A method to improve the purity of hydrogen peroxide

Abstract

This invention relates to the field of chemical purification technology, specifically to a method for improving the purity of hydrogen peroxide. The method includes sequentially subjecting an industrial-grade hydrogen peroxide solution to low-temperature pre-filtration, low-metal precipitation activated carbon fiber organic impurity capture, bifunctional confined trapping membrane contact adsorption purification, ceramic nanofiltration, and terminal microporous filtration; the surface of the bifunctional confined trapping membrane is immobilized with N-methyl-D-glucosamine groups and 1-aminoethylidene diphosphonic acid. This method can simultaneously reduce the content of organic impurities, metal ions, borosilicate impurities, and particulate matter in hydrogen peroxide, and reduce the risk of material leaching and hydrogen peroxide decomposition, making it suitable for the preparation of high-purity hydrogen peroxide.

Description

Technical Field

[0001] This invention relates to the field of chemical purification technology, specifically to a method for improving the purity of hydrogen peroxide. Background Technology

[0002] Hydrogen peroxide is an important green oxidant widely used in chemical, papermaking, textile, food, pharmaceutical, electronic cleaning, and semiconductor manufacturing industries. With the development of the integrated circuit, display panel, and photovoltaic electronic materials industries, the application of hydrogen peroxide has moved beyond simply focusing on its effective content; it now demands strict control over trace impurities such as organic residues, metal ions, borosilicate impurities, and particulate matter. Especially in electronic cleaning and semiconductor wet processes, TOC, Fe, Cu, B, Si, and fine particles in hydrogen peroxide can adversely affect wafer surface cleanliness, metal contamination control, and device reliability. Therefore, achieving simultaneous and deep removal of multiple impurities while maintaining the stability of hydrogen peroxide is a crucial problem that needs to be solved in the preparation of high-purity hydrogen peroxide.

[0003] Chinese invention patent application CN1699144A discloses a continuous production process for high-purity hydrogen peroxide purification. Using industrial-grade hydrogen peroxide as raw material, the process first adsorbs organic carbon through a macroporous adsorption resin column, then removes ionic impurities sequentially through anion and cation exchange resins and a mixed-bed resin, and finally removes particulate impurities through a microporous filter to obtain high-purity hydrogen peroxide. This invention employs a conventional continuous purification route of macroporous resin adsorption, ion exchange, mixed-bed filtration, and microporous filtration, which can remove organic, ionic, and particulate impurities to a certain extent. However, it mainly relies on resin exchange and filtration processes, lacking targeted capture methods for boron and silicon impurities existing in weakly ionized or neutral forms. Furthermore, the multi-stage resin system may still pose risks of resin extractable release, regeneration residues, or secondary pollution in a strongly oxidizing hydrogen peroxide environment.

[0004] Chinese invention patent application CN102485642A discloses a method for producing ultra-high purity hydrogen peroxide. This method involves filtering industrial-grade hydrogen peroxide through an SBA-15 molecular sieve loaded with a chelating agent, followed by ultrafiltration to reduce impurities and obtain ultra-high purity hydrogen peroxide. This invention enhances the adsorption and removal of some impurities through porous molecular sieve materials loaded with chelating agents, representing an improvement over simple ion exchange or membrane filtration. However, such adsorption materials are still mainly granular or packed adsorption and purification methods. They do not address the low TOC dissolution, low metal precipitation, and low decomposition induction risk associated with strongly oxidizing hydrogen peroxide systems, nor do they provide a membrane pore-confined composite trapping structure that simultaneously targets weakly ionized borosilicate impurities and metal ion impurities.

[0005] Chinese invention patent application CN113371683A discloses a method for producing electronic-grade hydrogen peroxide. Using industrial-grade hydrogen peroxide as raw material, the method involves vacuum distillation to concentrate the hydrogen peroxide, followed by purification through a series of processes including a polytetrafluoroethylene membrane, macroporous adsorption resin, chelating resin, anion exchange column, cation exchange column, mixed ion exchange column, and a multi-stage microporous filter to obtain electronic-grade hydrogen peroxide. While this invention improves hydrogen peroxide purity through a combination of distillation, membrane filtration, adsorption resin, chelating resin, and multi-stage ion exchange, the overall process is lengthy and still heavily relies on the resin column system and multi-stage filtration. It lacks sufficient synergistic control over the leaching of borosilicate impurities, metal ions, organic matter, and hydrogen peroxide stability. Furthermore, it does not address the construction of a low-precipitation, antioxidant composite functional trapping layer on the surface of a fluorine-containing microporous membrane.

[0006] Therefore, existing high-purity hydrogen peroxide purification technologies mostly employ combinations of units such as resin adsorption, ion exchange, chelation adsorption, distillation, nanofiltration, ultrafiltration, or microfiltration. While these technologies can reduce some organic impurities, metal ions, and particulate matter to a certain extent, they still have the following shortcomings: First, ordinary filtration and membrane separation mainly target particulate, colloidal, or some large molecular impurities, and have limited ability to remove dissolved metal ions and weakly ionized borosilicate impurities. Second, conventional ion exchange resins or chelation resins have a certain removal effect on metal ions, but lack the ability to simultaneously and deeply capture weakly ionized or neutral impurities such as boric acid and silicate. Third, ordinary adsorption materials or resin materials may face risks of TOC dissolution, metal precipitation, particle shedding, or inducing hydrogen peroxide decomposition in the strong oxidizing system of hydrogen peroxide. Fourth, the multi-stage resin and filtration combination process is relatively long, making it difficult to simultaneously achieve impurity staged removal, low material precipitation, and hydrogen peroxide stability.

[0007] Therefore, it is still necessary to propose a new method to improve the purity of hydrogen peroxide, enabling it to preferentially remove organic impurities through low-metal precipitation activated carbon fibers under low-temperature conditions, and further reduce trace extractables and particulate contamination by combining ceramic nanofiltration and terminal microporous filtration. This would improve the overall purity and stability of industrial-grade hydrogen peroxide while reducing the risk of material leaching and hydrogen peroxide decomposition. Summary of the Invention

[0008] To address the shortcomings of the existing technology, the present invention provides a method for improving the purity of hydrogen peroxide.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] A method for improving the purity of hydrogen peroxide, characterized by comprising the following steps:

[0011] (1) The industrial-grade hydrogen peroxide solution was pre-filtered at low temperature;

[0012] (2) The pre-filtered hydrogen peroxide solution is passed through low-metal precipitation type activated carbon fiber to collect organic impurities;

[0013] (3) The captured hydrogen peroxide solution is passed through a bifunctional confined trapping membrane for membrane contact adsorption purification;

[0014] (4) The hydrogen peroxide solution purified by membrane was subjected to nanofiltration and terminal microfiltration in sequence to obtain a high-purity hydrogen peroxide solution;

[0015] The bifunctional confined trapping membrane is obtained by activating a fluorinated microporous base membrane with electron beam irradiation, grafting a fluorinated cross-linked graft layer formed by glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate onto its surface, and then subjecting it to a ring-opening reaction with N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid, fluorinated amine end-capping, and hydrogen peroxide pre-aging treatment.

[0016] Preferably, the low-metal precipitation type activated carbon fiber is obtained by the following method: first soaking in an acid solution, then rinsing with ultrapure water until the conductivity is less than 0.5 μS / cm, then soaking in hydrogen peroxide solution at low temperature, and finally rinsing with ultrapure water until the total organic carbon in the rinsing solution is not higher than 0.5 mg / L and the total content of Fe, Cu, Ni and Cr is not higher than 0.05 μg / L.

[0017] Existing hydrogen peroxide purification processes mostly rely on single or conventional combinations of methods such as adsorption, ion exchange, or membrane filtration. Conventional filtration primarily removes particulate impurities, while conventional ion exchange has limited ability to remove weakly ionized or neutral borosilicate impurities. Furthermore, ordinary activated carbon or resin materials may cause organic matter dissolution or metal precipitation in highly oxidizing hydrogen peroxide systems. Therefore, existing processes struggle to simultaneously reduce TOC, metal ions, borosilicate impurities, and particulate contamination while maintaining low precipitation and stability in the hydrogen peroxide system.

[0018] To address the aforementioned problems, this invention employs a multi-stage purification pathway: low-temperature pre-filtration, low-metal-leaching activated carbon fiber organic impurity capture, bifunctional confined trapping membrane contact adsorption purification, ceramic nanofiltration, and terminal microfiltration. First, low-temperature pre-filtration removes suspended particles and colloidal impurities, reducing the contamination load on subsequent adsorption and membrane materials. Then, activated carbon fibers, after acid washing, ultrapure water rinsing, and low-temperature passivation with hydrogen peroxide, preferentially capture anthraquinone residues and organic impurities. Simultaneously, the pretreatment reduces the risk of metal precipitation and TOC leaching, ensuring that the hydrogen peroxide entering the bifunctional confined trapping membrane is in a low-organic-load state, which helps prevent organic impurities from occupying subsequent functional trapping sites. Subsequently, the bifunctional confined trapping membrane is activated by electron beam irradiation of a fluorinated microporous base membrane, and an epoxy-containing fluorinated cross-linked graft layer is formed on its surface. Then, the membrane is ring-opened by N-methyl-D-glucosamine and 1-aminoethylidene bisphosphonic acid, so that polyhydroxyamine groups and bisphosphonic acid groups are simultaneously fixed on the membrane pore walls. Among them, the polyhydroxy structure in N-methyl-D-glucosamine can trap weakly ionized impurities such as boric acid and silica through multi-point complexation, hydrogen bonding or spatial coordination, while the bisphosphonic acid structure in 1-aminoethylidene bisphosphonic acid can coordinate complex with metal ions such as Fe, Cu, Ni, and Cr, thereby achieving the simultaneous and directional removal of borosilicate impurities and metal impurities.

[0019] Preferably, the bifunctional confined trapping membrane is prepared from a fluorine-containing microporous membrane via the following steps:

[0020] S1, base film pre-passivation and electron beam irradiation activation;

[0021] S2. The activated base film is placed in a grafting solution containing epoxy monomers and fluorine monomers for grafting reaction to obtain an epoxy-containing fluorine crosslinked grafted film; the grafted film is placed in a ring-opening solution containing N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid for ring-opening reaction to obtain a modified base film.

[0022] S3. The modified base membrane is end-capped with fluorinated amine and then pre-aged with hydrogen peroxide solution to obtain a bifunctional confined trapping membrane.

[0023] The compound functional ring-opening solution is composed of N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid dissolved in water at a mass ratio of 2.14:1, wherein the mass fraction of N-methyl-D-glucosamine is 8.8% and the mass fraction of 1-aminoethylidene diphosphonic acid is 4.1%.

[0024] Preferably, the grafting solution further comprises a crosslinking agent; the monomers in the grafting solution include at least two of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, and ethylene glycol dimethacrylate; preferably, the monomers in the grafting solution are composed of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, and ethylene glycol dimethacrylate, with a mass ratio of 100:(15-25):(2-4); the solvent is a 40-50 wt% ethanol-water mixture.

[0025] This invention utilizes glycidyl methacrylate to provide ring-opening reaction sites, 2,2,3,3-tetrafluoropropyl methacrylate to enhance the oxidation resistance of the grafted layer in highly oxidizing hydrogen peroxide, and ethylene glycol dimethacrylate to form a cross-linked structure to reduce swelling, shedding, and release of extractables from the grafted layer. 2,2,2-trifluoroethylamine further seals residual epoxy groups, reducing the increase in TOC caused by hydrolysis or oxidation of residual active end groups in hydrogen peroxide. Hydrogen peroxide pre-aging removes trace amounts of unstable leachables and easily oxidized components from the membrane material in advance, thereby reducing secondary pollution and the risk of hydrogen peroxide decomposition during the actual purification process. Finally, a zirconia ceramic nanofiltration membrane and a PTFE terminal microporous filter retain trace extractables, fine particles, and colloidal impurities, resulting in reduced TOC, metal ion content, B / Si impurities, and particle count in the obtained hydrogen peroxide. Through the sequential coordination and functional division of labor among the purification units, graded, targeted, and low-precipitation purification of impurities of different forms is achieved, improving the overall purity and stability of the hydrogen peroxide product.

[0026] Preferably, the mass fraction of N-methyl-D-glucosamine in the ring-opening liquid is 8-10%, the mass fraction of 1-aminoethylidene diphosphonic acid is 3-5%, and the mass ratio of the two is (1.8-2.7):1.

[0027] Preferably, the fluorinated amine is 2,2,2-trifluoroethylamine, with an aqueous solution having a mass fraction of 1%-2%, a reaction temperature of 30-40℃, and a reaction time of 1-3 hours.

[0028] Preferably, the pressure of the low-temperature pre-filtration in step (1) is 0.1-0.3 MPa, and the pore size of the pre-filter is 0.1-0.5 μm; the column temperature for organic impurity capture in step (2) is 4-10 °C, and the empty bed contact time is 1-5 min.

[0029] Preferably, in step (3), the membrane purification temperature is 4-10℃, the membrane inlet pressure is 0.08-0.15MPa, the membrane crossflow velocity is 0.1-0.3m / s, and the average residence time is 5-15min.

[0030] Preferably, in step (4), the nanofiltration uses a ceramic nanofiltration membrane with a molecular weight cutoff of 200-500 Da, an operating pressure of 0.2-0.3 MPa, and a temperature of 4-10℃; the pore size of the terminal microporous filter is 0.01-0.1 μm.

[0031] A high-purity hydrogen peroxide was prepared using the method described above.

[0032] The beneficial effects of this invention are:

[0033] 1. This invention provides a method for improving the purity of hydrogen peroxide. Through a continuous combination of processes including low-temperature pre-filtration, low-metal precipitation activated carbon fiber organic impurity capture, bifunctional confined membrane adsorption purification, ceramic nanofiltration, and terminal microfiltration, the method achieves the graded removal of particulate impurities, organic impurities, metal ions, and borosilicate impurities from industrial-grade hydrogen peroxide. Compared to purification methods that simply use filtration, activated carbon adsorption, nanofiltration, or conventional ion exchange resins, this invention can simultaneously address the removal needs of different types of impurities, avoiding the problem of insufficient targeting of a single purification method, thereby effectively improving the overall purity of hydrogen peroxide products.

[0034] 2. The bifunctional confined trapping membrane of the present invention constructs a fluorinated cross-linked graft layer on the surface of a fluorinated microporous membrane, and further fixes N-methyl-D-glucosamine groups and 1-aminoethylidene diphosphonic acid. The polyhydroxy structure in N-methyl-D-glucosamine can trap weakly ionized impurities such as boric acid and silica through multi-point complexation, hydrogen bonding, or spatial coordination; the bisphosphonic acid structure in 1-aminoethylidene diphosphonic acid can coordinate with metal ions such as Fe and Cu. The combination of these two components allows for targeted trapping of borosilicate and metal impurities within the same membrane pore confinement space, achieving simultaneous removal of multiple trace impurities.

[0035] 3. This invention uses low-metal-precipitation activated carbon fiber as the front-end organic impurity capture material, and reduces the risk of metal precipitation and organic matter leaching from the activated carbon fiber itself through acid washing, ultrapure water rinsing, and low-temperature passivation with hydrogen peroxide. This step can preferentially remove organic impurities remaining in the anthraquinone production process, reduce the organic load on the subsequent bifunctional confined capture membrane, and reduce the occupation of functional sites on the membrane pore walls by organic impurities, thereby improving the capture efficiency of trace metals and borosilicate impurities in subsequent membrane contact adsorption purification.

[0036] 4. This invention further employs ceramic nanofiltration and terminal microfiltration after purification using a bifunctional confined trap membrane to retain trace extractables, fine particles, and colloidal impurities at the end of the purification process. The entire purification process is controlled at low temperatures to reduce the risk of hydrogen peroxide decomposition. This invention can obtain high-purity hydrogen peroxide products with low TOC, low metal content, low borosilicate content, and low particle number without introducing exogenous stabilizers or excessively relying on conventional mixed-bed ion exchange resins. It is suitable for applications requiring high hydrogen peroxide purity, such as electronic cleaning, semiconductor manufacturing, display panels, and photovoltaic electronic materials. Detailed Implementation

[0037] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0038] The raw materials described in this application are partially described; all other raw materials not described are commercially available.

[0039] 1-Aminoethylidene bisphosphonic acid, CAS No.: 15049-85-1.

[0040] Example 1

[0041] A method for improving the purity of hydrogen peroxide includes the following steps:

[0042] (1) Low temperature pre-filtration: A 35% industrial grade hydrogen peroxide solution is passed through a PTFE microporous pre-filter with a pore size of 0.20μm at a pressure of 0.20MPa to obtain a pre-filtered hydrogen peroxide solution;

[0043] (2) Organic impurity collection: The pre-filtered hydrogen peroxide solution is passed into the PFA collection column packed with the low metal precipitation type activated carbon fiber, the column temperature is controlled at 6°C, and the empty bed contact time is 2.5 min to obtain a hydrogen peroxide solution with low organic impurities.

[0044] (3) Purification by bifunctional confined trapping membrane: a hydrogen peroxide solution with low organic impurities is passed into a bifunctional confined trapping membrane for membrane contact adsorption purification. The membrane inlet pressure is controlled at 0.12 MPa, the temperature at 6℃, the cross-flow velocity at the membrane surface at 0.20 m / s, and the average residence time at 8 min to obtain a hydrogen peroxide solution with low metal and low borosilicate content.

[0045] (4) Nanofiltration and terminal microfiltration: The hydrogen peroxide solution treated by the bifunctional confined trapping membrane is passed through a zirconia ceramic nanofiltration membrane with a molecular weight cutoff of 300 Da at an operating pressure of 0.25 MPa and a temperature of 6 °C to obtain nanofiltration permeate; then, the nanofiltration permeate is passed through a PTFE terminal microfiltration filter with a pore size of 0.05 μm, and the resulting filtrate is directly fed into a PFA collection tank that has been pre-cleaned and purged with nitrogen to obtain a high-purity hydrogen peroxide solution.

[0046] The low-metal precipitation activated carbon fiber was obtained by the following method: First, the activated carbon fiber (provided by Jiangsu Kejing Carbon Fiber Co., Ltd.) was soaked in a 5% nitric acid solution for 2 hours; then, it was repeatedly rinsed with ultrapure water until the conductivity of the rinsing solution was lower than 0.2 μS / cm; then, the acid-washed activated carbon fiber was soaked in a 30% hydrogen peroxide solution at 8°C for 12 hours. After the treatment, it was rinsed with ultrapure water until the TOC of the rinsing solution was lower than 0.5 mg / L and the total content of Fe, Cu, Ni, and Cr was lower than 0.05 μg / L, thus obtaining the low-metal precipitation activated carbon fiber.

[0047] The preparation method of the bifunctional confined trapping membrane is as follows:

[0048] S1. An ethylene-tetrafluoroethylene copolymer microporous membrane (the ethylene-tetrafluoroethylene copolymer microporous membrane has a pore size of 0.20 μm, a thickness of 150 μm, and an effective area of ​​100 cm²) is sequentially washed in ethanol and ultrapure water for 30 min each, and then immersed in a 30% hydrogen peroxide solution at 8°C for 12 h; after that, it is rinsed with ultrapure water until the conductivity of the rinsing solution is lower than 0.1 μS / cm to obtain a pre-passivated fluorine-containing base membrane; the pre-passivated fluorine-containing base membrane is then activated by electron beam irradiation under nitrogen protection conditions with an irradiation dose of 40 kGy to obtain an activated base membrane;

[0049] S2. Under nitrogen protection, the activated base membrane is placed in a ternary composite grafting solution and reacted at 55°C for 4 hours. After the reaction, it is washed alternately with ethanol and ultrapure water to obtain an epoxy-containing fluorinated crosslinked grafted membrane. The epoxy-containing fluorinated crosslinked grafted membrane is placed in a composite functional ring-opening solution and reacted at 60°C for 6 hours. After the reaction, the membrane material is repeatedly washed with ultrapure water until the pH of the washing solution is 7.0 to obtain the modified base membrane. 400 mL of ternary composite grafting solution is used per 100 cm² of activated base membrane; 350 mL of composite functional ring-opening solution is used per 100 cm² of epoxy-containing fluorinated crosslinked grafted membrane.

[0050] S3. The modified base membrane was placed in a 1.5% (w / w) aqueous solution of 2,2,2-trifluoroethylamine and reacted at 35°C for 2 hours. The membrane material was then cleaned alternately with ultrapure water, a 30% (w / w) hydrogen peroxide solution, and ultrapure water until the TOC of the cleaning solution was below 0.5 mg / L. The membrane was then placed in a 35% (w / w) hydrogen peroxide solution and pre-aged at 6°C for 24 hours. After the pre-aging was completed, the membrane was further cleaned with a fresh 35% hydrogen peroxide solution for 4 hours to obtain a bifunctional confined trapping membrane.

[0051] The ternary compound grafting solution is composed of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate in a mass ratio of 100:20:3; the solvent is a 45wt% ethanol-water mixture, and the total mass concentration of the ternary monomers is 18%.

[0052] The compound functional ring-opening solution is composed of N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid dissolved in water at a mass ratio of 2.14:1, and the pH is adjusted to 8.2 with ammonia water; wherein the mass fraction of N-methyl-D-glucosamine is 8.8% and the mass fraction of 1-aminoethylidene diphosphonic acid is 4.1%.

[0053] Example 2

[0054] The process is basically the same as in Example 1, except that the mass ratio of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate in the ternary compound grafting solution is 100:15:2, and the total mass concentration of the ternary monomers is 18%; the remaining steps and conditions are the same as in Example 1.

[0055] Example 3

[0056] The process is basically the same as in Example 1, except that the mass ratio of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate in the ternary compound grafting solution is 100:25:4, and the total mass concentration of the ternary monomers is 18%; the remaining steps and conditions are the same as in Example 1.

[0057] Example 4

[0058] The process is basically the same as in Example 1, except that: in the compound functional ring-opening liquid, the mass fraction of N-methyl-D-glucosamine is 8.3%, the mass fraction of 1-aminoethylidene diphosphonic acid is 4.6%, and the mass ratio of the two is 1.80:1; the remaining steps and conditions are the same as in Example 1.

[0059] Example 5

[0060] The process is basically the same as in Example 1, except that: in the compound functional ring-opening liquid, the mass fraction of N-methyl-D-glucosamine is 9.4%, the mass fraction of 1-aminoethylidene diphosphonic acid is 3.5%, and the mass ratio of the two is 2.69:1; the remaining steps and conditions are the same as in Example 1.

[0061] Comparative Example 1

[0062] The process is basically the same as in Example 1, except that step (3) of dual-function confined trapping membrane purification is omitted, i.e., the low organic impurity hydrogen peroxide solution directly enters step (4) of nanofiltration and terminal microfiltration.

[0063] Comparative Example 2

[0064] The process is basically the same as in Example 1, except that in step (3), an ethylene-tetrafluoroethylene copolymer microporous membrane pre-cleaned with ethanol, ultrapure water and 30% hydrogen peroxide solution is used instead of the bifunctional confined trapping membrane. This membrane is not subjected to ternary compound grafting, compound function ring opening, fluorinated amine end capping and hydrogen peroxide cycle pre-aging treatment.

[0065] Comparative Example 3

[0066] The grafting solution is basically the same as in Example 1, except that: the grafting solution consists only of glycidyl methacrylate and ethylene glycol dimethacrylate in a mass ratio of 100:3, without the addition of 2,2,3,3-tetrafluoropropyl methacrylate, and is made up with an equal mass of 45wt% ethanol-water mixture; the total monomer concentration of the grafting solution is still 18%; the remaining steps and conditions are the same as in Example 1.

[0067] Comparative Example 4

[0068] The grafting solution is basically the same as in Example 1, except that: the grafting solution consists only of glycidyl methacrylate and 2,2,3,3-tetrafluoropropyl methacrylate in a mass ratio of 100:20, ethylene glycol dimethacrylate is not added, and the solution is made up with an equal mass of 45wt% ethanol-water mixture; the total monomer concentration of the grafting solution is still 18%; the remaining steps and conditions are the same as in Example 1.

[0069] Comparative Example 5

[0070] The process is basically the same as in Example 1, except that the compound functional ring-opening liquid is replaced with an aqueous solution of N-methyl-D-glucosamine, wherein the mass fraction of N-methyl-D-glucosamine is 12.9%, and 1-aminoethylidene diphosphonic acid is not added; the remaining steps and conditions are the same as in Example 1.

[0071] Comparative Example 6

[0072] The process is basically the same as in Example 1, except that the compound functional ring-opening liquid is replaced with an aqueous solution of 1-aminoethylidene diphosphonic acid, wherein the mass fraction of 1-aminoethylidene diphosphonic acid is 12.9%, and N-methyl-D-glucosamine is not added; the remaining steps and conditions are the same as in Example 1.

[0073] Comparative Example 7

[0074] The process is basically the same as in Example 1, except that the end-capping step of "placing the modified base membrane in a 1.5% (w / w) aqueous solution of 2,2,2-trifluoroethylamine and reacting it at 35°C for 2 hours" is omitted in the preparation of the bifunctional confined trapping membrane; the remaining steps and conditions are the same as in Example 1.

[0075] Comparative Example 8

[0076] The process is essentially the same as in Example 1, except that the bifunctional confined trapping membrane purification in step (3) is replaced with conventional mixed-bed ion exchange resin column purification. Both the strongly acidic cation exchange resin and the strongly basic anion exchange resin are rinsed with ultrapure water until the effluent conductivity is below 0.5 μS / cm, and then soaked in 30% hydrogen peroxide solution at 6°C for 4 hours before being packed into the column. The remaining pre-filtration, organic impurity collection, nanofiltration, and terminal microfiltration steps are the same as in Example 1.

[0077] Test Example 1

[0078] Test objective: To test the hydrogen peroxide mass fraction, TOC, metal ions, B, Si and particle number in the hydrogen peroxide solutions obtained in Examples 1-5 and Comparative Examples 1-8, and to evaluate the effects of different purification processes and different bifunctional confined trapping membrane structures on improving the purity of industrial-grade hydrogen peroxide.

[0079] Test samples: The hydrogen peroxide solutions obtained in Examples 1-5 and Comparative Examples 1-8 were used as test samples. Before testing, each sample was collected using a PFA sampling bottle that had been pre-cleaned with 30% hydrogen peroxide solution and rinsed with ultrapure water. Glassware was avoided during sampling to reduce background contamination from B, Si, and other metal elements.

[0080] Meanwhile, an untreated 35% industrial-grade hydrogen peroxide solution was used as a control, and the results are shown in Table 1.

[0081] Test method for hydrogen peroxide mass fraction: The mass fraction of hydrogen peroxide is determined according to the method for determining industrial hydrogen peroxide content in GB / T 1616-2014, using the acidic potassium permanganate titration method.

[0082] The specific method is as follows: Accurately weigh 0.3000g of sample and place it in a 250mL Erlenmeyer flask. Add 50mL of ultrapure water and 20mL of sulfuric acid solution, wherein the sulfuric acid solution is prepared by mixing concentrated sulfuric acid and ultrapure water at a volume ratio of 1:4. After the sample is mixed evenly, titrate with a standardized 0.0500mol / L potassium permanganate standard solution until the solution turns light pink and remains so for 30 seconds, which is the endpoint. Each sample is measured in triplicate, and the average value is taken.

[0083] The mass fraction of hydrogen peroxide is calculated using the following formula:

[0084] X=[c×(V-V0)×85.04] / (1000×m)×100%

[0085] In the formula:

[0086] X represents the mass fraction of hydrogen peroxide, in %;

[0087] c represents the concentration of the potassium permanganate standard solution, in mol / L;

[0088] V represents the volume of potassium permanganate standard solution consumed by the sample, in mL;

[0089] V0 represents the volume of potassium permanganate standard solution consumed in the blank, in mL;

[0090] m is the sample mass, in grams;

[0091] 85.04 represents the mass of hydrogen peroxide (g / mol) corresponding to 1 mol of potassium permanganate under acidic conditions.

[0092] Hydrogen peroxide decomposition rate is calculated using the following formula: Hydrogen peroxide decomposition rate = (mass fraction of hydrogen peroxide before purification - mass fraction of hydrogen peroxide after purification) / mass fraction of hydrogen peroxide before purification × 100%

[0093] 4. TOC Test Method: TOC was determined using a total organic carbon analyzer. Before testing, 5.00 mL of sample was placed in a pre-cleaned PFA volumetric flask and diluted to 50 mL with Grade I water as specified in GB / T 6682-2008. The solution was then mixed thoroughly and used as the test solution. The test employed a high-temperature catalytic oxidation-non-dispersive infrared detection method. The injection volume was 100 μL, and each sample was injected three times, with the average value taken. The blank sample was measured using Grade I water from the same batch, and the blank value was subtracted from the result calculation.

[0094] Because hydrogen peroxide has oxidizing properties, the sample should be diluted and allowed to stand for 15 minutes before injection to reduce the impact of high concentrations of hydrogen peroxide on the TOC combustion tube and detection signal. If the instrument is sensitive to the hydrogen peroxide matrix, a hydrogen peroxide matrix blank with the same dilution factor as the sample can be used for calibration.

[0095] 5. Testing methods for metallic elements, B, and Si: Fe, Cu, B, and Si were determined by ICP-MS. The tests were conducted in accordance with GB / T 39486-2020. Each sample was prepared in triplicate and measured separately.

[0096] Among them, B and Si are easily affected by the environment and glassware background, so a PFA injection system was used for testing, and reagent blank and glassware blank were measured simultaneously; the sample results were calculated after deducting the blank value.

[0097] 6. Particle Count Test Method

[0098] The number of particles with a diameter of not less than 0.2 μm was determined using a liquid particle counter. The test was conducted in accordance with the relevant requirements for the light-obscured liquid particle counter method in GB / T 29024.3-2025.

[0099] The specific method is as follows: Before testing, the instrument tubing is flushed with ultrapure water meeting the requirements of Grade I water in GB / T 6682-2008 until the blank particle count stabilizes; then, the sample inlet tubing is flushed three times with the sample to be tested. Each sample volume is 10 mL, the detection particle size threshold is set to 0.2 μm, and three consecutive measurements are taken. The average value is calculated, and the result is expressed as particles / mL. Sampling, transfer, and testing are all performed in a clean bench, and the sample container is a pre-cleaned PFA bottle.

[0100] Table 1. Test results after purification

[0101] raw material liquid 35.0 - 43.2 6.50 2.40 52.8 116.5 8200 Example 1 34.8 0.57 0.62 0.03 ＜0.02 0.22 0.53 9 Example 2 34.8 0.57 0.86 0.05 ＜0.02 0.33 0.78 15 Example 3 34.8 0.57 0.55 0.03 ＜0.02 0.29 0.65 8 Example 4 34.8 0.57 0.70 0.02 ＜0.02 0.42 0.88 11 Example 5 34.8 0.57 0.74 0.07 0.03 0.19 0.46 12 Comparative Example 1 34.8 0.57 1.85 0.82 0.31 34.6 78.5 28 Comparative Example 2 34.8 0.57 1.72 0.76 0.28 31.8 72.4 24 Comparative Example 3 34.5 1.43 2.95 0.06 ＜0.02 0.35 0.81 36 Comparative Example 4 34.5 1.43 3.26 0.07 0.03 0.38 0.86 52 Comparative Example 5 34.8 0.57 0.96 0.62 0.26 0.62 1.42 18 Comparative Example 6 34.8 0.57 0.92 0.04 ＜0.02 25.6 58.8 15 Comparative Example 7 34.6 1.14 2.48 0.06 ＜0.02 0.33 0.76 31 Comparative Example 8 34.7 0.86 1.10 0.08 0.04 18.6 45.7 23

[0102] Test Example 2

[0103] Low precipitation and hydrogen peroxide stability test of dual-function confined trap membrane

[0104] 1. Test objective: To evaluate the TOC dissolution, metal precipitation, and induced hydrogen peroxide decomposition of different membrane materials in a 35% hydrogen peroxide system, in order to verify the effects of fluorinated monomers, crosslinking monomers, 2,2,2-trifluoroethylamine end-capping, and hydrogen peroxide pre-aging on the low precipitation performance and stability of membrane materials.

[0105] 2. Test Samples: The bifunctional confined trapping membranes prepared in Examples 1-5 and the corresponding membrane materials in Comparative Examples 3-7 were used. The effective area of ​​each membrane material was cut to 100 cm². Before testing, the membranes were rinsed three times with primary water and then rinsed once with 35% hydrogen peroxide solution.

[0106] 3. Test Method: Each group of membrane materials was placed in a pre-cleaned PFA bottle, and 500 mL of 35% hydrogen peroxide solution was added. The bottles were sealed and placed in a constant temperature environment at 8°C, protected from light, for 72 hours. No stabilizer was added or the pH was adjusted during the test. After 72 hours, the soaking solution was collected, and the total content of TOC, Fe, Cu, Ni, and Cr, as well as the mass fraction of hydrogen peroxide, were determined according to the method described in Test Example 1.

[0107] TOC leaching amount is calculated by subtracting the TOC of the blank 35% hydrogen peroxide solution from the TOC of the immersion solution; the total precipitation amount of Fe, Cu, Ni, and Cr is calculated by subtracting the blank value from the content of the four metal elements in the immersion solution; the hydrogen peroxide decomposition rate is calculated by the change in the mass fraction of hydrogen peroxide before and after immersion.

[0108] Table 2. Tests on low precipitation and hydrogen peroxide stability of bifunctional confined trap membranes

[0109] Example 1 0.21 0.03 34.96 0.11 Example 2 0.36 0.04 34.93 0.20 Example 3 0.18 0.03 34.97 0.09 Example 4 0.25 0.03 34.95 0.14 Example 5 0.27 0.04 34.95 0.14 Comparative Example 3 1.28 0.06 34.75 0.71 Comparative Example 4 1.45 0.08 34.70 0.86 Comparative Example 5 0.38 0.05 34.91 0.26 Comparative Example 6 0.42 0.04 34.90 0.29 Comparative Example 7 1.06 0.05 34.70 0.86

[0110] The results above show that the TOC, metal ions, B, Si and particle number of the hydrogen peroxide solution obtained after purification are significantly reduced, and the mass fraction of hydrogen peroxide is basically maintained at about 34.8%, with a low decomposition rate. This indicates that the staged purification process of the present invention can achieve the simultaneous removal of multiple impurities while maintaining the stability of hydrogen peroxide.

[0111] Example 1 employed a fluorinated crosslinked graft layer and simultaneously introduced N-methyl-D-glucosamine and 1-aminoethylidene bisphosphonic acid, resulting in superior overall purification performance. This is mainly because the polyhydroxy structure in N-methyl-D-glucosamine facilitates the capture of weakly ionized impurities such as boric acid and silicate, while the bisphosphonic acid structure in 1-aminoethylidene bisphosphonic acid facilitates the complexation of metal ions. When both are immobilized on the membrane pore wall, simultaneous and directional removal of borosilicate and metal impurities can be achieved. Examples 2 and 3 altered the ratio of fluorinated monomers to crosslinked monomers, still achieving good overall purification results. This indicates that fluorinated monomers help improve the oxidation resistance of the membrane material in the hydrogen peroxide system, while crosslinked monomers help improve the stability of the graft layer. When the ratio is too low, the membrane material's low-precipitation performance is slightly weaker; when the ratio is too high, it may affect the effective exposure of functional groups. Therefore, it is necessary to control the ratio within an appropriate range. Examples 4 and 5 altered the ratio of N-methyl-D-glucosamine to 1-aminoethylidene bisphosphonic acid. The results showed that increasing the proportion of N-methyl-D-glucosamine was more beneficial for the removal of borosilicate impurities, and increasing the proportion of 1-aminoethylidene diphosphonic acid was more beneficial for the removal of metal ions. However, it was difficult to achieve balanced removal of various impurities by unilaterally increasing one of the functional groups.

[0112] Comparative Example 1 omitted the bifunctional confined trapping membrane purification step, and Comparative Example 2 used an unmodified fluorinated microporous membrane. Both showed significantly insufficient removal efficiency for borosilicate impurities and metal ions. This indicates that relying solely on pre-filtration, activated carbon fiber, nanofiltration, and microporous filtration, or using only ordinary microporous membranes, is insufficient to achieve deep capture of trace impurities. The bifunctional confined trapping membrane is the main reason for the high purification effect achieved in this invention. Comparative Example 3 did not introduce fluorinated monomers, and Comparative Example 4 did not introduce cross-linking monomers. Both exhibited high TOC dissolution, particle release, and hydrogen peroxide decomposition trends. This indicates that fluorinated monomers can improve the oxidation resistance of the grafted layer, and cross-linking monomers can enhance the structural stability of the grafted layer. Both are crucial for reducing the dissolution and decomposition-inducing effects of the membrane material in the highly oxidizing hydrogen peroxide system.

[0113] Comparative Example 5 used only N-methyl-D-glucosamine as a ring-opening agent, which showed some removal effect on B and Si. However, due to the lack of bisphosphonic acid groups derived from 1-aminoethylidene bisphosphonic acid, its complexation and capture ability for metal ions such as Fe and Cu was significantly insufficient. Comparative Example 6 used only 1-aminoethylidene bisphosphonic acid as a ring-opening agent, which showed good removal effect on metal ions such as Fe and Cu. However, due to the lack of polyhydroxyamine groups derived from N-methyl-D-glucosamine, its removal ability for B and Si impurities was significantly insufficient. These results indicate that the two functional groups target different objects, and a single functional group cannot simultaneously address the removal of both metal and borosilicate impurities. Only when both are combined and fixed on the membrane pore wall can a synergistic capture effect be achieved. In Comparative Example 7, after omitting the fluorinated amine end-capping treatment, the TOC dissolution and hydrogen peroxide decomposition trends increased, indicating that end-capping treatment can reduce the hydrolysis, oxidation, and dissolution of residual epoxy groups or active end groups in the hydrogen peroxide system, thereby improving the stability of the membrane material. Comparative Example 8 uses conventional mixed-bed ion exchange resin, which can reduce some metal ions, but it is insufficient in removing borosilicate impurities and poses risks of resin leaching and decreased hydrogen peroxide stability. This indicates that the bifunctional confined trapping membrane of the present invention is more suitable for deep purification of hydrogen peroxide than conventional mixed-bed resin.

Claims

1. A method for improving the purity of hydrogen peroxide, characterized in that, Includes the following steps: (1) The industrial-grade hydrogen peroxide solution was pre-filtered at low temperature; (2) The pre-filtered hydrogen peroxide solution is passed through low-metal precipitation type activated carbon fiber to collect organic impurities; (3) The captured hydrogen peroxide solution is passed through a bifunctional confined trapping membrane for membrane contact adsorption purification; (4) The hydrogen peroxide solution purified by membrane was subjected to nanofiltration and terminal microfiltration in sequence to obtain a high-purity hydrogen peroxide solution; The bifunctional confined trapping membrane is obtained by activating a fluorinated microporous base membrane with electron beam irradiation, grafting a fluorinated cross-linked graft layer formed by glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate onto its surface, and then undergoing ring-opening reaction with N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid, fluorinated amine end-capping, and hydrogen peroxide pre-aging treatment. The low-metal precipitation type activated carbon fiber is obtained by the following method: first soaking in acid solution, then rinsing with ultrapure water until the conductivity is lower than 0.5 μS / cm, then soaking in hydrogen peroxide solution at low temperature, and finally rinsing with ultrapure water until the total organic carbon in the rinsing solution is not higher than 0.5 mg / L and the total content of Fe, Cu, Ni, and Cr is not higher than 0.05 μg / L.

2. The method according to claim 1, characterized in that, The bifunctional confined trapping membrane is prepared from a fluorine-containing microporous membrane via the following steps: S1, base film pre-passivation and electron beam irradiation activation; S2. The activated base film is placed in a grafting solution containing epoxy monomers and fluorine monomers for grafting reaction to obtain an epoxy-containing fluorine crosslinked grafted film; the grafted film is placed in a ring-opening solution containing N-methyl-D-glucosamine and 1-aminoethylidene diphosphonic acid for ring-opening reaction to obtain a modified base film. S3. The modified base membrane is end-capped with fluorinated amine and then pre-aged with hydrogen peroxide solution to obtain a bifunctional confined trapping membrane.

3. The method according to claim 1, characterized in that, The grafting solution also contains a crosslinking agent; the monomers in the grafting solution are composed of glycidyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate and ethylene glycol dimethacrylate, in a mass ratio of 100:(15-25):(2-4).

4. The method according to claim 2, characterized in that, The open-ring solution contains 8-10% N-methyl-D-glucosamine and 3-5% 1-aminoethylidene diphosphonic acid, with a mass ratio of (1.8-2.7):

1.

5. The method according to claim 2, characterized in that, The fluorinated amine is 2,2,2-trifluoroethylamine, with an aqueous solution having a mass fraction of 1%-2%, a reaction temperature of 30-40℃, and a reaction time of 1-3 hours.

6. The method according to claim 1, characterized in that, The pressure of the low-temperature pre-filtration in step (1) is 0.1-0.3 MPa, and the pore size of the pre-filter is 0.1-0.5 μm; the column temperature for organic impurity capture in step (2) is 4-10℃, and the empty bed contact time is 1-5 min.

7. The method according to claim 1, characterized in that, In step (3), the membrane purification temperature is 4-10℃, the membrane inlet pressure is 0.08-0.15MPa, the membrane crossflow velocity is 0.1-0.3m / s, and the average residence time is 5-15min.

8. The method according to claim 1, characterized in that, In step (4), the nanofiltration uses a ceramic nanofiltration membrane with a molecular weight cutoff of 200-500 Da, an operating pressure of 0.2-0.3 MPa, and a temperature of 4-10℃; the pore size of the terminal microporous filter is 0.01-0.1 μm.

9. A high-purity hydrogen peroxide, characterized in that, Prepared by the method according to any one of claims 1-8.