration membrane |
| CN114904405A (en) * | 2022-03-17 | 2022-08-16 | 南京工业大学 | Positively charged acid-resistant nanofiltration membrane, preparation method and application |
| CN115337789A (en) * | 2022-06-24 | 2022-11-15 | 星达（泰州）膜科技有限公司 | Preparation method of nanofiltration membrane |
| WO2023231317A1 (en) * | 2022-05-30 | 2023-12-07 | 沃顿科技股份有限公司 | Nanofiltration membrane preparation method and nanofiltration membrane prepared thereby |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113457449A (en) * | 2021-07-26 | 2021-10-01 | 中国海洋大学 | Polyamide nanofiltration membrane with multivalent/monovalent salt selectivity and preparation method thereof |
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| CN114471157A (en) * | 2022-01-24 | 2022-05-13 | 烟台金正环保科技有限公司 | Preparation method of positively charged acid-resistant nanofiltration membrane and positively charged acid-resistant nanofiltration membrane |
| CN114904405A (en) * | 2022-03-17 | 2022-08-16 | 南京工业大学 | Positively charged acid-resistant nanofiltration membrane, preparation method and application |
| CN114904405B (en) * | 2022-03-17 | 2023-08-18 | 南京工业大学 | Positively charged acid-resistant nanofiltration membrane, preparation method and application |
| WO2023231317A1 (en) * | 2022-05-30 | 2023-12-07 | 沃顿科技股份有限公司 | Nanofiltration membrane preparation method and nanofiltration membrane prepared thereby |
| CN115337789A (en) * | 2022-06-24 | 2022-11-15 | 星达（泰州）膜科技有限公司 | Preparation method of nanofiltration membrane |
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