Membrane chromatography filter membrane for removing charged ions in liquid and preparation method of membrane chromatography filter membrane

Abstract

The invention belongs to the field of wet electronic chemical purification, and particularly relates to a membrane chromatography filter membrane for removing charged ions in liquid and a preparation method thereof.The preparation method comprises the following steps that S1, membrane casting liquid is prepared, specifically, a positive electricity layer membrane casting liquid, a neutral layer membrane casting liquid and a negative electricity layer membrane casting liquid are prepared; s2, sequentially extruding the positive electricity layer membrane casting solution, the neutral layer membrane casting solution and the negative electricity layer membrane casting solution by using a three-layer die head, and coating on a polyester film; s3, exposing under the conditions of set temperature, humidity and air velocity, so that the casting membrane solution is subjected to preliminary phase splitting; s4, immersing the coated film in a pure water coagulating bath to complete phase splitting and curing; and S5, rinsing, drying and rolling to obtain the membrane chromatography filter membrane. By designing a special three-layer composite structure of'positive electricity layer-neutral layer-negative electricity layer ', the filter membrane can simultaneously adsorb anions and cations in a solution in a single filtering process, the limitation that a traditional single charge membrane can only remove one kind of ions is solved, and the purification efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wet electronic chemical purification, and particularly relates to a membrane chromatography filter membrane for removing charged ions in a liquid and a preparation method thereof. BACKGROUND

[0002] In the electronic industry, especially in the high-end manufacturing field of semiconductors, display panels and photovoltaics, the purity of the chemicals used is extremely strict. Even if there are trace amounts of metal ions or inorganic ions in these chemicals, it may cause product defects, performance degradation or yield reduction. Therefore, developing efficient and reliable ion removal technology has become one of the key issues in this field.

[0003] Currently, common ion removal methods mainly include ion exchange resin method, distillation / rectification method, etc. Although the ion exchange resin method is widely used, it has the disadvantages of high operating pressure, low flux, slow processing speed, etc., and the resin regeneration process is complex, which increases the operating cost and time. Although the distillation / rectification method can effectively separate impurities, it has high energy consumption and complex equipment, which is not suitable for continuous and large-scale processing, especially for trace ion removal of high-purity chemicals.

[0004] Membrane chromatography technology, as an efficient separation method, was early mainly applied to the separation and purification of biological macromolecules (such as proteins and nucleic acids). It combines the advantages of membrane filtration and chromatographic adsorption, and has the characteristics of high flux, simple operation and easy scaling-up. However, the application of this technology in inorganic ion removal has not been fully developed. Traditional single-charged membrane materials can usually only adsorb one type of charged ions, and it is difficult to simultaneously and efficiently remove anions and cations in the solution, which limits its applicability in electronic chemical purification.

[0005] In addition, existing membrane materials have limitations in structural design and functional integration. Most membrane products only have a single function (such as filtration or adsorption), which makes it difficult to remove ions efficiently while considering the filtration of particulate impurities, resulting in complex process flow and increased equipment investment.

[0006] Therefore, there is an urgent need in the art for a membrane chromatography technology solution that can simultaneously and efficiently remove anions and cations, has a filtering function, and is suitable for high-purity chemical processing in the electronic industry. SUMMARY

[0007] To solve the problems raised in the background art, the present application proposes a membrane chromatography filter membrane for removing charged ions in a liquid and a preparation method thereof. By designing a special three-layer composite structure with a "positive layer - neutral layer - negative layer", the filter membrane can simultaneously adsorb anions and cations in the solution in a single filtration process, solving the limitation of traditional single-charge membranes that can only remove one type of ion and improving the purification efficiency.

[0008] The technical scheme adopted by the present application to solve its technical problems is: a preparation method of a membrane chromatography filter membrane for removing charged ions in a liquid, comprising the following steps:

[0009] S1, preparing casting solution: respectively preparing positive layer casting solution, neutral layer casting solution and negative layer casting solution, the positive layer casting solution is modified by adding a positive modifier in the casting solution, the negative layer casting solution is modified by adding a negative modifier in the casting solution, and the neutral layer casting solution is unmodified casting solution;

[0010] S2, simultaneously extruding the positive layer casting solution, the neutral layer casting solution and the negative layer casting solution using a three-layer die head and coating them on a polyester film;

[0011] S3, exposing under the conditions of set temperature, humidity and air flow rate to make the casting solution preliminarily phase separate;

[0012] S4, immersing the coated film in a pure water coagulation bath to complete phase separation and solidification;

[0013] S5, after rinsing and drying, winding up to obtain the membrane chromatography filter membrane.

[0014] Further, in S1, the casting solution comprises a polymer, a hydrophilic polymer, a charge modifier, a solvent and a non-solvent.

[0015] The content of each component in the casting solution is: polymer 10-15%, hydrophilic polymer 0-2%, solvent 20-80%, and non-solvent 18-70%.

[0016] Further, in S1, the positive modifier comprises polyquaternary ammonium salt, polydiallyldimethylammonium chloride, poly(methacryloyloxyethyltrimethylammonium chloride) or polyethyleneimine, and the content is 0.5-5%.

[0017] Further, in S1, the negative modifier comprises sulfonated polyether sulfone, polyacrylic acid, polymethacrylic acid, polymaleic anhydride, sodium polystyrene sulfonate or polyphosphate, and the content is 0.5-5%.

[0018] Further, the polymer comprises polyether sulfone or nylon-6.

[0019] Further, the hydrophilic polymer comprises polyvinylpyrrolidone K90 or polyvinylpyrrolidone K30.

[0020] Further, the solvent comprises N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, formic acid or acetic acid.

[0021] The non-solvent comprises water, ethanol, ethylene glycol, glycerol, triethylene glycol or polyethylene glycol.

[0022] Further, in S3, the temperature is set to 20-25℃; the humidity is set to 80-90%; and the air flow rate is set to 0.8-1.2 m / s.

[0023] A membrane chromatography filter membrane for removing charged ions in a liquid, the filter membrane is a three-layer composite structure, comprising a positive layer, a neutral layer and a negative layer arranged in sequence; the neutral layer is located between the positive layer and the negative layer, and is used for supporting and isolating the positive layer and the negative layer; the overall thickness of the filter membrane is 120-250 μm, wherein the thickness of the positive layer and the negative layer is 50-100 μm respectively, and the thickness of the neutral layer is 20-50 μm.

[0024] Application of the membrane chromatography filter membrane in removing charged ions in a liquid, the application is adsorbing and removing trace metal ions or inorganic ions in electronic industry chemicals.

[0025] Compared with the prior art, the beneficial effects of the present application are:

[0026] (1) The present application designs a special three-layer composite structure of "positive layer-neutral layer-negative layer", so that the filter membrane can adsorb anions and cations in the solution at the same time in a single filtration process, solving the limitation of traditional single-charge membrane which can only remove one kind of ion, and improving the purification efficiency.

[0027] (2) The membrane chromatography technology adopted by the present application is based on pressure-driven filtration, which has higher permeation flux, lower operating pressure and faster processing speed compared with traditional ion exchange resin; at the same time, compared with distillation / distillation and other thermal separation technologies, the energy consumption is significantly reduced, which is more in line with the production requirements of energy saving and environmental protection.

[0028] (3) The neutral layer of the filter membrane of the present application not only plays the role of supporting and isolating the positive and negative layers and preventing charge interference, but also has a microporous structure which can effectively intercept insoluble particulate impurities in the liquid, realizing the integration of "adsorbing ions" and "filtering particles" in the same membrane unit, and simplifying the purification process and equipment.

[0029] (4) The present application is designed for the harsh requirements of trace ion removal in electronic industry chemicals, has excellent ion removal rate, and is suitable for preparing ultrapure water, ultrapure reagents and the like, and guarantees the yield of high-end electronic manufacturing products.

[0030] (5) The present application adopts a three-layer die co-extrusion preparation process, which can realize accurate control and firm combination of the three-layer structure, has good process repeatability, is suitable for continuous production, and provides a guarantee for large-scale industrial application. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The dyeing result graph of methylene blue for example 1 and example 6;

[0032] Figure 2 The dyeing result chart of the Carmine for Example 1 and Example 6;

[0033] Figure 3 The electron microscope chart of the membrane chromatography filter membrane prepared for Example 1. DETAILED DESCRIPTION

[0034] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0035] Example 1:

[0036] The present embodiment provides a preparation method of a membrane chromatography filter membrane for removing charged ions in a liquid, and the specific steps are as follows:

[0037] First, three casting solutions are prepared: a positive layer casting solution, a neutral layer casting solution and a negative layer casting solution.

[0038] The composition of the positive layer casting solution includes: polyether sulfone 13%, hydrophilic polymer polyvinylpyrrolidone (PVP) 1%, positive modifier polydiallyldimethylammonium chloride 4%, solvent N-methylpyrrolidone (NMP) 28.67%, and non-solvent polyethylene glycol 400 (PEG400) 53.33%.

[0039] The composition of the neutral layer casting solution includes: polyether sulfone 12%, hydrophilic polymer polyvinylpyrrolidone (PVP) 2%, solvent N-methylpyrrolidone (NMP) 30%, and non-solvent polyethylene glycol 400 (PEG400) 56%.

[0040] The composition of the negative layer casting solution includes: polyether sulfone 13%, hydrophilic polymer polyvinylpyrrolidone (PVP) 1%, negative modifier sulfonated polyether sulfone 1%, solvent N-methylpyrrolidone (NMP) 29.72%, and non-solvent polyethylene glycol 400 (PEG400) 55.28%.

[0041] Table 1 is a component table of the membrane chromatography filter membrane for removing charged ions in a liquid in Example 1.

[0042]

[0043] Subsequently, coating was performed using a three-layer co-extrusion die. The lip gap of the three-layer die was set to 0.15 mm, 0.1 mm and 0.15 mm from top to bottom, and the feed rate of each layer was set to 3 L / h, 2 L / h and 3 L / h, respectively. The three casting solutions were simultaneously extruded to form a three-layer stacked liquid film, which was coated on the polyester film.

[0044] Next, the coated liquid film was exposed to a wind tunnel with a temperature of 21°C, a humidity of 65% and an air flow rate of 1.0 m / s for 20 seconds, so that the casting solution was initially phase-separated.

[0045] Then, the initially phase-separated film was immersed in a pure water coagulation bath to complete the final phase separation and solidification.

[0046] Finally, the solidified film was thoroughly rinsed with pure water, dried and wound to obtain the membrane chromatography filter. As shown in Figure 3 , the filter has a total thickness of about 150 μm, has a composite structure of a positive layer, a neutral layer and a negative layer, and is suitable for adsorbing and removing trace metal ions or inorganic ions in electronic industry chemicals.

[0047] Examples 2-5:

[0048] The process conditions of Examples 2-5 were the same as those of Example 1, and the formula compositions are shown in Table 2.

[0049]

[0050] Example 6:

[0051] Three casting solutions were prepared according to Table 3, the lip gap of the three-layer die was set to 0.2 mm, 0.1 mm and 0.2 mm from top to bottom, and the feed rate of the three-layer die was set to 5 L / h, 3 L / h and 5 L / h, respectively, for extrusion. After extrusion, a three-layer stacked liquid film was formed, the liquid film entered a wind tunnel with a temperature of 21°C, a humidity of 85% and an air flow rate of 1.0 m / s, and stayed for 5 min to form an initially phase-separated structure, then entered a pure water coagulation bath for final phase separation and solidification, and finally was thoroughly rinsed with pure water, dried and wound to obtain the roll film.

[0052] Table 3 is a component table of the membrane chromatography filter for removing charged ions in a liquid according to Example 6.

[0053]

[0054] As shown in Figure 1 and Figure 2 , one side of the filter films prepared in Example 1 and Example 6 can be dyed with the positive dye methylene blue, and the other side can be dyed with the negative dye carmine, and the color does not fade after rinsing, which proves that the two sides of the filter film have positive and negative charges, respectively.

[0055] Experimental case 7-8:

[0056] The process conditions of example 2-5 are the same as example 6, and the formula composition is shown in table 4:

[0057]

[0058] Table 5: test results of examples 1-8, the basic data are as follows:

[0059]

[0060] Table 6 is the ion removal ability characterization data of the membrane chromatography filter membrane prepared by examples 1-8.

[0061]

[0062] In summary, the present application prepares a membrane chromatography filter membrane with a special structure of "positive layer-neutral layer-negative layer" by three-layer die co-extrusion technology. The test data of examples 1-8 show that the filter membrane can not only simultaneously and efficiently adsorb and remove anions and cations in the liquid, but also reduce the conductivity of a variety of typical ion solutions from hundreds of μS / cm to single-digit level, and has the function of filtering particulate impurities. The dyeing and SEM results directly prove the stable charging characteristics and regular three-layer microstructure of the filter membrane on both sides. The process of the present application is controllable and has good repeatability, and provides an innovative solution with high throughput, low energy consumption and integration for solving the problem of trace ion pollution in electronic industry chemicals, which has the prospect of industrial application.

[0063] Although the embodiments of the present application have been shown and described, it can be understood by those skilled in the art that various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a membrane chromatography filter membrane for removing charged ions from liquids, characterized in that, Includes the following steps: S1. Preparation of casting solutions: Prepare positive charge layer casting solution, neutral charge layer casting solution and negative charge layer casting solution respectively. The positive charge layer casting solution is prepared by adding a positive charge modifier to the casting solution. The negative charge layer casting solution is prepared by adding a negative charge modifier to the casting solution. The neutral charge layer casting solution is an unmodified casting solution. S2. Using a three-layer die head, the positively charged layer casting solution, the neutral layer casting solution, and the negatively charged layer casting solution are simultaneously extruded and coated onto a polyester film. S3. Expose the casting solution to set temperature, humidity and air flow rate conditions to allow for initial phase separation; S4. Immerse the coated film in a pure water coagulation bath to complete phase separation and curing. S5. After rinsing and drying, the membrane is wound up to obtain a membrane chromatography filter membrane.

2. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 1, characterized in that: In S1, the casting solution contains polymers, hydrophilic polymers, charge modifiers, solvents, and non-solvents; The composition of the casting solution is as follows: polymer 10-15%, hydrophilic polymer 0-2%, solvent 20-80%, and non-solvent 18-70%.

3. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 1, characterized in that, In S1, the positively charged modifier includes polyquaternary ammonium salt, polydiallyldimethylammonium chloride, poly(methacryloyloxyethyltrimethylammonium chloride), or polyethyleneimine, with a content of 0.5-5%.

4. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 1, characterized in that, In S1, the negative charge modifier includes sulfonated polyethersulfone, polyacrylic acid, polymethacrylic acid, polymaleic anhydride, sodium polystyrene sulfonate or polyphosphate, with a content of 0.5-5%.

5. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 2, characterized in that, The polymers include polyethersulfone or nylon-6.

6. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 2, characterized in that, Hydrophilic polymers include polyvinylpyrrolidone K90 or polyvinylpyrrolidone K30.

7. A method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 2, characterized in that, Solvents include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, formic acid, or acetic acid; Non-solvents include water, ethanol, ethylene glycol, glycerol, triethylene glycol, or polyethylene glycol.

8. The method for preparing a membrane chromatography filter membrane for removing charged ions from a liquid according to claim 1, characterized in that, In S3, the set temperature is 20-25℃; humidity is 80-90%; and air velocity is 0.8-1.2m / s.

9. A membrane chromatography filter membrane for removing charged ions from liquids, characterized in that: The filter membrane has a three-layer composite structure, including a positively charged layer, a neutral layer and a negatively charged layer arranged sequentially. The neutral layer is located between the positive and negative charge layers and is used to support and isolate the positive and negative charge layers. The overall thickness of the filter membrane is 120-250 μm, of which the thicknesses of the positive and negative charged layers are 50-100 μm and the thickness of the neutral layer is 20-50 μm.

10. The application of the membrane chromatography filter membrane as described in any one of claims 1-8 in the removal of charged ions from a liquid, characterized in that, The application is to adsorb and remove trace metal or inorganic ions from chemicals in the electronics industry.

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