A synthesis process for electronic grade sodium carbonate

Abstract

The present invention belongs to the technical field of sodium carbonate synthesis, and specifically relates to a synthesis process of electronic grade sodium carbonate. It comprises the following steps: S1, configuring industrial sodium bicarbonate into a 30% sodium bicarbonate solution, then adding a nano-cerium oxide / graphene composite catalyst, stirring and mixing, and microwave heating to obtain a pyrolysis solution for standby use; S2, adding a complexing agent, ultrasonically stirring, and filtering with a microporous membrane filter to obtain a preliminarily purified pyrolysis solution; S3, sequentially performing ultrafiltration and nanofiltration treatments to obtain a pyrolysis solution purified by membrane separation; S4, adding seed crystals after concentration, performing gradient temperature control crystallization, centrifuging and collecting crystals, washing, and vacuum drying. The synthesis process of electronic grade sodium carbonate provided by the present invention can not only improve the decomposition efficiency of sodium bicarbonate and increase the yield of sodium carbonate, but also adsorb metal impurities and achieve Cl ‑ The catalyst of the present invention can be recycled and has a long service life.

Description

Technical Field

[0001] The invention belongs to the technical field of sodium carbonate synthesis, and particularly relates to a synthesis process of electronic-grade sodium carbonate. Background Art

[0002] Electronic-grade sodium carbonate is a high-purity carbonate compound, mainly used in electronic industries such as semiconductors, electronic components, and liquid crystal displays. Sodium carbonate is one of the most favorable raw materials for the manufacture of positive electrodes for sodium-ion batteries. The production of electronic-grade sodium carbonate requires extremely high purity and uniformity, and has higher requirements for its purity and the content of more than a dozen impurity ions.

[0003] Today's industrial sodium bicarbonate contains Fe 3+ 、Cl - Conventional ion exchange is difficult to remove deeply, and the current purification process is evaporative crystallization, which easily introduces micropowders, resulting in a wide particle size distribution. In addition, multiple recrystallizations produce high-salt wastewater, which is costly to treat. High-temperature calcination decomposes sodium bicarbonate, which has low thermal efficiency and requires a lot of energy.

[0004] Based on this, we proposed a synthesis process for electronic-grade sodium carbonate, hoping to solve the shortcomings of the existing technology. Summary of the Invention

[0005] The purpose of the present invention is to provide a synthesis process of electronic grade sodium carbonate in response to the existing problems.

[0006] The present invention is achieved through the following technical solutions:

[0007] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0008] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add the nano-cerium oxide / graphene composite catalyst, stir and mix, and microwave-heat to 160-180° C. to obtain a pyrolysis solution for later use;

[0009] S2. adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1 to 2 hours, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0010] S3, sequentially subjecting the preliminarily purified pyrolysis liquid to ultrafiltration and nanofiltration to obtain a pyrolysis liquid purified by membrane separation;

[0011] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals are added to perform gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, spray-washed with ultrapure water, and then vacuum-dried.

[0012] Further preferably, the addition amount of the nano-cerium oxide / graphene composite catalyst in step S1 is 0.3-0.5 wt%;

[0013] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0014] (1) dissolving graphene oxide and salmon sperm DNA in Tris-HCl buffer, ultrasonically dispersing for 20 to 30 minutes to obtain a dispersion, then adding cerium ammonium nitrate and EDTA in a molar ratio of 1:1 to 1.5 to the dispersion, stirring at 200 to 300 r / min and 60 to 70° C. for 1 to 3 hours, and then placing in a vacuum freeze drying oven for drying to obtain a catalyst precursor for use;

[0015] (2) The precursor is placed in a pulse microwave plasma device, argon gas is introduced, the parameters of the pulse microwave are adjusted, and the precursor is taken out after treatment for 20 to 30 minutes. It is mixed with zinc powder in a mass ratio of 1:2 to 3 and placed in a corundum plate. The temperature is raised to 500 to 600 ° C under nitrogen protection. After the heat treatment is carried out for 2 to 3 hours, it is cooled to room temperature and taken out and placed in a corona device for corona treatment.

[0016] Further preferably, the amount of graphene oxide added in step (1) is 4-10 mg / mL, and the amount of salmon sperm DNA added is 100-200 μg / mL.

[0017] Further preferably, the drying parameters in step (1) are: precooling temperature of -50 to -30°C, precooling for 2 to 4 hours, drying temperature of 6 to 10°C, and drying time of 16 to 20 hours.

[0018] Further preferably, the microwave frequency in step (2) is 2.45 GHz, the pulse width is 20 to 30 μs, and the pulse repetition frequency is 10 to 20 kHz;

[0019] The voltage of the corona treatment is 20-30 kV, and the treatment time is 2-3 minutes.

[0020] Further preferably, the preparation of the complexing agent in step S2 comprises the following steps:

[0021] 1) adding polyvinylamine and 4-formylphenylboronic acid to a boric acid buffer solution at a molar ratio of 1:1-2, stirring and mixing, heating to 50-60° C., reacting for 2-3 hours, and then freeze-drying to obtain a polymer backbone with boronic acid groups;

[0022] 2) dissolving the polymer backbone with boronic acid groups in N,N-dimethylformamide to form a solution with a concentration of 2-4 wt%, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen protection at 200-300 rpm and 60-80° C. for 20-30 hours to obtain a copolymer for use;

[0023] 3) The copolymer and thioglycolic acid are added to ethanol in a molar ratio of 1:3-5, and after ultrasonic dispersion, the mixture is placed under ultraviolet light for 20-30 minutes, concentrated under reduced pressure, washed with ether 3-4 times, and vacuum dried at 50-60° C. for 30-40 minutes. The mixture is then immersed in a hydrochloric acid solution with a pH of 4, stirred at 160-200 r / min for 6-8 hours, and centrifuged. The precipitated product is collected, washed with deionized water 3-5 times, and vacuum dried at 50-60° C. for 1-2 hours.

[0024] Further preferably, the mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups in step 2) is 1 to 2:1;

[0025] The amount of azobisisobutyronitrile is 1-2 wt% of the mass of carboxybetaine methacrylate;

[0026] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:2-4.

[0027] Further preferably, the pore size of the ultrafiltration membrane used in the ultrafiltration in step S3 is 1 to 100 nm, the ultrafiltration pressure is 0.2 to 0.3 MPa, and the temperature is 20 to 30° C.;

[0028] The operating pressure of the nanofiltration is 1-3 MPa and the temperature is 20-30°C.

[0029] Further preferably, the seed crystals in step S4 are monodisperse cubic crystals with D50=50 μm.

[0030] Further preferably, the gradient temperature-controlled crystallization in step S4 is temperature-controlled by microwaves, first using a 500W microwave and adjusting the temperature to 60°C at 1°C / min, and after nucleation, adjusting the microwave power to 200W and cooling to 30°C at 0.2°C / min;

[0031] The vacuum drying temperature is 60-70°C.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] The synthesis process of electronic grade sodium carbonate provided by the present invention can not only improve the decomposition efficiency of sodium bicarbonate and increase the yield of sodium carbonate, but also adsorb metal impurities and achieve Cl - The catalyst of the present invention can be recycled for 10 times to maintain an activity of more than 95%. The recycling of the catalyst effectively extends the service life of the catalyst and reduces production costs.

[0034] First, the present invention adds a special nano-cerium oxide / graphene composite catalyst during the pyrolysis of sodium bicarbonate. The catalyst of the present invention can reduce the decomposition temperature of sodium bicarbonate, improve the decomposition efficiency, reduce energy consumption, and selectively adsorb Fe 3+ The catalyst can be reused after washing with 0.1M HNO3, and its activity is maintained at more than 95% after 10 cycles. The catalyst has a long service life and reduces the production cost of sodium carbonate synthesis to a certain extent.

[0035] Secondly, a specially prepared complexing agent is added to the pyrolysis solution. The complexing agent of the present invention contains multiple amino and carboxyl groups, which can form coordination bonds and electrostatic interactions with metal ions in the pyrolysis solution. This achieves the complexation of metal ions. Ultrasonic stirring treatment allows the complexation reaction to proceed fully. Then, a microporous membrane filter is used for filtration to separate the formed complex from the pyrolysis solution to obtain a preliminarily purified pyrolysis solution. Ultrafiltration and nanofiltration are then performed in sequence. Ultrafiltration can effectively remove small molecular organic matter, colloids and other impurities in the pyrolysis solution. Nanofiltration is then used to further remove monovalent and divalent ion impurities in the pyrolysis solution, such as CL - etc., thereby further improving the purity of the product.

[0036] Finally, microwave-assisted gradient crystallization is used to enhance heat transfer and programmed cooling to achieve directional crystal growth and improve the quality of electronic-grade sodium carbonate. DETAILED DESCRIPTION

[0037] In order to further explain the present invention, it is described below with reference to the following specific embodiments.

[0038] Example 1

[0039] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0040] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add a nano-cerium oxide / graphene composite catalyst in an amount of 0.3 wt %, stir and mix, and microwave-heat to 160° C. to obtain a pyrolysis solution for later use;

[0041] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0042] (1) Graphene oxide (4 mg / mL) and salmon sperm DNA (100 μg / mL) were dissolved in Tris-HCl buffer and ultrasonically dispersed for 20 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion in a molar ratio of 1:1, stirred at 200 r / min and 60°C for 1 h, and then placed in a vacuum freeze drying box for drying to obtain a catalyst precursor for use. Specifically, the precooling temperature was -50°C, the precooling was 2 h, the drying temperature was 6°C, and the drying time was 16 h.

[0043] (2) The precursor was placed in a pulse microwave plasma device, argon gas was introduced, the frequency of the pulse microwave was adjusted to 2.45 GHz, the pulse width was 20 μs, and the pulse repetition frequency was 10 kHz. After treating for 20 minutes, the precursor was taken out and mixed with zinc powder in a mass ratio of 1:2 and placed in a corundum plate. The temperature was raised to 500 ° C under nitrogen protection, and after the heat treatment was carried out for 2 hours, it was cooled to room temperature and taken out and placed in a corona device. The voltage of the treatment was controlled to 20 kV and the treatment was carried out for 2 minutes.

[0044] S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1 hour, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0045] The preparation of the complexing agent comprises the following steps:

[0046] 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:1, stirred and mixed, heated to 50°C, reacted for 2 hours, and then freeze-dried to obtain a polymer backbone with boronic acid groups;

[0047] 2) dissolving the polymer backbone with boronic acid groups in N,N-dimethylformamide to form a 2 wt% solution, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen at 200 rpm and 60° C. for 20 h to obtain a copolymer for later use;

[0048] The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups is 1:1;

[0049] The amount of azobisisobutyronitrile is 1 wt% of the mass of carboxybetaine methacrylate;

[0050] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:2;

[0051] 3) The copolymer and thioglycolic acid were added to ethanol at a molar ratio of 1:3, and ultrasonically dispersed. The mixture was then irradiated with ultraviolet light for 20 minutes, concentrated under reduced pressure, washed three times with ether, and vacuum dried at 50° C. for 30 minutes. The mixture was then immersed in a hydrochloric acid solution with a pH of 4, stirred at 160 rpm for 6 hours, and centrifuged. The precipitated product was collected, washed three times with deionized water, and vacuum dried at 50° C. for 1 hour.

[0052] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 1 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.2 MPa, the temperature was 20° C., and the nanofiltration operating pressure was 1 MPa, the temperature was 20° C., to obtain the membrane separation purified pyrolysis liquid;

[0053] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals (monodisperse cubic crystals, D50=50μm) are added and gradient temperature-controlled crystallization is performed using microwaves. First, a 500W microwave is used and the temperature is adjusted to 60°C at 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at 0.2°C / min for gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 60°C.

[0054] Example 2

[0055] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0056] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add a nano-cerium oxide / graphene composite catalyst in an amount of 0.4 wt %, stir and mix, and microwave-heat to 170° C. to obtain a pyrolysis solution for later use;

[0057] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0058] (1) Graphene oxide (7 mg / mL) and salmon sperm DNA (150 μg / mL) were dissolved in Tris-HCl buffer and ultrasonically dispersed for 25 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion in a molar ratio of 1:1.3, stirred at 250 r / min and 65°C for 2 h, and then placed in a vacuum freeze drying oven for drying to obtain a catalyst precursor for use. Specifically, the precooling temperature was -40°C, the precooling was 3 h, the drying temperature was 8°C, and the drying time was 18 h.

[0059] (2) The precursor was placed in a pulsed microwave plasma device, argon gas was introduced, the frequency of the pulsed microwave was adjusted to 2.45 GHz, the pulse width was 25 μs, and the pulse repetition frequency was 15 kHz. After treatment for 25 min, the precursor was taken out and mixed with zinc powder in a mass ratio of 1:2.5 and placed in a corundum plate. The temperature was raised to 550 ° C under nitrogen protection, and the temperature was kept at this temperature for 2.5 h. After cooling to room temperature, the precursor was taken out and placed in a corona device. The voltage of the treatment was controlled to 25 kV and the treatment was completed for 2.5 min.

[0060] S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1.5 h, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0061] The preparation of the complexing agent comprises the following steps:

[0062] 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:1.5, stirred and mixed, heated to 55°C, reacted for 2.5 hours, and then freeze-dried to obtain a polymer backbone with boronic acid groups;

[0063] 2) dissolving the above-mentioned polymer backbone with boronic acid groups in N,N-dimethylformamide to form a 3 wt% solution, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen protection at 250 rpm and 70° C. for 25 hours to obtain a copolymer for use;

[0064] The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups is 1.5:1;

[0065] The amount of azobisisobutyronitrile is 1.5 wt% of the mass of carboxybetaine methacrylate;

[0066] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:3;

[0067] 3) The copolymer and thioglycolic acid were added to ethanol at a molar ratio of 1:4, and after ultrasonic dispersion, the mixture was placed under ultraviolet light for 25 minutes, concentrated under reduced pressure, washed with ether three times, and vacuum dried at 55°C for 35 minutes. The mixture was then immersed in a hydrochloric acid solution with a pH of 4, stirred at 180 rpm for 7 hours, and centrifuged. The precipitated product was collected, washed with deionized water four times, and vacuum dried at 55°C for 1.5 hours.

[0068] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 50 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.25 MPa, the temperature was 25° C., and the nanofiltration operating pressure was 2 MPa, the temperature was 25° C., to obtain the membrane separation purified pyrolysis liquid;

[0069] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals (monodisperse cubic crystals, D50=50μm) are added and gradient temperature-controlled crystallization is performed using microwaves. First, a 500W microwave is used and the temperature is adjusted to 60°C at 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at 0.2°C / min for gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 65°C.

[0070] Example 3

[0071] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0072] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add a nano-cerium oxide / graphene composite catalyst in an amount of 0.5 wt %, stir and mix, and microwave-heat to 180° C. to obtain a pyrolysis solution for later use;

[0073] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0074] (1) Graphene oxide (10 mg / mL) and salmon sperm DNA (200 μg / mL) were dissolved in Tris-HCl buffer and ultrasonically dispersed for 30 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion at a molar ratio of 1:1.5, stirred at 300 r / min and 70°C for 3 h, and then placed in a vacuum freeze drying box for drying to obtain a catalyst precursor for standby use. Specifically, the precooling temperature was -30°C, the precooling was 4 h, the drying temperature was 10°C, and the drying time was 20 h.

[0075] (2) The precursor was placed in a pulsed microwave plasma device, argon gas was introduced, the frequency of the pulsed microwave was adjusted to 2.45 GHz, the pulse width was 30 μs, and the pulse repetition frequency was 20 kHz. After treatment for 30 min, the precursor was taken out and mixed with zinc powder in a mass ratio of 1:3 and placed in a corundum plate. The temperature was raised to 600 ° C under nitrogen protection, and after heat treatment for 3 h, it was cooled to room temperature and taken out and placed in a corona device. The voltage of the treatment was controlled to 30 kV and the treatment was completed for 3 min.

[0076] S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 2 h, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0077] The preparation of the complexing agent comprises the following steps:

[0078] 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:2, stirred and mixed, heated to 60°C, reacted for 3 hours, and then freeze-dried to obtain a polymer backbone with boronic acid groups;

[0079] 2) dissolving the polymer backbone with boronic acid groups in N,N-dimethylformamide to form a 4 wt% solution, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen at 300 rpm and 80° C. for 30 h to obtain a copolymer for later use;

[0080] The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups is 2:1;

[0081] The amount of azobisisobutyronitrile is 2 wt% of the mass of carboxybetaine methacrylate;

[0082] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:4;

[0083] 3) The copolymer and thioglycolic acid were added to ethanol at a molar ratio of 1:5, and ultrasonically dispersed. The mixture was then irradiated with ultraviolet light for 30 minutes, concentrated under reduced pressure, washed four times with ether, and vacuum dried at 60°C for 40 minutes. The mixture was then immersed in a hydrochloric acid solution with a pH of 4, stirred at 200 rpm for 8 hours, and centrifuged. The precipitated product was collected, washed five times with deionized water, and vacuum dried at 60°C for 2 hours.

[0084] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 100 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.3 MPa, the temperature was 30°C, and the nanofiltration operating pressure was 3 MPa, the temperature was 30°C, to obtain the membrane separation purified pyrolysis liquid;

[0085] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals (monodisperse cubic crystals, D50=50μm) are added and gradient temperature-controlled crystallization is performed using microwaves. First, a 500W microwave is used and the temperature is adjusted to 60°C at 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at 0.2°C / min for gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 70°C.

[0086] Comparative Example 1

[0087] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0088] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, and microwave-heat the solution to 170°C to obtain a pyrolysis solution for later use;

[0089] S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1.5 h, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0090] The preparation of the complexing agent comprises the following steps:

[0091] 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:1.5, stirred and mixed, heated to 55°C, reacted for 2.5 hours, and then freeze-dried to obtain a polymer backbone with boronic acid groups;

[0092] 2) dissolving the above-mentioned polymer backbone with boronic acid groups in N,N-dimethylformamide to form a 3 wt% solution, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen protection at 250 rpm and 70° C. for 25 hours to obtain a copolymer for use;

[0093] The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups is 1.5:1;

[0094] The amount of azobisisobutyronitrile is 1.5 wt% of the mass of carboxybetaine methacrylate;

[0095] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:3;

[0096] 3) The copolymer and thioglycolic acid were added to ethanol at a molar ratio of 1:4, and after ultrasonic dispersion, the mixture was placed under ultraviolet light for 25 minutes, concentrated under reduced pressure, washed with ether three times, and vacuum dried at 55°C for 35 minutes. The mixture was then immersed in a hydrochloric acid solution with a pH of 4, stirred at 180 rpm for 7 hours, and centrifuged. The precipitated product was collected, washed with deionized water four times, and vacuum dried at 55°C for 1.5 hours.

[0097] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 50 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.25 MPa, the temperature was 25° C., and the nanofiltration operating pressure was 2 MPa, the temperature was 25° C., to obtain the membrane separation purified pyrolysis liquid;

[0098] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals (monodisperse cubic crystals, D50=50μm) are added and gradient temperature-controlled crystallization is performed using microwaves. First, a 500W microwave is used and the temperature is adjusted to 60°C at 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at 0.2°C / min for gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 65°C.

[0099] Comparative Example 2

[0100] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0101] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add a nano-cerium oxide / graphene composite catalyst in an amount of 0.4 wt %, stir and mix, and microwave-heat to 170° C. to obtain a pyrolysis solution for later use;

[0102] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0103] (1) Graphene oxide (7 mg / mL) and salmon sperm DNA (150 μg / mL) were dissolved in Tris-HCl buffer and ultrasonically dispersed for 25 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion in a molar ratio of 1:1.3, stirred at 250 r / min and 65°C for 2 h, and then placed in a vacuum freeze drying oven for drying to obtain a catalyst precursor for use. Specifically, the precooling temperature was -40°C, the precooling was 3 h, the drying temperature was 8°C, and the drying time was 18 h.

[0104] (2) The precursor was placed in a pulsed microwave plasma device, argon gas was introduced, the frequency of the pulsed microwave was adjusted to 2.45 GHz, the pulse width was 25 μs, and the pulse repetition frequency was 15 kHz. After treatment for 25 min, the precursor was taken out and mixed with zinc powder in a mass ratio of 1:2.5 and placed in a corundum plate. The temperature was raised to 550 ° C under nitrogen protection, and the temperature was kept at this temperature for 2.5 h. After cooling to room temperature, the precursor was taken out and placed in a corona device. The voltage of the treatment was controlled to 25 kV and the treatment was completed for 2.5 min.

[0105] S2. Filtering the pyrolysis solution using a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0106] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 50 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.25 MPa, the temperature was 25° C., and the nanofiltration operating pressure was 2 MPa, the temperature was 25° C., to obtain the membrane separation purified pyrolysis liquid;

[0107] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals (monodisperse cubic crystals, D50=50μm) are added and gradient temperature-controlled crystallization is performed using microwaves. First, a 500W microwave is used and the temperature is adjusted to 60°C at 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at 0.2°C / min for gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 65°C.

[0108] Comparative Example 3

[0109] A synthesis process for electronic grade sodium carbonate comprises the following steps:

[0110] S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add a nano-cerium oxide / graphene composite catalyst in an amount of 0.4 wt %, stir and mix, and microwave-heat to 170° C. to obtain a pyrolysis solution for later use;

[0111] The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps:

[0112] (1) Graphene oxide (7 mg / mL) and salmon sperm DNA (150 μg / mL) were dissolved in Tris-HCl buffer and ultrasonically dispersed for 25 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion in a molar ratio of 1:1.3, stirred at 250 r / min and 65°C for 2 h, and then placed in a vacuum freeze drying oven for drying to obtain a catalyst precursor for use. Specifically, the precooling temperature was -40°C, the precooling was 3 h, the drying temperature was 8°C, and the drying time was 18 h.

[0113] (2) The precursor was placed in a pulsed microwave plasma device, argon gas was introduced, the frequency of the pulsed microwave was adjusted to 2.45 GHz, the pulse width was 25 μs, and the pulse repetition frequency was 15 kHz. After treatment for 25 min, the precursor was taken out and mixed with zinc powder in a mass ratio of 1:2.5 and placed in a corundum plate. The temperature was raised to 550 ° C under nitrogen protection, and the temperature was kept at this temperature for 2.5 h. After cooling to room temperature, the precursor was taken out and placed in a corona device. The voltage of the treatment was controlled to 25 kV and the treatment was completed for 2.5 min.

[0114] S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1.5 h, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution;

[0115] The preparation of the complexing agent comprises the following steps:

[0116] 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:1.5, stirred and mixed, heated to 55°C, reacted for 2.5 hours, and then freeze-dried to obtain a polymer backbone with boronic acid groups;

[0117] 2) dissolving the above-mentioned polymer backbone with boronic acid groups in N,N-dimethylformamide to form a 3 wt% solution, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen protection at 250 rpm and 70° C. for 25 hours to obtain a copolymer for use;

[0118] The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups is 1.5:1;

[0119] The amount of azobisisobutyronitrile is 1.5 wt% of the mass of carboxybetaine methacrylate;

[0120] The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:3;

[0121] 3) The copolymer and thioglycolic acid were added to ethanol at a molar ratio of 1:4, and after ultrasonic dispersion, the mixture was placed under ultraviolet light for 25 minutes, concentrated under reduced pressure, washed with ether three times, and vacuum dried at 55°C for 35 minutes. The mixture was then immersed in a hydrochloric acid solution with a pH of 4, stirred at 180 rpm for 7 hours, and centrifuged. The precipitated product was collected, washed with deionized water four times, and vacuum dried at 55°C for 1.5 hours.

[0122] S3, the preliminarily purified pyrolysis liquid was subjected to ultrafiltration (the pore size of the ultrafiltration membrane was 50 nm) and nanofiltration treatment in sequence, the ultrafiltration pressure was 0.25 MPa, the temperature was 25° C., and the nanofiltration operating pressure was 2 MPa, the temperature was 25° C., to obtain the membrane separation purified pyrolysis liquid;

[0123] S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, the temperature is adjusted to 30°C at 1°C / min for crystallization. After completion, the crystals are collected by centrifugation, sprayed and washed with ultrapure water, and then vacuum-dried at 65°C.

[0124] Experimental testing

[0125] The purity of sodium carbonate was determined by high-precision titration, the content of metal impurities was detected by ICP-MS, and Cl was detected by ion chromatography. - concentration.

[0126] The specific test results are shown in Table 1 below.

[0127] purity(%) Total metal impurities (ppb) Cl- content (ppm) Example 1 99.9995 2.3 0.07 Example 2 99.9996 1.8 0.06 Example 3 9.9996 1.9 0.06 Comparative Example 1 99.99 49.5 0.56 Comparative Example 2 26.3 Comparative Example 3

[0128] It can be concluded from Table 1 above that the synthesis process of electronic grade sodium carbonate provided by the present invention can not only improve the decomposition efficiency of sodium bicarbonate and increase the yield of sodium carbonate, but also adsorb metal impurities and achieve Cl - The removal of ions can obtain high-purity electronic grade sodium carbonate.

[0129] Catalyst cycle testing

[0130] The catalyst of Example 2 was washed with 0.1 M HNO 3 and reused 10 times, and then the metal adsorption efficiency before and after the recycling was compared.

[0131] The specific test results are shown in Table 2 below.

[0132] Table 2

[0133] index First cycle 10th cycle Fe adsorption capacity (mg / g) 15 14.3

[0134] As can be seen from Table 2 above, the activity of the catalyst of the present invention remains >95% after being recycled 10 times. The recycling of the catalyst effectively extends the service life of the catalyst, thereby reducing production costs.

[0135] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A synthesis process for electronic grade sodium carbonate, characterized in that, The steps include: S1. Dissolve industrial sodium bicarbonate in ultrapure water to prepare a 30% sodium bicarbonate solution, then add the nano-cerium oxide / graphene composite catalyst, stir and mix, and microwave-heat to 160-180° C. to obtain a pyrolysis solution for use; The addition amount of the nano-cerium oxide / graphene composite catalyst is 0.3-0.5wt%; The preparation of the nano-cerium oxide / graphene composite catalyst comprises the following steps: (1) Graphene oxide and salmon sperm DNA were dissolved in Tris-HCl buffer and ultrasonically dispersed for 20-30 min to obtain a dispersion. Then, ammonium cerium nitrate and EDTA were added to the dispersion at a molar ratio of 1:1-1.5, stirred at 200-300 r / min and 60-70 °C for 1-3 h, and then placed in a vacuum freeze drying oven for drying to obtain a catalyst precursor for use. (2) Place the precursor in a pulsed microwave plasma device, introduce argon gas, adjust the pulsed microwave parameters, treat for 20-30 minutes, take it out, mix it with zinc powder in a mass ratio of 1:2-3, place it in a corundum plate, heat it to 500-600 ° C under nitrogen protection, keep it warm for 2-3 hours, cool it to room temperature, take it out and place it in a corona device for corona treatment; S2. Adding a complexing agent to the pyrolysis solution, stirring under ultrasonic conditions for 1 to 2 hours, and then filtering through a microporous membrane filter to obtain a preliminarily purified pyrolysis solution; S3, sequentially subjecting the preliminarily purified pyrolysis liquid to ultrafiltration and nanofiltration to obtain a pyrolysis liquid purified by membrane separation; S4. After the pyrolysis liquid purified by membrane separation is concentrated to a supersaturation of 1.8, seed crystals are added to perform gradient temperature-controlled crystallization. After completion, the crystals are collected by centrifugation, spray-washed with ultrapure water, and then vacuum-dried.

2. the synthesis technique of electronic grade sodium carbonate according to claim 1, is characterized in that, The amount of graphene oxide added in step (1) is 4-10 mg / mL, and the amount of salmon sperm DNA added is 100-200 μg / mL.

3. The synthesis technique of electronic grade sodium carbonate according to claim 1, wherein The drying parameters described in step (1) are: precooling temperature of -50~-30℃, precooling for 2~4h, drying temperature of 6~10℃, and drying time of 16~20h.

4. The synthesis technique of electronic grade sodium carbonate according to claim 1, wherein The microwave frequency in step (2) is 2.45 GHz, the pulse width is 20-30 μs, and the pulse repetition frequency is 10-20 kHz; The voltage of the corona treatment is 20-30 kV, and the treatment time is 2-3 minutes.

5. The synthesis process of electronic grade sodium carbonate according to claim 1, wherein The preparation of the complexing agent described in step S2 comprises the following steps: 1) Polyvinylamine and 4-formylphenylboronic acid were added to a boric acid buffer solution at a molar ratio of 1:1-2, stirred and mixed, and then heated to 50-60°C for 2-3 hours. The mixture was then freeze-dried to obtain a polymer backbone with boronic acid groups. 2) dissolving the polymer backbone with boronic acid groups in N,N-dimethylformamide to form a solution with a concentration of 2-4 wt%, then adding carboxybetaine methacrylate, azobisisobutyronitrile, and 4-cyanopentanoic acid dithiobenzoate, stirring and mixing, and reacting under nitrogen protection at 200-300 rpm and 60-80°C for 20-30 hours to obtain a copolymer for use; 3) The copolymer and thioglycolic acid are added to ethanol at a molar ratio of 1:3-5, and after ultrasonic dispersion, the mixture is irradiated under ultraviolet light for 20-30 minutes, concentrated under reduced pressure, washed with ether 3-4 times, and vacuum dried at 50-60°C for 30-40 minutes. The mixture is then immersed in a hydrochloric acid solution with a pH of 4, stirred at 160-200 r / min for 6-8 hours, and centrifuged. The precipitated product is collected, washed with deionized water 3-5 times, and vacuum dried at 50-60°C for 1-2 hours.

6. The synthesis process of electronic grade sodium carbonate according to claim 5, wherein The mass ratio of the carboxybetaine methacrylate to the polymer backbone with boronic acid groups in step 2) is 1-2:1; The amount of azobisisobutyronitrile is 1-2 wt % of the mass of carboxybetaine methacrylate; The molar ratio of azobisisobutyronitrile to 4-cyanopentanoic acid dithiobenzoate is 1:2-4.

7. The synthesis process of electronic grade sodium carbonate according to claim 1, wherein The pore size of the ultrafiltration membrane used in the ultrafiltration in step S3 is 1-100 nm, the ultrafiltration pressure is 0.2-0.3 MPa, and the temperature is 20-30° C.; The operating pressure of the nanofiltration is 1-3 MPa and the temperature is 20-30°C.

8. The synthesis process of electronic grade sodium carbonate according to claim 1, wherein The seed crystals described in step S4 are monodisperse cubic crystals with D50=50 μm.

9. The synthesis process of electronic grade sodium carbonate according to claim 1, wherein The gradient temperature-controlled crystallization in step S4 is performed using microwaves for temperature control. A 500W microwave is first used to adjust the temperature to 60°C at a rate of 1°C / min. After nucleation, the microwave power is adjusted to 200W and the temperature is lowered to 30°C at a rate of 0.2°C / min. The vacuum drying temperature is 60-70°C.