Nanoporous membrane material for reducing ag / au / pd content in electronic grade sulfuric acid and preparation method thereof

Abstract

The application discloses a kind of nanometer porous membrane materials for reducing the content of Ag / Au / Pt in electronic grade sulfuric acid and preparation method, the nanometer porous membrane material uses N-methyl pyrrolidone as solvent, polyvinylidene fluoride as polymer, glass fiber, graphite powder as additive, with sulfonated graphene oxide as chemical adsorption complexing agent, it is configured into stable film liquid with suitable viscosity for blade coating, and PVDF / SGO nanometer porous membrane material is obtained by blade coating.The application can effectively solve the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification by preparing a new type of superabsorbent material-PVDF / SGO nanometer porous membrane material, especially for Ag, Au, Pt metal ion removal capacity is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic chemical products, and particularly relates to a nano-porous membrane material for reducing the content of Ag / Au / Pt 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, electronic-grade sulfuric acid is mainly used for cleaning and etching wafers. The presence of Ag 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 ions have strong chemical stability and low solubility, so when they exist as impurities in electronic-grade sulfuric acid, they can reduce the corrosion of sulfuric acid and reduce its etching effect. In addition, the presence of Pt ions in electronic-grade sulfuric acid can affect the activity and dissolution ability of electronic-grade sulfuric acid on the metal surface;

[0008] 4. Reducing IC yield: During the processing of silicon wafers, insoluble solid particles or metal ions can conduct electricity between fine circuits, causing short circuits. A few metal ions or dust can cause ICs with small line widths to be scrapped, resulting in a 50% decrease in IC yield.

[0009] 5. 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.

[0010] 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 a type of 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 various industries for electronic-grade sulfuric acid and the sharp increase in demand for high-purity sulfuric acid. SUMMARY

[0011] To overcome the shortcomings of the prior art, one of the purposes of the present application is to provide a nano-porous membrane material for reducing the content of Ag / Au / Pt in electronic-grade sulfuric acid.

[0012] The second purpose of the present application is to provide a method for preparing a nano-porous membrane material for reducing the content of Ag / Au / Pt in electronic-grade sulfuric acid.

[0013] One of the purposes of the present application is achieved by the following technical solution: a nano-porous membrane material for reducing the content of Ag / Au / Pt in electronic-grade sulfuric acid, wherein N-methyl pyrrolidone is used as a solvent, polyvinylidene fluoride is used as a polymer, glass fiber and graphite powder are used as additives, and sulfonated graphene oxide is used as a chemical adsorption complexing agent. The membrane liquid is configured to have appropriate viscosity for blade coating and is stable. The PVDF / SGO nano-porous membrane material is obtained by blade coating.

[0014] Optionally, the mass ratio of N-methyl pyrrolidone to polyvinylidene fluoride is 85-95:5-15, 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.

[0015] Optionally, the mass ratio of carbon, oxygen, sulfur, nitrogen in the sulfonated graphene oxide is 6.2:3.7:0.4:0.5.

[0016] The second object of the present application is achieved by the following technical scheme: a preparation method of a nano-porous membrane material for reducing the content of Ag / Au / Pt in electronic-grade sulfuric acid, comprising the following steps:

[0017] (1) configuring a base blade coating liquid: weighing 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%, mixing the above components with each other, stirring with a stirrer for 1-3 hours, and vacuum defoaming for 5-30 minutes to obtain the base blade coating liquid;

[0018] (2) configuring a blade coating liquid: weighing glass fiber accounting for 5-20% of the total weight of the base blade coating liquid, graphite powder accounting for 5-15% of the total weight of the base blade coating liquid, and sulfonated graphene oxide accounting for 0.5-2% of the total weight of the base blade coating liquid, mixing the glass fiber, graphite powder, and sulfonated graphene oxide with the base blade coating liquid obtained in step (1) with each other, stirring with a stirrer for 1-3 hours, and vacuum defoaming for 5-30 minutes to obtain the blade coating liquid;

[0019] (3) blade coating: pouring the blade coating liquid obtained in step (2) into a blade coating machine, using the blade coating machine to coat a film with a thickness of 200-1000 microns on a quartz plate, and then immersing the film in ultrapure water for 1-24 hours to obtain a blade-coated thin film;

[0020] (4) drying: air-drying the blade-coated thin film obtained in step (3) for 1-3 hours to obtain a PVDF / SGO nano-porous membrane material.

[0021] Optionally, in step (1), the mass percentage of the N-methyl pyrrolidone is 88-92%, and the mass percentage of the polyvinylidene fluoride is 8-12%, the sum of the mass percentages of the two components being 100%.

[0022] Optionally, in step (2), the amount of the graphene oxide is 2-4% of the total weight of the base blade coating liquid, the amount of the glass fiber is 5-20% of the total weight of the base blade coating liquid, the amount of the graphite powder is 5-15% of the total weight of the base blade coating liquid, and the amount of the graphene oxide is 0.5-2% of the total weight of the base blade coating liquid.

[0023] Optionally, in step (3), the process parameters of the blade coating machine are as follows: the reciprocating blade coating speed is 8-12 mm / s, and the blade coating temperature is at room temperature.

[0024] Optionally, the molecular weight of the polyvinylidene fluoride is 300-500 million.

[0025] Optionally, the preparation method of the sulfonated graphene oxide is as follows:

[0026] (21) graphene oxide is added into ultrapure water, ultrasonic dispersion is carried out for 50-70 min to obtain a suspension; the dosage ratio of the graphene oxide and the ultrapure water is 0.1-1 g: 250 ml;

[0027] (22) p-aminobenzenesulfonic acid is added into the suspension obtained in step (21), stirring is carried out under the condition of 75-85 ℃ oil bath, and reaction is carried out for 5-7 h to obtain SGO precipitate; the mass ratio of the p-aminobenzenesulfonic acid and the graphene oxide is 0.2-0.8: 1;

[0028] (23) the SGO precipitate obtained in step (22) is centrifuged and filtered under the condition of 4500-5500 rpm, and the flocculent product is obtained by washing with ultrapure water for multiple times to remove residual p-aminobenzenesulfonic acid;

[0029] (24) the flocculent product is centrifuged under the condition of ultrahigh speed 4500-5500 rpm, the supernatant is removed after centrifugation, and sulfonated graphene oxide is obtained after freeze-drying.

[0030] Optionally, in step (21), the graphene oxide is prepared by the following steps:

[0031] (211) graphite powder and sodium nitrate are added into a reactor at room temperature, and a rotor is added; 300 ml of concentrated sulfuric acid is poured, and magnetic stirring is carried out; the dosage ratio of the graphite powder, the sodium nitrate and the concentrated sulfuric acid is 3-5 g: 2-3 g: 100 ml;

[0032] (212) potassium permanganate is slowly added into the reactor under ice bath, a preservative film is covered, and reaction is carried out at room temperature for 4 days, and heat release is carried out by stirring 2-3 times per day; the mass ratio of the potassium permanganate and the graphite powder is 3-5: 1;

[0033] (213) after reaction for 4 days, 500-1000 ml of deionized water is slowly and repeatedly added, stirring is carried out, and heat release is carried out; 50-100 ml of hydrogen peroxide is added, stirring is carried out for multiple times, and the reaction is a golden sand-shaped graphene oxide dispersion liquid, which is cooled to room temperature;

[0034] (214) the golden sand-shaped graphene oxide dispersion liquid is subjected to first centrifugation under the condition of 4500-5500 rpm, centrifugation is carried out for 5 min, the upper layer is poured out after centrifugation, deionized water is added to disperse the gel-shaped graphene oxide, stirring is carried out, and second centrifugation is carried out under the condition of 4500-5500 rpm, and the upper layer is poured out after centrifugation to remove sulfuric acid;

[0035] (215)Add deionized water, shake well, ice bath ultrasonic 3-5 min, under the condition of 1500-2500 rpm, centrifugal 3-5 min, repeat the operation until the upper liquid is not thick, collect the lower liquid, freeze-drying the lower liquid to obtain graphene oxide.

[0036] Compared with the prior art, the application has the beneficial effects that:

[0037] (1) The present application can effectively solve the problem of high content of specific metal ion impurities in the existing high-purity sulfuric acid purification by preparing a new type of super-absorbing material, PVDF / SGO nano-porous membrane material, especially for Ag, Au, Pt metal ion removal capacity.

[0038] The PVDF / SGO nano-porous membrane material of the present application is arranged behind the four-stage rectifying tower to increase the adsorption and removal of specific metal ions in electronic-grade sulfuric acid. Its porous structure can effectively remove organic macromolecules, bacteria, viruses, anion impurities and other impurities in electronic-grade sulfuric acid, and can effectively remove Ag, Au, Pt metal ion impurities, meeting the high-purity requirements of various industries for electronic-grade sulfuric acid, and the sharp increase in demand for high-purity sulfuric acid.

[0039] (2) The new type of super-absorbing material, PVDF / SGO nano-porous membrane material prepared by the present application has reasonable formula design, which effectively improves the service life of the membrane material. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 SEM test image (100 nm) of the PVDF / SGO nano-porous membrane material of the preferred embodiment 2 of the present application;

[0041] Figure 2 SEM test image (2 μm) of the PVDF / SGO nano-porous membrane material of the preferred embodiment 2 of the present application;

[0042] Figure 3 SEM test image (10 μm) of the sulfonated graphene oxide SGO used in the preferred embodiment 2 of the present application;

[0043] Figure 4 SEM image taken at Figure 3 EDS test of carbon, oxygen, sulfur, nitrogen element distribution graph in ①, ② of the SEM image;

[0044] Figure 5 EDS test of carbon, oxygen, sulfur, nitrogen element content graph in ① of the SEM image taken at Figure 3

[0045] Figure 6 Figure 3 ​​The carbon, oxygen, sulfur, nitrogen element content chart in the EDS test at ② in the SEM image;

[0046] Figure 7 The SEM, EDS test chart (10 μm) of another part of the sulfonated graphene oxide SGO used in the preferred embodiment 2 of the application;

[0047] Figure 8 For taking Figure 7 The carbon, oxygen, sulfur, nitrogen element distribution chart in the EDS test at ③ in the SEM image;

[0048] Figure 9 For taking Figure 7 The carbon, oxygen, sulfur, nitrogen element content chart in the EDS test at ③ in the SEM image;

[0049] Figure 10 The PVDF / SGO nanometer porous membrane material of the preferred embodiment 2 of the application removes Ag metal ion data chart of high-purity sulfuric acid;

[0050] Figure 11 The PVDF / SGO nanometer porous membrane material of the preferred embodiment 2 of the application removes Au metal ion data chart of high-purity sulfuric acid;

[0051] Figure 12 The PVDF / SGO nanometer porous membrane material of the preferred embodiment 2 of the application removes Pt metal ion data chart of high-purity sulfuric acid. DETAILED DESCRIPTION

[0052] Hereinafter, the 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.

[0053] In the application, unless specified, all the parts and percentages are weight units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art, unless otherwise specified.

[0054] The application provides a nanometer porous membrane material for reducing the content of Ag / Au / Pt in electronic-grade sulfuric acid, which is prepared by using 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, so as to obtain a PVDF / SGO nanometer porous membrane material.

[0055] As a further implementation, the mass ratio of the N-methylpyrrolidone to the polyvinylidene fluoride is 85-95:5-15, the amount of the glass fiber is 5-20% of the total mass of the N-methylpyrrolidone and the polyvinylidene fluoride, the amount of the graphite powder is 5-15% of the total mass of the N-methylpyrrolidone and the polyvinylidene fluoride, and the amount of the graphene oxide is 0.5-2% of the total mass of the N-methylpyrrolidone and the polyvinylidene fluoride.

[0056] As a further implementation, the mass ratio of the carbon, oxygen, sulfur, and nitrogen in the sulfonated graphene oxide is 6.2:3.7:0.4:0.5.

[0057] The application also provides a preparation method of a nanoporous membrane material for reducing the Ag / Au / Pt content in electronic-grade sulfuric acid, comprising the following steps:

[0058] (1) configuring a base blade coating solution: weighing N-methylpyrrolidone 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%, mixing the above components with each other, stirring them with a stirrer for 1-3 hours, and vacuum defoaming them for 5-30 minutes to obtain the base blade coating solution;

[0059] (2) configuring a blade coating solution: weighing glass fiber 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 base blade coating solution, mixing the glass fiber, the graphite powder, the sulfonated graphene oxide, and the base blade coating solution obtained in step (1) with each other, stirring them with a stirrer for 1-3 hours, and vacuum defoaming them for 5-30 minutes to obtain the blade coating solution;

[0060] (3) blade coating: pouring the blade coating solution obtained in step (2) into a blade coating machine, using the blade coating machine to coat a film with a thickness of 200-1000 μm on a quartz plate, and then immersing the film in ultrapure water for 1-24 hours to obtain a blade-coated film;

[0061] (4) drying: air-drying the blade-coated film obtained in step (3) for 1-3 hours to obtain a PVDF / SGO nanoporous membrane material.

[0062] As a further implementation, in step (1), the mass percentage of the N-methylpyrrolidone is 88-92%, the mass percentage of the polyvinylidene fluoride is 8-12%, and the sum of the mass percentages of the two components is 100%.

[0063] As a further implementation manner, in step (2), the amount of the graphene oxide is 2-4% of the total weight of the base coating solution; the amount of the glass fiber is 5-20% of the total weight of the base coating solution; the amount of the graphite powder is 5-15% of the total weight of the base coating solution; and the amount of the graphene oxide is 0.5-2% of the total weight of the base coating solution.

[0064] As a further implementation manner, in step (3), the process parameters of the blade coating machine are as follows: the back-and-forth blade coating speed is 8-12 mm / s, and the blade coating temperature is at room temperature.

[0065] As a further implementation manner, the molecular weight of the polyvinylidene fluoride is 300-500 W.

[0066] As a further implementation manner, the preparation method of the sulfonated graphene oxide is as follows:

[0067] (21) The graphene oxide is added into ultrapure water and ultrasonically dispersed for 50-70 min to obtain a suspension; the amount ratio of the graphene oxide to the ultrapure water is 0.1-1 g: 250 ml;

[0068] (22) The p-aminobenzenesulfonic acid is added into the suspension obtained in step (21) and stirred at 75-85°C under oil bath conditions 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;

[0069] (23) The SGO precipitate obtained in step (22) is centrifuged and filtered at 4500-5500 rpm, and the residual p-aminobenzenesulfonic acid is removed by washing with ultrapure water for multiple times to obtain a flocculent product;

[0070] (24) 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.

[0071] As a further implementation manner, in step (21), the graphene oxide is prepared by the following steps:

[0072] (211) The graphite powder and sodium nitrate are added into a reactor at room temperature, and a rotor is added; 300 ml of concentrated sulfuric acid is poured, and magnetic stirring is performed; the amount ratio of the graphite powder, the sodium nitrate, and the concentrated sulfuric acid is 3-5 g: 2-3 g: 100 ml;

[0073] (212) The potassium permanganate is slowly added into the reactor under ice bath, a preservative film is covered, and reaction is performed at room temperature for 4 days; the heat release is performed by stirring 2-3 times per day; the mass ratio of the potassium permanganate to the graphite powder is 3-5: 1;

[0074] (213)After 4 days of reaction, slowly add 500-1000 ml of deionized water, stir, and release heat; add 50-100 ml of hydrogen peroxide, stir several times, and the reaction is a golden sand-like graphite oxide dispersion liquid, which is cooled to room temperature;

[0075] (214)Centrifuge the golden sand-like graphite oxide dispersion liquid for the first time at 4500-5500 rpm, centrifuge for 5 min, and pour off the upper layer. Add deionized water to disperse the gel-like graphene oxide, stir, and centrifuge for the second time at 4500-5500 rpm. After centrifugation, pour off the upper layer to remove sulfuric acid.

[0076] (215)Add deionized water, shake well, and ice-bath ultrasonic for 3-5 min. Centrifuge for the third time at 1500-2500 rpm for 3-5 min. Repeat the operation until the upper liquid is not thick. Collect the lower liquid and freeze-dry the lower liquid to obtain graphene oxide.

[0077] The following are specific embodiments of the present application. The raw materials, equipment, etc. used in the following examples can be obtained by purchase unless otherwise specified.

[0078] Example 1

[0079] A PVDF / SGO nano-porous membrane material is prepared by the following steps:

[0080] (1) Prepare a base coating solution: weigh 85% N-methyl pyrrolidone DMF and 15% polyvinylidene fluoride PVDF by mass percentage. 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, and vacuum defoam for 5 min to obtain a base coating solution. The PVDF is selected from Solef 6010 PVDF from Sino-American, with a molecular weight of 400,000.

[0081] (2) Prepare a coating solution: weigh 5% glass fiber, 5% graphite powder, and 0.5% sulfonated graphene oxide based on the total weight of the base coating solution. Mix the glass fiber, graphite powder, and sulfonated graphene oxide with the base coating solution obtained in step (1) with each other, stir for 1 h with a stirrer, and vacuum defoam for 5 min to obtain a coating solution.

[0082] (3) Coating: pour the coating solution obtained in step (2) into a coating machine, use the coating machine to coat a 200 μm thick film on a quartz plate, then immerse the film in ultrapure water for 1 h to obtain a coated film.

[0083] (4) Drying: dry the coated film obtained in step (3) for 1 h to obtain a PVDF / SGO nano-porous membrane material.

[0084] Example 2

[0085] A PVDF / SGO nanoporous membrane material is prepared by the following steps:

[0086] (1) Prepare a base coating solution: weigh 90% N-methyl pyrrolidone DMF and 10% polyvinylidene fluoride PVDF, the sum of the mass percentages of the two components being 100%, mix the above components with each other, stir with a blender for 2 h, and then vacuum defoam for 15 min to obtain the base coating solution; wherein the PVDF is selected from Solef6010 PVDF from Sino-American, with a molecular weight of 400,000.

[0087] (2) Prepare a coating solution: weigh 15% glass fiber, 10% graphite powder, and 1% sulfonated graphene oxide, each based on the total weight of the base coating solution, mix the glass fiber, graphite powder, and sulfonated graphene oxide with the base coating solution obtained in step (1), stir with a blender for 2 h, and then vacuum defoam for 15 min to obtain the coating solution.

[0088] (3) Coating: pour the coating solution obtained in step (2) into a coating machine, use the coating machine to coat a 300 μm-thick film on a quartz plate, and then immerse the film in ultrapure water for 12 h to obtain a coated film.

[0089] (4) Drying: dry the coated film obtained in step (3) for 2 h to obtain a PVDF / SGO nanoporous membrane material.

[0090] Example 3

[0091] A PVDF / SGO nanoporous membrane material is prepared by the following steps:

[0092] (1) Prepare a base coating solution: weigh 95% N-methyl pyrrolidone DMF and 5% polyvinylidene fluoride PVDF, the sum of the mass percentages of the two components being 100%, mix the above components with each other, stir with a blender for 3 h, and then vacuum defoam for 30 min to obtain the base coating solution; wherein the PVDF is selected from Solef6010 PVDF from Sino-American, with a molecular weight of 400,000.

[0093] (2) Prepare a coating solution: weigh 20% glass fiber, 15% graphite powder, and 2% sulfonated graphene oxide, each based on the total weight of the base coating solution, mix the glass fiber, graphite powder, and sulfonated graphene oxide with the base coating solution obtained in step (1), stir with a blender for 3 h, and then vacuum defoam for 30 min to obtain the coating solution.

[0094] (3) Casting: the casting solution obtained in step (2) was poured into a casting coater, and a film with a thickness of 1000 μm was cast on a quartz plate using the casting coater, and then the film was immersed in ultrapure water for 24 h to obtain a cast film;

[0095] (4) Drying: the cast film obtained in step (3) was air-dried for 3 h to obtain a PVDF / SGO nanoporous membrane material.

[0096] The sulfonated graphene oxide SGO of Examples 1-3 was prepared by the following steps:

[0097] (21) The graphene oxide GO was added to ultrapure water and ultrasonically dispersed for 60 min to obtain a suspension; the amount ratio of the graphene oxide to ultrapure water was 0.5 g: 250 ml; in step (21), the graphene oxide GO was prepared by the following steps: (211) 10 g of graphite powder and 7.5 g of sodium nitrate were added to a reactor at room temperature, and a rotor was added; 300 ml of concentrated sulfuric acid was poured in, and magnetic stirring was performed; (212) 40 g of potassium permanganate was slowly added to the reactor under ice bath, and the reactor was covered with a preservative film, and the reaction was carried out at room temperature for 4 days, and the heat was removed by stirring 2-3 times a day; (213) after 4 days of reaction, 800 ml of deionized water was slowly and repeatedly added, stirred, and the heat was removed; 60 ml of hydrogen peroxide was added and stirred repeatedly, and the reaction was a golden sand-like graphene oxide dispersion liquid, which was cooled to room temperature; (214) the golden sand-like graphene oxide dispersion liquid was centrifuged at 5000 rpm for the first time, and the supernatant was discarded after centrifugation, and the gel-like graphene oxide was dispersed by adding deionized water, and was centrifuged at 5000 rpm for the second time, and the supernatant was discarded after centrifugation to remove sulfuric acid; (215) deionized water was added and shaken, and ultrasonic treatment was carried out for 5 min under ice bath, and was centrifuged at 2000 rpm for 5 min, and the operation was repeated until the supernatant was not viscous, and the lower liquid was collected and freeze-dried to obtain graphene oxide GO.

[0098] (22) 0.2 g of p-aminobenzenesulfonic acid was added to the suspension obtained in step (21), and stirring was carried out under the condition of 80°C oil bath for 6 h to obtain SGO precipitate;

[0099] (23) The SGO precipitate obtained in step (22) was centrifuged and filtered at 5000 rpm, and was washed repeatedly with ultrapure water to remove residual p-aminobenzenesulfonic acid to obtain a flocculent product;

[0100] (24) The flocculent product was centrifuged at an ultrahigh speed of 5000 rpm, and the supernatant was removed after centrifugation, and was freeze-dried to obtain sulfonated graphene oxide.

[0101] Comparative Example 1

[0102] The difference between Comparative Example 1 and Example 2 is that the concentration of the base blade coating solution in step (1) is too high, specifically, 82% by mass of DMF and 18% by mass of PVDF are weighed and mixed to prepare the base blade coating solution; the rest of the conditions are the same as those in Example 2.

[0103] Comparative Example 2

[0104] The difference between Comparative Example 2 and Example 2 is that the concentration of the base blade coating solution in step (1) is too low, specifically, 96% by mass of DMF and 4% by mass of PVDF are weighed and mixed to prepare the base blade coating solution; the rest of the conditions are the same as those in Example 2.

[0105] Comparative Example 3

[0106] The difference between Comparative Example 3 and Example 2 is that the polyvinylidene fluoride PVDF in step (1) is selected from Solef 1015 PVDF from Solvay, USA, with a molecular weight of 1 million; the rest of the conditions are the same as those in Example 2.

[0107] Comparative Example 4

[0108] The difference between Comparative Example 4 and Example 2 is that no glass fibers are added in step (2); the rest of the conditions are the same as those in Example 2.

[0109] Comparative Example 5

[0110] The difference between Comparative Example 5 and Example 2 is that no graphite powder is added in step (2); the rest of the conditions are the same as those in Example 2.

[0111] Comparative Example 6

[0112] The difference between Comparative Example 6 and Example 2 is that the sulfonated graphene oxide SGO used in step (2) is purchased from the sulfonated graphene oxide with model number 045697616 from Exploration Platform; the rest of the conditions are the same as those in Example 2.

[0113] Comparative Example 7

[0114] Comparative Example 7 is different from Example 2 in that: in step (2), sulfonated graphene oxide SGO is prepared by using graphene oxide GO instead of sulfonated graphene oxide SGO, and the rest of the conditions are the same as Example 2. Among them, the graphene oxide GO is prepared by the following steps: (211) at room temperature, 10 g of graphite powder and 7.5 g of sodium nitrate are added to the reactor, and the rotor is added; pour 300 ml of concentrated sulfuric acid and stir with a magnetic stirrer; (212) slowly add 40 g of potassium permanganate to the reactor under ice bath, cover with plastic wrap, and react at room temperature for 4 days, stirring 2-3 times a day to release heat; (213) after 4 days of reaction, slowly add 800 ml of deionized water, stir, and release heat; add 60 ml of hydrogen peroxide, stir several times, and the reaction is a golden sand-like graphene oxide dispersion liquid, which is cooled to room temperature; (214) the golden sand-like graphene oxide dispersion liquid is centrifuged at 5000 rpm for the first time, centrifuged for 5 min, and the upper layer is poured off after centrifugation. Deionized water is added to disperse the gel-like graphene oxide, and the second centrifugation is carried out at 5000 rpm. After centrifugation, the upper layer is poured off to remove sulfuric acid; (215) add deionized water and shake well, and ultrasonic for 5 min under ice bath. The third centrifugation is carried out at 2000 rpm, and the centrifugation is repeated for 5 min. Repeat the operation until the upper liquid is not viscous, collect the lower liquid, and freeze-dry the lower liquid to obtain graphene oxide GO.

[0115] Comparative Example 8

[0116] Comparative Example 8 is different from Example 2 in that: in step (2), the mass ratio of p-aminobenzenesulfonic acid to graphene oxide in the preparation of sulfonated graphene oxide SGO is different, specifically, the mass ratio of p-aminobenzenesulfonic acid to graphene oxide is 0.1:1, and the rest of the conditions are the same as Example 2.

[0117] Comparative Example 9

[0118] Comparative Example 9 is different from Example 2 in that: in step (2), the mass ratio of p-aminobenzenesulfonic acid to graphene oxide in the preparation of sulfonated graphene oxide SGO is different, specifically, the mass ratio of p-aminobenzenesulfonic acid to graphene oxide is 0.9:1, and the rest of the conditions are the same as Example 2.

[0119] Effect evaluation and performance detection

[0120] The performance of the nano-porous membrane material of Examples 1-3 and each comparative example in removing specific metal ions and service life was detected, and the detection items and results are shown in Table 1.

[0121] 1. Cross-flow filtration experiment

[0122] The nano-porous membrane material prepared in Examples 1-3 and each comparative example was tested using a cross-flow filtration integrated device. First, the membrane material of each example was made into a membrane module with a diameter of 10 cm and a thickness of 0.5 cm, and then the cross-flow filtration experiment was carried out. The membrane is then assembled on the cross-flow filtration integrated device, and then the electronic-grade sulfuric acid of the same batch is introduced into the liquid inlet. During the cross-flow filtration operation, the electronic-grade sulfuric acid flow generates two forces on the membrane surface, one is the normal force perpendicular to the membrane surface, which makes the electronic-grade sulfuric acid penetrate the membrane surface, and the other is the tangential force parallel to the membrane surface, which flushes away the retentate (including metal ions) on the membrane surface. Each time the electronic-grade sulfuric acid is filtered for 3 minutes, and 1 ml of the electronic-grade sulfuric acid at the tail end of the liquid outlet is taken; the continuous experiment is performed for 7 times, and 7 times of electronic-grade sulfuric acid filtrate are obtained.

[0123] 2. ICP-MS experiment

[0124] The ICP-MS equipment in the hundred-level clean room is used to test the trace metal ions of the sulfuric acid stock solution and the electronic-grade sulfuric acid filtrate. The trace metal ions of (1) high-purity sulfuric acid stock solution, (2) 1-time sulfuric acid filtrate, (3) 2-time sulfuric acid filtrate, (4) 3-time sulfuric acid filtrate, (5) 4-time sulfuric acid filtrate, (6) 5-time sulfuric acid filtrate, (7) 6-time sulfuric acid filtrate, and (8) 7-time sulfuric acid filtrate are tested. ① ICP-MS stands for Inductively Coupled Plasma-Mass Spectrometry. ICP serves as an ion source. ICP uses a high-frequency radio frequency signal with high power applied to the inductive coil to form a high-temperature plasma inside the coil, and through the pushing of gas, it ensures the balance and continuous ionization of the plasma. The sample to be analyzed is pumped into the atomizer by a peristaltic pump to form an aerosol, which is carried into the center area of the plasma torch by the carrier gas, and vaporization, decomposition, excitation and ionization occur. The high-temperature plasma ionizes most elements in the sample to form monovalent positive ions. ② The ions in the plasma are effectively transmitted to the mass spectrometer through the ICP-MS interface; ③ The mass spectrometer is a mass selection and analyzer. By selecting ions with different mass-to-charge ratios (m / z) to pass through, the intensity of a certain ion is detected, and the trace amount of a certain element is calculated and analyzed. The test results select the trace amount of a specific metal ion to explain the filtering effect of the membrane material on the specific metal ion.

[0125] Table 1 is the test results of the removal of specific metal ions by the nanoporous membrane material of each embodiment

[0126]

[0127] Table 2 is Figure 4 、 7 The test results of the mass ratio of carbon, oxygen, sulfur and nitrogen of sulfonated graphene oxide SGO in three places in the SEM image shown in

[0128] Wt% ① ② 3 Carbon atoms 61.0 62.7 61.2 Oxygen atoms 37.9 36.3 38.1 Sulfur atoms 0.3 0.4 0.4 Nitrogen atoms 0.8 0.5 0.3

[0129] Figures 1-2The SEM test diagram of the PVDF / SGO nanoporous membrane material of the preferred embodiment 2 of the present application is shown in the figure. Figures 1-2 As shown in the figure, the PVDF / SGO nanoporous membrane material prepared by the present application has uniform surface and internal pore distribution, with a surface pore diameter of 50-100 nm and an internal pore diameter of about 100 nm.

[0130] Figures 3-9 The SEM and EDS test diagrams of the sulfonated graphene oxide SGO prepared by the present application are shown in the figure. The sulfonated graphene oxide SGO prepared by the present application is in a sheet shape, with a single-layer sulfonated graphene oxide thickness of about 0.8-1.2 nm and an average radial size of 40-60 μm. 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.

[0131] As shown in the above table and Figures 10-12 By preparing the new type of super-absorbent material, the PVDF / SGO nanoporous membrane material, the content of Ag, Au, and Pt specific metal ions in the 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 can be effectively solved.

[0132] In addition, in Comparative Example 1-2, the concentration of the base blade coating solution is too high or too low, which leads to the failure of film formation, and thus the trace amount of metal ions cannot be filtered.

[0133] In Comparative Example 3, the PVDF with a molecular weight of 1 million has poor film formation effect, and the membrane has less SGO, and the filtering effect is not as good as that of the membrane material prepared by the present application.

[0134] In Comparative Examples 4-5, no glass fiber or graphite powder additive is added during the preparation of the membrane material, so that the membrane material cannot be formed, the trace amount of metal ions cannot be filtered, and the filtering amount of the membrane material cannot be tested.

[0135] In Comparative Example 6, the SGO is purchased, and the SGO has many impurities, which introduces more metal ion impurities in the filtering process, so that the percentage exceeds 100%.

[0136] In Comparative Example 7, the graphene oxide GO is used instead of the sulfonated graphene oxide SGO, and the higher the sulfonation degree of the GO, the better the adsorption effect.

[0137] In the mass ratio of p-aminobenzenesulfonic acid to GO, the content of p-aminobenzenesulfonic acid in Comparative Example 8 is too low, the sulfonation degree of GO is low, and the filtering effect is reduced. The content of p-aminobenzenesulfonic acid in Comparative Example 9 is too high, the sulfonation degree of GO reaches a threshold value, the adsorption effect cannot be further improved, and more impurities are introduced.

[0138] 3. Membrane material service life test

[0139] In the cross-flow filtration experiment, each instance of the membrane material is continuously used for filtering and purifying sulfuric acid, after 50 times of filtration, the membrane material is taken out, and the damage of the membrane material is observed. The results show that the nano-porous membrane material prepared by the application has no damage under the microscope after 50 times of filtration.

[0140] In summary, the new super-absorbing material PVDF / SGO nano-porous 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.

[0141] The above embodiments are only preferred embodiments of the application, and cannot be used to limit the protection scope of the application, and any non-substantial changes and replacements made by those skilled in the art on the basis of the application shall fall within the protection scope of the application.

Claims

1. A nanoporous membrane material for reducing the Ag / Au / Pt content in electronic grade sulfuric acid, characterized by, 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 sulfonated graphene oxide as a chemical adsorption complexing agent, and by configuring the membrane liquid with suitable viscosity for blade coating and stability, and then performing blade coating to obtain the PVDF / SGO nanoporous membrane material. The mass ratio of the N-methyl pyrrolidone to the polyvinylidene fluoride is 85-95:5-15, the amount of the glass fiber is 5-20% of the total mass of the N-methyl pyrrolidone and the polyvinylidene fluoride, the amount of the graphite powder is 5-15% of the total mass of the N-methyl pyrrolidone and the polyvinylidene fluoride, and the amount of the graphene oxide is 0.5-2% of the total mass of the N-methyl pyrrolidone and the polyvinylidene fluoride. The molecular weight of the polyvinylidene fluoride is 300-500 thousand.

2. The nanoporous membrane material for reducing the Ag / Au / Pt content in electronic grade sulfuric acid according to claim 1, wherein The sulfonated graphene oxide is prepared by the following method: (21) The graphene oxide is added to ultrapure water and ultrasonically dispersed for 50-70 min to obtain a suspension; the amount ratio of the graphene oxide to the ultrapure water is 0.1-1 g:250 ml; (22) The p-aminobenzenesulfonic acid is added to the suspension obtained in step (21), and stirred at 75-85°C under oil bath conditions 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; (23) The SGO precipitate obtained in step (22) 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; (24) 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.

3. A method for preparing a nanoporous membrane material for reducing the Ag / Au / Pt content in electronic grade sulfuric acid, characterized by, The method comprises the following steps: (1) configuring a base blade coating liquid: weighing 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%, mixing the above components with each other, stirring with a stirrer for 1-3 h, and vacuum defoaming for 5-30 min to obtain the base blade coating liquid; the molecular weight of the polyvinylidene fluoride is 300-500 thousand; (2) configuring a blade coating liquid: weighing glass fiber of 5-20%, graphite powder of 5-15%, and sulfonated graphene oxide of 0.5-2% of the total weight of the base blade coating liquid, mixing the glass fiber, the graphite powder, the sulfonated graphene oxide, and the base blade coating liquid obtained in step (1) with each other, stirring with a stirrer for 1-3 h, and vacuum defoaming for 5-30 min to obtain the blade coating liquid; (3) blade coating: pouring the blade coating liquid obtained in step (2) into a blade coating machine, using the blade coating machine to coat a film with a thickness of 200-1000 μm on a quartz plate, and then immersing the film in ultrapure water for 1-24 h to obtain a blade-coated film; (4) drying: air-drying the blade-coated film obtained in step (3) for 1-3 h to obtain the PVDF / SGO nanoporous membrane material.

4. The method for preparing a nanoporous membrane material with reduced Ag / Au / Pt content in electronic-grade sulfuric acid as described in claim 3, characterized in that, In step (1), the mass percentage of the N-methylpyrrolidone is 88-92%, the mass percentage of the polyvinylidene fluoride is 8-12%, and the sum of the mass percentages of the two components is 100%.

5. The method for preparing a nanoporous membrane material with reduced Ag / Au / Pt content in electronic-grade sulfuric acid as described in claim 3, characterized in that, In step (3), the process parameters of the blade coating machine are as follows: the reciprocating blade coating speed is 8-12 mm / s, and the blade coating temperature is room temperature.

6. The method for preparing a nanoporous membrane material with reduced Ag / Au / Pt content in electronic-grade sulfuric acid as described in claim 3, characterized in that, The preparation method of the sulfonated graphene oxide is as follows: (21) The graphene oxide is added into ultrapure water and ultrasonically dispersed for 50-70 min to obtain a suspension; the dosage ratio of the graphene oxide to the ultrapure water is 0.1-1 g: 250 ml; (22) In the suspension obtained in step (21), p-aminobenzenesulfonic acid is added, and stirring is performed under the condition of an oil bath at 75-85 ℃ 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; (23) The SGO precipitate obtained in step (22) is centrifuged and filtered under the condition of 4500-5500 rpm, and the residual p-aminobenzenesulfonic acid is removed by washing with ultrapure water for multiple times to obtain a flocculent product; (24) The flocculent product is centrifuged under the condition of ultrahigh speed of 4500-5500 rpm, the supernatant is removed after centrifugation, and the sulfonated graphene oxide is obtained after freeze-drying.

7. The method for preparing a nanoporous membrane material with reduced Ag / Au / Pt content in electronic-grade sulfuric acid as described in claim 6, characterized in that, In step (21), the graphene oxide is prepared by the following steps: (211) At room temperature, graphite powder and sodium nitrate are added into a reactor, and a rotor is added; 300 ml of concentrated sulfuric acid is poured, and magnetic stirring is performed; the dosage ratio of the graphite powder, the sodium nitrate and the concentrated sulfuric acid is 3-5 g: 2-3 g: 100 ml; (212) Potassium permanganate is slowly added into the reactor under ice bath, a preservative film is covered, and reaction is performed at room temperature for 4 days, and heat release is performed by stirring 2-3 times per day; the mass ratio of the potassium permanganate to the graphite powder is 3-5: 1; (213) After reaction for 4 days, 500-1000 ml of deionized water is slowly and repeatedly added, stirring is performed, and heat release is performed; 50-100 ml of hydrogen peroxide is added, and stirring is repeatedly performed, the reaction is a golden sand-like graphene oxide dispersion liquid, and cooling is performed to room temperature; (214) The golden sand-like graphene oxide dispersion liquid is subjected to first centrifugation under the condition of 4500-5500 rpm, centrifugation is performed for 5 min, the upper layer is poured out after centrifugation, deionized water is added to disperse the gel-like graphene oxide, stirring is performed, and second centrifugation is performed under the condition of 4500-5500 rpm, the upper layer is poured out after centrifugation, and sulfuric acid is removed; (215) Deionized water is added, shaking is uniformly performed, ice bath ultrasonic is performed for 3-5 min, third centrifugation is performed under the condition of 1500-2500 rpm, centrifugation is performed for 3-5 min, the operation of the present step is repeated until the upper liquid is not viscous, the lower liquid is collected, and the lower liquid is freeze-dried to obtain graphene oxide.

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