Preparation method and application of N, S co-doped porous graphene hydrogel adsorbent

Abstract

The present invention discloses a preparation method and application of a N, S co-doped porous graphene hydrogel adsorbent. A certain concentration of graphene oxide dispersion and a hydrogen peroxide solution are evenly mixed, and a dopant 2,5-diaminobenzenesulfonic acid is used as a source of N and S to prepare a N, S co-doped porous graphene hydrogel material by a one-step hydrothermal method. Due to the defect sites generated by the partial reduction of the abundant oxygen-containing functional groups on the surface of graphene oxide at high temperature, the doping of N and S is facilitated, and the structure and surface chemical properties of the graphene after doping are significantly changed. The adsorbent has the advantages of simple preparation process, low cost, abundant defect sites, and easy separation and recovery. It is used to adsorb ultra-trace metal ions in high-purity PMA and has excellent adsorption performance.

Description

Technical Field

[0001] The invention belongs to the technical field of adsorption material synthesis, is applied to the removal of ultra-trace metal ions in organic solvents, and particularly relates to an ultra-trace metal ion adsorbent in a propylene glycol methyl ether acetate (PMA) system. Background Art

[0002] Ultra-clean, high-purity reagents are key basic chemical materials in the electronics industry. They play a crucial role in multiple integrated circuit production processes, including photolithography, cleaning, etching, development, and packaging. High concentrations of metal ions in these reagents, which come into direct contact with silicon wafers during photolithography and cleaning, can severely impact silicon wafers, semiconductor product yield, and reliability. Ultra-clean, high-purity reagents used in integrated circuits have even higher requirements for metal impurity levels. According to the SEMI C8 standard, the metal ion content must be less than 1 ppb.

[0003] Electronic-grade propylene glycol methyl ether acetate (PMA) is a common ultra-clean, high-purity reagent. Due to its ester, ether, and hydroxyl groups, it has a strong solubility for both polar and non-polar substances. It is primarily used as a solvent for photoresist preparation and a photoresist stripper, and is also commonly used as an integrated circuit cleaning agent. With the rapid development of integrated circuit technology, the demand for electronic-grade PMA is increasing, and so are the quality requirements, particularly for products with metal ion contents less than 1 ppb.

[0004] Patent CN104109101A discloses an apparatus for purifying ultrapure electronic-grade chemical reagents for semiconductors. This patent utilizes low-temperature vacuum distillation, primarily through phase changes in the chemical reagents combined with electrodialysis, to purify the reagents. The initial single metal ion content of the chemical reagents used is less than 10 ppb, and after purification, the concentration of single metal ions in the reagents is less than 1 ppb. The main drawbacks of this method are high energy consumption and high equipment investment costs.

[0005] Patent CN101993360A discloses a method for preparing electronic-grade propylene glycol methyl ether acetate. This patent uses a strongly acidic cation exchange resin as an esterification reaction catalyst. Its advantage is that the catalyst is easily separated from the reactants and the possibility of introducing metal ions into the system is reduced. By introducing an entrainer such as toluene or n-hexane, combined with azeotropic distillation to remove water from propylene glycol methyl ether acetate, and then further distilling and removing the ion tower, high-purity propylene glycol methyl ether acetate with a metal ion content of less than 5 ppb is obtained. This patent also uses distillation as the main method to remove metal ions, which has high energy consumption and the metal ion content fails to reach below 1 ppb.

[0006] Patent CN112920161A discloses an electronic-grade dioxane and its preparation method. The patent uses anion and cation exchange resins to adsorb dioxane to remove metal ions, dry it to remove moisture, and then purify it by vacuum distillation. The metal ion content of the obtained dioxane is less than 1 ppb.

[0007] As can be seen from the aforementioned patent disclosures, distillation is often used to remove metal ions from solvents. However, the removal of ultra-trace metal ions from organic reagents often requires consideration of metal ion introduction, placing stringent demands on the materials used for the towers and equipment involved. The high energy consumption and cost associated with distillation have prompted researchers to consider and research low-energy, high-efficiency processes.

[0008] Adsorption is a simple and efficient method with low energy consumption and low cost, and has attracted wide attention due to the high designability and adjustability of adsorption materials. There are more than 20 kinds of metal ions in the organic phase PMA, but the content is extremely low at the ppb level, among which Na + , K + Alkali metal ions have high charge density and low polarizability, making them difficult to capture by adsorbent materials. To date, several nanomaterials in granular or powdered form have been developed for metal ion adsorption. While these materials offer high adsorption capacities and rapid adsorption rates, their high production costs, poor recyclability, and potential for secondary contamination hinder their large-scale application.

[0009] The present invention provides a preparation method and application of an adsorbent for ultra-trace metal ions in propylene glycol methyl ether acetate. This method primarily utilizes the rich pores and defect structures of porous graphene hydrogel materials to further enhance the binding ability of the porous graphene material with various ultra-trace metal ions through nitrogen and sulfur co-doping. The unique positional relationship between the amino and sulfonic acid groups in the dopant 2,5-diaminobenzenesulfonic acid facilitates enhanced interaction between functional sites and metal ions in the solvent. The prepared material has the advantages of low cost, a simple preparation process, good adsorption performance, and good recyclability without the need for molding. The adsorption method can significantly reduce process costs and energy consumption, and has good prospects for industrial application. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for preparing N, S co-doped porous graphene hydrogel for removing ultra-trace metal ions in high-purity PMA systems, so as to reduce costs, reduce secondary pollution, improve adsorption performance, and provide a better adsorbent for removing ultra-trace metal ions in organic systems.

[0011] The present invention adopts the following technical solutions:

[0012] A method for preparing a N, S co-doped porous graphene hydrogel comprises the following steps:

[0013] Step 1: Mix a certain amount of graphene oxide with ultrapure water and ultrasonically disperse it in an ultrasonic machine for 1 hour to obtain a uniform dispersion. Add a certain amount of hydrogen peroxide solution and dopant 2,5-diaminobenzenesulfonic acid to the dispersion, mix well, and transfer to a 50ml Teflon hydrothermal reactor. React at 90-200°C for 10-48 hours, cool to room temperature, and then wash with ultrapure water to obtain N, S co-doped porous graphene hydrogel. Wherein, the concentration of the graphene oxide dispersion is 1-10 mg / ml, the mass fraction of the hydrogen peroxide solution is 0.1-30%, the volume ratio of the graphene oxide dispersion to the hydrogen peroxide solution is (1-100):1, and the amount of the dopant added is 10-600 mg;

[0014] Step 2: The N, S co-doped porous graphene hydrogel prepared in step 1 is washed repeatedly through a certain concentration of acid, ultrapure water, a certain concentration of alkali, and ultrapure water, thereby obtaining an N, S co-doped porous graphene hydrogel adsorbent for adsorbing ultra-trace metal ions in high-purity PMA.

[0015] The acid described in step 2 includes one of acetic acid, hydrochloric acid, nitric acid and sulfuric acid.

[0016] The base described in step 2 is one of ammonia water and tetramethylammonium hydroxide solution.

[0017] The acid concentration in step 2 is one of 1 M, 2 M, 3 M, and 5 M.

[0018] The base concentration in step 2 is one of 1 M, 2 M, 3 M, and 5 M.

[0019] The concentration of high-purity PMA described in step 2 is 99.5%.

[0020] Application: N, S co-doped porous graphene hydrogel for ultra-trace metal ions (Na + , K + , Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ etc.) adsorption.

[0021] The present invention adopts the above technical solution and has the following beneficial effects:

[0022] The present invention employs a dual-heteroatom doping strategy to effectively alter the surface chemistry of porous graphene. N and S co-doping not only increases adsorption active sites but also effectively improves the adsorbent's pore structure, resulting in more interconnected pore channels, which facilitates the rapid diffusion of metal ions. The adsorbent disclosed herein employs a dual-heteroatom doping strategy to alter the surface chemistry of graphene oxide, effectively enhancing its ability to interact with ultra-trace metal ions. Furthermore, the adsorbent possesses abundant micropores, defect structures, and numerous adsorption active sites, promising promising applications.

[0023] The N, S co-doped porous graphene hydrogel described in the invention is used to adsorb trace amounts of metal ions in high-purity PMA, demonstrating excellent adsorption performance. The adsorbent can be separated using simple separation methods such as filtration and centrifugation, and regenerated by further acid and alkaline washing, offering the advantages of simple operation and significantly reducing time costs. Under optimal fixed-bed adsorption conditions, the metal ion content in PMA can reach the G3 standard of <1 ppb. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 XPS characterization of N, S co-doped porous graphene hydrogel SNGH-0.5;

[0025] Figure 2 FT-IR spectrum of N, S co-doped porous graphene hydrogel;

[0026] Figure 3 The scanning electron microscope image of N, S co-doped porous graphene hydrogel;

[0027] Figure 4 Schematic diagram of the dynamic experimental setup of N, S co-doped porous graphene hydrogel. Specific implementation methods

[0028] The present invention is further described by the following specific examples.

[0029] Example 1

[0030] (1) Take 10 ml of 2 mg / ml graphene oxide dispersion, 1 ml of 3 wt% hydrogen peroxide solution and 10 mg of 2,5-diaminobenzenesulfonic acid, mix them evenly, react at 180 °C for 12 hours, cool to room temperature, filter, and wash repeatedly with ultrapure water, 1 M hydrochloric acid solution, ultrapure water, 1 M tetramethylammonium hydroxide solution, ultrapure water, etc. to obtain N, S co-doped porous graphene hydrogel material; denoted as SNGF-0.5, according to XPS characterization analysis, its N content is 2.61wt% and S content is 0.24wt%.

[0031] like Figure 1 As shown in the figure, the XPS characterization results of SNGF-0.5 show that the configuration of N in its carbon material skeleton is divided into graphitic N, pyrrolic N and pyridinic N, and the existence form of S is SO and S=O configuration. Figure 2 The FT-IR spectrum of SNGF-0.5 shows that there are multiple functional groups in the material, such as -1 The broad absorption peak is the bending vibration peak of OH, 1728 cm -1 The peak is the C=O stretching vibration peak of the carboxyl group, located at 1625 cm -1 The C=C stretching vibration absorption peak is 1421 cm -1 The peak is the C=N stretching vibration peak, 842cm -1 The vibration peak at 1014 cm is attributed to the NH stretching vibration peak. -1 The S=O stretching vibration peak at 584 cm -1 This is caused by the CS stretching vibration peak at , which proves that N and S elements were successfully introduced into SNGF-0.5. Figure 3 The electron microscope image shows that the graphene sheets in SNGF-0.5 are thinner, with more wrinkles and defects on the surface, and the overall structure presents a porous and interconnected three-dimensional network structure.

[0032] Example 2

[0033] (1) Take 10 ml of 2 mg / ml graphene oxide dispersion, 1 ml of 3 wt% hydrogen peroxide solution and 20 mg of 2,5-diaminobenzenesulfonic acid, mix them evenly, react at 180 °C for 12 hours, cool to room temperature, filter, and wash repeatedly with ultrapure water, 1 M hydrochloric acid solution, ultrapure water, 1 M tetramethylammonium hydroxide solution, ultrapure water, etc. to obtain N, S co-doped porous graphene hydrogel material; denoted as SNGF-1, in which the N content is 3.66 wt% and the S content is 0.51 wt%.

[0034] Figure 2 The FT-IR spectrum of SNGF-1 showed that there were multiple functional groups in the material, such as -1 The broad absorption peak is the bending vibration peak of OH, 1728 cm -1 The peak is the C=O stretching vibration peak of the carboxyl group, located at 1625 cm -1 The C=C stretching vibration absorption peak is 1421 cm -1 The peak is the C=N stretching vibration peak, 842 cm -1 The vibration peak at 1014 cm is attributed to the NH stretching vibration peak. -1 The S=O stretching vibration peak at 584 cm -1This is caused by the CS stretching vibration peak at , which proves that the N and S elements were successfully introduced into SNGF-1. Figure 3 As shown in the electron microscope image, the SNGF-1 graphene sheet is relatively thin and has abundant pores and defect structures.

[0035] Example 3

[0036] (1) Take 10 ml of 2 mg / ml graphene oxide dispersion, 1 ml of 3 wt% hydrogen peroxide solution and 100 mg of 2,5-diaminobenzenesulfonic acid, mix them evenly, react at 180 °C for 12 hours, cool to room temperature, filter, and use ultrapure water, 1 M hydrochloric acid solution, ultrapure water, 1 M tetramethylammonium hydroxide solution, ultrapure water and other steps to wash repeatedly in a cycle to obtain N, S co-doped porous graphene hydrogel material; denoted as SNGF-5, N content 6.04 wt%, S content 1.76 wt%.

[0037] Figure 2 The FT-IR spectrum of SNGF-5 shows that there are multiple functional groups in the material, such as -1 The broad absorption peak is the bending vibration peak of OH, 1728 cm -1 The peak is the C=O stretching vibration peak of the carboxyl group, located at 1625 cm -1 The C=C stretching vibration absorption peak is 1421 cm -1 The peak is the C=N stretching vibration peak, 842 cm -1 The vibration peak at 1014 cm is attributed to the NH stretching vibration peak. -1 The S=O stretching vibration peak at 584 cm -1 This is caused by the CS stretching vibration peak at , which proves that the N and S elements were successfully introduced into SNGF-5. Figure 3 Electron microscopy images were displayed, showing that the surface of the graphene sheets of SNGF-5 is relatively rough. As the dosage of 2,5-diaminobenzenesulfonic acid increases, the defect structures of the graphene sheets are excessively blocked and covered, resulting in fewer defect structures compared to SNGH-0.5 and SNGH-1. Overall, SNGH-0.5 has abundant defect sites and a moderate amount of sulfonic acid groups. Its porous and interconnected three-dimensional structure facilitates the transport of metal ions between graphene sheets, increasing the opportunity for metal ions to contact the active sites of graphene. This makes SNGH-0.5 more effective in adsorbing metal ions from PMA than SNGH-1 and SNGH-5.

[0038] Example 4

[0039] The adsorbent prepared in Example 1-3 was used to adsorb ultra-trace metal ions (Na + , K + , Ca2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ ), Na + The initial concentration was 31.24 ppb, K + The initial concentration was 4.18 ppb, Ca 2+ The initial concentration was 6.22ppb, Cu 2+ The initial concentration was 2.03 ppb, Zn 2+ The initial concentration was 2.34 ppb, Fe 3+ The initial concentration was 6.49 ppb, the adsorbent dosage was 5 g / L, the adsorption temperature was 35°C, and after 48 hours of adsorption, the adsorbent was filtered and recovered. The ultra-trace metal ion content in the adsorbed solution was determined by ICP-MS. + The content of Na in PMA was reduced from 31.24 ppb to 2.13 ppb, and the content of other metal ions was reduced to ≤ 1 ppb. SNGF-1 can reduce the content of Na in PMA + The content decreased from 31.24 ppb to 3.11 ppb, K + The content of Na in PMA was reduced from 4.18 ppb to 1.59 ppb, and the content of other metal ions was reduced to ≤1 ppb. SNGF-5 can reduce the content of Na in PMA + The content decreased from 31.24 ppb to 6.09 ppb, K + The content decreased from 4.18 ppb to 2.69 ppb, and the content of other metal ions decreased to ≤1 ppb.

[0040] Example 5

[0041] The adsorbent SNGF-0.5 prepared in Example 1 was used to adsorb trace metal ions (Na + , K + , Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ ), the adsorbent dosage was 5 g / L, the adsorption temperature was 35°C, and after 48 hours of adsorption, the adsorbent was filtered and recovered. The metal ion content of the adsorbed solution was determined by ICP-MS. + The content decreased from 31.24 ppb to 2.13 ppb, and the content of other metal ions decreased to ≤1 ppb.

[0042] Example 6

[0043] The adsorbent SNGF-1 prepared in Example 2 was used to adsorb trace metal ions (Na +, K + , Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ ), the adsorbent dosage was 5 g / L, the adsorption temperature was 35°C, and after 48 hours of adsorption, the adsorbent was filtered and recovered, and the metal ion content of the solution after adsorption was determined. + The content decreased from 31.24 ppb to 3.11 ppb, K + The content decreased from 4.18 ppb to 1.59 ppb, and the content of other metal ions decreased to ≤1 ppb.

[0044] Example 7

[0045] The adsorbent SNGF-0.5 recovered after adsorption of ultra-trace metal ions in Example 5 was regenerated and repeatedly washed with 1 M hydrochloric acid solution, ultrapure water, 1 M tetramethylammonium hydroxide solution, and ultrapure water until neutral. It was then used to adsorb ultra-trace metal ions in high-purity PMA. The adsorbent dosage was 5 g / L and the adsorption temperature was 35°C. After adsorption for 48 hours, the adsorbent was filtered and recovered. The ultra-trace metal ion content of the solution after adsorption was determined by ICP-MS. The regenerated adsorbent SNGF-0.5 can remove Na from PMA. + The content decreased from 31.24 ppb to 3.21 ppb, and the content of other metal ions decreased to ≤1 ppb.

[0046] Example 8

[0047] The adsorbent SNGF-0.5 prepared in Example 1 was used in a dynamic adsorption experiment to adsorb ultra-trace metal ions (Na + , K + , Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ ), the dynamic adsorption experiment flow chart is as follows Figure 4 As shown, the fixed bed is made of PFA to prevent the introduction of metal ions into the system. A certain amount of SNGH-0.5 was loaded into the fixed bed. Analytical-grade PMA was pumped through the bed from bottom to top using a PFA pump to remove metal ions from the solvent before entering the high-purity PMA storage tank. The specific experimental conditions were as follows: 12.8 g of adsorbent, a reaction temperature of 25°C, and a flow rate of 0.85 BV / h. The purified sample was analyzed using ICP-MS for metal ion content. The results are shown in Table 1:

[0048] Table 1 Dynamic adsorption experiment sample test table

[0049]

[0050] As shown in the table, the qualified samples obtained after different batches of processing are named 1, 2, 3, 4, and 5 respectively. + , K + , Ca 2+ 、Cu 2+ 、Zn 2+ 、Fe 3+ The levels of all other metal ions not shown in the table were reduced to ≤1 ppb, and the metal ion content met the G3 standard.

[0051] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A method for preparing a N, S co-doped porous graphene hydrogel adsorbent, characterized in that: The following steps are involved: Step 1: mixing a certain amount of graphene oxide with ultrapure water, ultrasonically dispersing the mixture in an ultrasonic machine for 1 hour to obtain a uniform dispersion, adding a certain amount of hydrogen peroxide solution and a dopant 2,5-diaminobenzenesulfonic acid to the dispersion, mixing the mixture evenly, transferring the mixture to a Teflon hydrothermal reactor, reacting the mixture at 90-200° C. for 10-48 hours, cooling the mixture to room temperature, and washing the mixture with ultrapure water to obtain a N, S co-doped porous graphene hydrogel; wherein the concentration of the graphene oxide dispersion is 1-10 mg / ml, the mass fraction of the hydrogen peroxide solution is 0.1-30%, the volume ratio of the graphene oxide dispersion to the hydrogen peroxide solution is (1-100):1, and the amount of the dopant added is 10-600 mg; Step 2: The N, S co-doped porous graphene hydrogel prepared in step 1 is washed with a certain concentration of acid, ultrapure water, a certain concentration of alkali, and ultrapure water for multiple cycles to obtain an N, S co-doped porous graphene hydrogel adsorbent for adsorbing trace metal ions in high-purity PMA.

2. The preparation method according to claim 1, wherein: In step 1, the concentration of the graphene oxide dispersion is 2-6 mg / ml, the mass fraction of the hydrogen peroxide solution is 0.3-30%, and the volume ratio of the graphene oxide dispersion to the hydrogen peroxide is (10-100):

1. After the graphene oxide dispersion, the hydrogen peroxide solution and the dopant are uniformly mixed, the mixture is reacted at 120-180° C. for 12-24 h. The amount of the dopant added is 10-400 mg.

3. The preparation method according to claim 2, wherein: In step 2, the acid includes one of acetic acid, hydrochloric acid, nitric acid and sulfuric acid.

4. The preparation method according to claim 2, wherein: The base described in step 2 is one of ammonia water and tetramethylammonium hydroxide solution.

5. The preparation method according to claim 2, wherein: The acid concentration in step 2 is one of 1 M, 2 M, 3 M, and 5 M.

6. The preparation method according to claim 2, wherein: The concentration of the base in step 2 is one of 1 M, 2 M, 3 M, and 5 M.

7. The preparation method according to claim 2, characterized in that: The concentration of high-purity PMA described in step 2 is 99.5%.

8. The N, S co-doped porous graphene hydrogel adsorbent prepared according to the preparation method according to any one of claims 1 to 7.

9. The N, S co-doped porous graphene hydrogel adsorbent according to claim 8 is used to adsorb trace metal ions in high-purity PMA.

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