A process for separating boron isotopes and preparing boric acid-10

Abstract

The invention belongs to the technical field of boron isotope separation, and specifically relates to a process for separating boron isotopes to prepare boric acid-10; the process adopts a chromatographic column with ferroferric oxide / resin microspheres as a stationary phase, a boric acid-sodium borate aqueous solution with a pH value of 6-7 as an adsorption liquid, and a sodium hydroxide aqueous solution with a pH value of 10-11 as a desorption liquid, and iteratively separates and obtains a boric acid-rich boric acid. 10 B, and then further prepare boric acid-monosodium borate aqueous solution; the process can be used to prepare boric acid in aqueous solution mainly composed of boric acid 10 B is enriched to a higher degree; the chromatographic column has a relatively stable boric acid adsorption capacity and 10 B. 11 B separation performance, long service life, and has certain application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of boron isotope separation, and in particular relates to a process for separating boron isotopes to prepare boric-10 acid. Background Art

[0002] 10 B and 11 B is the two stable isotopes of boron, with natural abundances of 19.9% ​​and 80.1% respectively. 10 The thermal neutron capture cross section of B is much larger than 11 B, used in the nuclear industry for reactor control rod materials (such as boron carbide), pressurized water reactor coolants (such as boric acid aqueous solution) and neutron shielding materials (such as boron-containing polyethylene), and in medicine as a targeting agent for the treatment of certain tumors (boron neutron capture therapy); in these applications, 10 The abundance of B has certain requirements, except for some neutron shielding materials, it is above 85%. 10 The main methods of B include: BF3 low temperature distillation, BF3 complex chemical exchange distillation, and adsorption separation. The first two methods have high requirements for raw materials and equipment, and the cost of further producing applicable materials such as boron carbide-10 and boric acid-10 is very high, which limits the production of these high 10 Application of B-abundant materials. Adsorption separation can be separated by aqueous solution whose main component is boric acid. 10 B and 11 B, has the characteristics of easy development and implementation, safety, energy saving, etc., has development potential, and is more efficient when implemented through chromatography.

[0003] Through adsorption separation, the aqueous solution containing boric acid as the main component is used to separate 10 B and 11 B, then concentrated to produce boric acid-10, the key is to develop 10 B / 11 B separation factor, adsorption separation materials with higher boric acid-10 or boric acid-10 salt adsorption capacity, and elution process; among them, adsorption separation materials based on nano-Fe3O4 have certain application prospects.

[0004] In the prior art, ion exchange or adsorption resins, such as strongly acidic cation exchange resins, strongly basic anion exchange resins, weakly basic anion exchange resins, and boron-specific adsorption resins AMBERLITE IRA743 and weakly acidic cation exchange resins, are used to adsorb boric acid in aqueous solution. 10 B and 11 The adsorption and separation efficiency of B isotopes are low and have no practical value ( 10 B / 11 B separation coefficient, i.e. separation factor, is lower than 1.1).

[0005] CN109464981A provides a method for preparing a magnetic nanomaterial and a method for separating boron isotopes using the magnetic nanomaterial, and discloses a method for preparing four powdery magnetic nanomaterials, Fe3O4, SiO2@Fe3O4, Carbon@Fe3O4, and Fe3O4@CuO; the four powdery materials react with an aqueous solution containing boric acid as the main component. 10 B / 11 The B separation factor is 1.118-1.332, among which Fe3O4 has the best overall effect. The preparation method of the nano material Fe3O4 includes the following steps: (1) weighing 8.1g FeCl3·6H2O and 3.9g FeCl2·4H2O, placing them in a round-bottom flask, adding 540mL deionized water and a magnet, fixing the round-bottom flask on a magnetic stirrer, filling with nitrogen protection, and dissolving under magnetic stirring; (2) after the two substances are completely dissolved, under strong magnetic stirring and nitrogen protection, adding 60mL ammonia water to adjust the pH to about 8, at which time the solution changes from red to black, and the reaction time is 1h; (3) after the reaction is completed, separating the product with a magnet, washing, and adjusting the pH of the solution to neutral with hydrochloric acid during the last washing; (4) vacuum drying the product at 40°C for 8h. The doctoral dissertation "Study on the Application and Mechanism of Boron Adsorption and Boron Isotope Separation by Magnetic Nanoparticles (Fe3O4)" (Chen Tao, Tianjin University, May 2022) discloses the adsorption, desorption and isotope separation efficiency of boron in aqueous boric acid solutions of different concentrations, pH values ​​and temperatures, as well as the performance attenuation of the material, of Fe3O4 nanoparticles prepared by basically the same method. The nanomaterials prepared by these two existing technologies are ultrafine powders, which are difficult to apply directly, and cannot be used as chromatographic column stationary phases; the nanopowders are pressure-formed, crushed, and sieved to obtain granules with a particle size of 0.2-1mm. When used in chromatographic columns, they have low wear resistance (easy to lose powder), and a contradiction between strength and internal pore volume. When the strength is guaranteed, the internal pores are significantly compressed, and the adsorption and separation ability of the granules for boric acid is greatly reduced.

[0006] In the master's thesis "Preparation of Fe3O4-loaded Resin and Study on Boron Isotope Separation Performance" (Wang Qingfeng, Tianjin University, May 2021), a microsphere material (Fe3O4@Resin) prepared by pre-exchange-coprecipitation method and loaded with Fe3O4 nanoparticles (loading amount of about 8.1wt%) by macroporous strongly acidic cation exchange resin (D001 resin microspheres) was disclosed, and its physical and chemical properties and chromatographic separation of boron isotopes were studied; the indicators of the D001 resin used were: styrene-divinylbenzene system, the functional group was −SO3 −, mass full exchange capacity (dry) ≥ 4mmol / g, volume full exchange capacity (wet) ≥ 1mmol / mL, particle size 0.315-1.25mm, water content 42-55%. Among them, Fe3O4@Resin-1 has a better effect. The preparation method is as follows: 40mL D001 resin converted to hydrogen form after pretreatment, 8.1g FeCl3·6H2O and 540mL deionized water are added to a round-bottom flask, and stirred for 12h under N2 conditions to make D001 resin and Fe 3+ Perform sufficient ion exchange; then add 3.9g FeCl2·4H2O and wait until it is completely dissolved in the mixture (Fe 3+ with Fe 2+ The molar ratio of the feed was 3:2), and then 60 mL of ammonia water was slowly added to adjust the pH to about 8 for coprecipitation reaction; the reaction was completed after 1 hour, and the coprecipitate was washed, dried, and sieved to obtain Fe3O4@Resin-1 particles with a particle size of 0.56-0.8 mm (the iron oxide content was 8.1 wt% based on the dry basis of Fe3O4@Resin-1 and Fe3O4). Fe3O4 nanopowder (without resin) was also synthesized by coprecipitation method as a control: 8.1 g of FeCl3·6H2O, 3.9 g of FeCl2·4H2O, and 540 mL of deionized water were added to a round-bottom flask, stirred under N2 conditions, and 60 mL of ammonia water was added after the complete dissolution to cause coprecipitation reaction, and finally Fe3O4 nanopowder was obtained. The XRD method detected that the grain size of Fe3O4 nanoparticles in Fe3O4@Resin-1 was 13nm, and the grain size of the pure Fe3O4 nanopowder in comparison was also 13nm; the SEM method detected that the surface of Fe3O4@Resin particles was coated with a layer of Fe3O4 nanoparticles, and it was relatively rough. The zero charge point (pHzpc) of Fe3O4@Resin-1 was 6.75, and the boron adsorption and separation factor were both large at pH 6-7 of boric acid aqueous solution, among which the maximum boron adsorption was 2.869mg·g at pH 7. −1 , at pH 6, about 2.65 mg g −1 , which significantly decreased at other pH values; the separation factor was 1.315 at pH 6 and about 1.305 at pH 7, which decreased at other pH values; the adsorption kinetics data were consistent with the pseudo-second-order kinetic model; the adsorption isotherm data were consistent with the Langmuir model. Fe3O4@Resin-1 material (58.81 g) was wet-packed in a stainless steel column with a length of 25 cm and an inner diameter of 2.2 cm, and boron isotope chromatographic separation (dynamic separation) was performed: the boron concentration was 5.405 g·L −1 , 10 B abundance 19.78% ( 11 The boric acid aqueous solution (B abundance 80.22%) was adjusted to pH 7 with sodium hydroxide aqueous solution and the flow rate was 5 mL min−1 , the column temperature was 25℃, and the liquid was continuously injected for 60 min; then the concentration of 0.01 mol·L −1 The hydrochloric acid solution was used as the eluent at a flow rate of 5 mL min −1 , the column temperature was 25℃, and the liquid was continuously added for 1.5h to elute the boric acid adsorbed on the Fe3O4@Resin-1 filler; finally, deionized water was continuously added until the effluent was neutral, and the hydrochloric acid solution in the chromatographic column was completely replaced by water to complete the regeneration; the adsorption-regeneration process was repeated five times. As a result, the separation factor reached 1.312, the column pressure drop was below 2MPa, and the elution was 10 The boric acid aqueous solution with a boric acid abundance of 22.76% was used; however, the boron adsorption separation performance gradually decreased with each adsorption-regeneration process. 10 The adsorption amounts of B were 0.03275g, 0.03218g, 0.03172g, 0.03131g, and 0.03088g, respectively, and the recovery rates were 95.98%, 94.31%, 92.97%, 91.76%, and 90.50%, respectively. In the prior art, the Fe3O4 nanoparticles loaded by the microsphere material are basically coated on the surface of the resin microspheres. Under the extrusion force of the chromatographic column bed, the Fe3O4 nanoparticle coating is easily worn and detached; Fe 3+ with Fe 2+ The molar ratio of the feed is 3:2, and the 3+ with Fe 2+ The molar ratio of feed required to generate Fe3O4 through neutralization precipitation reaction is different from 2:1.

[0007] In the papers "Application and Mechanism Study of Boron Adsorption and Boron Isotope Separation by Magnetic Nanoparticles (Fe3O4)" and "Preparation of Ferroferric Oxide-Loaded Resin and Study on Boron Isotope Separation Performance", the preferred elution process of the separation material after the adsorption of boric acid is a two-step washing with a dilute acid solution (pH 2-6) and water. The performance of the adsorption separation material decays quickly, and it is actually difficult to apply it to industrial processes.

[0008] CN119186536A (applied by an affiliated unit of the present applicant) provides a method for preparing boron isotope separation resin microspheres, comprising the following steps:

[0009] (1) Cross-linking degree 15-30, specific surface area 100-180m 2 / g, pore volume 0.6-1.0mL / g, outer diameter such as 0.3-1.3mm, dried polystyrene-divinylbenzene resin microspheres, dimethyl sulfoxide is added and the temperature is raised to 50-65°C for swelling for more than 3h, 93-98wt% concentrated sulfuric acid is added for sulfonation treatment, the temperature is controlled at 55-65°C, and solid-liquid separation is performed after the sulfonation rate reaches 0.3-0.4mmol / g, the microspheres are washed with water, and 2-5mol / L ammonia solution is added to soak for 2-5h for primary ion exchange transformation from hydrogen type to ammonium type, and washed with water to obtain water-containing ammonium type macroporous polystyrene-divinylbenzene ion exchange resin microspheres; during the sulfonation treatment process, the weight ratio of polystyrene-divinylbenzene microspheres, dimethyl sulfoxide, and concentrated sulfuric acid is 1:(4-5):(0.3-0.5);

[0010] (2) The ammonium-type macroporous polystyrene-divinylbenzene ion exchange resin microspheres containing water in step (1) are transferred to a rotary drum that can be evacuated, equipped with external heating and an atomizing nozzle, sealed and started, and vacuum dried at 60-70° C. until the water content is less than 1wt%, thereby obtaining dried ammonium-type resin microspheres; further evacuated and cooled to 50-60° C., filled with high-purity nitrogen to positive pressure, and atomized sprayed with a ferric chloride-ferrous chloride aqueous solution with a concentration of 2-3 mol / L and a temperature of 50-60° C. for 4-6 hours, and the drum continues to rotate. After the surface solution of the resin microspheres is completely absorbed for 0.5-1h, the rotation is stopped, and the material temperature is maintained at 50-60°C and the positive pressure in the drum is maintained for 3-5h to perform homogenization and secondary ion exchange transformation from ammonium type to iron type; the spraying volume of the ferric chloride-ferrous chloride aqueous solution is 70-85% of the saturated water absorption volume of the dried ammonium type resin microspheres; in the ferric chloride-ferrous chloride aqueous solution, the molar ratio of ferric chloride to ferrous chloride is 2:1, and the effect is better when it contains 0.01-0.03 mol / L of titanium trichloride;

[0011] The drum is started, and the external heating temperature is controlled to be 60-70° C. and the required vacuum conditions are controlled. Within 8-12 hours, 25-40% of the total weight of the water contained in the resin microsphere material is uniformly evaporated and removed, and high-purity nitrogen is filled to positive pressure, and the temperature of the resin microsphere material is reduced to 50-60° C.; the drum continues to rotate, and a nitrogen gas flow with a temperature of 50-60° C., a relative humidity of 35-45%, and ammonia content of 0.5-1v% is introduced at a required fixed flow rate to treat the resin microsphere material, so that no ammonia is consumed during ventilation for 4-8 hours (that is, the ammonia content in the outlet and inlet gas flows is the same, and the three ion exchange transformation from trivalent iron type to ammonium type is carried out at the same time), and the ammonia-nitrogen gas flow is continued for 0.5-1 hour; during the treatment with the ammonia-nitrogen gas flow, the temperature of the resin microsphere material is maintained at 50-60° C. and the positive pressure in the drum is maintained;

[0012] The drum continues to rotate and high-purity nitrogen is passed through to maintain the positive pressure in the drum. Deoxygenated water at 40-50°C is sprayed on the resin microsphere material. The amount of water sprayed is 2-3 times the accumulated volume of the resin microsphere material. The drum is rotated for 30-60 minutes to wash the resin microsphere material once. The drum is stopped to discharge the liquid between the resin microspheres. The washing and drainage process is repeated 2-3 times. The drum is stopped to discharge the liquid between the resin microspheres. The drum is started to spray the resin microsphere material with a concentration of 0.8-1 mol / L and a temperature of 30-40 ℃ sodium hydroxide aqueous solution, the spraying amount is 1-1.5 times of the accumulated volume of the resin microsphere material, the drum is stopped, and the mixture is allowed to stand for 2-3 hours for four ion exchange transformation treatments from ammonium type to sodium type, and then the liquid between the resin microspheres is discharged; room temperature deoxygenated water is used instead, and the water washing and liquid discharge process is repeated 3-5 times, and then the resin microsphere material is sprayed with room temperature deoxygenated water to immerse the resin microsphere material, and the resin microsphere and the immersion water are discharged into a container pre-substituted with nitrogen and the container is sealed to obtain boron isotope separation resin microspheres.

[0013] CN119186536A also provides the boron isotope separation resin microspheres prepared for separation of boric acid aqueous solution by chromatography. 10 B and 11 Application of B, the boric acid aqueous solution is a boric acid-sodium hydroxide aqueous solution with a pH of 6-7.5, and the desorption liquid is pure water; the separation operation conditions include: the column temperature of the chromatographic column is 15-35°C, the boric acid concentration in the boric acid-sodium hydroxide aqueous solution is 80-95% of the saturated concentration of boric acid in water under the column temperature condition, the apparent or axial flow rate of the boric acid-sodium hydroxide aqueous solution or pure water in the bed is 0.4-0.6m / h, and the liquid is fed in a top-in-bottom-out manner; when the adsorption and separation efficiency of the chromatographic column decreases, it can be regenerated with a 0.2-0.5mol / L sodium hydroxide aqueous solution. The beneficial effects of the invention include: the prepared boron isotope separation resin microspheres, the ferroferric oxide nanoparticles are loaded in the inner pores of the resin microspheres, which can be loaded in the chromatographic column, with the boric acid-sodium hydroxide aqueous solution as the raw material and pure water as the desorption liquid, for 10 B. 11 The adsorption and separation of B in the boric acid aqueous solution can 10 B was enriched to a higher degree, and the boric acid adsorption capacity of the chromatographic column and 10 B. 11 B separation performance can be basically restored by regeneration treatment with sodium hydroxide aqueous solution, thus obtaining a longer service life; however, since the loading amount of ferroferric oxide nanoparticles in the resin microspheres is difficult to exceed 15wt%, the adsorption separation capacity is limited, and the desorption capacity of pure water as a desorption liquid is also insufficient, the performance of the separation resin microspheres decreases rapidly and requires frequent regeneration treatment. 10 It is difficult to obtain the iterative separation of aqueous solution of B boric acid 10A boric acid aqueous solution with a boric acid abundance of more than 85%; at the same time, the preparation process in the drum of step (2) is relatively complicated and difficult to control; comprehensively judging, it is believed that this method is difficult to apply.

[0014] Therefore, it is necessary to prepare microspherical materials with better overall performance, certain application prospects, high loading capacity of ferroferric oxide nanoparticles, and the ability to be loaded into chromatographic columns for boron isotope separation. By conventional and simple chromatographic separation methods, the boron isotope in aqueous solution, which is mainly composed of boric acid, can be separated. 10 B is enriched to a higher degree, and the chromatographic column has a relatively stable adsorption separation performance and a longer service life; at the same time, the desorption capacity of the desorption liquid is high, the separation performance decreases slowly, and frequent regeneration treatment is not required. 10 B Boric acid aqueous solution is easy to obtain by iterative separation 10 Aqueous solution containing boric acid with a B abundance of more than 85%. Summary of the invention

[0015] In order to solve the above technical problems, the present invention provides a process for separating boron isotopes to prepare boric acid-10, which adopts a chromatographic column with ferroferric oxide / resin microspheres as the stationary phase, a boric acid-monosodium borate aqueous solution with a pH value of 6-7 as the adsorption liquid, and a sodium hydroxide aqueous solution with a pH value of 10-11 as the desorption liquid, and iteratively separates and obtains the rich boric acid. 10 Boric acid-monosodium borate aqueous solution of B is further used to prepare boric acid-10;

[0016] The ferroferric oxide / resin microspheres are prepared by the following steps:

[0017] (1) In a stirred reactor with a jacket, nitrogen replacement is performed, the jacket water temperature is controlled at 70-80°C, ferrous chloride or ferrous sulfate aqueous solution at 70-80°C is added, stirring is started, and sodium carbonate aqueous solution at 70-80°C is added until the slurry pH value is 8.0-8.5, the addition time of sodium carbonate aqueous solution is 1-2 hours, stirring is stopped and heat-insulated aging treatment is performed for 5-10 hours, sodium methyl silicate aqueous solution is added, stirred evenly, heat-insulated treatment is performed for 3-5 hours, and the feed liquid is filtered to obtain a methylsilicic acid-coated, water-containing ferrous hydroxide filter cake; the molar ratio of sodium methyl silicate to ferrous chloride or ferrous sulfate is (1-1.5):100; the concentration of ferrous chloride or ferrous sulfate aqueous solution is 1.5-2.5 mol / L, and the concentration of sodium carbonate aqueous solution is 1.8-2.5 mol / L;

[0018] (2) In a stirred container, nitrogen is replaced, styrene, acrylic acid, divinylbenzene from which the polymerization inhibitor has been removed, ethanolamine, porogen isoamyl alcohol-cyclohexane solution, and initiator azobisisobutylamidine hydrochloride are added, stirred and dissolved to prepare a polymerization solution, the filter cake obtained in step (1) and silane coupling agent KH-550 are added, stirred evenly, and a mixed slurry is obtained after colloid mill (circulation) treatment; wherein the divinylbenzene is p-divinylbenzene or m-divinylbenzene; and the molar ratio of styrene, acrylic acid, and divinylbenzene is (6-8):(0.5-0. 8):1; the molar ratio of acrylic acid to ethanolamine is 1:(1.0-1.1); the weight ratio of the total amount of styrene, acrylic acid, and divinylbenzene to the isoamyl alcohol-cyclohexane solution, azobisisobutyramidine hydrochloride, and KH-550 is 100:(80-120):(0.6-1):(1-2); the weight ratio of the total amount of styrene, acrylic acid, and divinylbenzene to the iron in the filter cake as Fe3O4 is 100:(25-36); the isoamyl alcohol content in the isoamyl alcohol-cyclohexane solution is 5-8wt%;

[0019] (3) In a stirred reactor with a jacket and a vacuum system, nitrogen is replaced, the jacket water temperature is controlled at 75-80°C, an aqueous solution containing 0.4-1wt% polyvinyl alcohol is added as a suspension dispersion, stirring is started, and when the temperature rises to above 70°C, the mixed slurry obtained in step (2) is added. After the feed liquid is heated to above 70°C and reacted for 3-5 hours, the vacuum system is turned on to evaporate and remove the cyclohexane in the porogen contained in the microspheres generated in the feed liquid; the vacuum system is closed, nitrogen is filled to normal pressure, and the feed liquid is filled with nitrogen. A sodium hydroxide aqueous solution of the required concentration is added to make the NaOH concentration in the feed liquid 0.1-0.2 mol / L, and the feed liquid is discharged and filtered after reacting for 2-3 hours, and the filtered microspheres are washed with water to obtain a semi-finished microsphere material; wherein the volume ratio of the suspension dispersion to the mixed slurry is (230-350):100, and the average diameter of the microspheres is controlled to be 0.5-0.8 mm by adjusting the stirring speed; the alcoholysis degree of the polyvinyl alcohol is 85-90%, and the degree of polymerization is 1500-2000;

[0020] (4) In a stirred reactor with a jacket, the jacket water temperature is controlled at 75-80°C, water at 70-80°C is added, the semi-finished microsphere material obtained in step (3) is added, stirring is started, a hydrochloric acid aqueous solution is added to adjust the pH value of the liquid to 7.0-8.5, oxygen is introduced into the space above the liquid surface of the reactor, the gas above the liquid surface is replaced, and the reactor is closed, oxygen is continued to be introduced and a positive pressure of 5-10 kPa is maintained in the reactor, and the reaction is carried out at a liquid temperature of 70-80°C for 15-25 hours until the liquid in the reactor no longer consumes oxygen, after which the liquid is discharged and filtered, and the filtered microsphere material is washed with water to obtain ferroferric oxide / resin microsphere material; wherein the weight ratio of the added water to the semi-finished microsphere material is (200-250):100.

[0021] The process for separating boron isotopes to prepare boronic acid-10 comprises the following preferred separation operating conditions: the chromatographic column is installed vertically, the column temperature is 15-35°C, the adsorption liquid (boric acid-monosodium borate aqueous solution) and the desorption liquid (sodium hydroxide aqueous solution) are both introduced from top to bottom; the boric acid concentration in the boric acid-monosodium borate aqueous solution is 80-95% of the saturated concentration in water under the column temperature condition; and the superficial or axial flow rate of the adsorption liquid and the desorption liquid in the stationary phase bed is 0.4-0.6 m / h. The preferred equipment conditions include: the chromatographic column adopts a cylindrical barrel, a separation bed filled with the stationary phase, i.e., the ferroferric oxide / resin microspheres, is arranged in the barrel, a screen, porcelain balls, metal orifice plates and other heavy pressure materials are arranged on the separation bed to compress the separation bed and disperse the liquid flow, a screen and a support are arranged under the separation bed, and an insulation layer or a circulating water jacket is arranged outside the barrel; an electric valve is appropriately arranged in the inlet and outlet interfaces of the chromatographic column or its connecting pipeline, as well as measurement / control components of a temperature measuring instrument, a concentration meter and a flow meter; the electric valve and the instrument are connected to an intelligent controller, the intelligent controller is connected to a computer, and the control of the inlet and outlet, the solution segmentation logic and the flow control are realized through the computer settings, so as to control the inlet selection, the outlet direction and the segmentation and collection of the outlet. The measurement components of the concentration meter include a boric acid concentration transmitter and a pH value transmitter.

[0022] The adsorption liquid, i.e., a boric acid-monosodium borate aqueous solution with a pH value of 6-7, can be prepared from water, boric acid, sodium hydroxide or a sodium hydroxide aqueous solution with a concentration of 1-3 mol / L; in the inlet flow of the chromatographic column, the single inlet volume of the adsorption liquid can be 12-25% of the volume of the separation bed. After a period of operation, if the separation efficiency of the chromatographic column is reduced, it can be regenerated with a sodium hydroxide aqueous solution with a concentration of 0.3-0.5 mol / L. After regeneration, the inlet water is flushed until the conductivity of the discharged water is less than 1000 μs / cm, so that the performance of the chromatographic column can be restored to a large extent; the discharged liquid in the regeneration process contains sodium hydroxide and monosodium borate, which can be used to prepare the boric acid-monosodium borate aqueous solution with a pH value of 6-7, i.e., the adsorption liquid.

[0023] The boric acid and sodium hydroxide (or concentrated sodium hydroxide solution) used to prepare the adsorption liquid and the desorption liquid should have appropriately high purity, and the impurity content other than water should preferably be less than 0.1wt%, and more preferably less than 0.03wt%. The water used to prepare the boric acid-monosodium borate aqueous solution and the pure water used as the desorption liquid should have as low organic component and O2 content as possible, and the electrical conductivity should be less than 0.2μs / cm. It is preferably pure water obtained by ion exchange or reverse osmosis, which is further distilled to obtain high-purity distilled water after slight boiling to remove impurities such as O2 and CO2.

[0024] The effluent from the chromatographic column is divided and collected for use respectively; the total concentration of boric acid and monosodium borate is calculated as boric acid, such as 0.5 g / L or more. 10B outflow, for example, the portion of 0.5-15 g / L after the total concentration of boric acid and monosodium borate reaches the maximum value in terms of boric acid can be used as the enriched 10 B effluent is collected, concentrated and further processed and utilized, including 10 B abundance iteration chromatography separation, and the conventional processing process of preparing boric acid powder or borate from the concentrated solution containing boric acid. The effluent with a total concentration of boric acid and monosodium borate of less than 0.2g / L, preferably less than 0.1g / L in terms of boric acid, is collected as a desorption liquid and recycled. The portion with a pH value below 10 is collected and adjusted to 10-11 by adding a 1-3mol / L sodium hydroxide aqueous solution to continue to be used as a desorption liquid. 11 The collected portion of B is used to prepare boric acid or borate products that have no requirements for boron isotope abundance, and the remaining portion is used according to the specific composition, such as being concentrated to prepare an adsorption solution, i.e., boric acid-monosodium borate aqueous solution.

[0025] Aqueous solution containing boric acid such as 10 A method for concentrating a boric acid-monosodium borate aqueous solution of B, including a reverse osmosis method and / or an MVR method. The MVR method is an evaporation concentration method using a steam mechanical recompression technology, which is characterized in that the secondary steam flow produced when the aqueous solution or the water-containing feed liquid is evaporated and concentrated by indirect heat exchange is mechanically recompressed to increase the temperature and pressure of the steam, increase its thermal enthalpy, and then used as an indirect heat exchange heat source for evaporation and concentration of the aqueous solution or the water-containing feed liquid, and the water in the feed liquid is evaporated and basically becomes condensed water, thereby utilizing the latent heat of the evaporated steam to a large extent; the steam compressor is generally driven by electricity, and in the boric acid aqueous solution concentration process of the present invention, the energy-saving level of theoretical ten-effect evaporation can be achieved.

[0026] In the present invention, the boric acid-10 refers to 10 Boric acid or boric acid aqueous solution with a B abundance higher than 50%, specific 10 The B abundance range may include 50-60%, 60-80%, 80-95%, above 95%, etc.

[0027] The process for separating boron isotopes to prepare boric acid-10 has the following beneficial effects: a ferroferric oxide / resin microsphere material is specially developed and prepared, and a conventional and simple chromatographic separation method is used to separate boric acid from an aqueous solution. 10 B was enriched to a higher degree by 10 B Boric acid aqueous solution is iteratively separated to obtain 10 Aqueous solution containing boric acid with a boric acid abundance of more than 95%; the chromatographic column has a relatively stable boric acid adsorption capacity and 10 B. 11 B separation performance, long service life, overall performance is better than the existing chromatography separation technology, and has certain application prospects.

[0028] From the effects of the following embodiments and comparative examples, it is believed that the main principles of the present invention are as follows, and the above beneficial effects are also the result of the following factors:

[0029] 1. In the method of the present invention, under the chromatographic separation conditions, the ferroferric oxide / resin microspheres can maintain a high 10 B. 11 B separation efficiency, indicating that the ferroferric oxide nanoparticles loaded in the pores of the resin microspheres have an effect on the adsorption of the boric acid-sodium borate aqueous solution at pH 6-7. 10 Component B has good affinity, and the desorption efficiency of sodium hydroxide aqueous solution with a pH value of 10-11 is higher; the corrosion of the loaded ferroferric oxide nanoparticles by the desorption solution is also much lighter than that of the prior art using a dilute hydrochloric acid aqueous solution with a pH value of 3.5-4.5 as the desorption solution. In the adsorption solution with a pH value of 6-7, the concentration of boric acid is 0.5-1 mol / L (depending on the solution temperature and column temperature), and the concentration of monosodium borate is generally 0.01-0.05 mol / L (which can be achieved by adding 0.01-0.05 mol / L of sodium hydroxide); in the desorption solution with a pH value of 10-11, the concentration of sodium hydroxide is 10 -4 -10 - 3 mol / L. When the desorption liquid contacts the adsorption liquid, the low concentration of sodium hydroxide contained in it is immediately neutralized by boric acid to generate monosodium borate. Therefore, the separation bed has a horizontal and layered transition zone with a pH value of 7-10 along its axis, which gradually moves downward, and the desorption effect is better than that of pure water.

[0030] 2. In the method of the present invention, the use of a sodium hydroxide aqueous solution with a pH value of 10-11 as the desorption liquid can achieve a higher desorption rate than using high-purity distilled water and / or a dilute hydrochloric acid aqueous solution with a pH value of 3.5-4.5 as the desorption liquid. 10 B. 11B separation efficiency, and the decline of separation efficiency is much slower; and after the chromatographic column has been running for a long time, the adsorption and separation efficiency can be regenerated with a sodium hydroxide solution of 0.3-0.5mol / L and its performance can be basically restored. The technical effects of these two aspects show that the surface of the ferric oxide nanoparticles loaded by the resin microspheres will gradually generate and deposit boric acid polymers, which are difficult to elute with water and a dilute hydrochloric acid aqueous solution with a pH value of 3.5-4.5, resulting in a rapid decline in the adsorption and separation performance of the chromatographic column. However, when a sodium hydroxide aqueous solution with a pH value of 10-11 is used as a desorption liquid in the method of the present invention, because it has a certain solubility for boric acid polymers, the deposition rate and deposition amount of boric acid polymers on the surface of ferric oxide nanoparticles will be significantly reduced; at the same time, the impurity content other than water in the boric acid and sodium hydroxide used is less than 0.1wt%, and the adsorption liquid and desorption liquid are prepared with high-purity distilled water, which reduces the contamination of the impurity components contained in the ferric oxide / resin microspheres. Under the combined effect of these factors, the long-term adsorption and separation performance and service life of the chromatographic column are guaranteed. At the same time, using a sodium hydroxide aqueous solution with a pH value of 10-11 as the desorption liquid can not only obtain a better desorption effect, but also the effluent from the chromatographic column can be fully utilized.

[0031] 3. The monosodium borate has a molecular formula of NaB(OH)4, which can be ionized to [B(OH)4] - Boric acid is a Lewis acid. When combined with water in aqueous solution, it can ionize into trace amounts of [B(OH)4] - and H + When a 0.3-0.5 mol / L sodium hydroxide aqueous solution is used to regenerate the chromatographic column, the effluent contains monosodium borate generated by the reaction of the residual boric acid with sodium hydroxide, and monosodium borate generated by the dissolution and depolymerization of the boric acid polymer and the reaction with sodium hydroxide, which can be used to prepare the boric acid-monosodium borate aqueous solution (i.e., adsorption solution) at pH 6-7. The effluent can be considered to contain only sodium hydroxide and monosodium borate.

[0032] 4. The ferroferric oxide / resin microspheres have a Fe3O4 content of 20-25wt% on a dry basis. In step (1) of the preparation process, the role of sodium methyl silicate is to hydrolyze the generated methyl silicic acid, which reacts with the hydroxyl groups on the surface of the aqueous ferrous hydroxide colloid particles to coat the ferrous hydroxide colloid particles and make them hydrophobic and lipophilic, so that the slurry is easy to separate and filter, and the content of water-soluble inorganic salts in the filter cake is low, and no water washing is required; excess sodium methyl silicate and methyl silicic acid enter the filtrate; if sodium methyl silicate is not added, the slurry filtration and filter cake water washing are slow, and the filter cake is not easy to be evenly dispersed in the organic phase in step (2).

[0033] In step (2), the role of acrylic acid is to act as a monomer for polymerization in step (3) (olefin groups participate in polymerization), and the introduced carboxyl groups are basically evenly distributed in the polymer molecular chains of the resin microspheres, making the microsphere resin skeleton have a certain hydrophilicity; the role of ethanolamine is to combine with the carboxyl groups of acrylic acid through its alkaline amine groups, mask the acidity of acrylic acid, avoid affecting the effect of acrylic acid participating in the polymerization reaction due to the reaction with ferrous hydroxide, and make the microsphere resin skeleton have a hydrophilic effect; the filter cake is easy to disperse evenly in the organic phase, and during the colloid mill treatment of the mixed slurry, the methylsilicic acid-coated, water-containing ferrous hydroxide colloid particles are broken and refined, and the newly exposed hydroxyl groups on the surface react with the ethoxy groups of the silane coupling agent KH-550, so that the main body of the KH-550 molecule is combined with the newly formed surface of the ferric hydroxide fine colloid particles, and the mixed slurry is in a sol state, has a Tyndall effect (visible light path when irradiated with a light beam) and is very stable; if KH-550 is not added, the slurry after the colloid mill treatment is easy to stratify, and the final preparation of the ferric oxide / resin microsphere material in the adsorption liquid 10 B. 11 The separation efficiency of B becomes worse.

[0034] In step (3), the mixed slurry gradually forms into balls in the suspension dispersion. After the cyclohexane in the microspheres is removed under vacuum conditions, the microspheres and their inner pores have low hydrophilicity. 0.1-0.2 mol / L NaOH in the slurry gradually enters the inner pores of the microspheres, dissolves and removes ethanolamine bound to acrylic acid, and dissolves and removes methylsilicic acid and KH-550 bound to ferrous hydroxide, so that the semi-finished microspheres and their inner pores have good hydrophilicity.

[0035] In step (4), under the oxidizing effect of oxygen gradually dissolving into the feed liquid and entering the inner pores of the microspheres, the ferrous hydroxide contained in the semi-finished microspheres is gradually converted into ferroferric oxide nanoparticles, which are dispersed in the inner pores of the microspheres. In the process of generating ferroferric oxide nanoparticles, the sodium carboxyl group side chains (generated by carboxyl groups and NaOH entering the inner pores of the microspheres) of the microsphere resin polymer molecular chain are polar and hydrophilic, which may have a significant effect on the particle size, distribution, etc. of the ferroferric oxide nanoparticles. When oxygen is introduced below the liquid surface through a Φ0.5mm nozzle and the same positive pressure in the reactor is maintained, the reaction time can be shortened to less than 8 hours, but the prepared ferroferric oxide / resin microsphere material has a higher affinity to the adsorption liquid. 10 B. 11 The separation efficiency of B deteriorates, indicating that in the process of oxidizing ferrous hydroxide to generate ferroferric oxide nanoparticles, the effect is not good when the oxidation rate is fast.

[0036] 5. The prepared ferroferric oxide / resin microspheres have the strength and wear resistance required for long-term operation of the chromatographic column; the moisture content on a dry basis is 42-56%, that is, the pore volume is 0.48-0.63mL / g, and the specific surface area is 50-70m 2 / g. Under the condition of 20-25wt% Fe3O4 loading, the pore volume is relatively high. It is difficult for the ferroferric oxide / resin microspheres prepared by the conventional resin microsphere impregnation method to have such a high Fe3O4 loading and pore volume; the source of the pore volume includes the space occupied by the ferrous hydroxide colloid particles and the porogen. The ferric hydroxide / ferrous hydroxide filter cake coated with methyl silicic acid obtained in step (1) has a calcination weight loss of 63-75wt% after calcination at 600°C for 3h under air conditions, and has a large water content. In the process of conversion into ferroferric oxide nanoparticles, water is lost to produce part of the inner pores, and at the same time, it is more evenly dispersed in the inner pores of the microspheres due to the influence of the polar and hydrophilic sodium carboxyl side chains in the polymer molecular skeleton. When the amount of ferric hydroxide / ferrous hydroxide filter cake coated with methyl silicic acid or the amount of the porogen isoamyl alcohol-cyclohexane solution is further increased, the strength of the prepared ferroferric oxide / resin microspheres will decrease, and it is not easy to meet the strength requirements required by the chromatographic column. When the amount of ferric hydroxide / ferrous hydroxide filter cake coated with methyl silicic acid is increased without using a porogen, or when the porogen does not contain isoamyl alcohol, the prepared ferric oxide / resin microspheres have an effect on the adsorption of 10 B. 11 The separation efficiency of B will be worse; the role of isoamyl alcohol may be to improve the dissolution and dispersion uniformity of the initiator azobisisobutyramidine hydrochloride, the combination of acrylic acid and ethanolamine (all have significant polarity) in the polymerization solution to a certain extent, thereby improving the monomer polymerization effect and the distribution uniformity of allyl groups in the polymer molecular chain, that is, the distribution uniformity of sodium carboxyl side chains on the surface of the polymer skeleton. The normal pressure boiling point of isoamyl alcohol is 132°C, and the normal pressure boiling point of cyclohexane is 80.7°C. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is specifically described and illustrated below in conjunction with embodiments. Example 1

[0038] In this embodiment 1, a process for separating boron isotopes to prepare boric acid-10 is used, using a chromatographic column with ferroferric oxide / resin microspheres as the stationary phase, a boric acid-monosodium borate aqueous solution with a pH value of 6-7 as the adsorption liquid, and a sodium hydroxide aqueous solution with a pH value of 10-11 as the desorption liquid, and iterative separation is performed to obtain a rich 10 Boric acid-monosodium borate aqueous solution of B is further used to prepare boric acid-10;

[0039] The separation equipment conditions of the chromatographic column include: the chromatographic column is installed vertically, and is assembled from a transparent organic glass inner tube (inner wall diameter 100 mm, net height inside the tube 4750 mm) and a transparent organic glass outer tube, and circulating water is passed through the outer tube for heat preservation or auxiliary temperature control; the filling height of ferroferric oxide / resin microspheres is 4590 mm (filling volume 36.0 L), the bed is covered with a five-layer stainless steel screen of Φ100 mm and 60 mesh, and a Φ3 mm porcelain ball of 120 mm height is filled on the screen (the function is to compress the separation bed and disperse the liquid flow), and the bed is supported by a five-layer stainless steel screen of Φ100 mm and 60 mesh and a Φ3 mm porcelain ball to form a separation bed; the adsorption liquid (boric acid-monosodium borate aqueous solution) and the desorption liquid (sodium hydroxide aqueous solution) are both in a top-in and bottom-out manner. The upper end of the chromatographic column is provided with a high-purity nitrogen inlet / exhaust interface and a needle valve, and a liquid inlet temperature controller is provided and connected to control the inlet temperature of the adsorption liquid or desorption liquid; the liquid inlet temperature controller is connected to the liquid inlet flow pump (plunger pump), and the inlet of the flow pump (adsorption liquid or desorption liquid) is selected and controlled by the liquid inlet electric valve. The lower end of the chromatographic column is provided and connected with a liquid outlet temperature detector, a boric acid concentration transmitter (photoelectric type), a pH value transmitter, and a liquid outlet electric valve. The liquid inlet electric valve, liquid inlet flow pump, liquid inlet temperature controller, boric acid concentration transmitter, pH value transmitter, and liquid outlet electric valve are connected to an intelligent controller, and the intelligent controller is connected to a computer, and the computer settings are used to realize the inlet selection, the flow rate of the liquid inlet flow pump, the inlet temperature, the cutting and collection of the discharge liquid, and the cutting is performed according to the boric acid concentration and pH value of the discharge liquid.

[0040] After the ferroferric oxide / resin microspheres are loaded into the column, high-purity distilled water at 25°C (made by further distilling deionized pure water after slight boiling to remove impurities such as O2 and CO2) is used to fill the entire chromatographic column. The column is first washed for 10 hours (first, water is introduced at a flow rate of 18 L / h for 1 hour, and then reduced to 9 L / h), and then the column is washed for 10 hours (flow rate 9 L / h) with a sodium hydroxide aqueous solution with a pH value of 10.6 (concentration of 0.0004 mol / L, which is the desorption solution used subsequently); at the same time, circulating water at 25°C is passed from bottom to top in the outer casing.

[0041] Then, the boric acid-monosodium borate aqueous solution was added. 10 B and 11 Dynamic and quasi-dynamic separation test of B.

[0042] The dynamic separation test comprises the following steps:

[0043] (a) First, add 4.8 L of 25°C boric acid-monosodium borate aqueous solution (adsorption solution, which is 13.3% of the volume of 36.0 L of the ferroferric oxide / resin microsphere bed in the chromatographic column), and then add 25°C sodium hydroxide aqueous solution with a pH value of 10.6 used for washing the column (desorption solution), and the inlet flow rate is 2.0 L / h (the apparent or axial flow velocity in the separation bed is about 0.51 m / h, and the volume proportion of the resin microspheres in the separation bed is about 50%). The total concentration of boric acid and monosodium borate in the effluent is cut and collected according to the conditions before reaching the maximum value, after reaching the maximum value, 0.5-2 g / L, 2-15 g / L, and ≥15 g / L in terms of boric acid, and the effluent with a concentration of 2-15 g / L collected after the total concentration in terms of boric acid reaches the maximum value is the enriched effluent. 10 B boric acid aqueous solution; each time the boric acid-monosodium borate aqueous solution is prepared by adding 2 mol / L sodium hydroxide aqueous solution dropwise to 4.4 L saturated boric acid aqueous solution at 25°C under air-tight conditions, adjusting to the required pH value, then diluting to 4.8 L with water and stirring evenly, wherein the impurity content of the boric acid and sodium hydroxide used in the preparation of the solution is less than 0.03 wt % except for water, and high-purity distilled water is used;

[0044] (b) When the total concentration of boric acid and monosodium borate in the effluent solution increased to 0.5 g / L in terms of boric acid, the column was again charged with 4.8 L of 25°C boric acid-monosodium borate aqueous solution, and then charged with sodium hydroxide aqueous solution with a pH value of 10.6, with the inlet flow rate remaining unchanged at 2.0 L / h;

[0045] (c) repeating steps (a) to (b);

[0046] The column was injected with boric acid-monosodium borate aqueous solution with pH values ​​of 7.0, 7.0, 6.5, 6.5, 6.0, 6.0, 7.0, 7.0, 6.5, 6.5, 6.0, and 6.0 twelve times;

[0047] In the boric acid-monosodium borate aqueous solution, 10 B and 11 The B abundance was 19.9% ​​and 80.1% respectively. The total concentration of boric acid and monosodium borate was 0.79 mol / L (49 g / L in terms of boric acid, which is about 90% of the concentration of saturated boric acid aqueous solution). According to the addition amount of 2 mol / L sodium hydroxide aqueous solution, the concentration of monosodium borate was about 0.052 mol / L at pH 7.0, about 0.033 mol / L at pH 6.5, and about 0.015 mol / L at pH 6.0.

[0048] After the dynamic separation test, a quasi-dynamic separation test was performed: the boric acid-monosodium borate aqueous solution at 25°C and pH 6.5 was first introduced for 15 hours (flow rate 2.0 L / h), and then high-purity nitrogen was introduced for 6 hours (99.99v%, flow rate 4.0 L / h, in-and-out, v% is volume content) to discharge most of the solution between the resin microspheres, and then a sodium hydroxide aqueous solution at 25°C and pH 10.6 was introduced for 24 hours (flow rate 2.0 L / h); when the sodium hydroxide aqueous solution at pH 10.6 was first introduced, the liquid outlet electric valve was closed, and when the gas in the chromatographic column was exhausted from the top outlet (filled with liquid), the liquid outlet electric valve was opened and all the discharged liquids with a total concentration of boric acid and monosodium borate of more than 0.5 g / L in terms of boric acid were collected to obtain a rich 10 B Boric acid aqueous solution.

[0049] The concentration of boric acid and borate in aqueous solution is determined by chemical method (acid-base titration). 10 B. 11 The abundance of B was determined by ICP-MS.

[0050] The main results of Example 1 are: first, the effluent (rich) collected in the dynamic separation test after the total concentration of boric acid reached the maximum value and the concentration was 2-15g / L 10 B boric acid aqueous solution), detection 10 B abundance was higher than 37.2%; secondly, the abundance obtained by quasi-dynamic separation experiment was 10 B Boric acid aqueous solution, detection 10 The abundance of B is 29.5%.

[0051] The concentration of boric acid and borate in aqueous solution is determined by chemical method (acid-base titration). 10 B. 11 The abundance of B was determined by ICP-MS.

[0052] The ferroferric oxide / resin microsphere material used in this embodiment 1 is prepared by the following steps:

[0053] (1) In a stirred reactor with a jacket (volume 200 L), nitrogen (purity 99.9% by volume) was replaced, the jacket water temperature was controlled at 75°C, 130 L of 75°C ferrous chloride aqueous solution was added, stirring was started, and 75°C sodium carbonate aqueous solution was added until the slurry pH value was 8.3. The addition time of sodium carbonate aqueous solution was 1.5 h, stirring was stopped and heat-insulated for 8 h, sodium methyl silicate aqueous solution was added, stirred evenly, stirring was stopped and heat-insulated for 4 h (stirring for 2 min every 0.5 h), and the feed liquid was filtered (try to The filter cake was sampled and tested, and it was found to be hydrophobic and lipophilic, with a calcination loss of 69 wt % after calcination at 600 ° C for 3 h in air, and contained 29.7 wt % iron in terms of Fe3O4; the molar ratio of sodium methyl silicate to ferrous chloride was 1.25:100; the concentrations of the ferrous chloride aqueous solution and the sodium carbonate aqueous solution were both 2.0 mol / L, and the ferrous chloride and sodium carbonate used were both industrial products;

[0054] (2) In a stirred anhydrous container (volume 200 L), nitrogen is replaced, 34 kg of styrene, acrylic acid, and p-divinylbenzene, from which the inhibitor has been removed by an anion exchange resin separation column, as well as 34 kg of porogen isoamyl alcohol-cyclohexane solution, ethanolamine, and initiator azobisisobutylamidine hydrochloride are added, stirred and dissolved to prepare a polymerization solution, 30.5 kg of the filter cake stored for 5 hours in step (1) and silane coupling agent KH-550 are added, stirred evenly, and a mixed slurry is obtained after 3 hours of colloid mill circulation treatment to obtain a mixed slurry, 200 mL of which is sampled, and the rest is immediately used in step (3) ); wherein the molar ratio of styrene, acrylic acid and p-divinylbenzene is 7:0.65:1; the molar ratio of acrylic acid and ethanolamine is 1:1.05; the weight ratio of the total amount of styrene, acrylic acid and p-divinylbenzene to the isoamyl alcohol-cyclohexane solution, azobisisobutyramidine hydrochloride and KH-550 is 100:100:0.8:1.5; the weight ratio of the total amount of styrene, acrylic acid and p-divinylbenzene to the iron in the filter cake in terms of Fe3O4 is 100:29; the isoamyl alcohol content in the isoamyl alcohol-cyclohexane solution is 6.5wt%;

[0055] (3) In a stirred reactor (volume 500 L) with a jacket and a vacuum system, nitrogen replacement was performed, and the jacket water temperature was controlled to 78°C. 300 L of an aqueous solution containing 0.7 wt% of polyvinyl alcohol (PVA 17-88, alcoholysis degree 86-90%, polymerization degree 1700) was added as a suspension dispersion. Stirring was started and the stirring speed was controlled to 96 rpm. When the temperature reached 70°C, the mixed slurry (about 100 L) obtained in step (2) was added. The feed liquid was heated to 70°C and reacted for 4 hours to generate microspheres. The vacuum system was started and the system pressure was gradually reduced (to an absolute pressure of 80 kPa at 35 minutes and then constant pressure). The circulating water temperature of the glass condenser in front of the vacuum pump was 25°C. The reaction was continued until no condensate was generated (the cyclohexane in the porogen contained in the microspheres in the feed liquid was completely evaporated and removed, and the condensate included an aqueous phase and an organic phase). The vacuum system was closed and nitrogen was filled to normal pressure. A sodium hydroxide aqueous solution of the required concentration was added to the feed liquid to make the NaOH concentration in the feed liquid 0. 2mol / L, after reacting for 2h, the feed liquid was discharged and filtered (the filtrate, i.e., the suspension dispersion, contained only trace suspended matter and was still basically transparent), the filtered microspheres were washed with water (until the pH value of the washing water dropped to 9), and semi-finished microspheres were obtained. 200mL of the sample was taken, and the rest was immediately used in step (3); the average diameter of the microspheres was 0.68mm, and the wet and dry materials before and after vacuum drying at 70°C had good hydrophilicity, and the dried microspheres could absorb water quickly;

[0056] (4) The stirred reactor (volume 500 L) used in step (3) was rinsed with water, the jacket water temperature was controlled at 78°C, 200 L of water at 78°C was added, the semi-finished microsphere material of step (3) was added, stirring was started, and a hydrochloric acid aqueous solution was added to adjust the pH value of the liquid to 8.1. Oxygen was introduced into the space above the liquid surface of the reactor to replace the gas above the liquid surface (oxygen concentration was above 99v%), and then the reactor was closed. Oxygen was continued to be introduced and the positive pressure in the reactor was maintained at 7.5-8.0 kPa. The reaction was carried out at a feed liquid temperature of 78°C for 19.3 h until the oxygen flow meter returned to zero (the feed liquid in the reactor no longer consumed oxygen), and then the feed liquid was discharged and filtered (the filtrate contained only trace suspended matter and was basically transparent). The filtered microsphere material was washed with water until the conductivity of the discharged water dropped to below 100 μs / cm to obtain ferroferric oxide / resin microsphere material, which was immediately bagged and sealed for storage; wherein the weight ratio of the added water to the semi-finished microsphere material was about 220:100.

[0057] The prepared hydrous ferroferric oxide / resin microspheres were sampled and tested. They could be adsorbed by a magnet, had a smooth surface without sediment, and were uniformly black in appearance and cross-section. This indicated that the generated ferroferric oxide nanoparticles were loaded in the inner pores of the resin microspheres. The microspheres were dried in a vacuum oven at an absolute pressure of 70 kPa and 70 °C for 5 h to a constant weight. They contained 22.1 wt% Fe3O4 and had a specific surface area (BET) of 58 m 2 / g; the pore volume on a dry basis is 0.55mL / g (water on the surface of the microspheres and between the particles is absorbed with slow filter paper, 5.00g of the material is weighed and dried for 3h to constant weight under vacuum conditions at a temperature of 60°C and a final absolute pressure of 5kPa, and the weight is calculated based on the weight loss); the dried microsphere material can absorb water quickly and has good hydrophilicity; the detection strength and wear resistance meet the requirements for long-term operation of the chromatographic column. Example 2

[0058] After the dynamic and quasi-dynamic separation tests described in Example 1 were completed, the steps (a) to (c) in Example 1 were continued to be operated eighteen times to perform the dynamic separation test of Example 2, with the following differences: A. the column temperature in step (a) was changed to 35°C, and the adsorption liquid, desorption liquid and outer tube circulating water at 35°C were used; B. the adsorption liquid, i.e., boric acid-monosodium borate aqueous solution, was added each time, and the temperature was changed from 35°C, saturated boric acid aqueous solution ( 10 B and 11 B abundance is 19.9% ​​and 80.1% respectively), add 4.4L of 2mol / L sodium hydroxide aqueous solution, adjust to pH 6.5, then add water to dilute to 4.8L and stir well to prepare, the total concentration of boric acid and monosodium borate is 1.15mol / L (71g / L in terms of boric acid, about 90% of the concentration of saturated boric acid aqueous solution), according to the addition amount of 2mol / L sodium hydroxide aqueous solution, the concentration of monosodium borate is about 0.045mol / L; C. Use desorption solution (sodium hydroxide aqueous solution) with pH values ​​of 10.0, 10.6 and 11.0 respectively, and separate six times each.

[0059] One of the main results of Example 2 is that the effluent collected after six separations using the same pH value desorption solution (sodium hydroxide aqueous solution) and the total concentration of boric acid reached the maximum value and the concentration was 2-15g / L, and the three mixed samples were sampled and mixed, and the 10 B abundance was higher than 36.1%. Example 3

[0060] After the dynamic separation test described in Example 2 was completed, the steps (a)-(c) in Example 1 were continued for nine times to carry out the dynamic separation test of Example 3, except that: the adsorption liquid, i.e., the boric acid-sodium borate aqueous solution, was separated in Examples 1-2 and the 2-15 g / L effluent collected after the total concentration in terms of boric acid reached the maximum value was combined, mixed, evaporated and concentrated, and cooled to a saturated rich solution of 25°C. 10 B Boric acid aqueous solution ( 10B abundance is 36.9%), add 2mol / L sodium hydroxide aqueous solution, adjust to pH 6.5, dilute to 4.8L with high-purity distilled water and stir well to prepare, the total concentration of boric acid and monosodium borate is 0.80mol / L (49.6g / L in terms of boric acid, about 91% of the concentration of saturated boric acid aqueous solution), according to the addition amount of 2mol / L sodium hydroxide aqueous solution, the concentration of monosodium borate is about 0.034mol / L; the desorption liquid is sodium hydroxide aqueous solution with a pH value of 10.6, and the column temperature is 25℃. The 1-12g / L concentration effluent after the total concentration in terms of boric acid reaches the maximum value is collected separately.

[0061] One of the main results of Example 3 is that the collected effluent with a concentration of 1-12 g / L after the total concentration of boric acid reached the maximum value was sampled and mixed, and then tested. 10 The abundance of B is 56.2%. Example 4

[0062] After the dynamic separation test described in Example 3 was completed, the steps (a)-(c) in Example 3 were continued for three times to carry out the dynamic separation test of Example 4, except that: the adsorption liquid, i.e., the boric acid-sodium borate aqueous solution, was separated in Example 3, and the 1-12 g / L effluent collected after the total concentration in terms of boric acid reached the maximum value was combined, mixed, evaporated, concentrated, and cooled to a saturated rich solution of 25°C. 10 B Boric acid aqueous solution ( 10 B abundance is 56.2%), add 2mol / L sodium hydroxide aqueous solution, adjust to pH 6.5, dilute to 4.8L with high-purity distilled water and stir well; the desorption liquid is sodium hydroxide aqueous solution with pH 10.6 and the column temperature is kept at 25℃. The 1-12g / L concentration effluent after the total concentration in terms of boric acid reaches the maximum value is collected separately.

[0063] One of the main results of Example 4 is that the collected effluent with a concentration of 1-12 g / L after the total concentration of boric acid reached the maximum value was sampled and mixed, and then tested. 10 B abundance was higher than 81.4%. Example 5

[0064] After the dynamic separation test described in Example 4 is completed, the steps (a)-(c) in Example 3 are continued to be operated once, and the dynamic separation test of this Example 5 is carried out, except that: the adsorption liquid, i.e., boric acid-sodium borate aqueous solution, is separated in Example 4, and the 1-12 g / L effluent collected after the total concentration in terms of boric acid reaches the maximum value is combined, mixed, evaporated and concentrated, and cooled to a saturated rich solution of 25°C. 10 B Boric acid aqueous solution ( 10B abundance is 81.4%), add 2mol / L sodium hydroxide aqueous solution, adjust to pH 6.5, dilute to 4.8L with high-purity distilled water and stir well; the desorption liquid is sodium hydroxide aqueous solution with pH 10.6 and the column temperature is kept at 25℃. The 1-12g / L concentration effluent after the total concentration in terms of boric acid reaches the maximum value is collected separately.

[0065] One of the main results of Example 5 is that the collected effluent with a concentration of 1-12 g / L after the total concentration in terms of boric acid reached the maximum value was detected. 10 The abundance of B is 95.8%. Example 6

[0066] After the dynamic separation test described in Example 5 was completed, the dynamic separation test of Example 6 was carried out three times by continuing to operate basically according to steps (a)-(c) in Example 1. The pH value of the adsorption liquid, i.e., the boric acid-monosodium borate aqueous solution, was 6.5 each time, and the desorption liquid was still the sodium hydroxide aqueous solution with a pH value of 10.6.

[0067] One of the main results of Example 5 is that the collected effluent with a concentration of 2-15 g / L after the total concentration in terms of boric acid reached the maximum value was detected. 10 B abundance is higher than 36.4%; combined with other results such as the liquid volume of the 2-15g / L concentration discharge liquid, compared with the effect under the same operating conditions in Example 1, it is believed that the separation performance of the separation column after use in Examples 1-6 does not decrease by more than 3.6%. Example 7

[0068] After the dynamic separation test described in Example 6 is completed, the chromatographic column is fed with high-purity distilled water at 25°C for 18 hours (flow rate 2.0 L / h, to wash the column until the boric acid concentration in the effluent is less than 0.1 g / L), and then with a 0.4 mol / L sodium hydroxide aqueous solution at 25°C for 10 hours (flow rate 2.0 L / h), and then with a sodium hydroxide aqueous solution with a pH value of 10.6 for 10 hours (flow rate 2.0 L / h).

[0069] Afterwards, the chromatographic column basically repeated the separation process of Examples 1, 3-5 (one separation operation cycle), and a total of six separation operation cycles were repeated. The desorption solution was a sodium hydroxide aqueous solution with a pH value of 10.6, and the column temperature was 25°C. In each separation operation cycle, the steps (a)-(c) in Example 1 were first operated thirty times, the column temperature was 25°C, and the adsorption solution introduced each time was a pH value of 6.5 and a total concentration of 0.79 mol / L (49 g / L in terms of boric acid, which is approximately 90% of the concentration of a saturated boric acid aqueous solution). The desorption solution continued to be a sodium hydroxide aqueous solution with a pH value of 10.6; the effluent with a concentration of 2-15 g / L collected after the total concentration in terms of boric acid reached the maximum value was combined and mixed, and used as the raw material for repeating the operation of Example 3, and then evaporated and concentrated, and the saturated rich solution was obtained by cooling to 25°C. 10 B boric acid aqueous solution, and used to prepare an adsorption solution with a pH value of 6.5; finally, the separation process and discharge liquid detection of Examples 4-6 were completely repeated. In the process of repeating Examples 1, 3-5, in each example, only the combined mixed solution of the discharge liquid with a concentration of 2-15g / L (when repeating Example 1) or 1-12g / L (when repeating Examples 3-5) collected after the total concentration of boric acid reached the maximum value was taken for testing once. 10 B abundance.

[0070] The main results of Example 7 include: first, in the discharge liquid after entering the 25°C, 0.4 mol / L sodium hydroxide aqueous solution, the concentration of monosodium borate first increased and then decreased, reaching a maximum of 2.7 g / L in terms of boric acid, indicating that the above-mentioned decrease in the separation performance of the chromatographic column may be related to the deposition of polyboric acid on the surface of the ferroferric oxide nanoparticles loaded in the pores of the resin microspheres. The alkaline washing process can dissolve and depolymerize the deposited polyboric acid to generate sodium borate; second, in the first four separation operation cycles, the separation effects of Examples 1, 3-6 can be reproduced well, and each enrichment 10 Mixture B 10 The concentration, total amount and abundance of B boric acid did not decrease substantially. When the total concentration of boric acid collected in Example 5 reached the maximum value, the effluent with a concentration of 1-12 g / L was detected. 10 B abundance was higher than 95.1%. Comparative Example 1

[0071] After the dynamic separation test described in Example 7 is completed, the separation process of alkaline washing regeneration and one separation operation cycle described in Example 7 is repeated, except that the desorption liquid (sodium hydroxide aqueous solution with a pH value of 10.6) used in step (a) is replaced by high-purity distilled water.

[0072] The main result of this comparative example 1 is that the separation effects when repeating the processes of Examples 1, 3-5 are slightly lower than those in Example 7. 10 Mixture B10 The concentration, total amount and abundance of boric acid in Example 7 could not reach the level of the third separation operation cycle as a whole; when the total concentration of boric acid collected in Example 5 reached the maximum value, the effluent with a concentration of 1-12 g / L was detected. 10 The abundance of B is 70.3%. Comparative Example 2

[0073] After the dynamic separation test described in Comparative Example 1 is completed, the separation process of alkaline washing regeneration and one separation operation cycle described in Example 7 is repeated, except that the desorption liquid used in step (a) (sodium hydroxide aqueous solution with a pH value of 10.6) is replaced by a dilute hydrochloric acid aqueous solution with a pH value of 4.0 (prepared with high-purity distilled water).

[0074] The main result of this comparative example 2 is that the separation effects when repeating the processes of Examples 1, 3-5 are also slightly lower than those in Example 7. 10 Mixture B 10 The concentration, total amount and abundance of boric acid in Example 7 could not reach the level of the third separation operation cycle as a whole; when the total concentration of boric acid collected in Example 5 reached the maximum value, the effluent with a concentration of 1-12 g / L was detected. 10 The abundance of B is 53.6%.

[0075] The comparison of the effects in Example 7 and Comparative Examples 1-2 shows that, compared with using high-purity distilled water or a dilute hydrochloric acid aqueous solution with a pH value of 4.0 as the desorption liquid, when the present invention uses a sodium hydroxide aqueous solution with a pH value of 10.6 as the desorption liquid, the separation performance and stability of the chromatographic column are higher.

[0076] After the dynamic separation test of Comparative Example 2 was completed, the chromatographic column was rinsed with high-purity distilled water at 25°C for 18 hours (flow rate 2.0L / h), and then all the separation bed microspheres were unloaded and immersed in high-purity distilled water for preservation; the surface of the separation bed layer and the unloaded microspheres were fully inspected before unloading, and no fragmentation of the used ferroferric oxide / resin microspheres was found. The unloaded hydrous ferroferric oxide / resin microspheres can still be adsorbed by a magnet, with a smooth surface and no sediment, and the appearance and cross section are black. The sample was tested to contain 21.9wt% Fe3O4 on a dry basis. Example 8

[0077] Using the preparation conditions of the ferroferric oxide / resin microspheres described in Example 1, the steps (2) to (4) of Example 1 were basically followed to prepare another ferroferric oxide / resin microsphere, the main differences being that: in step (2), p-divinylbenzene was replaced with the same amount of m-divinylbenzene, and 34 kg of the filter cake prepared and stored for 40 h in step (1) was added; in step (3), 300 L of an aqueous solution containing 1.0 wt % of polyvinyl alcohol (PVA 17-88) was used as the suspending dispersion; in step (4), oxygen was introduced into the space above the liquid level in the reactor and the positive pressure in the reactor was maintained at 8.5-9.0 kPa, and the reaction was carried out at a feed liquid temperature of 78° C. for 22.7 h until the oxygen flow meter returned to zero (the feed liquid in the reactor no longer consumed oxygen).

[0078] The prepared hydrous ferroferric oxide / resin microspheres were sampled and tested. They could be adsorbed by a magnet, had a smooth surface without sediment, and were uniformly black in appearance and cross-section. This indicated that the generated ferroferric oxide nanoparticles were loaded in the inner pores of the resin microspheres. The microspheres were dried in a vacuum oven at an absolute pressure of 70 kPa and 70 °C for 5 h to a constant weight. They contained 24.6 wt% Fe3O4 and had a specific surface area (BET) of 65 m 2 / g; the pore volume on a dry basis is 0.63mL / g (water on the surface of the microspheres and between the particles is absorbed with slow filter paper, 5.00g of the material is weighed and dried for 3h to constant weight under vacuum conditions at a temperature of 60°C and a final absolute pressure of 5kPa, and the weight is calculated based on the weight loss); the dried microsphere material can absorb water quickly and has good hydrophilicity; the detection strength and wear resistance meet the requirements for long-term operation of the chromatographic column.

[0079] The ferrosoferric oxide / resin microspheres were loaded into the chromatographic column (filling height 4590 mm, volume 36.0 L) after the separation operation in Example 7 was completed. The entire chromatographic column was first filled with high-purity distilled water at 25°C, and the column was washed for 10 hours (water was introduced at a flow rate of 18 L / h for 1 hour, and then reduced to 9 L / h), and then the column was washed with a sodium hydroxide aqueous solution with a pH value of 10.6 (i.e., the desorption liquid used subsequently) for 10 hours (flow rate 9 L / h); at the same time, circulating water at 25°C was passed from bottom to top in the outer sleeve.

[0080] Then, the boric acid-monosodium borate aqueous solution was added. 10 B and 11The first group of dynamic separation tests of B was repeated for a total of 20 separation operation cycles, with a sodium hydroxide aqueous solution with a pH value of 10.6 as the desorption liquid and a column temperature of 25°C. In each separation operation cycle, the steps (a) to (c) in Example 1 were first operated 30 times, with a column temperature of 25°C. The adsorption liquid introduced each time had a pH value of 6.5 and a total concentration of 0.79 mol / L (49 g / L in terms of boric acid, which is approximately 90% of the concentration of a saturated boric acid aqueous solution). The desorption liquid continued to be a sodium hydroxide aqueous solution with a pH value of 10.6. The effluent with a concentration of 2-15 g / L collected after the total concentration in terms of boric acid reached the maximum value was combined and mixed, and used as the raw material for repeating the operation of Example 3, and then evaporated and concentrated, and the saturated rich solution obtained by cooling to 25°C was obtained. 10 B boric acid aqueous solution, and used to prepare an adsorption solution with a pH value of 6.5; finally, the separation process and discharge liquid detection of Examples 4-6 were completely repeated. In the process of repeating Examples 1, 3-5, in each example, only the combined mixed solution of the discharge liquid with a concentration of 2-15g / L (when repeating Example 1) or 1-12g / L (when repeating Examples 3-5) collected after the total concentration of boric acid reached the maximum value was taken for testing once. 10 B abundance.

[0081] After the first set of dynamic separation tests, the chromatographic column was fed with high-purity distilled water at 25°C for 18 hours (flow rate 2.0 L / h, to wash the column until the boric acid concentration in the effluent was less than 0.1 g / L), and then with a 0.4 mol / L sodium hydroxide aqueous solution at 25°C for 10 hours (flow rate 2.0 L / h), and then with a sodium hydroxide aqueous solution with a pH value of 10.6 for 10 hours (flow rate 2.0 L / h) to complete the alkaline washing regeneration treatment of the chromatographic column.

[0082] Finally, the boric acid-monosodium borate aqueous solution was 10 B and 11 The second group of dynamic separation tests of B was repeated for twenty separation operation cycles, basically in accordance with the dynamic separation test before the chromatographic column alkaline washing and regeneration treatment, but the feed amount of the adsorption liquid was increased to 7.2L each time (20% of the volume of the ferroferric oxide / resin microsphere bed of 36.0L in the chromatographic column, consisting of 6.6L of saturated boric acid aqueous solution at 25°C, dropwise addition of 2mol / L sodium hydroxide aqueous solution, adjusted to the required pH value, then diluted to 7.2L with water and stirred evenly), the feed liquid flow rate remained unchanged at 2.0L / h (the apparent or axial flow velocity in the separation bed was about 0.51m / h).

[0083] The main results of the chromatographic separation in Example 8 include: the effect of the first group of dynamic separation tests is basically the same as that in Examples 1-7. After the total concentration of boric acid collected in each separation operation cycle reaches the maximum value, the effluent with a concentration of 1-12 g / L is detected. 10The abundance of B was higher than 95.5%, with the highest reaching 97.3%. The second group of dynamic separation tests can roughly reproduce the effect of the first group of dynamic separation tests. After the total concentration of boric acid collected in each separation operation cycle reached the maximum value, the effluent with a concentration of 1-12g / L was detected. 10 The abundance of B was higher than 92.0%, with the highest reaching 95.2%, indicating that the alkaline washing regeneration treatment of the chromatographic column was effective. Comparative Example 3

[0084] This comparative example 3 is a comparative example for preparing ferroferric oxide / resin microspheres.

[0085] The ferroferric oxide / resin microspheres of Comparative Example 3 were prepared using the same preparation conditions as in Example 1 and in accordance with steps (1) to (4) of Example 1, with the main difference being that the ingredients in step (2) did not contain acrylic acid and ethanolamine.

[0086] The ferroferric oxide / resin microspheres prepared in this comparative example 3, after being dried in a vacuum drying oven at an absolute pressure of 70 kPa and 70° C. for 5 hours to constant weight, have a water absorption rate that is slower than that of the ferroferric oxide / resin microspheres prepared in Examples 1 and 8 and vacuum dried under the same conditions, indicating that the acrylic acid in the polymerization ingredients improves the hydrophilicity of the microsphere resin skeleton. Comparative Example 4

[0087] This comparative example 4 is a comparative example for preparing ferroferric oxide / resin microspheres.

[0088] The ferroferric oxide / resin microspheres of Comparative Example 4 were prepared using the same preparation conditions as in Example 1 and in accordance with steps (2) to (4) of Example 1. The main differences were that the ingredients in step (2) did not contain isoamyl alcohol (34 kg of cyclohexane was used as a porogen), and 34 kg of filter cake prepared and stored for 38 h in step (1) of Comparative Example 3 was used. Comparative Example 5

[0089] This comparative example 5 is a comparative example for preparing ferroferric oxide / resin microspheres.

[0090] Using some of the preparation conditions of the ferroferric oxide / resin microspheres used in Example 1, the ferroferric oxide / resin microspheres of Comparative Example 5 were prepared according to the following steps:

[0091] In another glass-lined reactor (volume 600L, no water in the reactor), add the cross-linking degree 25 and specific surface area 152m 2 / g, pore volume 0.83mL / g, average pore diameter 22nm, dried (120℃x3h drying weight loss 0.13wt%) polystyrene-divinylbenzene resin microspheres (the same as used in Example 1, made from a mixed ingredient containing a porogen, after being formed into balls by suspension polymerization, the porogen is removed and the white balls are washed with hot water and cold water successively and dried, with an outer diameter range of 0.6-0.9mm, hydrophobic) 20kg, a closed reactor, evacuated to below 3kPa (absolute pressure), and filled with high-purity nitrogen (99.99v%, O2 content less than 30ppmv) to 30-40kPa (gauge pressure) and repeat 3 times, replace the air in the kettle and maintain positive pressure in the following operations of this step, press in 90kg of dimethyl sulfoxide (purity 99.7wt%), heat to 60℃ and swell at 60-65℃ for 3h, start stirring, press in 20kg of 93wt% concentrated sulfuric acid, control the temperature at 80-85℃ for sulfonation treatment, and the sulfonation rate reaches 4.18mmol / g ( 4.18meq / g, hydrophilic), stop stirring, discharge the liquid phase through the bottom discharge port of the kettle, inject oxygen-free water to wash until the pH of the water outlet at the bottom discharge port is 2.4, add oxygen-free water to the volume of the feed liquid to about 550L; continue stirring, add 9.0L of 2.4mol / L ferric chloride aqueous solution, add 6.76L of 1.6mol / L ferrous chloride aqueous solution after 4h, raise the temperature of the feed liquid to 55℃ after 1h, control the temperature at 55-60℃ and add 8.8mol / L ammonia aqueous solution (dropping time 2.2h) to The pH value of the feed liquid is 8.1, and a coprecipitation reaction is carried out. After 1 hour, stirring is stopped, and the microspheres are placed and aged for 10 hours (the strength of the deposition layer on the surface of the resin microspheres gradually increases). After that, the liquid phase (black slurry, containing ferroferric oxide that has not been deposited on the surface of the resin microspheres and can be adsorbed by a magnet) is discharged through the discharge port at the bottom of the kettle. Anoxic water is added to wash until the pH value of the water discharged from the discharge port at the bottom of the kettle reaches 5.2. Anoxic water is added to immerse the resin microspheres, and the resin microspheres and the immersion water are discharged into a container that has been replaced with nitrogen in advance and the container is sealed to obtain ferroferric oxide / resin microspheres.

[0092] As a result, the hydrous ferroferric oxide / resin microspheres prepared in this comparative example 5 can be adsorbed by a magnet, and there is a slightly rough black deposition layer on the surface. The black surface deposition layer has a certain strength but will deform or even fall off when squeezed. The cross section is light black, and the sampling test shows that it contains 8.6wt% Fe3O4 on a dry basis. The method of separating boron isotopes using ferroferric oxide / resin microspheres, the content and distribution of ferroferric oxide are basically the same as those of Fe3O4@Resin-1 in the master's thesis "Preparation of ferroferric oxide loaded resin and study on boron isotope separation performance" (Wang Qingfeng, Tianjin University, May 2021), but Fe 3+ with Fe 2 + The feed molar ratio was changed to 2:1.

[0093] Comparative Examples 6-7

[0094] The ferroferric oxide / resin microspheres prepared in Examples 2 and 3 of CN119186536A applied by the related unit were used as the adsorption separation agent of Comparative Examples 6 and 7, respectively, and the Fe3O4 contents on a dry basis were 12.4wt% and 10.2wt%, respectively.

[0095] The ferroferric oxide / resin microspheres prepared in Comparative Examples 3-5 and the ferroferric oxide / resin microspheres described in Comparative Examples 6-7 were successively subjected to chromatographic column (filling height 4590 mm, volume 36.0 L) and ancillary equipment conditions identical to those in Example 1 in aqueous boric acid. 10 B. 11 B boron isotope separation test. After each microsphere is loaded into the column, the entire chromatographic column is first filled with high-purity distilled water at 25°C, and the column is washed for 10 hours (water is introduced at a flow rate of 18L / h for 1 hour, and then reduced to 9L / h), and then the column is washed for 10 hours (flow rate 9L / h) with a sodium hydroxide aqueous solution with a pH value of 10.6 (i.e., the desorption liquid used subsequently); at the same time, circulating water at 25°C is passed from bottom to top in the outer sleeve; then, the steps (a)-(c) in Example 1 are performed three times to carry out a dynamic separation test. The pH value of the adsorption liquid, i.e., the boric acid-monosodium borate aqueous solution, is 6.5 each time, and the desorption liquid is still a sodium hydroxide aqueous solution with a pH value of 10.6. The main result is that after the total concentration of boric acid collected reaches the maximum value, the concentration of the effluent is 2-15g / L, and the detection 10 The B abundance is lower than 28.4%, and the separation performance is much lower than that of the ferroferric oxide / resin microspheres prepared and used in Examples 1 and 8.

[0096] The ferroferric oxide / resin microspheres described in Comparative Example 6 were subjected to the separation process of Examples 1 and 3-6 (one separation operation cycle), with high-purity distilled water being used as the desorption liquid and the column temperature being 25°C. The steps (a)-(c) in Example 1 were first operated 30 times, with the column temperature being 25°C. The adsorption liquid introduced each time had a pH value of 6.5 and a total concentration of 0.79 mol / L (49 g / L in terms of boric acid, which is approximately 90% of the concentration of a saturated aqueous boric acid solution), and the liquid inlet flow rate was 2.0 L / h (the apparent or axial flow velocity in the separation bed was approximately 0.51 m / h, and the volume of the resin microspheres in the separation bed accounted for approximately 50%). The effluents with a concentration of 2-15 g / L collected after the total concentration in terms of boric acid reached the maximum value were combined and mixed, and used as the raw material for repeating the operation of Example 3. The saturated boric acid solution was then concentrated by evaporation and cooled to 25°C to obtain the saturated boric acid solution. 10B boric acid aqueous solution, and used to prepare an adsorption solution with a pH value of 6.5; finally, the separation process and discharge liquid detection of Examples 4-6 were completely repeated. In the process of repeating Examples 1, 3-5, in each example, only the combined mixed solution of the discharge liquid with a concentration of 2-15g / L (when repeating Example 1) or 1-12g / L (when repeating Examples 3-5) collected after the total concentration of boric acid reached the maximum value was taken for testing once. 10 The main result is that the total concentration of boric acid in the final collection reaches the maximum, and the concentration of 1-12g / L discharge liquid is detected. 10 The abundance of B is 42.5%.

[0097] The ferroferric oxide / resin microspheres of the above Examples 1, 8 and Comparative Examples 5-7 were dried in a vacuum drying oven at 70°C for 5h to constant weight. The crystal phase of iron in each ferroferric oxide / resin microsphere was determined by XRD method. The crystal size averages were 3.9nm, 4.0nm, 12nm, 4.1nm, and 3.4nm, respectively. The valence ratio of iron in the ferroferric oxide / resin microspheres of Examples 1 and 8 was determined by redox titration method. It was inferred that the content of Fe3O4 crystal phase in the loaded iron oxide was above 94.6%. In the above Examples and Comparative Examples, the preparation of ferroferric oxide / resin microspheres and the physical and chemical index tests thereof were completed by the applicant, and the chromatographic separation test was completed jointly with the associated units.

Claims

1. A process for separating boron isotopes to prepare boric acid-10, using a chromatographic column with ferroferric oxide / resin microspheres as the stationary phase, a boric acid-sodium borate aqueous solution with a pH value of 6-7 as the adsorption liquid, and a sodium hydroxide aqueous solution with a pH value of 10-11 as the desorption liquid, and iteratively separating to obtain a rich 10 Boric acid-monosodium borate aqueous solution of B is further used to prepare boric acid-10; The ferroferric oxide / resin microsphere material is prepared by the following steps: (1) In a first jacketed stirred reactor, nitrogen replacement is performed, the jacket water temperature is controlled at 70-80°C, ferrous chloride or ferrous sulfate aqueous solution at 70-80°C is added, stirring is started, and sodium carbonate aqueous solution at 70-80°C is added until the slurry pH value is 8.0-8.5, the sodium carbonate aqueous solution is added for 1-2 hours, stirring is stopped and heat-insulated and aged for 5-10 hours, sodium methyl silicate aqueous solution is added, stirred evenly, heat-insulated for 3-5 hours, and the feed liquid is filtered to obtain a methylsilicic acid-coated, water-containing ferrous hydroxide filter cake; the molar ratio of sodium methyl silicate to ferrous chloride or ferrous sulfate is (1-1.5):100; the concentration of ferrous chloride or ferrous sulfate aqueous solution is 1.5-2.5 mol / L, and the concentration of sodium carbonate aqueous solution is 1.8-2.5 mol / L; (2) In a stirred container, nitrogen is replaced, styrene, acrylic acid, divinylbenzene from which the polymerization inhibitor has been removed, ethanolamine, porogen isoamyl alcohol-cyclohexane solution, and initiator azobisisobutylamidine hydrochloride are added, stirred and dissolved to prepare a polymerization solution, the filter cake obtained in step (1) and silane coupling agent KH-550 are added, stirred evenly, and treated with a colloid mill to obtain a mixed slurry; wherein the divinylbenzene is p-divinylbenzene or m-divinylbenzene; and the molar ratio of styrene, acrylic acid, and divinylbenzene is (6-8):(0.5-0.8) :1; the molar ratio of acrylic acid to ethanolamine is 1:(1.0-1.1); the weight ratio of the total amount of styrene, acrylic acid, and divinylbenzene to the isoamyl alcohol-cyclohexane solution, azobisisobutyramidine hydrochloride, and KH-550 is 100:(80-120):(0.6-1):(1-2); the weight ratio of the total amount of styrene, acrylic acid, and divinylbenzene to the iron in the filter cake as Fe3O4 is 100:(25-36); the isoamyl alcohol content in the isoamyl alcohol-cyclohexane solution is 5-8wt%; (3) In a stirred reactor with a jacket and a vacuum system, nitrogen is replaced, the jacket water temperature is controlled at 75-80°C, an aqueous solution containing 0.4-1wt% of polyvinyl alcohol is added as a suspension dispersion, stirring is started, and when the temperature rises to above 70°C, the mixed slurry obtained in step (2) is added. After the feed liquid is heated to above 70°C and reacted for 3-5 hours, the vacuum system is turned on to evaporate and remove the cyclohexane in the porogen contained in the microspheres generated in the feed liquid; the vacuum system is closed, nitrogen is filled to normal pressure, and a sodium hydroxide aqueous solution of the required concentration is added to the feed liquid so that the NaOH concentration in the feed liquid is 0.1-0.2 mol / L. After reacting for 2-3 hours, the feed liquid is discharged and filtered, and the filtered microspheres are washed with water to obtain a semi-finished microsphere material; wherein, The volume ratio of the suspension dispersion to the mixed slurry is (230-350):100, and the average diameter of the microspheres is controlled to be 0.5-0.8 mm by adjusting the stirring speed; the alcoholysis degree of the polyvinyl alcohol is 85-90%, and the degree of polymerization is 1500-2000; (4) In a second stirred reactor with a jacket, the jacket water temperature is controlled at 75-80°C, water at 70-80°C is added, the semi-finished microsphere material obtained in step (3) is added, stirring is started, and a hydrochloric acid aqueous solution is added to adjust the pH value of the liquid to 7.0-8.

5. Oxygen is introduced into the space above the liquid surface of the reactor, and the gas above the liquid surface is replaced. After closing the reactor, oxygen is continued to be introduced and a positive pressure of 5-10 kPa is maintained in the reactor. The reaction is carried out at a liquid temperature of 70-80°C for 15-25 hours until the liquid in the reactor no longer consumes oxygen, and then the liquid is discharged and filtered. The filtered microsphere material is washed with water to obtain a ferroferric oxide / resin microsphere material; wherein the weight ratio of the added water to the semi-finished microsphere material is (200-250):

100.

2. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: The separation operating conditions include: the chromatographic column is installed vertically, the column temperature is 15-35°C, the adsorption liquid and the desorption liquid are both in-and-out from the top; the boric acid concentration in the boric acid-monosodium borate aqueous solution is 80-95% of the saturated concentration in water under column temperature conditions; the apparent or axial flow rate of the adsorption liquid and the desorption liquid in the stationary phase bed is 0.4-0.6m / h.

3. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: The chromatographic column adopts a cylindrical barrel, in which a separation bed filled with the ferroferric oxide / resin microsphere material is arranged, a screen and a heavy pressure material are arranged above the separation bed, a screen and a support are arranged below the separation bed, and an insulation layer or a circulating water jacket is arranged outside the barrel; electric valves and measuring / control components of a temperature measuring instrument, a concentration meter and a flow meter are appropriately arranged in the inlet and outlet liquid interfaces of the chromatographic column or its connecting pipelines; the electric valves and the instruments are connected to an intelligent controller, the intelligent controller is connected to a computer, and the control of liquid inlet and liquid outlet, solution segmentation logic and flow control are realized through computer settings, thereby controlling the liquid inlet selection, the liquid outlet destination and the segmentation and collection of the liquid outlet.

4. The process for separating boron isotopes to prepare boric acid-10 according to claim 3, characterized in that: The measuring components of the concentration meter include a boric acid concentration transmitter and a pH value transmitter.

5. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: In the inlet flow of the chromatographic column, the single inlet volume of the adsorption liquid is 12-25% of the separation bed volume.

6. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: In the effluent of the chromatographic column, the portion of 0.5-15 g / L after the total concentration of boric acid and monosodium borate reaches the maximum value in terms of boric acid is taken as the enriched portion. 10 The liquid B is collected and concentrated before further processing and utilization.

7. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: In the effluent flow of the chromatographic column, the portion with a total concentration of boric acid and monosodium borate below 0.2 g / L in terms of boric acid is collected as a desorption liquid and recycled, and the portion with a pH value below 10 is collected and adjusted back to 10-11 by adding sodium hydroxide aqueous solution and continues to be used as a desorption liquid.

8. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: The content of impurities other than water in the boric acid and sodium hydroxide used in preparing the adsorption liquid and the desorption liquid is less than 0.1wt%; the water used is pure water obtained by ion exchange or reverse osmosis, which is degassed by slight boiling and then further distilled to obtain high-purity distilled water.

9. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: After the separation efficiency of the chromatographic column decreases, it is regenerated with a sodium hydroxide aqueous solution with a concentration of 0.3-0.5 mol / L. After regeneration, the inlet water is rinsed until the conductivity of the effluent water is lower than 1000 μs / cm; the effluent containing sodium hydroxide and monosodium borate during the regeneration process is used to prepare the adsorption solution.

10. The process for separating boron isotopes to prepare boric acid-10 according to claim 1, characterized in that: rich 10 The boric acid-monosodium borate aqueous solution B is concentrated by reverse osmosis and / or MVR method.