Method for removing potassium and calcium in circulating mother liquor and preparing electronic grade sodium acetate

Abstract

The application belongs to the technical field of sodium acetate production, and provides a method for removing potassium and calcium in a circulating mother liquor and preparing electronic-grade sodium acetate, wherein the sodium acetate circulating mother liquor is filtered to obtain a to-be-purified mother liquor; the to-be-purified mother liquor is mixed with an adsorption material and then separated to obtain a purified mother liquor; and the purified mother liquor is returned to production to obtain electronic-grade sodium acetate. The sodium-type strong acid cation exchange adsorption material is used to deeply purify the sodium acetate circulating mother liquor, potassium and calcium impurities can be removed at the same time under the coexistence of high-concentration sodium ions and acetate, and the continuous enrichment of the impurities with the mother liquor circulation is inhibited. The adsorption material takes sodium ions as exchangeable ions, is compatible with the sodium acetate production system, and can reduce the introduction of mother liquor acidification and foreign impurities. The purified mother liquor after treatment can be returned to the production system for continuous concentration and crystallization, the purity and batch stability of the electronic-grade sodium acetate are ensured, the sodium acetate recovery rate is improved, and the mother liquor discharge and high-salt waste liquid generation are reduced.

Description

Technical Field

[0001] This invention relates to the field of sodium acetate production technology, and in particular to a method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate. Background Technology

[0002] Sodium acetate is an important organic chemical product widely used in food processing, pharmaceutical manufacturing, biopharmaceuticals, environmental remediation, printing and dyeing, and chemical synthesis. It can be used as an acidity regulator, buffer, wastewater treatment agent, printing and dyeing auxiliary agent, and chemical intermediate. With the development of semiconductors, liquid crystal displays, new energy materials, and high-end fine chemicals, related production processes have placed higher demands on the purity of raw materials and the content of metal impurities. Electronic-grade sodium acetate features high purity, low metal ion content, and good batch stability, making it suitable for applications requiring high impurity control, such as the formulation of electronic chemicals, precision cleaning, and the preparation of electronic materials.

[0003] Sodium acetate is typically prepared by neutralizing acetic acid with sodium hydroxide or sodium carbonate. The resulting sodium acetate solution is then subjected to processes such as filtration to remove impurities, evaporation and concentration, cooling and crystallization, solid-liquid separation, and drying. During the crystallization process, a mother liquor containing a high concentration of sodium acetate is generated. To improve the yield of sodium acetate, reduce raw material loss, and lower wastewater discharge, industrial production usually recycles the mother liquor by returning it to the neutralization, concentration, or crystallization process.

[0004] However, during the recycling of the mother liquor, metallic impurities such as potassium and calcium from sodium hydroxide, sodium carbonate, acetic acid, process water, production equipment, and pipeline systems are difficult to completely precipitate with the sodium acetate crystals and gradually accumulate in the mother liquor. As the number of mother liquor cycles increases, the concentration of potassium and calcium ions continuously rises. When the concentration of potassium and calcium impurities in the circulating mother liquor is high, impurity ions can enter the sodium acetate product through adsorption on the crystal surface, intercrystalline entrainment, embedding in crystal defects, and encapsulation by residual mother liquor. Even with crystallization control measures such as optimizing the cooling rate, adding seed crystals, or extending the crystal growth time, these mainly reduce impurity entrainment and improve crystal particle size, and cannot fundamentally eliminate the continuous accumulation of potassium and calcium ions in the circulating mother liquor. Therefore, as the number of mother liquor cycles increases, the metallic impurity content of the resulting sodium acetate product may gradually increase, leading to a decrease in product purity and batch stability, making it difficult to consistently meet the requirements for high purity and low metallic impurity content in electronic-grade sodium acetate. Currently, to address the accumulation of impurities in the circulating mother liquor, industrial methods also involve periodically discharging a portion of the mother liquor and replenishing it with fresh material to control the impurity concentration. While this method can delay impurity enrichment, it results in the loss of a large amount of sodium acetate with the mother liquor and increases the volume of high-salt wastewater to be treated. Using precipitants to remove calcium ions may introduce new anions or metallic impurities and easily generate fine precipitates, increasing the load on subsequent filtration. Potassium salts typically have high water solubility, making deep removal difficult using conventional chemical precipitation methods. Although multiple recrystallizations can reduce impurity content to some extent, they suffer from long process times, high energy consumption for evaporation and cooling, and reduced product yield, hindering continuous and large-scale production.

[0005] Ion exchange adsorbents can exchange cations in solution through functional groups, providing a potential pathway for removing metallic impurities such as potassium and calcium. However, sodium acetate circulating mother liquor contains a large number of sodium and acetate ions, with sodium ion concentrations far exceeding those of the potassium and calcium ions to be removed, resulting in a significant competitive exchange effect. Ordinary cation exchange materials may encounter problems such as insufficient potassium ion removal rate, low exchange capacity utilization, sodium acetate loss, or regenerator residue in high-concentration sodium salt systems. Furthermore, the adsorbent material itself may release organic matter, metal ions, or other soluble impurities, causing secondary pollution to electronic-grade sodium acetate. Therefore, how to simultaneously and deeply remove trace amounts of potassium and calcium impurities in a high-concentration sodium acetate matrix, while considering sodium acetate recovery rate, adsorbent material regeneration performance, and product purity, is a pressing problem to be solved in this technical field.

[0006] Therefore, it is necessary to develop a deep purification method for sodium acetate circulating mother liquor. By selecting an adsorbent material compatible with the sodium acetate system and reasonably controlling the dosage of the adsorbent material, the contact time, and the conditions for mother liquor reuse, potassium and calcium ions in the circulating mother liquor can be synergistically removed without significantly losing sodium acetate or introducing new harmful impurities. This will inhibit the continuous accumulation of impurities as the mother liquor circulates, thereby achieving a high proportion of recycling of the circulating mother liquor and the stable preparation of electronic-grade sodium acetate. Summary of the Invention

[0007] The purpose of this invention is to overcome the deficiencies in the prior art and provide a method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate, comprising the following steps: (1) Filter the sodium acetate circulating mother liquor to obtain the mother liquor to be purified; (2) The mother liquor to be purified and the adsorption material are mixed and adsorbed, and then separated to obtain the purified mother liquor; (3) The purified mother liquor is returned to the production process to obtain electronic grade sodium acetate.

[0009] Preferably, the sodium acetate circulating mother liquor in step (1) is circulated 1 to 3 times.

[0010] Preferably, in step (2), the concentration of potassium ions in the mother liquor to be purified is 50~500 mg / L and the concentration of calcium ions is 10~30 mg / L.

[0011] Preferably, the adsorbent material in step (2) includes one or more of the following: T-42, Purolite C100 series, AmberLite IRC120Na, AmberLite HPR1100 Na, DIAION SK1B and ResinTech CG8 series.

[0012] Preferably, the adsorbent material in step (2) is subjected to sodium treatment before use; The sodium treatment includes the following steps: The adsorbent material is mixed with a sodium salt solution for treatment.

[0013] Preferably, the concentration of the sodium salt solution is 5-15%; The sodium salt is one or more of sodium chloride, sodium sulfate, sodium acetate, sodium carbonate, and sodium bicarbonate; The processing time is 3 to 5 hours.

[0014] Preferably, the mass ratio of the mother liquor to be purified to the adsorbent material in step (2) is 1~6:1.

[0015] Preferably, the temperature for mixing and adsorption in step (2) is 20~30℃.

[0016] Preferably, the mixing and adsorption time in step (2) is 1 to 4 hours.

[0017] Preferably, the mixing and adsorption speed in step (2) is 100~300 rpm.

[0018] This invention provides a method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate. The method involves filtering the circulating mother liquor to obtain a mother liquor to be purified; mixing the mother liquor to be purified with an adsorbent material for adsorption and separation to obtain a purified mother liquor; and returning the purified mother liquor to the production line to obtain electronic-grade sodium acetate. This invention uses a sodium-type strongly acidic cation exchange adsorbent material for deep purification of the circulating mother liquor, simultaneously removing potassium and calcium impurities under conditions of high concentrations of sodium ions and acetate ions, and inhibiting their continuous accumulation with the mother liquor circulation. The adsorbent material uses sodium ions as exchangeable ions, is compatible with the sodium acetate production system, and can reduce mother liquor acidification and the introduction of foreign impurities. The treated purified mother liquor can be returned to the production system for further concentration and crystallization, ensuring the purity and batch stability of electronic-grade sodium acetate while improving sodium acetate recovery rate and reducing mother liquor discharge and high-salt waste liquid generation. The adsorbent material can also be regenerated and recycled, offering advantages such as simple process, mild operating conditions, low operating costs, and easy integration with existing production lines, making it suitable for continuous and large-scale production of electronic-grade high-purity sodium acetate. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow for potassium and calcium removal from the circulating mother liquor and the preparation of electronic-grade sodium acetate according to the present invention. Detailed Implementation

[0020] This invention provides a method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate, comprising the following steps: (1) Filter the sodium acetate circulating mother liquor to obtain the mother liquor to be purified; (2) The mother liquor to be purified and the adsorption material are mixed and adsorbed, and then separated to obtain the purified mother liquor; (3) The purified mother liquor is returned to the production process to obtain electronic grade sodium acetate.

[0021] In this invention, the sodium acetate circulating mother liquor in step (1) is obtained after crystallization and separation during the preparation of sodium acetate.

[0022] In this invention, the sodium acetate circulating mother liquor in step (1) is circulated 1 to 3 times.

[0023] In this invention, the potassium ion concentration of the mother liquor to be purified in step (2) is preferably 50~500 mg / L, more preferably 100~400 mg / L, and even more preferably 200~300 mg / L; the calcium ion concentration is preferably 10~30 mg / L, more preferably 15~25 mg / L, and even more preferably 18~22 mg / L.

[0024] In this invention, the adsorbent material in step (2) includes one or more of the following: T-42, Purolite C100 series, AmberLiteIRC120 Na, AmberLite HPR1100 Na, DIAION SK1B and ResinTech CG8 series.

[0025] In this invention, the adsorbent material was purchased from Kelin (Beijing) Technology Co., Ltd.

[0026] In this invention, the adsorbent material in step (2) is subjected to sodium treatment before use.

[0027] In this invention, the sodium treatment comprises the following steps: The adsorbent material is mixed with a sodium salt solution for treatment.

[0028] In this invention, the concentration of the sodium salt solution is preferably 5-15%, more preferably 6-14%, and even more preferably 8-12%.

[0029] In this invention, the sodium salt is one or more of sodium chloride, sodium sulfate, sodium acetate, sodium carbonate, and sodium bicarbonate.

[0030] In this invention, the processing time is preferably 3 to 5 hours, more preferably 3.5 to 4.5 hours, and even more preferably 3.8 to 4.2 hours.

[0031] In this invention, the exchangeable ions in the adsorbent material are converted into sodium ions through sodium treatment; after the sodium treatment is completed, the material is washed with water until no chloride ions remain in the washing solution, and then it is ready for use.

[0032] In this invention, the adsorbent material uses a cross-linked copolymer of styrene and divinylbenzene as the matrix, sulfonic acid groups as cation exchange functional groups, and sodium ions as exchangeable ions.

[0033] In this invention, the mass ratio of the mother liquor to be purified to the adsorbent material in step (2) is preferably 1~6:1, more preferably 2~5:1, and even more preferably 3~4:1.

[0034] In this invention, the temperature of the mixed adsorption in step (2) is preferably 20~30℃, more preferably 22~28℃, and even more preferably 24~26℃.

[0035] In this invention, the mixing and adsorption time in step (2) is preferably 1 to 4 hours, more preferably 1.5 to 3.5 hours, and even more preferably 2 to 3 hours.

[0036] In this invention, the rotation speed of the mixing adsorption in step (2) is preferably 100~300 rpm, more preferably 150~250 rpm, and even more preferably 160~240 rpm.

[0037] In this invention, potassium and calcium ions in the mother liquor to be purified are exchanged and adsorbed by the adsorption material through mixed adsorption.

[0038] In this invention, after separation in step (2), purified mother liquor and adsorbent material are obtained; the purified mother liquor is returned to the sodium acetate production system and, through processes such as evaporation and concentration, cooling and crystallization, solid-liquid separation and drying, electronic-grade high-purity sodium acetate is obtained; the adsorbent material is regenerated using a regenerator.

[0039] In this invention, the regenerator is selected from one or more of hydrochloric acid, sulfuric acid, and sodium salt solution. When regeneration is performed using sodium salt solution, the regenerated adsorbent material is washed with ultrapure water and then returned to step (2) for recycling. When regeneration is performed using hydrochloric acid or sulfuric acid, the potassium and calcium ions adsorbed on the adsorbent material are first desorbed using hydrochloric acid or sulfuric acid, causing the adsorbent material to be converted into the hydrogen form; then, the hydrogen form adsorbent material is sodium-formed using sodium salt solution, causing it to be converted back into the sodium form; finally, it is washed with water, and the washed sodium-form strongly acidic cation exchange adsorbent material is returned to step (2) for recycling. The sodium salt solution used in the regeneration process is the same as the sodium salt solution used in the sodium-formation treatment.

[0040] A schematic diagram of the process flow for potassium and calcium removal from the circulating mother liquor and the preparation of electronic-grade sodium acetate in this invention is shown below. Figure 1 As shown.

[0041] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0042] Example 1

[0043] The mother liquor from the sodium acetate production process, after three cycles of use, was collected. After filtration to remove entrained sodium acetate crystals and suspended impurities, a mother liquor to be purified was obtained. Initial concentrations of potassium and calcium ions in the mother liquor were measured to be 342.5 mg / L and 20.5 mg / L, respectively. T-42 type strongly acidic cation exchange adsorbent material was weighed and soaked in a 10% sodium chloride aqueous solution for 4 hours to fully convert it to the sodium form. It was then repeatedly washed with deionized water until no significant chloride ion residue remained in the washing solution. The pretreated adsorbent material was added to the mother liquor to be purified, maintaining a mass ratio of 1:1 between the mother liquor and the wet adsorbent material. Adsorption was carried out at 25℃ and 200 r / min for 1.5 hours with stirring. After adsorption, the adsorbent material was separated from the mother liquor by filtration to obtain the purified mother liquor. The concentrations of potassium and calcium ions in the purified mother liquor were reduced to approximately 0.10 mg / L and 0.05 mg / L, respectively, corresponding to removal rates of 99.97% and 99.75%. The purified mother liquor is returned to the sodium acetate production system, and finally electronic-grade anhydrous sodium acetate product is obtained. After testing, its purity reaches 99.993%.

[0044] Example 2

[0045] The mother liquor from the sodium acetate production process, after three cycles of use, was collected. After filtration to remove entrained sodium acetate crystals and suspended impurities, a purified mother liquor was obtained. Initial concentrations of potassium and calcium ions in the purified mother liquor were measured to be 368.0 mg / L and 18.5 mg / L, respectively. T-42 type strongly acidic cation exchange adsorbent material was weighed and soaked in a 10% sodium chloride aqueous solution for 4 hours to fully convert it to the sodium form. It was then repeatedly washed with deionized water until no significant chloride ion residue remained in the washing solution. The pretreated adsorbent material was added to the purified mother liquor, maintaining a mass ratio of 2:1 between the mother liquor and the wet adsorbent material. Adsorption was carried out at 25℃ and 200 r / min for 1.5 hours with stirring. After adsorption, the adsorbent material was separated from the mother liquor by filtration to obtain the purified mother liquor. The concentrations of potassium and calcium ions in the purified mother liquor were reduced to approximately 2.4 mg / L and 0.1 mg / L, respectively, corresponding to removal rates of 99.35% and 99.46%. The purified mother liquor is returned to the sodium acetate production system, and finally electronic-grade anhydrous sodium acetate product is obtained. After testing, its purity reaches 99.990%.

[0046] Example 3

[0047] The mother liquor from the sodium acetate production process, after three cycles of use, was collected. After filtration to remove entrained sodium acetate crystals and suspended impurities, a purified mother liquor was obtained. The initial concentrations of potassium and calcium ions in the purified mother liquor were measured to be 342.5 mg / L and 20.5 mg / L, respectively. Purolite C100 type strongly acidic cation exchange adsorbent material was weighed and soaked in a 10% sodium chloride aqueous solution for 4 hours to fully convert it to the sodium form. It was then repeatedly washed with deionized water until no obvious chloride ion residue remained in the washing solution. The pretreated adsorbent material was added to the purified mother liquor, maintaining a mass ratio of 1:1 between the purified mother liquor and the wet adsorbent material. Adsorption was carried out at 25℃ and 200 r / min for 1.5 hours with stirring. After adsorption, the adsorbent material was separated from the mother liquor by filtration to obtain the purified mother liquor. Testing revealed that the concentrations of potassium and calcium ions in the purified mother liquor were reduced to approximately 0.4 mg / L and 0.2 mg / L, respectively, corresponding to removal rates of 99.88% and 99.02%. The purified mother liquor was returned to the sodium acetate production system, ultimately yielding electronic-grade anhydrous sodium acetate, which, upon testing, achieved a purity of 99.992%.

[0048] Example 4

[0049] The mother liquor from the sodium acetate production process, after three cycles of use, was collected. After filtration to remove entrained sodium acetate crystals and suspended impurities, a purified mother liquor was obtained. Initial concentrations of potassium and calcium ions in the purified mother liquor were measured to be 342.5 mg / L and 20.5 mg / L, respectively. T-42 type strongly acidic cation exchange adsorbent material was weighed and soaked in a 10% sodium chloride aqueous solution for 4 hours to fully convert it to the sodium form. It was then repeatedly washed with deionized water until no significant chloride ion residue remained in the washing solution. The pretreated adsorbent material was added to the purified mother liquor, maintaining a mass ratio of 2:1 between the mother liquor and the wet adsorbent material. Adsorption was carried out at 25℃ and 200 r / min for 1.5 hours with stirring. After adsorption, the adsorbent material was separated from the mother liquor by filtration to obtain the purified mother liquor. The concentrations of potassium and calcium ions in the purified mother liquor were reduced to approximately 3.0 mg / L and 0.1 mg / L, respectively, corresponding to removal rates of 99.12% and 99.51%. The purified mother liquor is returned to the sodium acetate production system, and finally electronic-grade anhydrous sodium acetate product is obtained. After testing, its purity reaches 99.990%.

[0050] As can be seen from the examples, after treatment by the method of the present invention, the removal rate of potassium ions in the sodium acetate crystallization mother liquor is not less than 99%, the removal rate of calcium ions is not less than 99%, and the purity of electronic-grade anhydrous sodium acetate is not less than 99.990%. The present invention, by controlling the number of mother liquor circulation cycles, the mass ratio of mother liquor to adsorbent material, and the contact time, can deeply remove potassium and calcium ions from the circulating mother liquor, reducing the entrainment and encapsulation of impurities during the crystallization process. This method can improve the mother liquor recycling rate, reduce sodium acetate loss and saline wastewater discharge, and can be used for the stable preparation of electronic-grade (4N) sodium acetate.

[0051] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for removing potassium and calcium from circulating mother liquor and preparing electronic-grade sodium acetate, characterized in that, Includes the following steps: (1) Filter the sodium acetate circulating mother liquor to obtain the mother liquor to be purified; (2) The mother liquor to be purified and the adsorption material are mixed and adsorbed, and then separated to obtain the purified mother liquor; (3) The purified mother liquor is returned to the production process to obtain electronic grade sodium acetate.

2. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 1, characterized in that, In step (1), the sodium acetate circulating mother liquor is circulated 1 to 3 times.

3. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 2, characterized in that, In step (2), the potassium ion concentration of the mother liquor to be purified is 50~500 mg / L and the calcium ion concentration is 10~30 mg / L.

4. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 3, characterized in that, The adsorbent material in step (2) includes one or more of the following: T-42, Purolite C100 series, AmberLite IRC120 Na, AmberLiteHPR1100 Na, DIAION SK1B and ResinTech CG8 series.

5. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 4, characterized in that, In step (2), the adsorbent material undergoes sodium treatment before use; The sodium treatment includes the following steps: The adsorbent material is mixed with a sodium salt solution for treatment.

6. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 5, characterized in that, The concentration of the sodium salt solution is 5-15%; Sodium salts are one or more of sodium chloride, sodium sulfate, sodium acetate, sodium carbonate, and sodium bicarbonate; The processing time is 3 to 5 hours.

7. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 6, characterized in that, In step (2), the mass ratio of the mother liquor to be purified to the adsorption material is 1~6:

1.

8. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 7, characterized in that, The temperature for mixed adsorption in step (2) is 20~30℃.

9. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 8, characterized in that, The mixing and adsorption time in step (2) is 1 to 4 hours.

10. The method for potassium and calcium removal and preparation of electronic-grade sodium acetate from circulating mother liquor as described in claim 9, characterized in that, In step (2), the mixing and adsorption speed is 100~300 rpm.

Images