High-stability calcium perborate as well as synthesis method and application thereof

Abstract

The invention discloses high-stability calcium perborate and a synthesis method and application thereof.The synthesis method includes the steps that soluble calcium salt and borax are dissolved in water and heated and stirred to form a mixed solution A, then a hydrogen peroxide solution and a stabilizer are mixed, the pH value is adjusted to 8.0-10.0 through an alkaline regulator, and a solution B is obtained; under the conditions of stirring and constant temperature, the obtained solution B is slowly dropwise added into the obtained solution A for reaction, and the pH value of the system is maintained to be 8.5-9.5 by supplementing an alkaline regulator; after the reaction is completed, the obtained white suspension is subjected to suction filtration, a filter cake is washed, dried in vacuum and smashed, and the high-stability calcium perborate product can be obtained, compared with a traditional synthesis method, the active oxygen retention rate of the calcium perborate synthesized through the method is larger than or equal to 92% after the calcium perborate is stored for 30 days under the conditions that the temperature is 40 DEG C and the relative humidity is 75%.

Description

Technical Field

[0001] This invention relates to the field of inorganic peroxide synthesis technology, specifically to a highly stable calcium perborate, its synthesis method, and its applications. Background Technology

[0002] There are several methods for synthesizing calcium perborate. One common method involves synthesizing calcium metaborate from borax and calcium hydroxide at a molar ratio of 2.3:1 and 35°C. Then, naturally air-dried calcium metaborate is reacted with 30% hydrogen peroxide in the presence of a stabilizer to synthesize calcium perborate. However, this method produces calcium perborate with a significant drawback: poor stability. During storage, especially under high temperature and humidity conditions, it easily absorbs moisture, clumps, and decomposes, leading to a rapid decrease in active oxygen content. This shortcoming severely limits its transportation, storage, and practical application, increasing usage costs. Furthermore, the calcium metaborate must be air-dried before further reactions can proceed, which is time-consuming and labor-intensive.

[0003] Therefore, this invention proposes a highly stable calcium perborate, its synthesis method, and its applications. Summary of the Invention

[0004] In view of the problems existing in the prior art, the purpose of this invention is to provide a calcium perborate with a simple process, low cost, and fundamentally improved stability at the crystal structure level, as well as its synthesis method and application.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: This invention proposes a method for synthesizing highly stable calcium perborate, comprising the following steps: 1) Dissolve soluble calcium salts and borax in water, heat and stir to form mixed solution A; 2) Mix hydrogen peroxide solution with stabilizer, and adjust the pH value to 8.0-10.0 with alkaline regulator to obtain solution B; 3) Under stirring and constant temperature conditions, the solution B obtained in step 2) is slowly added dropwise to the solution A obtained in step 1) to carry out the reaction, and the pH value of the system is maintained at 8.5-9.5 by adding alkaline regulator; 4) After the reaction in step 3) is completed, the resulting white suspension is filtered, and the filter cake is washed, vacuum dried and pulverized to obtain a highly stable calcium perborate product.

[0006] Further, in step 1), the soluble calcium salt is calcium chloride or calcium nitrate, and the molar ratio of the soluble calcium salt:borax:water is 1.8~2.2:1:111.

[0007] Further, in step 2), the concentration of the hydrogen peroxide solution is 25-35 wt%, and the amount added is 6 times the amount of borax; the amount of the stabilizer added is 0.5%-3.0% of the theoretical product mass.

[0008] Furthermore, the stabilizer is one or both of sodium silicate and disodium ethylenediaminetetraacetate.

[0009] Furthermore, the alkalinity regulator is a sodium hydroxide solution or ammonia.

[0010] Furthermore, in step 3), the dropping process is controlled by a peristaltic pump with a dropping rate of 1-3 mL / min. The reaction temperature is controlled at 45-65°C and the dropping time is not less than 30 minutes. After the dropping is completed, the reaction needs to be matured for 30-90 minutes.

[0011] Further, in step 4), the washing is performed sequentially with ice water and anhydrous ethanol; the vacuum drying temperature is 60-80°C, the vacuum degree is -0.08 to -0.1 MPa, and the time is 2-4 hours.

[0012] This invention proposes a highly stable calcium perborate synthesized by the method described above, wherein the active oxygen content of the calcium perborate is ≥11.8%, and the active oxygen retention rate is ≥92% after storage for 30 days at 40°C and 75% relative humidity.

[0013] This invention also proposes the application of the highly stable calcium perborate as an oxidant, bleaching agent, or bactericide in wastewater treatment agents or synthetic reagents.

[0014] In wastewater treatment, calcium perborate can rapidly release active oxygen to oxidize harmful substances and bacteria, thereby purifying the water. When hydrogen peroxide is released, it also activates the denaturation sites of bacterial proteins, thus denaturing the proteins and killing the bacteria.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) In this invention, soluble calcium salt and borax are first dissolved in water and heated and stirred to form a mixed solution A. Then, hydrogen peroxide solution is mixed with a stabilizer, and the pH value is adjusted to 8.0-10.0 with an alkaline adjuster to obtain solution B. Then, under stirring and constant temperature conditions, the obtained solution B is slowly added dropwise to the obtained solution A to carry out the reaction, and the pH value of the system is maintained at 8.5-9.5 by adding alkaline adjuster. After the reaction is completed, the resulting white suspension is filtered, and the filter cake is washed, vacuum dried and pulverized to obtain a highly stable calcium perborate product. 2) The synthesis method of the present invention is simple and low in cost, and the method for synthesizing calcium perborate can fundamentally improve the stability at the crystal structure level, thus solving the technical problems that urgently need to be solved in this field. 3) Compared with traditional synthesis methods, the active oxygen retention rate of the present invention is ≥92% after 30 days of storage at 40°C and 75% relative humidity; the oxygen content of the traditionally synthesized calcium perborate is 11.5%, and the active oxygen retention rate is only 76.3% after 30 days of storage under the same accelerated experimental conditions. Detailed Implementation

[0016] The present invention will be further described below with reference to embodiments, but the scope of protection of the present invention is not limited to the scope described. Example 1

[0017] 1) In a 500mL three-necked flask, add 22.2g of calcium chloride (CaCl2, 0.2mol) and 38.1g of borax (Na2B4O7·10H2O, 0.1mol), add 200mL of deionized water, heat to 50°C and stir to dissolve, to obtain solution A.

[0018] 2) Add 68g of 30% hydrogen peroxide solution (0.6mol H2O2) and 0.5g of sodium silicate (Na2SiO3·9H2O) to a beaker, and adjust the pH to 9.0 with 10% NaOH solution to obtain solution B.

[0019] 3) Under vigorous stirring, add solution B dropwise to solution A at a rate of 2 mL / min using a peristaltic pump. Maintain the reaction temperature at 55 ± 2°C and maintain the pH of the system at 9.0 ± 0.2 by adding 10% NaOH dropwise. After the addition is complete, continue the ripening reaction for 60 minutes.

[0020] 4) After cooling the reaction solution to room temperature, filter it under vacuum, wash it twice with 50 mL of ice water, and then wash it once with 20 mL of anhydrous ethanol. Place the filter cake in a vacuum drying oven and dry it at 70°C and -0.09 MPa for 3 hours. After pulverizing, pass it through a 100-mesh sieve to obtain 35.5 g of white powder product.

[0021] The product was tested and found to contain 12.1% active oxygen. After being placed in a constant temperature and humidity chamber at 40°C and 75% RH for 30 days, the active oxygen retention rate was 93.5%. Example 2

[0022] 1) In a 500mL three-necked flask, add 22.2g of calcium chloride (CaCl2, 0.2mol) and 38.1g of borax (Na2B4O7·10H2O, 0.1mol), add 200mL of deionized water, heat to 50°C and stir to dissolve, to obtain solution A.

[0023] 2) Add 68g of 30% hydrogen peroxide solution (0.6mol H2O2), 0.3g of EDTA-2Na and 0.3g of sodium silicate to a beaker, and adjust the pH to 9.0 with 10% NaOH solution to obtain solution B.

[0024] 3) Under vigorous stirring, add solution B dropwise to solution A at a rate of 2 mL / min using a peristaltic pump. Maintain the reaction temperature at 55 ± 2°C and maintain the pH of the system at 9.0 ± 0.2 by adding 10% NaOH dropwise. After the addition is complete, continue the ripening reaction for 60 minutes.

[0025] 4) After cooling the reaction solution to room temperature, filter it under vacuum, wash it twice with 50 mL of ice water, and then wash it once with 20 mL of anhydrous ethanol. Place the filter cake in a vacuum drying oven and dry it at 70°C and -0.09 MPa for 3 hours. After pulverizing, pass it through a 100-mesh sieve to obtain 35.8 g of white powder product.

[0026] The reactive oxygen species content was measured at 12.2%. After a 30-day accelerated test, the reactive oxygen species retention rate was 94.1%.

[0027] Comparative Example Using the traditional method, hydrogen peroxide is directly and rapidly added to a mixed solution of calcium salts and borax without a stabilizer, resulting in imprecise pH and temperature control. The resulting product initially contained 11.5% reactive oxygen species, and after 30 days under the same accelerated experimental conditions, the reactive oxygen species retention rate was only 76.3%.

Claims

1. A method for synthesizing highly stable calcium perborate, characterized in that... Includes the following steps: 1) Dissolve soluble calcium salts and borax in water, heat and stir to form mixed solution A; 2) Mix hydrogen peroxide solution with stabilizer, and adjust the pH value to 8.0-10.0 with alkaline regulator to obtain solution B; 3) Under stirring and constant temperature conditions, the solution B obtained in step 2) is slowly added dropwise to the solution A obtained in step 1) to carry out the reaction, and the pH value of the system is maintained at 8.5-9.5 by adding alkaline regulator; 4) After the reaction in step 3) is completed, the resulting white suspension is filtered, and the filter cake is washed, vacuum dried and pulverized to obtain a highly stable calcium perborate product.

2. The method for synthesizing highly stable calcium perborate according to claim 1, characterized in that... 1) The soluble calcium salt in the step is calcium chloride or calcium nitrate, and the molar ratio of the soluble calcium salt:borax:water is 1.8~2.2:1:

111.

3. The method for synthesizing highly stable calcium perborate according to claim 1, characterized in that... 2) The concentration of the hydrogen peroxide solution mentioned in the step is 25-35 wt%, and the amount added is 6 times the amount of borax; the amount of stabilizer added is 0.5%-3.0% of the theoretical product mass.

4. The method for synthesizing highly stable calcium perborate according to claim 3, characterized in that... The stabilizer is one or both of sodium silicate and disodium ethylenediaminetetraacetate.

5. The method for synthesizing highly stable calcium perborate according to claim 1, characterized in that... The alkalinity regulator is sodium hydroxide solution or ammonia water.

6. The method for synthesizing highly stable calcium perborate according to claim 1, characterized in that... 3) The dropping process in the step is controlled by a peristaltic pump with a dropping rate of 1-3 mL / min. The reaction temperature is controlled at 45-65°C and the dropping time is not less than 30 minutes. After the dropping is completed, the reaction needs to be matured for 30-90 minutes.

7. The method for synthesizing highly stable calcium perborate according to claim 1, characterized in that... 4) The washing process in the step involves sequentially washing with ice water and anhydrous ethanol; the vacuum drying temperature is 60-80°C, the vacuum degree is -0.08 to -0.1 MPa, and the time is 2-4 hours.

8. A highly stable calcium perborate synthesized by the method according to any one of claims 1-6, characterized in that... The active oxygen content of this calcium perborate is ≥11.8%, and the active oxygen retention rate is ≥92% after storage for 30 days at 40°C and 75% relative humidity.

9. The application of the highly stable calcium perborate as described in claim 7 as an oxidant, bleaching agent, or bactericide in wastewater treatment agents or synthetic reagents.