Method for removing divalent metal ions in high-purity boric acid

Abstract

The invention relates to the technical field of refining of high-purity boric acid, and particularly discloses a method for removing divalent metal ions in high-purity boric acid, which comprises the following steps: dissolving the high-purity boric acid in water, filtering, adsorbing by adsorbent resin, filtering to obtain a refined boric acid solution, cooling, crystallizing, evaporating, crystallizing, carrying out suction filtration, and crushing to obtain the refined boric acid. The preparation method of the adsorption resin comprises the following steps: (1) blending polystyrene master batches with acetyl chloride, dispersing, and adding Lewis acid for reaction to obtain acetylated polystyrene particles; and (2) dispersing acetylated polystyrene particles, mixing with p-aminobenzene arsenic acid to react, filtering, and washing with alcohol to obtain the adsorption resin. After the high-purity boric acid is treated by the adsorbent resin prepared by the invention, the purity of the high-purity boric acid can reach 99.99%, and the effect of removing divalent metal ions in the high-purity boric acid can be realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high-purity boric acid refining, and more particularly to a method for removing divalent metal ions from high-purity boric acid. BACKGROUND

[0002] High-purity boric acid generally refers to boric acid with a purity of 99.6% or higher. Due to its excellent physical and chemical properties, high-purity boric acid is used in many fields. In the field of metallurgy, high-purity boric acid can prevent surface oxidation during metal welding and prolong the service life of metal materials during welding. In the field of electronics and optical fibers, high-purity boric acid is an important glass fiber additive that can be used for modification of heat resistance and mechanical strength of glass fibers to improve the weather resistance of glass fiber materials.

[0003] For the field of electronics and optical fibers, the purity of high-purity boric acid directly affects the precision of electronic instruments, so high-purity boric acid with a purity of 99.99% or higher is often required for high-precision instruments. However, due to defects in raw materials and processes during the refining of high-purity boric acid, a small amount of divalent metal ions such as Fe 2+ , Ca 2+ , Mg 2+ , Pb 2+ may be introduced into the refined high-purity boric acid. If not removed, it may cause a significant decrease in instrument precision and various problems, such as unstable performance of semiconductor devices and reduced optical transparency of optical glass. In addition, some metal ions (such as Pb 2+ ) are toxic to the human body, and if their content in high-purity boric acid exceeds the standard, it may harm human health. Therefore, how to remove a small amount of divalent metal ion impurities from high-purity boric acid has become a research focus.

[0004] Chinese patent application file with publication number CN102020287A discloses a high-purity boric acid refining process for borosilicate glass. In the scheme, a modified peanut shell powder is used as an adsorbent, combined with an inorganic polymer flocculant and an ion exchange resin process to remove water-insoluble substances, metal ions and acid ions from industrial boric acid. After treatment, the prepared high-purity boric acid has a purity of 99.99%.

[0005] Although the above-mentioned application file achieves the refinement of high-purity boric acid, the application file only lists the removal effect of iron ions, and does not mention the removal effect of other metal ions. In addition, the modified peanut shell powder preparation process requires alkali leaching activation treatment of the peanut shell powder. In the acidic boric acid treatment solution, acid-base neutralization may cause a decrease in adsorption effect. Therefore, there is still a need to find an adsorbent that has good environmental adaptability and can efficiently adsorb divalent metal impurity ions. SUMMARY

[0006] In order to further efficiently remove divalent metal ions in high-purity boric acid, the present application provides a method for removing divalent metal ions in high-purity boric acid.

[0007] A method for removing divalent metal ions from high-purity boric acid comprises the following steps: (S01) taking high-purity boric acid, dissolving it in water at 65-70°C, stirring it, and filtering it to obtain a pre-solution; (S02) adding an adsorption resin to the pre-solution, maintaining the solution at a constant temperature of 70-75° C. with intermittent stirring, and then repeatedly returning the solution to the solution. After filtering, a refined boric acid solution and a used adsorption resin are obtained. The adsorption resin is based on acetylated polystyrene and has p-aminophenylarsonic acid as the active adsorption component, and is obtained through a carbonyl-ammonia condensation reaction. (S03) taking a refined boric acid solution, cooling it for crystallization, letting it stand and then filtering it to obtain a solid phase and a mother liquor, evaporating and crystallizing the mother liquor and mixing it with the solid phase, filtering it, drying and grinding it to obtain refined boric acid.

[0008] The preparation steps of the adsorption resin include the following: (I) Mixing polystyrene masterbatch with acetyl chloride, dispersing with a first solvent, adding a second solvent to continue dispersing, stirring, then adding a Lewis acid catalyst, reacting at a temperature of 25-30°C for 2-3 hours, allowing to stand, filtering, washing with water 2-3 times, and drying to obtain acetylated polystyrene particles; (II) Acetylated polystyrene particles, triethylamine, and anhydrous magnesium sulfate are mixed, the temperature and magnetic stirring speed are adjusted, and the mixture is dispersed. Then, p-aminophenylarsonic acid is added and reacted. The solid portion is filtered and washed with alcohol to obtain an adsorption resin.

[0009] By employing this technical solution, the purity of high-purity boric acid after treatment can reach 99.99%. The adsorption resin used in the treatment process can efficiently remove residual divalent metal ions from the high-purity boric acid. In the adsorption resin, acetylated polystyrene serves as a carrier for the active component, p-aminophenylarsonic acid, which adsorbs divalent metal impurities. After adsorption is complete, the adsorption resin is removed from the system by filtration. The amino functional group of p-aminophenylarsonic acid is grafted onto the carbonyl moiety of the acetylated polystyrene through a carbonyl-amine condensation reaction. Due to the complexation of the central arsenic atom and the electron donation effect of the arsenic-oxygen double bond (As=O), the arsenate group can coordinate with the divalent metal impurity ions in the pre-solution. Through stirring and temperature treatment, efficient adsorption of divalent metal impurities is achieved. After desorption with a desorption solution, the used adsorption resin can be re-added to the pre-solution to re-adsorb divalent metal impurities.

[0010] Preferably, in the step (S01), the mass ratio of water to high-purity boric acid is controlled to be (4-5):1 during the water dissolution process.

[0011] By adopting the above technical solution, the solubility of high-purity boric acid in water increases with the increase of the solid-liquid ratio. By adjusting the solid-liquid ratio, a nearly saturated aqueous solution of high-purity boric acid can be obtained. In the subsequent cooling and crystallization step, impurity ions with good water solubility can be retained in the liquid phase and removed, thereby obtaining high-purity boric acid with a higher impurity removal rate.

[0012] Preferably, in step (I), the first solvent is acetone, the second solvent is n-butane, and the volume ratio of acetone to n-butane is 1:(10-15).

[0013] By adopting the above technical solution, the small amount of acetone added can swell the polystyrene masterbatch, expanding its pore structure and facilitating the Friedel-Crafts alkylation reaction. Furthermore, the large pores enhance the physical adsorption of divalent metal impurity ions in the pre-solution by the adsorption resin, improving adsorption efficiency. n-Butane, a poor solvent for the polystyrene masterbatch, maintains its structural integrity during the reaction, resulting in acetylated polystyrene particles.

[0014] Preferably, in step (I), the Lewis acid catalyst is one of aluminum chloride, aluminum bromide, and antimony pentafluoride.

[0015] By adopting this technical solution, during the reaction, the Lewis acid catalyst combines with the alkylating agent acetyl chloride to form a more active alkyl carbocation. The resulting alkyl carbocation acts as an electrophile, attacking the π electron cloud on the aromatic ring of polystyrene, thereby forming an intermediate σ-complex and completing the grafting. The use of this Lewis acid catalyst helps promote the Friedel-Crafts alkylation reaction.

[0016] Preferably, in step (II), triethylamine is used as the reaction solvent.

[0017] By adopting this technical solution, triethylamine provides an alkaline environment and plays a dual role. First, the proton in the amino group of p-aminophenylarsonic acid is lost in the alkaline environment of triethylamine, generating a more nucleophilic amino anion, which accelerates the nucleophilic attack of p-aminophenylarsonic acid on the carbonyl group. Second, triethylamine stabilizes the reaction intermediates, promoting more efficient reaction.

[0018] Preferably, in step (II), the mass volume ratio of acetylated polystyrene particles, triethylamine, anhydrous magnesium sulfate, and p-aminophenylarsonic acid is (10-12) g: (45-50) mL: (1-2) g: (3.5-4.8) g.

[0019] By employing the above-mentioned technical solution, the reaction in this process is a nucleophilic addition of the lone pair of electrons of the amino nitrogen atom to the carbonyl group, resulting in a hemiaminal intermediate. This intermediate further reacts, eliminating a molecule of water, ultimately forming a C=N graft structure. Because the carbon-nitrogen double bond connects to the aromatic group, the resulting conjugated Schiff base system has a more uniform electron cloud distribution. Furthermore, the large steric groups of the benzene ring shield the reactive groups that could potentially disrupt the C=N structure, thereby increasing the stability of the graft structure. By adjusting the dosage of p-aminophenylarsonic acid, after the reaction is complete, the unreacted acetyl oxygen atoms on the polystyrene can form hydrogen bonds with the arsenic hydroxyl groups on the p-aminophenylarsonic acid, further stabilizing the graft structure.

[0020] Preferably, in the step (S02), the intermittent stirring treatment is carried out at a frequency of 300-350 rpm for 1-3 minutes, followed by standing for 5 minutes, and lasting for 1-1.5 hours.

[0021] Preferably, the step (S02) further includes a desorption treatment of the used adsorption resin, specifically: placing the used adsorption resin in a desorption liquid, adjusting the temperature to 45-55°C, the ultrasonic frequency to 20-21.5KHz, and ultrasonically treating for 20-30min, then filtering to remove the liquid phase, and then immersing the solid part in a 3.5%-4.2% mass fraction of disodium ethylenediaminetetraacetic acid aqueous solution for elution, washing with water and collecting; the desorption liquid is prepared by mixing water, 0.05mol / L sodium hydroxide, and ethylamine in a volume ratio of (200-300): (25-50): (10-12).

[0022] By adopting the above technical solution, the desorption effect of the used adsorption resin is best.

[0023] Preferably, in the step (S03), the cooling crystallization is: cooling to 45-50°C at a rate of 1-1.2°C / min, and then cooling to 7.5-10°C at a rate of 0.5-0.8°C / min.

[0024] By adopting this technical solution, dual-gradient cooling can accelerate the crystallization process and produce higher-quality boric acid crystals. The faster cooling in the first stage can quickly lower the solution temperature, causing the solution to reach a supersaturated state of boric acid and accelerating the nucleation and growth of crystals. The second stage, with a cooling gradient, slows the further growth rate of the crystals, allowing them sufficient time to arrange themselves in an orderly manner, resulting in more uniform boric acid crystals.

[0025] Preferably, in the step (S03), the evaporative crystallization is carried out under the conditions of relative air humidity of 15%-20% and temperature of 20-25°C.

[0026] By adopting the technical scheme, the residual boric acid in the mother liquor can be collected to the maximum extent, and the yield of refined boric acid is improved.

[0027] In summary, the present application has the following beneficial effects: 1、The present application uses acetylated polystyrene as a matrix, p-aminophenyl arsenic acid as an active adsorption component, and an adsorption resin is obtained through carbonyl-ammonia condensation reaction, which is used for removing divalent metal ions in high-purity boric acid. In the adsorption resin, acetylated polystyrene is used as a carrier to load the active component p-aminophenyl arsenic acid. The amino functional group of p-aminophenyl arsenic acid is grafted and combined with the carbonyl part of acetylated polystyrene through carbonyl-ammonia condensation reaction. Due to the complexation of the central arsenic atom and the electron-donating effect of the arsenic oxygen double bond site (As=O), the arsenate can coordinate with the divalent metal impurity ions in the pre-solution, and through stirring and temperature treatment process, efficient adsorption of divalent metal impurity ions is realized. Finally, the used adsorption resin is separated by filtration to remove the divalent metal impurity ions in the high-purity boric acid.

[0028] 2、In the present application, water, sodium hydroxide and ethylamine are preferably used as the components of the desorption liquid. Through heat and ultrasonic treatment, and using ethylenediaminetetraacetic acid disodium solution for elution, the divalent metal impurity ions adsorbed on the used adsorption resin are removed, so that the adsorption resin can be reused.

[0029] 3、After the adsorption resin of the present application is used, the purity of the high-purity boric acid can be improved to 99.99%, which meets the relevant standards of type II boric acid products. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The metal impurity ion content test results of the refined boric acid obtained after 4 cycles of the adsorption resins of Examples 1-3 and Comparative Examples 1-2 are shown in Table 1. DETAILED DESCRIPTION

[0031] The purity and main impurity content of the high-purity boric acid used in Examples 1-3 and Comparative Examples 1-2 are shown in Table 1.

[0032] Table 1 Purity and main impurity content of high-purity boric acid

[0033] Example 1 The method for removing divalent metal ions from high-purity boric acid in this example is as follows: (S01) Take 50g of high-purity boric acid and mix with 200g of deionized water. Adjust the magnetic stirring speed to 300rpm and the temperature to 65℃. Stir continuously for 1h. After removing the water-insoluble substances by filtration, a pre-solution is obtained.

[0034] (S02) Add 10g of adsorption resin to the pre-solution, adjust the temperature to 70℃, stir at a magnetic stirring speed of 300rpm for 1min, then let it stand for 5min and stir intermittently for 1h, then filter, repeat the intermittent stirring treatment of the filtered liquid phase, return the liquid twice, and finally filter and take the liquid part to obtain a refined boric acid solution. The adsorption resin is placed in 500mL of desorption liquid, adjust the temperature to 45℃, ultrasonic frequency to 20KHz, and ultrasonically treat for 20min, then filter and take the solid part, immerse it in 15mL of 3.5% mass fraction of disodium ethylenediaminetetraacetic acid aqueous solution for elution, wash it with water 3 times and then filter and collect it.

[0035] (S03) The purified boric acid solution was first cooled to 45°C at a rate of 1°C / min, then to 7.5°C at a rate of 0.5°C / min. The solution was allowed to stand for 8 hours and then filtered to obtain a solid phase and a mother liquor. The mother liquor was evaporated and crystallized at a relative humidity of 15% and a temperature of 20°C. The crystalline product was collected and mixed with the solid phase. Residual water was removed by filtration, and the product was then dried in an oven at 25°C and ground for 1 minute to obtain purified boric acid.

[0036] The preparation steps of the adsorption resin in this embodiment are as follows: (I) Take 10g of polystyrene masterbatch, mix it with 2.5mL of acetyl chloride, and then use 5mL of acetone to disperse it. Control the magnetic stirring speed to 100rpm. After stirring for 5min, add 50mL of n-butane and continue to disperse it for 5min. Then add 0.5g of aluminum chloride and continue stirring. Control the temperature to 25℃. After reacting for 25min, continue to add an equal amount of aluminum chloride. After reacting for another 1h, stop stirring and let it stand at room temperature for 2h. Filter the solid part, wash it with alcohol twice, remove the residual solvent and dry it to obtain acetylated polystyrene particles.

[0037] (II) Add 10 g of acetylated polystyrene particles to 45 mL of triethylamine, add 1 g of anhydrous magnesium sulfate, and stir at 100 rpm at 20°C for 5 min. Then, add 3.5 g of p-aminophenylarsonic acid and continue stirring for 3 h. Filter the solids and wash twice with alcohol to obtain an adsorption resin.

[0038] The desorption solution was prepared by mixing water, 0.05 mol / L sodium hydroxide, and ethylamine in a volume ratio of 40:5:2. The polystyrene masterbatch had a crosslinking degree of 8.3% and an average particle size of 0.2 mm.

[0039] Example 2 The method for removing divalent metal ions from high-purity boric acid in this embodiment is as follows: (S01) 50 g of high-purity boric acid was mixed with 225 g of deionized water. The magnetic stirring speed was adjusted to 300 rpm and the temperature was 70°C. The stirring was continued for 1.5 h. The pre-solution was obtained after filtering to remove the water-insoluble matter.

[0040] (S02) Add 12g of adsorption resin to the pre-solution, adjust the temperature to 70℃, stir at a magnetic stirring speed of 300rpm for 3min, then let it stand for 5min with intermittent stirring for 1.5h, then filter, repeat the intermittent stirring treatment of the filtered liquid phase, return the liquid twice, and finally filter and take the liquid part to obtain a refined boric acid solution. The adsorption resin is placed in 500mL of desorption liquid, adjust the temperature to 50℃, the ultrasonic frequency to 21.5KHz, and ultrasonically treat for 25min. Then filter and take the solid part, immerse it in 15mL of 4% by mass disodium ethylenediaminetetraacetic acid aqueous solution for elution, wash it with water 3 times and then filter and collect it.

[0041] (S03) The purified boric acid solution was first cooled to 50°C at a rate of 1.2°C / min, then to 10°C at a rate of 0.8°C / min. The solution was allowed to stand for 10 hours and then filtered to obtain a solid phase and a mother liquor. The mother liquor was evaporated and crystallized at a relative humidity of 20% and a temperature of 25°C. The crystalline product was collected and mixed with the solid phase. Residual water was removed by filtration, and the product was then dried in an oven at 30°C and ground for 2 minutes to obtain purified boric acid.

[0042] The preparation steps of the adsorption resin in this embodiment are as follows: (I) Take 10g of polystyrene masterbatch, mix it with 3mL of acetyl chloride, and then use 5mL of acetone to disperse it. Control the magnetic stirring speed to 100rpm. After stirring for 5min, add 50mL of n-butane and continue to disperse it for 5min. Then add 0.5g of aluminum bromide and continue stirring. Control the temperature to 30℃. After reacting for 35min, continue to add an equal amount of aluminum bromide. After reacting for another 2h, stop stirring and let it stand at room temperature for 3h. Filter the solid part, wash it with alcohol 3 times, remove the residual solvent and dry it to obtain acetylated polystyrene particles.

[0043] (II) Add 12 g of acetylated polystyrene particles to 50 mL of triethylamine, add 2 g of anhydrous magnesium sulfate, and stir at 125 rpm at 30°C for 20 min. Then, add 4.8 g of p-aminophenylarsonic acid and continue stirring for 5 h. The mixture is then filtered, and the solid fraction is washed twice with alcohol to obtain an adsorption resin.

[0044] The desorption solution was prepared by mixing water, 0.05 mol / L sodium hydroxide, and ethylamine in a volume ratio of 25:5:1. The polystyrene masterbatch had a crosslinking degree of 8.3% and an average particle size of 0.2 mm.

[0045] Example 3 The method for removing divalent metal ions from high-purity boric acid in this embodiment is as follows: (S01) 50 g of high-purity boric acid was mixed with 250 g of deionized water. The magnetic stirring speed was adjusted to 350 rpm and the temperature was adjusted to 70°C. The stirring was continued for 2 h. The pre-solution was obtained after filtering to remove the water-insoluble matter.

[0046] (S02) Add 15g of adsorption resin to the pre-solution, adjust the temperature to 75℃, stir at a magnetic stirring speed of 350rpm for 3min, then let it stand for 5min with intermittent stirring for 1.5h, then filter, repeat the intermittent stirring treatment of the filtered liquid phase, return the liquid twice, and finally filter and take the liquid part to obtain a refined boric acid solution. The adsorption resin is placed in 500mL of desorption liquid, adjust the temperature to 55℃, ultrasonic frequency to 21.5KHz, and ultrasonically treat for 30min. Then filter and take the solid part, immerse it in 15mL of 4.2% disodium ethylenediaminetetraacetic acid aqueous solution for elution, wash it with water 3 times and then filter and collect it.

[0047] (S03) The purified boric acid solution was first cooled to 50°C at a rate of 1.2°C / min, then to 10°C at a rate of 0.8°C / min. The solution was allowed to stand for 12 hours and then filtered to obtain a solid phase and a mother liquor. The mother liquor was evaporated and crystallized at a relative humidity of 20% and a temperature of 25°C. The crystalline product was collected and mixed with the solid phase. Residual water was removed by filtration, and the product was then dried in an oven at 30°C and ground for 2 minutes to obtain purified boric acid.

[0048] The preparation steps of the adsorption resin in this embodiment are as follows: (I) Take 10g of polystyrene masterbatch, mix it with 3mL of acetyl chloride, and then use 5mL of acetone to disperse it. Control the magnetic stirring speed to 150rpm. After stirring for 5min, add 75mL of n-butane and continue to disperse it for 10min. Then add 0.7g of antimony pentafluoride and continue stirring. Control the temperature to 30℃ and react for 35min. Then continue to add an equal amount of antimony pentafluoride. After reacting for another 2h, stop stirring and let it stand at room temperature for 3h. Filter the solid part, wash it with alcohol 3 times, remove the residual solvent and dry it to obtain acetylated polystyrene particles.

[0049] (II) Add 12 g of acetylated polystyrene particles to 50 mL of triethylamine, add 2 g of anhydrous magnesium sulfate, and stir at 35°C with a magnetic stirrer at 150 rpm for 20 min. Then, add 4.8 g of p-aminophenylarsonic acid and continue stirring for 5 h. Filter the solids and wash them three times with alcohol to obtain an adsorption resin.

[0050] The desorption solution was prepared by mixing water, 0.05 mol / L sodium hydroxide, and ethylamine in a volume ratio of 150:25:6. The polystyrene masterbatch had a crosslinking degree of 8.3% and an average particle size of 0.2 mm.

[0051] Comparative Example 1 The difference between this comparative example and Example 1 is that an equal amount of acetamide is used instead of p-aminophenylarsonic acid in step (II), and the other steps are the same as in Example 1.

[0052] Comparative Example 2 The difference between this comparative example and Example 1 is that phenolic resin (cross-linking degree: 11.7%, average particle size: 0.2 mm) is used instead of the polystyrene masterbatch in step (I), and the other steps are the same as in Example 1.

[0053] Performance testing 1. Referring to the test method and test standard of GB / T538-2018 "Industrial Boric Acid", the test results of the refined boric acid prepared in Examples 1-3 and Comparative Examples 1-2 are shown in Table 2.

[0054] Table 2 Purity and impurity content of refined boric acid obtained in Examples 1-3 and Comparative Examples 1-2

[0055] 2. Referring to the test method and test standard of GB / T538-2018 "Industrial Boric Acid", the treated liquids obtained after the first adsorption and the second liquid return operations in Example 1 and Comparative Examples 1-2 (S02) were tested for metal impurity content. The test results are shown in Tables 3-5.

[0056] Table 3 Metal impurity ion content in the treated liquid obtained after the first adsorption and the second liquid return operation in Example 1

[0057] Table 4 Metal impurity ion content in the treated liquid obtained after the first adsorption and the second liquid return operation in Comparative Example 1

[0058] Table 5 Metal impurity ion content in the treated liquid obtained after the first adsorption and the second liquid return operation in Comparative Example 2

[0059] 3. Referring to the test method and test standard of GB / T538-2018 "Industrial Boric Acid", the purified boric acid obtained after 4 cycles of use of the adsorption resins of Examples 1-3 and Comparative Examples 1-2 was tested for metal impurity ion content. The test results are as follows: Figure 1 As shown in FIG, wherein the 0th cycle refers to the first use of the adsorption resin.

[0060] Analysis of Examples 1-3 and Comparative Examples 1-2 and in combination with Table 2 shows that, among the embodiment schemes, the adsorption resin of Example 3 has the best effect on removing divalent metal ions in high-purity boric acid, and the refined boric acid obtained after treatment with the schemes of Examples 1-3 meets the relevant standards for Class II boric acid products.

[0061] Analysis of Example 1 and Comparative Examples 1-2 and in conjunction with Tables 3-5 shows that after Comparative Example 1 uses acetamide to replace the p-aminophenylarsonic acid in Example 1, the residual amount of lead and arsenic ions after the second liquid return treatment increases, indicating that desorption of lead and arsenic metal ions has occurred. This may be because the acetyl group as the active subject in Comparative Example 2 has a slightly weaker ability to adsorb and bind metal ions, and acetamide lacks the protection of the large steric hindered functional group of the benzene ring, resulting in the coordination structure of the acetyl group with the lead and arsenic metal ions being easily destabilized during the liquid return process, and then desorption. After Comparative Example 2 uses phenolic resin to replace the polystyrene masterbatch in Example 1, the adsorption effect of the adsorption resin on metal impurity ions decreases significantly. This is because the presence of a large number of phenolic hydroxyl structures on the phenolic resin can combine with the boric acid molecules in the pre-solution, hindering the active component from adsorbing metal impurity ions, thereby causing the adsorption effect of the adsorption resin to decrease. Combined with the changes in arsenic ion content, the arsenic ion content in the treatment liquid of Comparative Example 1 is the lowest because no arsenic-containing active component is used; while the arsenic ion content in the treatment liquid of Comparative Example 2 is the highest, which indirectly indicates that during the treatment process, the removal of the active component p-aminophenylarsenic acid on the adsorption resin is relatively serious, and the combination effect of phenolic resin and p-aminophenylarsenic acid is not good.

[0062] Analyze Examples 1-3 and Comparative Examples 1-2 and combine Figure 1 It can be seen that by testing the recycling performance of the adsorption resin, the adsorption effect of the adsorption resin in Examples 1-3 on metal impurity ions remains at a high level after 5 uses, while the adsorption effect of the comparative example 2 on metal impurity ions has been significantly reduced after the third cycle.

[0063] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A method for removing divalent metal ions from high-purity boric acid, characterized in that: The steps include: (S01) taking high-purity boric acid, dissolving it in water at 65-70°C, stirring it, and filtering it to obtain a pre-solution; (S02) adding an adsorption resin to the pre-solution, maintaining the solution at a constant temperature of 70-75° C. with intermittent stirring, and then repeatedly returning the solution to the solution. After filtering, a refined boric acid solution and a used adsorption resin are obtained. The adsorption resin is based on acetylated polystyrene and has p-aminophenylarsonic acid as the active adsorption component, and is obtained through a carbonyl-ammonia condensation reaction. (S03) taking a refined boric acid solution, cooling it for crystallization, letting it stand and then filtering it to obtain a solid phase and a mother liquor, evaporating and crystallizing the mother liquor and mixing it with the solid phase, filtering it, drying and grinding it to obtain refined boric acid.

2. A method for removing divalent metal ions from high-purity boric acid according to claim 1, characterized in that: In the step (S01), the mass ratio of water to high-purity boric acid is controlled to be (4-5):1 during the water dissolution process.

3. A method for removing divalent metal ions from high-purity boric acid according to claim 1, characterized in that: In the step (S02), the preparation of the adsorption resin includes the following steps: (I) Mixing polystyrene masterbatch with acetyl chloride, dispersing with a first solvent, adding a second solvent to continue dispersing, stirring, then adding a Lewis acid catalyst, reacting at a temperature of 25-30°C for 2-3 hours, allowing to stand, filtering, washing with water 2-3 times, and drying to obtain acetylated polystyrene particles; (II) Acetylated polystyrene particles, triethylamine, and anhydrous magnesium sulfate are mixed, the temperature and magnetic stirring speed are adjusted, and the mixture is dispersed. Then, p-aminophenylarsonic acid is added and reacted. The solid portion is filtered and washed with alcohol to obtain an adsorption resin.

4. A method for removing divalent metal ions from high-purity boric acid according to claim 3, characterized in that: In the step (I), the first solvent is acetone, the second solvent is n-butane, and the volume ratio of acetone to n-butane is 1:(10-15).

5. A method for removing divalent metal ions from high-purity boric acid according to claim 3, characterized in that: In the step (I), the Lewis acid catalyst is one of aluminum chloride, aluminum bromide, and antimony pentafluoride.

6. A method for removing divalent metal ions from high-purity boric acid according to claim 3, characterized in that: In the step (II), the mass volume ratio of acetylated polystyrene particles, triethylamine, anhydrous magnesium sulfate, and p-aminophenylarsonic acid is (10-12) g: (45-50) mL: (1-2) g: (3.5-4.8) g.

7. A method for removing divalent metal ions from high-purity boric acid according to claim 1, characterized in that: The step (S02) also includes desorption treatment of the used adsorption resin, specifically: placing the used adsorption resin in a desorption liquid, adjusting the temperature to 45-55°C, the ultrasonic frequency to 20-21.5KHz, and ultrasonic treatment for 20-30 minutes, then filtering to remove the liquid phase, and then immersing the solid part in a disodium ethylenediaminetetraacetic acid aqueous solution with a mass fraction of 3.5%-4.2% for elution, washing with water and collecting.

8. A method for removing divalent metal ions from high-purity boric acid according to claim 7, characterized in that: The desorption liquid is prepared by mixing water, 0.05 mol / L sodium hydroxide, and ethylamine in a volume ratio of (200-300): (25-50): (10-12).

9. The method for removing divalent metal ions from high-purity boric acid according to claim 1, wherein: In the step (S03), the cooling crystallization is as follows: cooling to 45-50°C at a rate of 1-1.2°C / min, and then cooling to 7.5-10°C at a rate of 0.5-0.8°C / min.

10. The method for removing divalent metal ions from high-purity boric acid according to claim 1, wherein: In the step (S03), the evaporation crystallization is carried out under the conditions of relative air humidity of 15%-20% and temperature of 20-25°C.

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