Composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic grade sulfuric acid and preparation method thereof

Abstract

The application discloses a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid and a preparation method thereof. The composite membrane material comprises a PVDF / SGO nanoporous membrane material and a PVDF / GO electrostatic spinning membrane material which is compounded on the surface of the nanoporous membrane material. The nanoporous membrane material is prepared by using N-methyl pyrrolidone as a solvent, polyvinylidene fluoride as a polymer, glass fiber and graphite powder as additives, and SGO as a complexing agent, and then being coated by a blade coating method to obtain the PVDF / SGO nanoporous membrane material. The electrostatic spinning membrane material is prepared by using N,N-dimethylformamide as a solvent, polyvinylidene fluoride as a polymer, and graphene oxide as a complexing agent, and then being spun to obtain the PVDF / GO electrostatic spinning membrane material. The composite membrane material can effectively solve the problem of high content of specific metal ion impurities such as Au, Ag, Pt, Ni and Bi in the existing high-purity sulfuric acid purification.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic chemical products, and particularly relates to a composite film material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid and a preparation method thereof. BACKGROUND

[0002] Electronic-grade sulfuric acid, also known as ultrapure sulfuric acid, high-purity sulfuric acid, etc., is widely used in the integrated circuit (IC), semiconductor and other microelectronic industries as a chemical reagent. In the wafer production process, electronic-grade sulfuric acid is mainly responsible for photoetching, cleaning, etching, etc. of wafers, which can effectively remove inorganic residues, impurity particles and carbon deposits on the wafers, thereby ensuring the quality and performance of the wafers. In addition, electronic-grade sulfuric acid can also be used as a solution, which is mainly used for producing electrolyte of lithium batteries and other rechargeable batteries.

[0003] There are mainly two methods for preparing electronic-grade sulfuric acid at present: industrial sulfuric acid distillation method, which uses industrial sulfuric acid as raw material and adds a strong oxidizing agent for distillation to obtain the product, and can be used for small-scale production; and sulfur trioxide gas absorption method, which uses ultrapure water to directly absorb clean sulfur trioxide gas to obtain the product, and can be used for large-scale production. The distillation method has high energy consumption and cost, some impurities are difficult to remove, the generated waste gas and acid mist are harmful to the human body and are not conducive to environmental protection, and is only suitable for small-scale production. The sulfur trioxide gas absorption method can effectively avoid the above-mentioned shortcomings of the distillation method, but the existing gas absorption method cannot effectively remove sulfur dioxide gas, so that the prepared sulfuric acid contains a certain amount of trace sulfur dioxide impurities, which affects the performance of the sulfuric acid.

[0004] With the rapid development of the integrated circuit, semiconductor and lithium battery markets in China, the technology is continuously improving, and the precision of components is continuously increasing. Electronic-grade sulfuric acid plays a crucial role in the manufacturing process of integrated circuits, semiconductors and lithium batteries, especially in the cleaning and etching process of silicon wafers. The presence of heavy metal impurities has a significant impact on the performance of electronic-grade sulfuric acid.

[0005] 1. Affecting the quality and production yield of wafers: In the semiconductor manufacturing process, sulfuric acid is mainly used for cleaning and etching wafers. The presence of Ag impurity ions can form small particles or defects on the surface of the wafer, which can affect the quality and production yield of the wafer, resulting in more waste and rework.

[0006] 2. Affecting the diffusion effect of the diffusing agent: Au and other impurity ions can affect the diffusion effect of the diffusing agent.

[0007] 3. Reducing etching effect: Pt has strong chemical stability and low solubility, so when it exists as an impurity in electronic-grade sulfuric acid, Pt impurity ions can reduce the corrosiveness of the sulfuric acid and reduce its etching effect. In addition, the presence of Pt impurity ions in electronic-grade sulfuric acid can affect the activity and dissolution ability of electronic-grade sulfuric acid on the metal surface.

[0008] 4. Insulation voltage drop resistance: Alkali metal impurities such as Ni, Na, Ca, etc. can melt into the oxide film, causing a decrease in insulation voltage drop resistance.

[0009] 5. Impact on integrated circuit performance: Heavy metal impurities such as Bi, Cr, etc. can cause a decrease in P-N junction voltage resistance when attached to the surface of a silicon wafer, affecting the electrical performance of integrated circuits (ICs).

[0010] 6. Reducing IC yield: During the processing of silicon wafers, insoluble solid particles or metal ions can conduct electricity between fine circuits, causing short circuits, and a few metal ions or dust can cause ICs with smaller line widths to be scrapped, resulting in a decrease in IC yield of about 50%.

[0011] 7. Photolithography defects and uneven oxide layer: Dust particles can cause photolithography defects and uneven oxide layers, affecting the quality of the mask and the plasma etching process.

[0012] Therefore, in order to obtain high-quality and high-yield integrated circuit chips, very pure electronic-grade sulfuric acid must be used to clean silicon wafers to remove various contaminants and reduce the impact of heavy metal impurities. This requires the development of an electronic-grade sulfuric acid with extremely low heavy metal content to address the problem of high specific metal ion impurity content in existing electronic-grade sulfuric acid purification, in order to meet the high-purity requirements of electronic-grade sulfuric acid for various industries and the sharp increase in demand for high-purity sulfuric acid. SUMMARY

[0013] To overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid.

[0014] The second purpose of the present application is to provide a preparation method of a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid.

[0015] One of the purposes of the present application is achieved by the following technical solution: a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid, the composite membrane material comprising a PVDF / SGO nano-porous membrane material, and a PVDF / GO electrostatic spinning membrane material composite on the surface of the PVDF / SGO nano-porous membrane material.

[0016] The PVDF / SGO nanoporous membrane material uses N-methyl pyrrolidone as a solvent, polyvinylidene fluoride as a polymer, glass fiber and graphite powder as additives, and sulfonated graphene oxide as a chemical adsorption complexing agent, and is configured into a stable membrane solution with suitable viscosity for blade coating, and the PVDF / SGO nanoporous membrane material is obtained through blade coating.

[0017] The PVDF / GO electrospinning membrane material uses N,N-dimethylformamide as a solvent, polyvinylidene fluoride as a polymer, and graphene oxide as a chemical adsorption complexing agent, and is configured into a stable membrane solution with suitable viscosity for electrospinning, and the PVDF / GO electrospinning membrane material is obtained through spinning.

[0018] Optionally, in the PVDF / SGO nanoporous membrane material, the mass ratio of N-methyl pyrrolidone to polyvinylidene fluoride is 85-95:5-15, and the sum of the mass percentages of the two components is 100%; the amount of glass fiber is 5-20% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride, the amount of graphite powder is 5-15% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride, and the amount of graphene oxide is 0.5-2% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride.

[0019] Optionally, in the PVDF / GO electrospinning membrane material, the mass ratio of N,N-dimethylformamide to polyvinylidene fluoride is 85-95:5-15, and the sum of the mass percentages of the two components is 100%, and the amount of graphene oxide is 0.01-6% of the total mass of N,N-dimethylformamide and polyvinylidene fluoride.

[0020] Optionally, the molecular weight of the polyvinylidene fluoride is 300-500 thousand.

[0021] Optionally, the composite membrane material is at least a three-layer structure, including a PVDF / SGO nanoporous membrane material, and PVDF / GO electrospinning membrane materials respectively compounded on the upper surface and the lower surface of the PVDF / SGO nanoporous membrane material.

[0022] The second object of the application is achieved by the following technical scheme: a preparation method of a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid, comprising the following steps:

[0023] (1) weigh N-methyl pyrrolidone with a mass percentage of 85-95%, and polyvinylidene fluoride with a mass percentage of 5-15%, and the sum of the mass percentages of the two components is 100%, mix the above components with each other to prepare a basic blade coating solution; weigh 0.01-6% of graphene oxide based on the total weight of the basic membrane solution, and then mix it with the basic membrane solution to prepare an electrospinning membrane solution, which is ready for use;

[0024] (2) Take N,N-dimethylformamide with a mass percentage of 85-95%, polyvinylidene fluoride with a mass percentage of 5-15%, and mix the two components with a total mass percentage of 100% to prepare a base coating solution; take glass fibers with a mass percentage of 5-20%, graphite powder with a mass percentage of 5-15%, and sulfonated graphene oxide with a mass percentage of 0.5-2%, and mix them with the base coating solution to prepare the coating solution;

[0025] (3) Pour the coating solution obtained in step (2) into a coating machine, use the coating machine to coat a quartz plate, then immerse the film in ultrapure water for 1-24 h, dry it for 1-3 h after demolding to obtain a PVDF / SGO nano-porous film material;

[0026] (4) Use an electrospinning machine to spin the electrospinning solution prepared in step (1) on the upper and lower surfaces of the PVDF / SGO nano-porous film material prepared in step (3) to form a PVDF / GO electrospinning film material with two layers, and dry it for 0.5-2 h to obtain a composite film material.

[0027] Alternatively, the specific preparation method of the electrospinning solution in step (1) is as follows:

[0028] (11) Prepare a base film solution: take N,N-dimethylformamide and polyvinylidene fluoride, mix the components with each other, stir them with a stirrer for 1-3 h, and vacuum defoam for 5-30 min to obtain a base film solution;

[0029] (12) Prepare an electrospinning film solution: take graphene oxide, mix it with the base film solution obtained in step (11), stir them with a stirrer for 1-3 h, and vacuum defoam for 5-30 min to obtain an electrospinning film solution.

[0030] Alternatively, the specific preparation method of the coating solution in step (2) is as follows:

[0031] (21) Prepare a base coating solution: take N-methyl pyrrolidone and polyvinylidene fluoride, mix the components with each other, stir them with a stirrer for 1-3 h, and vacuum defoam for 5-30 min to obtain a base coating solution;

[0032] (22) Prepare a coating solution: take glass fibers, graphite powder, and sulfonated graphene oxide, mix them with the base coating solution obtained in step (21), stir them with a stirrer for 1-3 h, and vacuum defoam for 5-30 min to obtain a coating solution.

[0033] Optionally, in step (3), the process parameters of the scraping coating machine are as follows: the reciprocating scraping speed is 8-12 mm / s, the scraping temperature is at room temperature, and the film thickness scraped by the scraping coating machine on the quartz plate is 200-1000 μm.

[0034] Optionally, in step (4), the spinning conditions are: spinning voltage of 8 to 16 kV, injection speed of 0.6 to 1.4 mL / h, and spinning time of 2 to 8 h.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] (1) This application prepares a novel super-adsorption material—a composite membrane containing PVDF / SGO nanoporous membrane and PVDF / GO electrospun membrane—which can effectively solve the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification, especially with high removal capacity for Au, Ag, Pt, Ni and Bi metal ions.

[0037] In specific applications, the composite membrane material of this invention can be installed in existing sulfuric acid purification distillation devices, specifically after a four-stage distillation column, to enhance the adsorption and removal of specific metal ions in electronic-grade sulfuric acid. Its porous structure can effectively remove impurities such as organic macromolecules, bacteria, viruses, and anionic impurities from electronic-grade sulfuric acid, as well as effectively remove metal ion impurities such as Au, Ag, Pt, Ni, and Bi, meeting the high purity requirements of various industries for electronic-grade sulfuric acid and the rapidly increasing demand for high-purity sulfuric acid.

[0038] (2) The preparation method of the present invention is simple to operate and has a low cost, and can effectively solve the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification.

[0039] (3) The novel super-adsorption material prepared by this invention—a composite membrane material containing PVDF / SGO nanoporous membrane material and PVDF / GO electrospun membrane material—has a reasonable formulation design and effectively improves the service life of the membrane material. Attached Figure Description

[0040] Figure 1 The image shows a scanning electron microscope (SEM) image (50 μm) of the composite membrane material of the preferred embodiment 2 of the present invention.

[0041] Figure 2 for Figure 1 Scanning electron microscope (SEM) image of region A in the middle (5 μm);

[0042] Figure 3 The image is a scanning electron microscope (SEM) image (500 μm) of the composite film material of the preferred embodiment 2 of the present invention.

[0043] Figure 4 SEM, EDS test image (10 μm) of graphene oxide GO used in preferred embodiment 2 of the present application;

[0044] Figure 5 SEM image taken from Figure 4 EDS test of carbon, oxygen element distribution in ①, ② of the SEM image;

[0045] Figure 6 SEM image taken from Figure 4 EDS test of carbon, oxygen element content in ① of the SEM image;

[0046] Figure 7 SEM image taken from Figure 4 EDS test of carbon, oxygen element content in ② of the SEM image;

[0047] Figure 8 SEM, EDS test image (10 μm) of another place of graphene oxide GO used in preferred embodiment 2 of the present application;

[0048] Figure 9 SEM image taken from Figure 8 EDS test of carbon, oxygen element distribution in ③, ④, ⑤ of the SEM image;

[0049] Figure 10 SEM image taken from Figure 8 EDS test of carbon, oxygen element content in ③ of the SEM image;

[0050] Figure 11 SEM image taken from Figure 8 EDS test of carbon, oxygen element content in ④ of the SEM image;

[0051] Figure 12 SEM image taken from Figure 8 EDS test of carbon, oxygen element content in ⑤ of the SEM image;

[0052] Figure 13 SEM test image (10 μm) of sulfonated graphene oxide SGO used in preferred embodiment 2 of the present application;

[0053] Figure 14 SEM image taken from Figure 13 EDS test of carbon, oxygen element distribution in ①, ② of the SEM image;

[0054] Figure 15 SEM image taken from Figure 13 EDS test of carbon, oxygen, sulfur, nitrogen element content in ① of the SEM image;

[0055] Figure 16 SEM image taken from Figure 13EDS test of the SEM image of the present application preferred embodiment 2 at ① place;

[0056] Figure 17 SEM, EDS test image (10 μm) of another place of the sulfonated graphene oxide SGO used in the present application preferred embodiment 2;

[0057] Figure 18 For taking Figure 17 EDS test of the SEM image of the present application preferred embodiment 2 at ③ place;

[0058] Figure 19 For taking Figure 17 EDS test of the SEM image of the present application preferred embodiment 2 at ③ place;

[0059] Figure 20 The composite film material of the present application preferred embodiment 2 removes Au metal ion data graph of high-purity sulfuric acid;

[0060] Figure 21 The composite film material of the present application preferred embodiment 2 removes Ag metal ion data graph of high-purity sulfuric acid;

[0061] Figure 22 The composite film material of the present application preferred embodiment 2 removes Pt metal ion data graph of high-purity sulfuric acid;

[0062] Figure 23 The composite film material of the present application preferred embodiment 2 removes Ni metal ion data graph of high-purity sulfuric acid;

[0063] Figure 24 The composite film material of the present application preferred embodiment 2 removes Bi metal ion data graph of high-purity sulfuric acid;

[0064] Among them, 11 is PVDF / GO electrostatic spinning film material; 12 is PVDF / SGO nano-porous film material. DETAILED DESCRIPTION

[0065] Hereinafter, the present application will be further described in conjunction with the drawings and specific embodiments, and it should be noted that the following described embodiments or technical features can be combined in any manner to form new embodiments without conflict.

[0066] In the present application, unless specified, all parts, percentages are weight units, and the equipment and raw materials used can be purchased from the market or commonly used in the art. The methods in the following examples are conventional methods in the art, unless otherwise specified.

[0067] The application provides a composite membrane material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid, which comprises a PVDF / SGO nanoporous membrane material and a PVDF / GO electrospun membrane material combined on the surface of the PVDF / SGO nanoporous membrane material.

[0068] The PVDF / SGO nanoporous membrane material is prepared by using N-methyl pyrrolidone (NMP) as a solvent, polyvinylidene fluoride (PVDF) as a polymer, glass fiber and graphite powder as additives, and sulfonated graphene oxide (SGO) as a chemical adsorption complexing agent.

[0069] The PVDF / GO electrospun membrane material is prepared by using N,N-dimethylformamide (DMF) as a solvent, polyvinylidene fluoride (PVDF) as a polymer, and graphene oxide (GO) as a chemical adsorption complexing agent.

[0070] In the application, the sulfonated graphene oxide SGO is prepared by the following method:

[0071] 11) The graphene oxide is added to ultrapure water and ultrasonically dispersed for 50-70 min to obtain a suspension; the mass ratio of the graphene oxide to the ultrapure water is 0.1-1 g: 250 ml;

[0072] 12) The p-aminobenzenesulfonic acid is added to the suspension obtained in step 1), and stirred at 75-85 DEG C in an oil bath for 5-7 h to obtain SGO precipitate; the mass ratio of the p-aminobenzenesulfonic acid to the graphene oxide is 0.2-0.8:1;

[0073] 13) The SGO precipitate obtained in step 2) is centrifuged and filtered at 4500-5500 rpm, and washed with ultrapure water for multiple times to remove residual p-aminobenzenesulfonic acid to obtain a flocculent product;

[0074] 14) The flocculent product is centrifuged at an ultrahigh speed of 4500-5500 rpm, the supernatant is removed after centrifugation, and the sulfonated graphene oxide is obtained after freeze-drying.

[0075] The graphene oxide GO used for preparing the sulfonated graphene oxide SGO or the graphene oxide GO used for preparing the coating solution is prepared by the following steps:

[0076] 21) at room temperature, graphite powder, sodium nitrate into the reactor, add rotor; pour into 300ml concentrated sulfuric acid, magnetic stirring; the amount ratio of graphite powder, sodium nitrate, concentrated sulfuric acid is 3-5g: 2-3g: 100ml;

[0077] 22) under ice bath, slowly add potassium permanganate into the reactor, cover the plastic wrap, room temperature reaction for 4 days, stirring 2-3 times a day to carry out heat; the mass ratio of potassium permanganate, graphite powder is 3-5: 1;

[0078] 23) after reaction for 4 days, slowly, multiple 500-1000ml deionized water, stirring, heat; add 50-100ml hydrogen peroxide, multiple stirring, reaction is golden sand-like graphite oxide dispersion liquid, cool to room temperature;

[0079] 24) golden sand-like graphite oxide dispersion liquid is centrifuged for the first time under the condition of 4500-5500rpm, centrifugation 5min, pour off the upper layer after centrifugation, add deionized water dispersion gel-like graphene oxide, stirring, centrifuged for the second time under the condition of 4500-5500rpm, pour off the upper layer after centrifugation, to remove sulfuric acid;

[0080] 25) add deionized water, shake, ice bath ultrasonic 3-5min, centrifuged for the third time under the condition of 1500-2500rpm, centrifugation 3-5min, repeat the operation of this step until the upper liquid is not viscous, collect the lower liquid, freeze-drying the lower liquid to obtain graphene oxide GO.

[0081] The mass ratio of carbon and oxygen in the graphene oxide prepared by the method is 6:4; the mass ratio of carbon, oxygen, sulfur and nitrogen in the sulfonated graphene oxide prepared is 6.2:3.7:0.4:0.5.

[0082] As a further preferred scheme, in the PVDF / SGO nano-porous membrane material, the mass ratio of N-methyl pyrrolidone and polyvinylidene fluoride is 85-95: 5-15, and the sum of the mass percentages of the two components is 100%; the amount of glass fiber is 5-20% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride, the amount of graphite powder is 5-15% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride, and the amount of graphene oxide is 0.5-2% of the total mass of N-methyl pyrrolidone and polyvinylidene fluoride.

[0083] As a further preferred scheme, in the PVDF / GO electrospun membrane material, the mass ratio of N,N-dimethylformamide and polyvinylidene fluoride is 85-95: 5-15, and the sum of the mass percentages of the two components is 100%, and the amount of graphene oxide is 0.01-6% of the total mass of N,N-dimethylformamide and polyvinylidene fluoride.

[0084] As a further preferred solution, the polyvinylidene fluoride used in the present application has a molecular weight of 300-500 million.

[0085] As a further preferred solution, the composite film material is at least a three-layer structure, comprising a PVDF / SGO nanoporous film material, and a PVDF / GO electrospun film material respectively compounded on the upper surface and the lower surface of the PVDF / SGO nanoporous film material.

[0086] The present application also provides a preparation method of a composite film material for reducing the content of Au / Ag / Pt / Ni / Bi in electronic-grade sulfuric acid, comprising the following steps:

[0087] (1) Take N-methyl pyrrolidone with a mass percentage of 85-95%, and polyvinylidene fluoride with a mass percentage of 5-15%, the sum of the mass percentages of the two components being 100%, mix the above components with each other to prepare a basic wiped film solution; take graphene oxide with a mass percentage of 0.01-6% of the total weight of the basic film solution, and then mix it with the basic film solution to prepare an electrospun film solution, ready for use;

[0088] (2) Take N,N-dimethylformamide with a mass percentage of 85-95%, and polyvinylidene fluoride with a mass percentage of 5-15%, the sum of the mass percentages of the two components being 100%, mix the above components with each other to prepare a basic wiped film solution; take glass fibers with a mass percentage of 5-20%, graphite powder with a mass percentage of 5-15%, and sulfonated graphene oxide with a mass percentage of 0.5-2% of the total weight of the basic wiped film solution, and mix them with the basic wiped film solution to prepare a wiped film solution;

[0089] (3) Pour the wiped film solution obtained in step (2) into a wiped film coater, use the wiped film coater to coat a film on a quartz plate, then immerse the film in ultrapure water for 1-24 h, and after demolding, dry it for 1-3 h to obtain a PVDF / SGO nanoporous film material;

[0090] (4) Use an electrospinning machine to spin the electrospun film solution prepared in step (1) on the upper surface and the lower surface of the PVDF / SGO nanoporous film material obtained in step (3) to form a PVDF / GO electrospun film material with two layers on top of each other, and after drying for 0.5-2 h, obtain a composite film material.

[0091] As a further preferred solution, the specific preparation method of the electrospun film solution in step (1) is as follows:

[0092] (11) Prepare a basic film solution: take N,N-dimethylformamide and polyvinylidene fluoride, mix the above components with each other, stir them with a stirrer for 1-3 h, and then vacuum defoam for 5-30 min to obtain a basic film solution;

[0093] (12) Configuration of electrostatic spinning film liquid: take the graphene oxide, mix the graphene oxide and the base film liquid obtained in step (11) with each other, stir with a blender for 1-3 h, and vacuum defoam for 5-30 min to obtain the electrostatic spinning film liquid.

[0094] As a further preferred solution, the specific preparation method of step (2) for scraping the film liquid is as follows:

[0095] (21) Configuration of base scraping film liquid: take N-methyl pyrrolidone and polyvinylidene fluoride, mix the above components with each other, stir with a blender for 1-3 h, and vacuum defoam for 5-30 min to obtain the base scraping film liquid.

[0096] (22) Configuration of scraping film liquid: take glass fiber, graphite powder, and sulfonated graphene oxide, mix the glass fiber, graphite powder, and sulfonated graphene oxide with the base scraping film liquid obtained in step (21) with each other, stir with a blender for 1-3 h, and vacuum defoam for 5-30 min to obtain the scraping film liquid.

[0097] As a further preferred solution, in step (3), the process parameters of the film scraping coater are as follows: the reciprocating film scraping speed is 8-12 mm / s, the film scraping temperature is at room temperature, and the film thickness of the film scraped by the film scraping coater on the quartz plate is 200-1000 μm.

[0098] As a further preferred solution, in step (4), the spinning conditions are as follows: the spinning voltage is 8-16 kV, the injection speed is 0.6-1.4 mL / h, and the spinning time is 2-8 h.

[0099] The following are specific embodiments of the present application. In the following embodiments, the raw materials and equipment used can be obtained by purchase unless otherwise specified.

[0100] Example 1

[0101] A composite film for reducing the content of metal ions in electronic-grade sulfuric acid is prepared by the following steps:

[0102] (1) Take N-methyl pyrrolidone NMP with a mass percentage of 85% and polyvinylidene fluoride PVDF with a mass percentage of 15%, and the sum of the mass percentages of the two components is 100%, mix the above components with each other, stir with a blender for 1 h, and vacuum defoam for 5 min to obtain a base film liquid; take 0.05% of the total weight of the base film liquid of graphene oxide GO, and then mix it with the base film liquid, stir with a blender for 1 h, and vacuum defoam for 5 min to prepare an electrostatic spinning film liquid, which is ready for use; wherein the PVDF is selected from the PVDF with a model number of Solef6010 from Sinochem Lanzhou Chemical Co., Ltd., and the molecular weight thereof is 400,000.

[0103] (2) Take 85% by mass of N, N-dimethylformamide DMF, 15% by mass of polyvinylidene fluoride PVDF, the sum of the mass percentages of the two components is 100%, mix the above components with each other, stir for 1 h with a stirrer, defoam for 5 min in vacuum, and prepare a base coating solution; take 5% of the total weight of the base coating solution as glass fiber, 5% as graphite powder, and 0.5% as sulfonated graphene oxide SGO, mix them with the base coating solution, stir for 1 h with a stirrer, defoam for 5 min in vacuum, and prepare the coating solution; wherein the PVDF is selected from the PVDF with the model Solef6010 from Sinochem Soeigy, USA, and the molecular weight thereof is 400,000.

[0104] (3) Pour the coating solution obtained in step (2) into a coating machine, and the process parameters of the coating machine are as follows: the reciprocating coating speed is 8 mm / s, the coating temperature is room temperature, use the coating machine to coat a film with a thickness of 200 μm on a quartz plate, then immerse the film in ultrapure water for 1 h, dry after demolding for 1 h, and obtain a PVDF / SGO nano-porous film material;

[0105] (4) Use an electrospinning machine to spin the electrospinning solution prepared in step (1) on the upper and lower surfaces of the PVDF / SGO nano-porous film material in step (3) to form a PVDF / GO electrospinning film material with two layers, and the spinning conditions are as follows: the spinning voltage is 8 kV, the injection speed is 0.6 mL / h, the spinning time is 2 h, and the drying time is 0.5 h, and then a composite film material is obtained.

[0106] Example 2

[0107] A composite film material for reducing the content of metal ions in electronic-grade sulfuric acid is prepared by the following method:

[0108] (1) Take 90% by mass of N-methyl pyrrolidone and 10% by mass of polyvinylidene fluoride, the sum of the mass percentages of the two components is 100%, mix the above components with each other, stir for 2 h with a stirrer, defoam for 15 min in vacuum, and obtain a base film solution; take 3% of the total weight of the base film solution as graphene oxide, and then mix it with the base film solution, stir for 2 h with a stirrer, defoam for 15 min in vacuum, and prepare an electrospinning film solution; wherein the PVDF is selected from the PVDF with the model Solef6010 from Sinochem Soeigy, USA, and the molecular weight thereof is 400,000.

[0109] (2) Take 90% by mass of N,N-dimethylformamide, 10% by mass of polyvinylidene fluoride, and mix the two components together. Stir for 2 hours, then defoam under vacuum for 15 minutes to prepare the base coating solution. Take 15% of the total weight of the base coating solution, and mix with 10% of the total weight of glass fiber and 1% of the total weight of sulfonated graphene oxide. Stir for 2 hours, then defoam under vacuum for 15 minutes to prepare the coating solution. The PVDF is selected from Solef 6010 PVDF from Solutia, with a molecular weight of 400,000.

[0110] (3) Pour the coating solution obtained in step (2) into a coating machine, and set the process parameters as follows: reciprocating speed of 10 mm / s, and room temperature. Use the coating machine to coat a film with a thickness of 300 μm on a quartz plate, then immerse the film in ultrapure water for 12 hours. After demolding, dry for 2 hours to obtain a PVDF / SGO nanoporous membrane material.

[0111] (4) Use an electrospinning machine to spin the electrospinning solution prepared in step (1) on the upper and lower surfaces of the PVDF / SGO nanoporous membrane material prepared in step (3) to form a PVDF / GO electrospinning film material with two layers. The spinning conditions are as follows: spinning voltage of 14 kV, injection speed of 1 mL / h, and spinning time of 4 hours. After drying for 1.5 hours, a composite membrane material is obtained.

[0112] Example 3

[0113] A composite membrane material for reducing the content of metal ions in electronic-grade sulfuric acid is prepared by the following method:

[0114] (1) Take 95% by mass of N-methylpyrrolidone and 5% by mass of polyvinylidene fluoride, and mix the two components together. Stir for 3 hours, then defoam under vacuum for 30 minutes to obtain a base film solution. Take 6% of the total weight of the base film solution, and mix with the base film solution. Stir for 3 hours, then defoam under vacuum for 30 minutes to prepare an electrospinning film solution. The PVDF is selected from Solef 6010 PVDF from Solutia, with a molecular weight of 400,000.

[0115] (2) Take 95% by mass of N,N-dimethylformamide, 5% by mass of polyvinylidene fluoride, and mix the two components together, stir for 3h, defoam for 30min under vacuum, and prepare the base blade coating solution; take 20% of the total weight of the base blade coating solution, 15% of the glass fiber, 2% of the graphite powder, and mix them with the base blade coating solution, stir for 3h, defoam for 30min under vacuum, and prepare the blade coating solution; wherein the PVDF is selected from the PVDF of Solef6010 type from Sinopec, and the molecular weight is 400,000.

[0116] (3) Pour the blade coating solution obtained in step (2) into the blade coating machine, and the process parameters of the blade coating machine are as follows: the reciprocating blade speed is 12mm / s, the blade coating temperature is room temperature, use the blade coating machine to coat a film with a thickness of 1000μm on the quartz plate, then immerse the film in ultrapure water for 24h, dry after demolding for 3h, and obtain the PVDF / SGO nano-porous membrane material;

[0117] (4) Use the electrospinning machine to spin the electrospinning solution prepared in step (1) on the upper and lower surfaces of the PVDF / SGO nano-porous membrane material in step (3) to form a PVDF / GO electrospinning membrane material with two layers, and the spinning conditions are as follows: the spinning voltage is 16kV, the injection speed is 1.4mL / h, the spinning time is 8h, and the drying time is 2h, and then a composite membrane material is obtained.

[0118] wherein the sulfonated graphene oxide SGO of examples 1-3 is prepared by the following steps:

[0119] 11) Add graphene oxide GO to ultrapure water, ultrasonic dispersion for 60min, and obtain a suspension; the amount ratio of the graphene oxide and the ultrapure water is 0.5g:250ml;

[0120] 12) In the suspension obtained in step 11), add 0.2g of p-aminobenzenesulfonic acid, stir under the condition of 80℃ oil bath, and react for 6h to obtain SGO precipitate;

[0121] 13) Centrifugal filtration of the SGO precipitate obtained in step 12) under the condition of 5000rpm, and wash with ultrapure water for multiple times to remove the residual p-aminobenzenesulfonic acid, and obtain a flocculent product;

[0122] 14) Centrifuge the flocculent product under the condition of ultrahigh speed 5000rpm, remove the supernatant after centrifugation, and freeze-dry to obtain sulfonated graphene oxide.

[0123] wherein the graphene oxide GO of examples 1-3 or in step 11) is prepared by the following steps:

[0124] 21) At room temperature, 10 g of graphite powder, 7.5 g of sodium nitrate were added to the reactor, and the rotor was added; 300 ml of concentrated sulfuric acid was poured in, and it was stirred magnetically;

[0125] 22) 40 g of potassium permanganate was slowly added to the reactor under ice bath, covered with plastic wrap, and reacted at room temperature for 4 days, with stirring 2-3 times a day to release heat;

[0126] 23) After 4 days of reaction, 800 ml of deionized water was slowly added multiple times, stirred, and heat was released; 60 ml of hydrogen peroxide was added, stirred multiple times, and the reaction was a golden sand-like graphite oxide dispersion liquid, which was cooled to room temperature;

[0127] 24) The golden sand-like graphite oxide dispersion liquid was centrifuged for the first time at 5000 rpm, centrifuged for 5 min, and the upper layer was poured out after centrifugation, and deionized water was added to disperse the gel-like graphene oxide, which was centrifuged for the second time at 5000 rpm, and the upper layer was poured out after centrifugation to remove sulfuric acid;

[0128] 25) Deionized water was added and shaken, and ultrasonic treatment was performed in an ice bath for 5 min, and the third centrifugation was performed at 2000 rpm for 5 min, and the operation was repeated until the upper liquid was not thick, and the lower liquid was collected and freeze-dried to obtain graphene oxide GO.

[0129] Comparative Example 1

[0130] Comparative Example 1 differs from Example 2 in that the membrane material is only a single layer of PVDF / GO electrospun membrane, lacking the PVDF / SGO nanoporous membrane, and the rest of the conditions are the same as Example 2.

[0131] Comparative Example 2

[0132] Comparative Example 2 differs from Example 2 in that the membrane material is only a single layer of PVDF / SGO nanoporous membrane, lacking the PVDF / GO electrospun membrane, and the rest of the conditions are the same as Example 2.

[0133] Comparative Example 3

[0134] Comparative Example 3 differs from Example 2 in that the polyvinylidene fluoride PVDF in steps (1) and (2) is selected from the PVDF of Solef 1015 type from Solutia, USA, with a molecular weight of 1 million, and the rest of the conditions are the same as Example 2.

[0135] Comparative Example 4

[0136] Comparative Example 4 differs from Example 2 in that the graphene oxide GO used in step (1) is purchased from the graphene oxide of type S926168 from the company Mclane, and the rest of the conditions are the same as Example 2.

[0137] Comparative Example 5

[0138] Compared with Example 2, the difference in Comparative Example 5 is that the sulfonated graphene oxide SGO used in step (2) was purchased from the Exploration Platform 045697616 model of sulfonated graphene oxide, and the other conditions were the same as in Example 2.

[0139] Comparative Example 6

[0140] Compared with Example 2, the difference of Comparative Example 6 is that glass fiber is not added in step (2), and the other conditions are the same as those in Example 2.

[0141] Comparative Example 7

[0142] Compared with Example 2, the difference of Comparative Example 7 is that no graphite powder is added in step (2), and the other conditions are the same as those in Example 2.

[0143] Effect evaluation and performance testing

[0144] The composite membrane materials of Examples 1-3 and each comparative example were tested for their ability to remove specific metal ions, service life, and other properties. The test items and results are shown in Table 1.

[0145] 1. Cross-flow filtration experiment

[0146] The composite membrane materials prepared in Examples 1-3 and various comparative examples were tested using a cross-flow filtration integrated device. First, the membrane materials of each example were prepared... A membrane was constructed and assembled into a cross-flow filtration integrated device. Then, the same batch of electronic-grade sulfuric acid was introduced into the inlet. During cross-flow filtration, the flow of electronic-grade sulfuric acid on the membrane surface generated two forces: a normal force perpendicular to the membrane surface, allowing the electronic-grade sulfuric acid to permeate through the membrane; and a tangential force parallel to the membrane surface, flushing away any residues (including metal ions) retained on the membrane surface. Each filtration of electronic-grade sulfuric acid lasted 3 minutes, and 1 ml of the final electronic-grade sulfuric acid was collected from the outlet. This experiment was repeated 7 times, yielding filtrates from each filtration.

[0147] 2. ICP-MS Experiment

[0148] The trace metal ion of the sulfuric acid stock solution and the electronic grade sulfuric acid filtrate is tested by using the ICP-MS equipment in the hundred-level clean room. The trace metal ion of (1) high-purity sulfuric acid stock solution, (2) first sulfuric acid filtrate, (3) second sulfuric acid filtrate, (4) third sulfuric acid filtrate, (5) fourth sulfuric acid filtrate, (6) fifth sulfuric acid filtrate, (7) sixth sulfuric acid filtrate and (8) seventh sulfuric acid filtrate is tested. ①The full name of ICP-MS is inductively coupled plasma-mass spectrometry (Inductively coupled plasma-Mass Spectrometry). ICP plays the role of ion source. ICP utilizes the high-frequency radio frequency signal with high power applied on the inductive coil to form high-temperature plasma in the coil. The balance and continuous ionization of the plasma are ensured by the pushing of the gas. The sample to be analyzed is pumped into the atomizer by the peristaltic pump to form the aerosol, which is carried into the central area of the plasma torch by the carrier gas, and the evaporation, decomposition, excitation and ionization occur. The high-temperature plasma makes most of the elements in the sample ionize one electron to form monovalent positive ions. ②The ions in the plasma are effectively transmitted to the mass spectrometer through the interface of ICP-MS; ③The mass spectrum is a mass screening and analyzer. The intensity of a certain ion is detected by selecting ions with different mass-to-charge ratios (m / z), and then the trace amount of a certain element is calculated and analyzed. The test results select the trace amount of specific metal ions to explain the filtering effect of the film material on the specific metal ions.

[0149] Table 1 is the test results of the removal and filtration of specific metal ions of the composite film material of each embodiment

[0150]

[0151] Table 2 is Figure 4 、 8 The test results of the carbon-oxygen mass ratio of five places of graphene oxide GO in the SEM images shown in

[0152] Wt% ① ② ③ ④ ⑤ Carbon atoms 59.5 57.5 62.6 60.3 62.1 Oxygen atoms 40.5 42.5 37.4 39.7 37.9

[0153] Table 3 is the test results of the carbon-oxygen mass ratio of three places of sulfonated graphene oxide SGO in the SEM images shown in Figure 13 、 17

[0154]

[0155]

[0156] Figures 1-3 The SEM test image of the PVDF / SGO composite film material of the preferred embodiment 2 of the present application is shown in Figures 1-3 ​As shown, the composite membrane material prepared by the present application can be clearly seen as a three-layer structure, wherein the middle layer is a nanoporous layer (thickness of about 200 pm), and the two sides are electrospun layers (each layer has a thickness of about 100 pm), and it can be seen from the cross-sectional and surface SEM images that the electrospun layers are well combined with the nanoporous layer. The composite membrane material can be used for filtering electronic-grade sulfuric acid.

[0157] Figures 4-12 As shown in the SEM and EDS test images of the graphene oxide GO prepared by the present application, the sulfonated graphene oxide GO prepared by the present application is in a sheet shape, the thickness of a single layer of the sulfonated graphene oxide is about 0.8-1.2 nm, and the average radial size is 40-60 pm. The mass ratio of C and O in the sulfonated graphene oxide SGO prepared by the present application is about 6:4.

[0158] Figures 13-19 As shown in the SEM and EDS test images of the sulfonated graphene oxide SGO prepared by the present application, the sulfonated graphene oxide SGO prepared by the present application is in a sheet shape, the thickness of a single layer of the sulfonated graphene oxide is about 0.8-1.2 nm, and the average radial size is 40-60 pm. The mass ratio of C, O, S and N in the sulfonated graphene oxide SGO prepared by the present application is about 6.2:3.7:0.4:0.5.

[0159] As shown in the above table and Figures 20-24 By preparing the new type of super-absorbent material-composite membrane material, the content of specific metal ions such as Au, Ag, Pt, Ni and Bi in electronic-grade sulfuric acid can be effectively reduced, and the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification process can be effectively solved.

[0160] In addition, in Comparative Example 1, the membrane material is only a single-layer PVDF / GO electrospun membrane, which cannot specifically filter Ag and Pt ions.

[0161] In Comparative Example 2, the membrane material is only a single-layer PVDF / SGO nanoporous membrane, which cannot specifically filter Ni and Bi ions.

[0162] In Comparative Example 3, the molecular weight of 1 million PVDF has poor film-forming effect, and the filtering effect is not ideal.

[0163] In Comparative Examples 4-5, the SGO / GO is purchased, and since the purchased SGO / GO has many impurities, more metal ion impurities are introduced in the filtering process, so the percentage exceeds 100%.

[0164] In Comparative Examples 6-7, no glass fiber or graphite powder additive is added in the preparation process of the membrane material, so that the membrane material cannot be shaped, cannot filter trace amounts of metal ions, and cannot test the filtering amount of the membrane material.

[0165] 3. Membrane service life test

[0166] In the cross-flow filtration experiment, each example membrane material is continuously used for filtering and purifying sulfuric acid, and after 50 times of filtration, the membrane material is taken out to observe the damage of the membrane material. The results show that the nano-porous membrane material prepared by the application has no damage under the microscope after 50 times of filtration.

[0167] The new super-absorbing material, the composite membrane material, prepared by the application effectively solves the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification, and the formula design is reasonable, which effectively improves the service life of the membrane material.

[0168] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the protection scope of the application. Any non-substantial changes and replacements made by those skilled in the art based on the application shall fall within the protection scope of the application.

Claims

1. A composite membrane material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid, characterized in that, The composite membrane material has at least a three-layer structure, including a PVDF / SGO nanoporous membrane material and PVDF / GO electrospun membrane material respectively composited on the upper and lower surfaces of the PVDF / SGO nanoporous membrane material. The PVDF / SGO nanoporous membrane material uses N-methylpyrrolidone as a solvent, polyvinylidene fluoride as a polymer, glass fiber and graphite powder as additives, and sulfonated graphene oxide as a chemical adsorption complexing agent to prepare a membrane liquid with suitable viscosity and stable coating. The membrane material is obtained by coating. The PVDF / GO electrospun membrane material uses N,N-dimethylformamide as a solvent, polyvinylidene fluoride as a polymer, and graphene oxide as a chemical adsorption complexing agent to prepare a membrane solution with suitable viscosity for electrospinning and stability. After spinning, the PVDF / GO electrospun membrane material is obtained. The polyvinylidene fluoride has a molecular weight of 300,000 to 500,000.

2. The composite membrane material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 1, characterized in that, In the PVDF / SGO nanoporous membrane, the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride is 85~95:5~15, and the sum of the mass percentages of the two components is 100%; the amount of glass fiber is 5~20% of the total mass of N-methylpyrrolidone and polyvinylidene fluoride, the amount of graphite powder is 5~15% of the total mass of N-methylpyrrolidone and polyvinylidene fluoride, and the amount of graphene oxide is 0.5~2% of the total mass of N-methylpyrrolidone and polyvinylidene fluoride.

3. The composite membrane material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 1, characterized in that, In the PVDF / GO electrospun film material, the mass ratio of N,N-dimethylformamide to polyvinylidene fluoride is 85~95:5~15, the sum of the mass percentages of the two components is 100%, and the amount of graphene oxide is 0.01~6% of the total mass of N,N-dimethylformamide and polyvinylidene fluoride.

4. A method for preparing a composite membrane material that reduces the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid, characterized in that, Includes the following steps: (1) Weigh 85-95% N-methylpyrrolidone and 5-15% polyvinylidene fluoride by mass, with the sum of the two components being 100%. Mix the above components together to prepare a basic coating solution. Weigh 0.01-6% of the total weight of the basic coating solution of graphene oxide and mix it with the basic coating solution to prepare an electrospinning coating solution for later use. The molecular weight of the polyvinylidene fluoride is 300,000 to 500,000. (2) Weigh 85-95% N,N-dimethylformamide and 5-15% polyvinylidene fluoride by mass, with the sum of the two components being 100%. Mix the above components together to prepare the basic coating solution. Weigh 5-20% glass fiber, 5-15% graphite powder, and 0.5-2% sulfonated graphene oxide by mass of the basic coating solution and mix them with the basic coating solution to prepare the coating solution. The molecular weight of the polyvinylidene fluoride is 300,000 to 500,000. (3) Pour the film coating liquid obtained in step (2) into the film coating machine, use the film coating machine to coat the film on the quartz plate, then soak the film in ultrapure water for 1~24h, and dry it for 1~3h after demolding to obtain PVDF / SGO nanoporous membrane material. (4) Using an electrospinning machine, the electrospinning solution prepared in step (1) is spun on the upper and lower surfaces of the PVDF / SGO nanoporous membrane in step (3) to form two layers of PVDF / GO electrospinned membrane. After drying for 0.5~2h, a composite membrane with at least three layers is obtained, including the PVDF / SGO nanoporous membrane and the PVDF / GO electrospinned membrane respectively composited on the upper and lower surfaces of the PVDF / SGO nanoporous membrane.

5. The method for preparing the composite membrane material with reduced Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 4, characterized in that, The specific preparation method of the electrospinning film solution in step (1) is as follows: (11) Preparation of basic membrane solution: Weigh N,N-dimethylformamide and polyvinylidene fluoride, mix the above components together, stir in a mixer for 1-3 hours, and then defoam under vacuum for 5-30 minutes to obtain the basic membrane solution; (12) Prepare electrospinning membrane solution: Weigh graphene oxide, mix graphene oxide with the basic membrane solution obtained in step (11), stir with a mixer for 1-3 hours, and then defoam under vacuum for 5-30 minutes to obtain electrospinning membrane solution.

6. The method for preparing the composite film material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 4, characterized in that, The specific preparation method of the coating solution in step (2) is as follows: (21) Prepare the basic coating solution: Weigh N-methylpyrrolidone and polyvinylidene fluoride, mix the above components together, stir in a mixer for 1-3 hours, and then defoam under vacuum for 5-30 minutes to obtain the basic coating solution. (22) Prepare the coating solution: Weigh glass fiber, graphite powder, and sulfonated graphene oxide. Mix the glass fiber, graphite powder, and sulfonated graphene oxide with the basic coating solution obtained in step (21). Stir for 1-3 hours and then defoam under vacuum for 5-30 minutes to obtain the coating solution.

7. The method for preparing the composite film material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 4, characterized in that, In step (3), the process parameters of the scraping coating machine are as follows: the reciprocating scraping speed is 8~12mm / s, the scraping temperature is at room temperature, and the film thickness scraped by the scraping coating machine on the quartz plate is 200~1000μm.

8. The method for preparing the composite membrane material for reducing the Au / Ag / Pt / Ni / Bi content in electronic-grade sulfuric acid as described in claim 4, characterized in that, In step (4), the spinning conditions are: spinning voltage of 8~16kV, injection speed of 0.6~1.4mL / h, and spinning time of 2~8h.

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