A method for removing divalent metal ions from high-purity boric acid

Abstract

This application relates to the field of high-purity boric acid refining technology, specifically disclosing a method for removing divalent metal ions from high-purity boric acid, comprising the following steps: high-purity boric acid is dissolved in water and filtered, adsorbed by an adsorption resin, filtered again to obtain a refined boric acid solution, and then subjected to cooling crystallization and evaporation crystallization, filtered, and pulverized to obtain refined boric acid. The preparation steps of the adsorption resin include the following: (I) polystyrene masterbatch is mixed with acetyl chloride, dispersed, and reacted with Lewis acid to obtain acetylated polystyrene particles; (II) the acetylated polystyrene particles are dispersed, mixed and reacted with p-aminophenylarsonic acid, filtered, and washed with alcohol to obtain the adsorption resin. After treatment with the adsorption resin prepared in this application, the purity of high-purity boric acid can reach 99.99%, and the effect of removing divalent metal ions from high-purity boric acid can be achieved.

Description

Technical Field

[0001] This application relates to the field of high-purity boric acid refining technology, and more specifically, it relates to a method for removing divalent metal ions from high-purity boric acid. Background Technology

[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, it has applications in many fields. In the metallurgical field, high-purity boric acid can prevent surface oxidation during metal welding, extending the service life of welded metal materials. In the electronics and optical fiber fields, high-purity boric acid is an important glass fiber additive, which can be used to modify the heat resistance, mechanical strength, and weather resistance of glass fiber materials.

[0003] In the electronics and fiber optics fields, the purity of high-purity boric acid directly affects the precision of electronic instruments. Therefore, high-precision instruments often require boric acid with a purity of 99.99% or higher. 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, may still be introduced into the refined high-purity boric acid. 2+ Ca 2+ Mg 2+ Pb 2+ If these substances are not removed before use, they may cause a significant decrease in instrument accuracy and lead to various problems, such as unstable performance of semiconductor devices and reduced light transmittance of optical glass. Furthermore, certain metal ions (such as Pb) can also cause problems. 2+ Some of these substances (such as divalent metal ions) are toxic to humans, and if their content in high-purity boric acid exceeds the standard, it may harm human health. Therefore, how to remove small amounts of divalent metal ion impurities from high-purity boric acid has become a key research focus.

[0004] Chinese patent application CN102020287A discloses a process for refining high-purity boric acid for borosilicate glass. The method uses a modified peanut shell powder as an adsorbent, combined with an inorganic polymer flocculant and ion exchange resin to remove water-insoluble matter, metal ions and acid radical ions from industrial boric acid. After processing, the high-purity boric acid obtained can reach a purity of 99.99%.

[0005] Although the aforementioned application documents achieved the purification of high-purity boric acid, they only listed the removal effect on iron ions and did not mention the removal effect on other metal ions. Furthermore, the modified peanut shell powder preparation process in the scheme requires alkaline leaching activation treatment of the peanut shell powder. However, in the acidic boric acid treatment solution, the acid-base neutralization may cause a decrease in the adsorption effect. Therefore, the need to find an adsorbent with good environmental adaptability and efficient adsorption of divalent metal impurity ions still exists. Summary of the Invention

[0006] To further and more efficiently remove divalent metal ions from high-purity boric acid, this application provides a method for removing divalent metal ions from high-purity boric acid.

[0007] A method for removing divalent metal ions from high-purity boric acid includes the following steps:

[0008] (S01) Take high-purity boric acid, dissolve it in water at 65-70℃, stir, and filter to obtain a pre-solution;

[0009] (S02) Add adsorption resin to the pre-solution, keep the temperature at 70-75℃, stir intermittently, then repeatedly return the liquid, filter to obtain purified boric acid solution and used adsorption resin; the adsorption resin is made of acetylated polystyrene as matrix and p-aminophenylarsonic acid as active adsorption component, and is obtained by carbonyl-amine condensation reaction.

[0010] (S03) Take a refined boric acid solution, cool it to crystallize, let it stand and then filter it to obtain a solid phase and a mother liquor. After the mother liquor is evaporated and crystallized, it is mixed with the solid phase, filtered, dried and ground to obtain refined boric acid.

[0011] The preparation steps of the adsorption resin include the following:

[0012] (I) Take polystyrene masterbatch and acetyl chloride, disperse it with the first solvent, then add the second solvent to continue dispersing, stir and treat, then add Lewis acid catalyst, react at 25-30℃ for 2-3 hours, let stand, filter and wash with water 2-3 times, and dry to obtain acetylated polystyrene particles.

[0013] (II) Mix acetylated polystyrene particles, triethylamine, and anhydrous magnesium sulfate, adjust the temperature and magnetic stirring speed, disperse, then add p-aminophenylarsonic acid, react, filter to take the solid part, wash with alcohol to obtain adsorption resin.

[0014] By adopting the above 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 high-purity boric acid. In the adsorption resin, acetylated polystyrene serves as a carrier to load the active component p-aminophenylarsonic acid, which adsorbs divalent metal impurity ions. After adsorption, the adsorption resin is removed from the system by filtration. The amino functional group of p-aminophenylarsonic acid is grafted to the carbonyl group of acetylated polystyrene through a carbonyl-amine condensation reaction. Due to the complexation of the central arsenic atom and the electron-donating 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 impurity ions is achieved. After use, the adsorption resin can be desorbed by a desorption solution and then reintroduced into the pre-solution for re-adsorption of divalent metal impurity ions.

[0015] Preferably, in step (S01), the mass ratio of water to high-purity boric acid in the water dissolution process is controlled to be (4-5):1.

[0016] 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 near-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 removed while remaining in the liquid phase, thereby obtaining high-purity boric acid with a higher impurity removal rate.

[0017] 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).

[0018] By employing the above technical solution, the addition of a small amount of acetone can swell the polystyrene masterbatch, expanding its pore structure and facilitating the Friedel-Crafts alkylation reaction. Furthermore, the larger pore size enhances 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 polystyrene masterbatch, maintains the structural integrity of the masterbatch during the reaction, resulting in acetylated polystyrene particles.

[0019] Preferably, in step (I), the Lewis acid catalyst is one of aluminum chloride, aluminum bromide, and antimony pentafluoride.

[0020] By employing the above-described technical solution, during the reaction, the Lewis acid catalyst combines with the alkylating agent acetyl chloride to form a more reactive alkyl carbocation. This alkyl carbocation acts as an electrophile, attacking the π-electron cloud on the aromatic ring of polystyrene, thereby yielding the intermediate σ-complex and completing the grafting process. Using the aforementioned Lewis acid catalyst helps to promote the Friedel-Crafts alkylation reaction.

[0021] Preferably, in step (II), triethylamine is used as the reaction solvent.

[0022] By employing the above technical solution, triethylamine provides an alkaline environment and plays two roles. Firstly, the proton in the amino group of p-aminophenylarsonic acid is lost in the alkaline environment of triethylamine, generating a more nucleophilic amino anion, thereby accelerating the nucleophilic attack of p-aminophenylarsonic acid on the carbonyl group. Secondly, triethylamine can also stabilize the reaction intermediates, promoting a more efficient reaction.

[0023] Preferably, in step (II), the mass-to-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.

[0024] By employing the above technical solution, the reaction in this process involves nucleophilic addition of the amino nitrogen atom's lone pair electrons to the carbonyl group, yielding a hemiacetal amine intermediate. This intermediate further reacts, eliminating one molecule of water, ultimately forming a C=N grafted structure. Because the carbon-nitrogen double bond is connected to the aryl group, the resulting conjugated Schiff base system has a more uniform electron cloud distribution, and the sterically hindered groups on the benzene ring shield the reactive groups that could potentially disrupt the C=N structure, increasing the stability of the grafted structure. By controlling the amount of p-aminophenylarsonic acid, after the reaction, the unreacted acetyl oxygen atom on the polystyrene can form hydrogen bonds with the arsenic hydroxyl group on the p-aminophenylarsonic acid, further stabilizing the grafted structure.

[0025] Preferably, in step (S02), the intermittent stirring treatment is performed at a magnetic stirring speed of 300-350 rpm for 1-3 minutes, followed by a standing period of 5 minutes, for a total duration of 1-1.5 hours.

[0026] Preferably, step (S02) further includes desorption treatment of the used adsorption resin, specifically: placing the used adsorption resin in a desorption solution, adjusting the temperature to 45-55℃, ultrasonically treating it at a frequency of 20-21.5KHz for 20-30 minutes, then filtering to remove the liquid phase, and then immersing the solid part in a 3.5%-4.2% (w / w) aqueous solution of disodium ethylenediaminetetraacetate for elution, washing with water, and collecting the solution; the desorption solution is prepared by mixing water, 0.05mol / L sodium hydroxide, and ethylamine in a volume ratio of (200-300):(25-50):(10-12).

[0027] The above technical solution achieves the best desorption effect on the adsorbent resin after use.

[0028] Preferably, in step (S03), the cooling crystallization is performed by 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.

[0029] By employing the above technical solution, a dual-gradient cooling process can be used to promote the crystallization process and obtain higher-quality boric acid crystals. The first stage of rapid cooling can quickly lower the temperature of the solution, causing the boric acid in the solution to reach a supersaturated state and accelerating the nucleation and growth process of crystals. The second stage of cooling gradient can slow down the further growth rate of crystals, allowing the crystals sufficient time to arrange themselves in an orderly manner, thereby obtaining more regular boric acid crystals.

[0030] Preferably, in step (S03), the evaporation crystallization is carried out under conditions of relative humidity of 15%-20% and temperature of 20-25℃.

[0031] By adopting the above technical solution, the residual boric acid in the mother liquor can be collected to the greatest extent, thereby improving the yield of refined boric acid.

[0032] In summary, this application has the following beneficial effects:

[0033] 1. This application uses acetylated polystyrene as the matrix and p-aminophenylarsonic acid as the active adsorbent component. An adsorption resin is obtained through a carbonyl-amine condensation reaction and is used to remove divalent metal ions from high-purity boric acid. In the adsorption resin, acetylated polystyrene serves as a support for loading the active component p-aminophenylarsonic acid. The amino functional group of p-aminophenylarsonic acid is grafted onto the carbonyl group of acetylated polystyrene via a carbonyl-amine condensation reaction. Due to the complexation of the central arsenic atom and the electron-donating effect of the arsenic-oxygen double bond (As=O), the arsenate group can coordinate with divalent metal impurity ions in the pre-solution. Through stirring and temperature treatment, efficient adsorption of divalent metal impurity ions is achieved. Finally, the high-purity boric acid is removed by filtration and separation using the post-adsorption resin.

[0034] 2. In this application, water, sodium hydroxide, and ethylamine are preferably used as the desorption solution components. The desorption solution is treated with heat and ultrasound, and eluted with disodium ethylenediaminetetraacetate solution to remove the divalent metal impurity ions adsorbed on the adsorption resin after use, thereby realizing the reuse of the adsorption resin.

[0035] 3. After treatment with the adsorption resin of this application, the purity of high-purity boric acid can be increased to 99.99%, meeting the relevant standards for Class II boric acid products. Attached Figure Description

[0036] Figure 1 The results are the test results of the content of metal impurity ions in the purified boric acid obtained after the adsorption resins of Examples 1-3 and Comparative Examples 1-2 were used 4 times. Detailed Implementation

[0037] 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.

[0038] Table 1 Purity and main impurity content of high-purity boric acid

[0039]

[0040] Example 1

[0041] The method for removing divalent metal ions from high-purity boric acid in this embodiment is as follows:

[0042] (S01) Take 50g of high-purity boric acid and mix it with 200g of deionized water. Adjust the magnetic stirring speed to 300rpm and the temperature to 65℃. Stir continuously for 1h. After filtering to remove water-insoluble matter, a pre-solution is obtained.

[0043] (S02) Add 10g of adsorption resin to the pre-solution, adjust the temperature to 70℃, and stir with a magnetic stirring speed of 300rpm for 1min. Then let it stand for 5min and stir intermittently for 1h. After that, filter. Repeat the intermittent stirring treatment on the filtered liquid phase and return the liquid twice. Finally, filter and take the liquid part to obtain a purified boric acid solution. After use, place the adsorption resin in 500mL of desorption solution, adjust the temperature to 45℃, and sonicate at a frequency of 20KHz for 20min. Then filter and take the solid part, immerse it in 15mL of 3.5% EDTA-tetraacetic acid disodium aqueous solution for elution, wash with water 3 times and filter to collect.

[0044] (S03) The purified boric acid solution was first cooled to 45°C at a rate of 1°C / min, then cooled to 7.5°C at a rate of 0.5°C / min, and allowed to stand for 8 hours. The solid phase and mother liquor were then obtained by filtration. The mother liquor was evaporated and crystallized at a relative humidity of 15% and a temperature of 20°C. The crystallized product was collected and mixed with the solid phase. The residual water was removed by suction filtration. The product was then dried in an oven at 25°C and ground for 1 minute to obtain purified boric acid.

[0045] The preparation steps of the adsorption resin in this embodiment are as follows:

[0046] (I) Take 10g of polystyrene masterbatch, mix it with 2.5mL of acetyl chloride, then disperse it with 5mL of acetone, control the magnetic stirring speed at 100rpm, stir for 5min, add 50mL of n-butane and continue to disperse for 5min, then add 0.5g of aluminum chloride, continue stirring, control the temperature at 25℃, react for 25min, then add an equal amount of aluminum chloride, react for another 1h and then stop stirring, let it stand at room temperature for 2h, filter and take the solid part, wash it twice with alcohol to remove the residual solvent and then dry it to obtain acetylated polystyrene particles.

[0047] (II) Take 10g of acetylated polystyrene particles and add them to 45mL of triethylamine. Add 1g of anhydrous magnesium sulfate and stir for 5min at 20℃ with the magnetic stirring speed controlled at 100rpm. Then add 3.5g of p-aminophenylarsonic acid and continue stirring for 3h. Then filter, take the solid part, wash twice with alcohol to obtain the adsorption resin.

[0048] 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.

[0049] Example 2

[0050] The method for removing divalent metal ions from high-purity boric acid in this embodiment is as follows:

[0051] (S01) Take 50g of high-purity boric acid and mix it with 225g of deionized water. Adjust the magnetic stirring speed to 300rpm and the temperature to 70℃. Stir continuously for 1.5h. After filtering to remove water-insoluble matter, a pre-solution is obtained.

[0052] (S02) Add 12g of adsorption resin to the pre-solution, adjust the temperature to 70℃, and stir with magnetic stirring at 300rpm for 3min. Then let it stand for 5min and stir intermittently for 1.5h. After filtration, repeat the intermittent stirring treatment on the filtered liquid phase, return the liquid twice, and finally filter and take the liquid part to obtain a purified boric acid solution. After use, place the adsorption resin in 500mL of desorption solution, adjust the temperature to 50℃, and sonicate at 21.5KHz for 25min. Then filter and take the solid part, immerse it in 15mL of 4% EDTA disodium acetate aqueous solution for elution, wash with water 3 times, and filter and collect.

[0053] (S03) The purified boric acid solution was first cooled to 50°C at a rate of 1.2°C / min, then cooled to 10°C at a rate of 0.8°C / min, and allowed to stand for 10 hours. The solid phase and mother liquor were then obtained by filtration. The mother liquor was evaporated and crystallized at a relative humidity of 20% and a temperature of 25°C. The crystallized product was collected and mixed with the solid phase. The residual water was removed by suction filtration. The product was then dried in an oven at 30°C and ground for 2 minutes to obtain purified boric acid.

[0054] The preparation steps of the adsorption resin in this embodiment are as follows:

[0055] (I) Take 10g of polystyrene masterbatch, mix it with 3mL of acetyl chloride, then disperse it with 5mL of acetone, control the magnetic stirring speed at 100rpm, stir for 5min, add 50mL of n-butane and continue to disperse for 5min, then add 0.5g of aluminum bromide, continue stirring, control the temperature at 30℃, react for 35min, then add an equal amount of aluminum bromide, react for another 2h and then stop stirring, let stand at room temperature for 3h, filter to take the solid part, wash with alcohol 3 times, remove the residual solvent and dry to obtain acetylated polystyrene particles.

[0056] (II) Add 12g of acetylated polystyrene particles to 50mL of triethylamine, add 2g of anhydrous magnesium sulfate, and stir for 20min at 30℃ with the magnetic stirring speed controlled at 125rpm. Then add 4.8g of p-aminophenylarsonic acid, continue stirring for 5h, then filter, take the solid part, wash twice with alcohol to obtain the adsorption resin.

[0057] 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.

[0058] Example 3

[0059] The method for removing divalent metal ions from high-purity boric acid in this embodiment is as follows:

[0060] (S01) Take 50g of high-purity boric acid and mix it with 250g of deionized water. Adjust the magnetic stirring speed to 350rpm and the temperature to 70℃. Stir continuously for 2h. After filtering to remove water-insoluble matter, a pre-solution is obtained.

[0061] (S02) Add 15g of adsorption resin to the pre-solution, adjust the temperature to 75℃, and stir with a magnetic stirring speed of 350rpm for 3min. Then let it stand for 5min and stir intermittently for 1.5h. After filtration, repeat the intermittent stirring treatment on the filtered liquid phase, return the liquid twice, and finally filter and take the liquid part to obtain a purified boric acid solution. After use, place the adsorption resin in 500mL of desorption solution, adjust the temperature to 55℃, and sonicate at a frequency of 21.5KHz for 30min. Then filter and take the solid part, immerse it in 15mL of 4.2% EDTA disodium acetate aqueous solution for elution, wash with water 3 times, and filter and collect.

[0062] (S03) The purified boric acid solution was first cooled to 50°C at a rate of 1.2°C / min, then cooled to 10°C at a rate of 0.8°C / min, and allowed to stand for 12 hours. The solid phase and mother liquor were then obtained by filtration. The mother liquor was evaporated and crystallized at a relative humidity of 20% and a temperature of 25°C. The crystallized product was collected and mixed with the solid phase. The residual water was removed by suction filtration. The product was then dried in an oven at 30°C and ground for 2 minutes to obtain purified boric acid.

[0063] The preparation steps of the adsorption resin in this embodiment are as follows:

[0064] (I) Take 10g of polystyrene masterbatch, mix it with 3mL of acetyl chloride, then disperse it with 5mL of acetone, control the magnetic stirring speed at 150rpm, stir for 5min, add 75mL of n-butane and continue to disperse for 10min, then add 0.7g of antimony pentafluoride, continue stirring, control the temperature at 30℃, react for 35min, then add an equal amount of antimony pentafluoride, react for another 2h and then stop stirring, let stand at room temperature for 3h, filter to take the solid part, wash with alcohol 3 times, remove the residual solvent and dry to obtain acetylated polystyrene particles.

[0065] (II) Take 12g of acetylated polystyrene particles and add them to 50mL of triethylamine. Add 2g of anhydrous magnesium sulfate and stir for 20min at 35℃ with the magnetic stirring speed controlled at 150rpm. Then add 4.8g of p-aminophenylarsonic acid and continue stirring for 5h. Then filter, take the solid part, wash it with alcohol 3 times to obtain the adsorption resin.

[0066] 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.

[0067] Comparative Example 1

[0068] 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), while the other steps are the same as in Example 1.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that phenolic resin (crosslinking degree: 11.7%, average particle size: 0.2 mm) is used instead of polystyrene masterbatch in step (Ⅰ), while the other steps are the same as in Example 1.

[0071] Performance testing

[0072] 1. The test results of the refined boric acid prepared in Examples 1-3 and Comparative Examples 1-2 are shown in Table 2, referring to the test methods and standards of GB / T538-2018 "Industrial Boric Acid".

[0073] Table 2 Purity and impurity content of purified boric acid obtained in Examples 1-3 and Comparative Examples 1-2

[0074]

[0075] 2. Referring to the test methods and standards of GB / T538-2018 "Industrial Boric Acid", the metal impurity content of the treated solutions obtained after the first adsorption and the two liquid return operations in Step (S02) of Example 1 and Comparative Examples 1-2 was tested. The test results are shown in Table 3-5.

[0076] Table 3. Metal impurity ion content in the treated solution obtained after the first adsorption and the second liquid return operation in Example 1.

[0077]

[0078] Table 4. Metal impurity ion content in the treated solution obtained after the first adsorption and the second liquid return operation in Comparative Example 1.

[0079]

[0080] Table 5. Metal impurity ion content in the treated solution obtained after the first adsorption and two liquid return operations in Comparative Example 2.

[0081]

[0082] 3. Referring to the test methods and standards of GB / T538-2018 "Industrial Boric Acid", the refined boric acid obtained after four cycles of adsorption resin use in 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; where the 0th cycle refers to the first use of the adsorption resin.

[0083] Analysis of Examples 1-3 and Comparative Examples 1-2, combined with Table 2, shows that among the example schemes, the adsorption resin of Example 3 has the best removal effect on divalent metal ions in high-purity boric acid. The refined boric acid obtained after treatment by Examples 1-3 meets the relevant standards for Class II boric acid products.

[0084] Analysis of Example 1 and Comparative Examples 1-2, combined with Tables 3-5, shows that in Comparative Example 1, after replacing p-aminophenylarsonic acid in Example 1 with acetamide, the residual amounts of lead and arsenic ions increased after the second liquid return treatment, indicating the desorption of lead and arsenic metal ions. This may be because the acetyl group, as the active host in Comparative Example 2, has a slightly weaker adsorption and binding capacity for metal ions, and acetamide lacks the protection of sterically hindered functional groups on the benzene ring, leading to the instability of the coordination structure between the acetyl group and lead and arsenic metal ions during the liquid return process, resulting in desorption. In Comparative Example 2, after replacing the polystyrene masterbatch in Example 1 with phenolic resin, the adsorption effect of the adsorption resin on metal impurity ions decreased significantly. This is because the phenolic resin has a large number of phenolic hydroxyl structures, which combine with boric acid molecules in the pre-solution, hindering the adsorption of metal impurity ions by the active component, thus leading to a decrease in the adsorption effect of the adsorption resin. Based on the changes in arsenic ion content, Comparative Example 1 had the lowest arsenic ion content in the treated solution because no arsenic-containing active component was used; while Comparative Example 2 had the highest arsenic ion content in the treated solution, indirectly indicating that the removal of p-aminophenylarsonic acid, an active component on the adsorption resin, was quite severe during the treatment process, and the combination effect of phenolic resin and p-aminophenylarsonic acid was not good.

[0085] Analysis of Examples 1-3 and Comparative Examples 1-2 in conjunction with Figure 1 It can be seen that, through testing the recycling performance of the adsorption resin, the adsorption resin in Examples 1-3 still maintained a high level of adsorption effect on metal impurity ions after 5 uses, while the adsorption effect on metal impurity ions in Comparative Example 2 had already decreased significantly after the 3rd cycle.

[0086] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for removing divalent metal ions from high-purity boric acid, characterized in that, Includes the following steps: (S01) Take high-purity boric acid, dissolve it in water at 65-70℃, stir, filter and obtain a pre-solution. During the water dissolution process, control the mass ratio of water to high-purity boric acid to be (4-5):

1. (S02) Add adsorption resin to the pre-solution, keep the temperature at 70-75℃, stir intermittently, then repeatedly return the liquid, filter to obtain purified boric acid solution and used adsorption resin; the adsorption resin is made of acetylated polystyrene as matrix and p-aminophenylarsonic acid as active adsorption component, and is obtained by carbonyl-amine condensation reaction. (S03) Take a refined boric acid solution, cool it to crystallize, let it stand and then filter it to obtain a solid phase and a mother liquor. After the mother liquor is evaporated and crystallized, it is mixed with the solid phase, filtered, dried and ground to obtain refined boric acid. The cooling crystallization is carried out at a rate of 1-1.2℃ / min to 45-50℃, and then at a rate of 0.5-0.8℃ / min to 7.5-10℃. The evaporation crystallization is carried out under the conditions of relative humidity of 15%-20% and temperature of 20-25℃.

2. The method for removing divalent metal ions from high-purity boric acid according to claim 1, characterized in that, In step (S02), the preparation of the adsorption resin includes the following steps: (I) Take polystyrene masterbatch and acetyl chloride, disperse it with the first solvent, then add the second solvent to continue dispersing, stir and treat, then add Lewis acid catalyst, react at 25-30℃ for 2-3 hours, let stand, filter and wash with water 2-3 times, and dry to obtain acetylated polystyrene particles. (II) Mix acetylated polystyrene particles, triethylamine, and anhydrous magnesium sulfate, adjust the temperature and magnetic stirring speed, disperse, then add p-aminophenylarsonic acid, react, filter to take the solid part, wash with alcohol to obtain adsorption resin.

3. The method for removing divalent metal ions from high-purity boric acid according to claim 2, characterized in that, 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).

4. The method for removing divalent metal ions from high-purity boric acid according to claim 2, characterized in that, In step (I), the Lewis acid catalyst is one of aluminum chloride, aluminum bromide, and antimony pentafluoride.

5. The method for removing divalent metal ions from high-purity boric acid according to claim 2, characterized in that, In step (II), the mass-to-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.

6. The method for removing divalent metal ions from high-purity boric acid according to claim 1, characterized in that, The step (S02) also includes a post-use adsorption resin desorption treatment, specifically: the post-use adsorption resin is placed in a desorption solution, the temperature is adjusted to 45-55℃, the ultrasonic frequency is 20-21.5KHz, and the ultrasonic treatment is carried out for 20-30 minutes. Then the liquid phase is removed by filtration, and the solid part is immersed in a 3.5%-4.2% (w / w) aqueous solution of disodium ethylenediaminetetraacetate for elution. After washing with water, it is collected.

7. The method for removing divalent metal ions from high-purity boric acid according to claim 6, characterized in that, The desorption solution is prepared by mixing water, 0.05 mol / L sodium hydroxide, and ethylamine in a volume ratio of (200-300):(25-50):(10-12).

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