Method for preparing potassium peroxoborate by recovering sodium peroxoborate mother liquor with modified potassium type resin

Abstract

This invention discloses a method for preparing potassium perborate from sodium perborate mother liquor using modified potassium-form resin, belonging to the field of resource comprehensive utilization technology. The method includes: pretreating a 732 type strong acid cation exchange resin to convert it to the potassium form, then modifying it with a 15-crown ether-5 ethanol solution to obtain a crown ether-modified potassium-form resin; passing the sodium perborate mother liquor through an exchange column packed with this resin, and performing ion exchange at 20-30℃, utilizing the specific selectivity of the crown ether for sodium ions to efficiently replace Na ions in the mother liquor with K ions in the resin, obtaining a pure potassium perborate solution; cooling the solution at -5~5℃ for crystallization, separation, and drying to obtain a high-purity potassium perborate product. This invention directly utilizes waste mother liquor as raw material, with a mild process, and produces a product with high active oxygen content (>16%), uniform particles, and good stability. It solves the problems of high cost, heavy pollution, and poor product quality associated with traditional processes, achieving green and high-value utilization of waste resources.

Description

Technical Field

[0001] This invention belongs to the field of inorganic fine chemical engineering and comprehensive resource utilization technology, specifically relating to a method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin. Background Technology

[0002] Potassium perborate is a highly efficient cleaning peroxide, mainly used in the detergent and bleaching industries. It is commonly used in clothing bleach, disinfectants, and also in papermaking, textiles, and other organic synthetic chemical industries. Currently, the mainstream industrial method for producing potassium perborate involves reacting boric acid (or metaborate) with potassium hydroxide (or potassium salt) to produce potassium metaborate. Then, hydrogen peroxide is added dropwise under controlled temperature conditions to carry out the peroxidation reaction. After the reaction, the product is obtained through solid-liquid separation, washing, and drying.

[0003] However, this traditional process has significant drawbacks: (1) The method releases a large amount of heat when adding hydrogen peroxide to synthesize potassium perborate, resulting in low utilization of hydrogen peroxide and affecting the product's active oxygen and stability. (2) A large amount of high-salinity wastewater is generated after the reaction, which has high treatment costs and is not environmentally friendly. (3) It relies entirely on fresh boric acid, potassium hydroxide and hydrogen peroxide as raw materials, resulting in high production costs.

[0004] Meanwhile, the production of sodium perborate generates a large amount of waste mother liquor containing sodium perborate, which contains considerable amounts of boron and reactive oxygen species. Traditional treatment methods mostly involve neutralization and discharge or simple concentration and reuse, failing to effectively recover the high-value components and resulting in resource waste. Effective recycling of this mother liquor could not only solve environmental problems but also turn waste into treasure and reduce the production cost of potassium perborate.

[0005] Therefore, there is an urgent need to develop a new method that can efficiently recycle sodium perborate mother liquor and produce highly reactive and stable potassium perborate in a green and low-cost manner. Summary of the Invention

[0006] To address the aforementioned problems, the present invention aims to overcome these issues in the prior art and provide a method for preparing potassium perborate by recovering sodium perborate mother liquor using modified potassium-type resin. This method uses waste sodium perborate mother liquor as raw material and achieves efficient sodium / potassium ion exchange through crown ether-modified potassium-type resin, thereby providing a mild, efficient, and environmentally friendly method for preparing high-purity potassium perborate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing potassium perborate by recovering sodium perborate mother liquor using modified potassium-type resin includes the following process steps: S1: Preparation of potassium form resin: After pretreatment of hydrogen form cation exchange resin, it is converted into potassium form resin and dried for later use; S2: Crown ether modification: The potassium form resin is modified with a crown ether solution to obtain a crown ether modified potassium form resin; S3: Mother liquor ion exchange: The sodium perborate mother liquor is passed through an exchange column packed with the crown ether modified potassium resin to perform ion exchange, and a potassium perborate solution is obtained. S4: Crystallization and separation: The potassium perborate solution is cooled and crystallized, and the solid and liquid are separated to obtain wet potassium perborate. S5: Drying: Dry the wet potassium perborate product to obtain the potassium perborate product.

[0008] Furthermore, in step S1, the pretreatment includes: washing the resin with acid and deionized water until neutral; then activating the resin with epichlorohydrin and an alkaline catalyst; and finally placing the activated resin in an exchange column to undergo ion exchange with a potassium salt solution to convert it into potassium-type resin.

[0009] Furthermore, the activation treatment is performed at a temperature of 50-60°C for 3-6 hours; the alkaline catalyst is potassium hydroxide; the potassium salt solution is potassium chloride solution with a concentration of 1.0-2.0 mol / L, and the potassium chloride solution is passed through the resin column from top to bottom at a rate of 2-3 BV / h for 1-2 hours, where BV is the bed volume of the resin in the exchange column.

[0010] Furthermore, in step S2, the crown ether solution is a 15-crown ether-5 solution; the concentration of the 15-crown ether-5 solution is 0.05–0.2 mol / L, the solvent is ethanol, the reaction temperature is 40–50℃, and the reaction time is 6–8 hours.

[0011] Furthermore, in step S3, the ion exchange temperature is 20–30°C, the flow rate is 2–3 BV / h, and the exchange time is 3–4 hours.

[0012] Furthermore, in step S3, the molar ratio of sodium perborate in the sodium perborate mother liquor to potassium ions in the crown ether modified potassium resin is 1:1.

[0013] Furthermore, in step S3, the effluent from the exchange column is monitored in real time, and the effluent is circulated back into the exchange column until the sodium ion concentration therein is lower than a set value.

[0014] Furthermore, in step S4, the cooling crystallization temperature is -5℃ to 5℃, the stirring speed is 30-50 r / min, and the crystallization time is 1-2 hours.

[0015] Furthermore, in step S5, the drying is performed in a vacuum oven at a temperature of 40-60°C for 0.5-2 hours.

[0016] The active oxygen content of the potassium perborate product obtained through the above process is greater than 16%.

[0017] The technical solution of the present invention has the following beneficial effects: (1) Waste recycling reduces costs: The waste liquid produced by sodium perborate production is used directly as raw material, making full use of the boron and active ingredients in it, eliminating the consumption of boric acid and hydrogen peroxide, the two main raw materials, and realizing the efficient recycling of waste resources, which greatly reduces production costs.

[0018] (2) Mild process and excellent product quality: The entire process is carried out under mild ion exchange and crystallization conditions, avoiding violent exothermic peroxidation reactions. The resulting potassium perborate product has high purity, with an active oxygen content that is stable at over 16%, large and uniform crystal particle size (about 150 μm), and high purity. It also has good flowability and slow-release properties, and its thermal stability is significantly better than that of products produced by traditional processes.

[0019] (3) Environmentally friendly: The process does not produce high-salt wastewater as in traditional methods, and the effective components in the mother liquor are fully utilized, achieving clean production.

[0020] (4) Modification of potassium-type resin with 15-crown ether-5: The core technology is outstanding and the effect is irreplaceable. Generally, the selectivity of resins for potassium ions is higher than that for sodium ions. Resin modified with crown ethers exhibits a much higher selectivity for sodium ions than for potassium ions. Because the cavity radius of 15-crown ether-5 is similar to that of sodium ions, the size of sodium ions is compatible with the cavity of the crown ether ring. Consequently, sodium ions in the solution can smoothly enter the resin, further displacing potassium from the resin to obtain a potassium perborate solution. This invention reverses the selectivity of conventional resins for potassium and sodium ions by modifying strongly acidic potassium-type resin with a specific crown ether (such as 15-crown ether-5), resulting in a resin with extremely high selectivity for sodium ions, thereby efficiently and thoroughly removing Na from the mother liquor. + Replace with K + This modification step is crucial to the success of this method; unmodified resins or other types of resins cannot achieve the same displacement efficiency and product quality.

[0021] (5) Simple process and easy to industrialize: The main processes are ion exchange and cooling crystallization. The operation is simple, the equipment requirements are low, and it is easy to realize continuous or semi-continuous production, which is suitable for industrial promotion. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] Example 1

[0024] A method for preparing potassium perborate by recovering sodium perborate mother liquor using modified potassium-type resin includes the following process steps: S1. Preparation of K-type resin: Take 0.25 L of 732 hydrogen-form cation exchange resin and wash it repeatedly with 5% hydrochloric acid and deionized water until the pH of the effluent is neutral. Immerse the washed resin in a 0.5 mol / L epichlorohydrin solution, add 0.5% (w / w) potassium hydroxide as a catalyst, and activate it by stirring at 60°C for 5 hours. After activation, wash the resin thoroughly with deionized water.

[0025] The activated resin was wet-packed into a 0.5 L exchange column, with the packing height being 1 / 2 of the column height (total column volume 0.5 L). A 1.5 mol / L potassium chloride solution was passed through the resin bed from top to bottom at 3 BV / h (0.75 L / h) for 1.5 hours to ensure complete conversion of the resin to the potassium form. After exchange, the resin was washed with deionized water until no chloride ions were detected. The resin was then vacuum-dried at 50 °C for 3 hours to obtain the potassium form resin, weighing 231 g.

[0026] S2: Crown ether modification: Prepare 2.5 L of a 0.1 mol / L 15-crown ether-5 ethanol solution. Add the above-mentioned potassium-form resin to this solution and stir at 50 °C for 6 hours. After the reaction is complete, cool, discard the supernatant, and wash the resin thoroughly with ethanol and deionized water successively. Finally, dry under vacuum at 50 °C for 3 hours to obtain crown ether-modified potassium-form resin, weighing 252 g. The potassium content of the modified resin was determined to be 3.17 mmol / g by flame photometry.

[0027] S3: Mother liquor ion exchange: The sodium perborate content in a certain sodium perborate mother liquor was determined to be 5% (w / w). 1296 g of the mother liquor (containing 64.8 g of sodium perborate, approximately 0.8 mol) was weighed. The mother liquor was passed through an exchange column packed with 252 g of crown ether modified potassium-type resin at a flow rate of 2.47 BV / h, with the column temperature controlled at 20-30℃. The effluent was collected, and the concentrations of Na⁺ and K⁺, as well as the contents of boron and reactive oxygen species, were monitored in real time. The initial effluent was circulated back into the resin column as feed, and exchange continued for 4 hours. Monitoring results showed that after approximately 3.5 hours, the Na⁺ concentration in the effluent had decreased below the set value, the K⁺ concentration stabilized, and the boron and reactive oxygen species contents were essentially the same as those in the feed mother liquor, indicating complete ion exchange and the acquisition of a pure potassium perborate solution.

[0028] S4: Crystallization and Separation: The potassium perborate solution was transferred to a three-necked flask and connected to a refrigeration unit to maintain the solution temperature at 0°C. The stirrer was turned on and stirred at 40 r / min for 1 hour, during which a large amount of crystals gradually precipitated from the solution. Stirring was stopped and cooling was resumed. The suspension was then vacuum filtered to separate the solid and liquid phases, yielding wet potassium perborate.

[0029] S5: Drying: The wet product was dried in a vacuum oven at 50°C for 1 hour to obtain 76.03 g of white granular potassium perborate product.

[0030] Product Analysis: Using standard methods, the active oxygen content of the product was determined to be 16.16%, and the median particle size D50 was determined to be 150.1 μm using a laser particle size analyzer.

[0031] Example 2

[0032] This embodiment is basically the same as the steps in Embodiment 1, with the following differences: (1) In step S2, the 15-crown ether-5 modification reaction temperature was controlled at 70℃ and the reaction time was 6 hours. The potassium content of the obtained modified resin was 3.17 mmol / g.

[0033] (2) In step S3, the mother liquor flow rate is 2.67 BV / h and the exchange time is 4 hours.

[0034] (3) In step S4, the crystallization temperature is -2℃, the stirring speed is 50 r / min, and the crystallization time is 2 hours.

[0035] Product Analysis: 76.12 g of potassium perborate product was obtained, with an active oxygen content of 16.15% and a median particle size D50 of 150.9 μm.

[0036] Comparative Example 1 (Traditional Process)

[0037] Weigh 200 g of tap water and add it to the reactor as a base medium, then start stirring at 100 r / min. Add 0.8 mol of potassium hydroxide, and after dissolving, add boric acid at a boric acid:potassium hydroxide molar ratio of 1:1 to produce potassium metaborate. Control the system temperature at 30-50℃. Prepare 50% hydrogen peroxide solution with the same molar amount of hydrogen peroxide as potassium hydroxide, and slowly add it dropwise to the system. After the addition is complete, continue stirring for 1 hour. After the reaction is complete, the reaction solution is vacuum filtered, washed with water, and the wet product is vacuum dried at 50℃ for 1 hour to obtain 72.64 g of potassium perborate product.

[0038] Product analysis: The reactive oxygen species content is 13.45%, and the median particle size D50 is 72.1 μm.

[0039] Comparative Example 2 (Unmodified Resin Process)

[0040] S1. Take 0.25 L of 732 hydrogen-form cation exchange resin and wash it with 5% hydrochloric acid and deionized water until neutral. Then, put the resin into a packed column, filling it to half the column height (total column volume 0.5 L). Purge with 1.5 mol / L potassium chloride solution at a flow rate of 3 BV / h for 1.5 hours to fully convert the resin to the potassium form. After drying, weigh 231 g. The potassium content was measured to be 3.46 mmol / g using a flame photometer. (The epichlorohydrin activation and crown ether modification steps are omitted subsequently).

[0041] S2. Take 1296 g of the same sodium perborate mother liquor as in Example 1, and pass it through the unmodified potassium-type resin column at a flow rate of 2.47 BV / h, controlling the temperature at 20-30 degrees Celsius for 4 hours.

[0042] S3. S4. The crystallization, separation, and drying steps are the same as in Example 1.

[0043] Product Analysis: 72.45 g of potassium perborate was obtained, with an active oxygen content of 15.72% and a median particle size D50 of 148.1 μm.

[0044] Comparative Example 3 (Different Resins + Modifications) S1. 0.25 L of Amberlite IRC-76 cation exchange resin (weak acid type carboxylic acid resin) was selected and subjected to the same acid washing, water washing, epichlorohydrin activation, potassium ion exchange and 15-crown ether-5 modification operations as in Example 1 to obtain modified resin. The potassium content measured by flame photometer was 3.17 mmol / g.

[0045] The subsequent steps are exactly the same as in Example 1.

[0046] Product Analysis: 72.59 g of potassium perborate was obtained, with an active oxygen content of 15.16% and a median particle size D50 of 145.1 μm.

[0047] Product stability test:

[0048] The potassium perborate products obtained in the above examples and comparative examples were stored and tested in a 50°C constant temperature oven. Samples were taken on days 1, 3, 10, 15, and 20 to determine the reactive oxygen species (ROS) content. The decomposition rate was calculated using the following formula: (Decomposition rate = (1 - ROS content on day N / Initial ROS content) × 100%). The results are shown in the table below. Results of reactive oxygen species stability test

[0049] Results analysis: Compared with traditional techniques (Comparative Example 1): Comparative Example 1 has low active oxygen content, fine particle size, poor stability, and requires the addition of raw materials such as boron and hydrogen peroxide. The product of the present invention has an overwhelming advantage in active oxygen content, crystal particle size, and thermal stability (low decomposition rate). At the same time, the raw material cost is lower and the environmental benefits are significant, indicating that the crown ether modified resin scheme of the present invention is superior.

[0050] Compared with the unmodified resin process (Comparative Example 2): Although Comparative Example 2 also utilized the mother liquor, the resin, lacking crown ether modification, had insufficient selectivity for sodium ions, resulting in incomplete replacement. Consequently, the product exhibited a lower active oxygen content (15.72%) compared to the present invention (>16.1%), finer particle size, and poorer stability (high decomposition rate after 20 days). This demonstrates that crown ether modification is a crucial and irreplaceable step in achieving efficient and thorough sodium-potassium replacement, thereby obtaining high-quality products.

[0051] Compared with different resin modification processes (Comparative Example 3): Even with the same crown ether modification steps, using a weak acid resin (IRC-76) instead of a strong acid resin (732) resulted in a final product with lower reactive oxygen species content and stability compared to the embodiments of the present invention. Comparative Example 3 exhibited lower reactive oxygen species content, finer particle size, and poorer stability. This demonstrates that combining a specific type of strong acid cation exchange resin (such as type 732) with crown ether modification can produce a synergistic effect, which is an important condition for achieving optimal technical results.

[0052] The technical solution of this invention mainly solves the following technical problems: (1) Solved the problem of low hydrogen peroxide utilization rate in the existing process: The existing process uses water as the reaction system medium. First, potassium metaborate is synthesized by boric acid and potassium hydroxide or potassium salt. Then, hydrogen peroxide is added dropwise and a cooling medium is introduced to control the temperature. During this process, the temperature is very easy to exceed the limit, and there is a high decomposition rate of hydrogen peroxide. Afterward, it is necessary to perform filtration, washing and drying. The process is complicated and generates a large amount of salty wastewater.

[0053] (2) Solved the problem of high cost of existing process: Existing process requires the addition of a variety of raw materials including hydrogen peroxide, boric acid, potassium hydroxide, etc. In particular, the utilization rate of hydrogen peroxide is not high, and the price of boric acid is also relatively high. Therefore, this invention fully recovers the active ingredients and boron elements by using sodium perborate mother liquor, directly saving a large amount of basic raw materials.

[0054] (3) It solves the problem of low active oxygen and poor stability in existing processes: The active oxygen content prepared by existing production processes is generally below 14%, while the potassium perborate of the present invention has high purity due to the proper separation of each process and no violent peroxidation reaction. Therefore, the active oxygen content is all above 16%.

[0055] In summary, this invention, through the core technologies of combining "selection of specific strong acid resins" and "directional modification of crown ethers," successfully solves the problem of efficiently preparing high-quality potassium perborate from sodium perborate mother liquor, and has significant inventiveness, practicality, and economic and environmental value.

[0056] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing potassium perborate by recovering sodium perborate mother liquor using modified potassium-type resin, characterized in that, The process includes the following steps: S1: Preparation of potassium form resin: After pretreatment of hydrogen form strong acid cation exchange resin, it is converted into potassium form resin and dried for later use. S2: Crown ether modification: The potassium form resin is modified with a crown ether solution to obtain a crown ether modified potassium form resin; S3: Mother liquor ion exchange: The sodium perborate mother liquor is passed through an exchange column packed with the crown ether modified potassium resin to perform ion exchange, and a potassium perborate solution is obtained. S4: Crystallization and separation: The potassium perborate solution is cooled and crystallized, and the solid and liquid are separated to obtain wet potassium perborate. S5: Drying: Dry the wet potassium perborate product to obtain the potassium perborate product.

2. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 1, characterized in that, In step S1, the pretreatment includes: washing the resin with acid and deionized water until neutral; then activating the resin with epichlorohydrin and an alkaline catalyst; and finally placing the activated resin in an exchange column to undergo ion exchange with a potassium salt solution to convert it into potassium-type resin.

3. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 2, characterized in that, The activation treatment is performed at a temperature of 50-60℃ for 3-6 hours; the alkaline catalyst is potassium hydroxide; the potassium salt solution is potassium chloride solution with a concentration of 1.0-2.0 mol / L, and the potassium chloride solution is passed through the resin column from top to bottom at a rate of 2-3 BV / h for 1-2 hours, where BV is the bed volume of the resin in the exchange column.

4. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 1, characterized in that, In step S2, the crown ether solution is a 15-crown ether-5 solution; the concentration of the 15-crown ether-5 solution is 0.05–0.2 mol / L, the solvent is ethanol, the reaction temperature is 40–50℃, and the reaction time is 6–8 hours.

5. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 3, characterized in that, In step S3, the ion exchange temperature is 20–30℃, the flow rate is 2–3 BV / h, and the exchange time is 3–4 hours.

6. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 5, characterized in that, In step S3, the molar ratio of sodium perborate in the sodium perborate mother liquor to potassium ions in the crown ether modified potassium resin is 1:

1.

7. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 5, characterized in that, In step S3, the effluent from the exchange column is monitored in real time, and the effluent is circulated back into the exchange column until the sodium ion concentration therein is lower than the set value.

8. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 1, characterized in that, In step S4, the cooling crystallization temperature is -5℃ to 5℃, the stirring speed is 30-50 r / min, and the crystallization time is 1-2 hours.

9. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 1, characterized in that, In step S5, the drying is performed in a vacuum oven at a temperature of 40-60°C for 0.5-2 hours.

10. The method for preparing potassium perborate by recovering sodium perborate mother liquor from modified potassium-type resin according to claim 1, characterized in that, Its features are, The obtained potassium perborate product has an active oxygen content greater than 16%.

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