A method for preparing a high-bulk-density potassium peroxymonosulfate composite salt

Abstract

This invention provides a method for preparing high bulk density potassium peroxymonosulfate composite salt. Through multi-dimensional process optimization including multi-point feeding and neutralization, ultrasonic action, crystal guiding agent, heating-heating-heating-cooling, and drying-mixing-sieving, the bulk density of PMS is synergistically improved, and the overall performance of the final product is superior to that of the prior art.

Description

Technical Field

[0001] This invention relates to the field of peroxide preparation technology, specifically to a method for preparing a high-bulk-density potassium peroxymonosulfate composite salt. Background Technology

[0002] Potassium persulfate (PMS) is a highly efficient and environmentally friendly acidic oxidant. Due to its strong non-chlorine oxidizing ability and environmentally friendly properties, it is widely used in water treatment, aquaculture disinfection, and industrial production. Bulk density is a key physical performance indicator of PMS products, directly affecting packaging efficiency, transportation costs, and ease of use. High bulk density products can reduce packaging volume, lower transportation costs, reduce dust generation during use, and improve the stability of dissolution rates.

[0003] Current industrial methods primarily employ the fuming sulfuric acid process to prepare PMS. This involves reacting high-concentration hydrogen peroxide with fuming sulfuric acid to generate peroxysulfuric acid, which is then neutralized with potassium hydroxide or potassium carbonate and cooled to crystallize, yielding the PMS product. However, existing technologies do not specify or define the bulk density of PMS products. Analysis of commercially available potassium peroxymonosulfate composite salt products reveals a common problem: low bulk density (typically 0.7–1.1 g / cm³). Low bulk density increases packaging material consumption and transportation costs due to its bulky volume. Furthermore, in downstream applications, low bulk density leads to stratification during mixing, resulting in poor flowability, uneven content, and even sticking during tableting, all directly impacting the uniformity of the final product's quality. Therefore, finding a method to improve the bulk density of potassium peroxymonosulfate composite salt products is crucial to overcoming the shortcomings of existing technologies and improving product quality. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing high packing density potassium peroxymonosulfate composite salt based on ultrasonic action, crystal guiding agents, and other multi-dimensional process optimizations to synergistically improve the packing density of PMS.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: A method for preparing a high-bulk-density potassium peroxymonosulfate composite salt includes the following steps: S1) Add sulfuric acid to hydrogen peroxide solution in a certain proportion and control the reaction temperature to obtain an oxidizing solution; S2) The oxidizing liquid and solid potassium carbonate are simultaneously added to water or centrifuged mother liquor for neutralization. During the neutralization process, potassium carbonate is added to the reactor through a multi-point feeding method. During the crystal nucleation period, 10-30 minutes after the addition of potassium carbonate, ultrasonic waves were applied for 3-5 minutes, with a frequency of 20-50 kHz and a power of 30-250 W. During the crystal growth period, 20 minutes to 5 hours after the addition of potassium carbonate, ultrasonic waves were applied for 3-5 minutes, with a frequency of 20-50 kHz and a power of 30-250 W. During the crystal growth period, one or more crystal guiding agents selected from sodium dodecylbenzenesulfonate, dodecylbenzenesulfonic acid, sodium α-alkenyl sulfonate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and perfluoroalkyl sulfonate are added, with the addition amount being 0.01%~0.2% of the mass of the oxidation solution; S3) After the feeding is completed, the formed crystal slurry is heated, kept warm, and then cooled before centrifugation. The heating range is 1~10℃, the holding time is 0.5~10h, and the temperature after cooling is consistent with the control temperature of the neutralization process. S4) The centrifuged wet product is dried, with the drying temperature controlled at 40~70℃ and the drying rate at 0.05~0.7 kg water / (h▪kg oven-dry material). S5) After mixing the anti-caking agent with the dried product evenly and sieving, a high-bulk-density potassium persulfate composite salt product is obtained.

[0006] Further, in step S1), the sulfuric acid has a mass fraction of 90-100% concentrated sulfuric acid and a sulfur trioxide content of 20-65% fuming sulfuric acid, the hydrogen peroxide has a mass fraction of 50-75%, the mass ratio of sulfuric acid to hydrogen peroxide is 2.5-4.2:1, and the reaction temperature is controlled within the range of -20-30℃.

[0007] Furthermore, the mass ratio of sulfuric acid to hydrogen peroxide is 2.8~3.8:1, and the reaction temperature is controlled within the range of -15~20℃.

[0008] Further, in step S2), the ratio of water or centrifugal mother liquor to oxidizing liquid is 3~6:1, the mass ratio of potassium carbonate to oxidizing liquid is 0.5~0.8, the temperature range of the neutralization process is controlled within -20~30℃, and potassium carbonate is added to the reactor through a multi-point feeding method, with the number of feeding points being 3~6.

[0009] Further, in step S2), the ratio of water or centrifugal mother liquor to oxidizing liquid is 4.5~6:1, the mass ratio of potassium carbonate to oxidizing liquid is 0.6~0.75, the temperature range of the neutralization process is controlled within -15~15℃, and potassium carbonate is added to the reactor through a multi-point feeding method, with the number of feeding points being 3~6.

[0010] Potassium carbonate can be fed at multiple points to reduce local alkali concentration and supersaturation during the reaction process, thereby reducing the loss of active oxygen and preventing explosive nucleation caused by high local supersaturation.

[0011] Furthermore, in step S2), the ultrasonic equipment used is an ultrasonic vibrating rod or an ultrasonic vibrating plate.

[0012] Ultrasonic crystallization is an important process intensification technique that significantly improves crystal packing density through several key pathways via its unique physical effects. It promotes uniform nucleation, suppresses undesirable crystal morphologies, and produces crystals with narrower particle size distributions and greater strength. Without ultrasound, nucleation is often unpredictable and uneven, easily occurring explosively or secondaryly at different locations in the crystallizer (such as the walls and agitator), resulting in inconsistent initial crystal sizes. The cavitation effect of ultrasound in liquids provides the solution with a large, uniformly distributed energy, significantly lowering the nucleation energy barrier. This results in the instantaneous induction of a large number of uniform crystal nuclei throughout the solution. A large number of uniform nuclei means that all crystals begin to grow almost simultaneously, ultimately yielding crystal products with very narrow particle size distributions. Monodisperse spherical or uniformly sized crystals can achieve the densest packing, like a pile of identical marbles, significantly increasing packing density.

[0013] Furthermore, under high supersaturation, crystals tend to grow rapidly along the edges of the crystal nucleus, forming dendritic or needle-like structures. These morphologies exhibit strong anisotropy and interlock, creating numerous macroscopic pores. The microjets and intense disturbances generated by ultrasonic cavitation can disrupt the diffusion boundary layer, significantly enhancing the mass transfer rate of solute molecules to the crystal surface and making the growth environment more uniform across the crystal surface. However, during ultrasonic treatment, excessively high ultrasonic power or excessively long treatment time may cause the formed crystals to be mechanically broken by the shock waves or microjets generated by the cavitation effect, resulting in excessively small crystal sizes or even fine powder, which has a counterproductive effect on crystal crystallization regulation. For thermosensitive substances such as potassium peroxymonosulfate complex salts, this can exacerbate the decomposition of reactive oxygen species.

[0014] Improper timing of ultrasonic treatment, resulting in crystal nuclei that are not in equilibrium with the growth process, can lead to an excessively wide crystal size distribution, forming fine crystals that are difficult to separate. Therefore, ultrasonic parameters need to be precisely controlled during the preparation of potassium peroxymonosulfate complex salts to avoid the aforementioned adverse effects.

[0015] Furthermore, in step S2), the crystal-directing agent added during the crystal growth period adsorbs onto the crystal surface, inhibiting disordered growth and inducing the formation of a regular, dense crystal morphology, thus avoiding the formation of needle-like or dendritic anisotropic crystals. The crystal-directing agent selected in this invention is an auxiliary agent with good compatibility with the potassium peroxymonosulfate composite salt production system. It will not degrade or will only degrade slightly when the two coexist, and will not have any adverse effects on the appearance or quality of the potassium peroxymonosulfate composite salt product or the production mother liquor system. In addition, through synergistic effects with several other control methods, a very small amount of crystal-directing agent can achieve a good bulk density control effect.

[0016] Furthermore, in step S3), the formed crystal slurry is subjected to an appropriate heating-holding-cooling cycle, which can cause recrystallization inside the crystal, eliminate internal stress, and make the crystal stronger; promote the dissolution of small crystals and the growth of large crystals, and then cool it to the neutralization process control temperature to further stabilize the crystal.

[0017] Furthermore, in step S4), during the initial stage of drying, the liquid bridging forces between particles cause the crystal particles to adhere to each other. If the drying rate is too fast, the pressure generated by solvent vaporization may cause the aggregates to form a porous structure, or form hard "solid bridges" after drying, resulting in hard, porous aggregates instead of free-flowing, dense particles.

[0018] Further, in step S5), the anti-caking agent is magnesium carbonate. The anti-caking agent is mixed with the dried product at a mass ratio of 1:50~200. The stirring speed during mixing is 100~300 rpm / min, and the mixing time is 0.5~1.5 h. After mixing, the mixture is sieved, and 30~200 mesh material is taken as the high bulk density potassium peroxymonosulfate composite salt product.

[0019] Furthermore, in step S5), excessively large crystals or agglomerates are lightly crushed during the mixing process, and then excessively fine particles are removed by sieving to obtain a product with a more reasonable particle size distribution, effectively improving the product's bulk density.

[0020] Furthermore, in step S5), the bulk density of the obtained high-bulk-density potassium persulfate composite salt product is ≥1.2 g / cm³. 3 .

[0021] Compared with the prior art, the present invention has the following advantages: This invention discloses a method for preparing a high-packing-density potassium peroxymonosulfate composite salt. Through multi-dimensional process optimization, the packing density of PMS is synergistically improved, and its overall performance is superior to that of existing technologies.

[0022] (1) Multi-point feeding and neutralization: avoids the formation of fine crystals caused by local overconcentration, and makes the pH and concentration distribution of the reaction system uniform, providing a stable environment for crystal growth.

[0023] (2) Effect of ultrasound: During the nucleation period, ultrasound promotes uniform nucleation and reduces the number of crystal nuclei; during the growth period, ultrasound accelerates solute diffusion, promotes directional crystal growth, and increases the particle size.

[0024] (3) Crystal guiding agent: By adsorbing on the crystal surface, it inhibits disordered growth and induces the formation of regular and dense crystal morphology.

[0025] (4) Heating-holding-cooling: By heating and ripening, small crystals are eliminated, the crystal size distribution is concentrated, and the porosity is reduced.

[0026] (5) Drying, mixing and sieving: control the drying conditions to avoid crystal agglomeration, the mixing process will lightly crush the excessively large crystals or agglomerates, and the particle size distribution will be reasonable after sieving, further improving the packing density. Attached Figure Description

[0027] Figure 1 These are optical micrographs of potassium peroxymonosulfate composite salt crystals with a particle size of 40-60 nm, prepared in Example 1 of this invention and in comparison with existing technologies.

[0028] Figure 2 This is a particle size distribution diagram of the high packing density potassium peroxymonosulfate composite salt crystals prepared in Examples 1, 2 and 3 of this invention and the potassium peroxymonosulfate composite salt crystals prepared by prior art. Detailed Implementation

[0029] The embodiments of the present invention will now be described in further detail with reference to the accompanying drawings. Example 1

[0030] S1) Add 300g of 98% sulfuric acid to 100g of 70% hydrogen peroxide solution, and control the temperature at around 0℃ to react and obtain an oxidizing solution.

[0031] S2) Add 2000g of mother liquor to the reactor and start stirring; simultaneously add 240g of solid potassium carbonate through 3 feed points, and control the temperature at around 0℃ during the feeding process; The nucleation phase begins 10 minutes after potassium carbonate is added, and ultrasound is applied: frequency 30 kHz, power 50 W, duration 4 min. The growth period begins 60 minutes after the potassium carbonate is added. Ultrasound is applied at a frequency of 30 kHz, a power of 100 W, and a duration of 4 minutes, while 0.1 g of sodium dodecylbenzenesulfonate is added simultaneously.

[0032] S3) After the feeding is completed, the reaction slurry is heated to 5°C, kept at that temperature for 2 hours, and then cooled to 0°C.

[0033] S4) After centrifugation, the wet product is dried at 50°C, and the drying rate is controlled at 0.15 kg water / (h·kg oven-dry material).

[0034] S5) The dried product is mixed with magnesium carbonate at a ratio of 1:100 (stirred at 300 rpm / min for 1 h), and sieved through a 30-200 mesh to obtain the potassium persulfate composite salt product. Example 2

[0035] S1) Add 310g of 105% sulfuric acid to 100g of 70% hydrogen peroxide solution, and control the temperature at about 5℃ to react and obtain an oxidizing solution.

[0036] S2) Add 2000g of mother liquor to the reactor and start stirring; add 250g of solid potassium carbonate simultaneously through 6 feed points, and control the temperature at about 5℃ during the feeding process; The nucleation phase begins 10 minutes after potassium carbonate is added, and ultrasound is applied: frequency 50 kHz, power 50 W, duration 5 min. The growth period begins 60 minutes after the potassium carbonate is added. Ultrasound is applied at a frequency of 50 kHz, a power of 50 W, and a duration of 5 minutes, while 0.1 g of sodium α-olefin sulfonate is added simultaneously.

[0037] S3) After the feeding is completed, the reaction slurry is heated to 5°C, kept at that temperature for 2 hours, and then cooled to -5°C.

[0038] S4) After centrifugation, the wet product is dried at 60℃, and the drying rate is controlled at 0.25 kg water / (h·kg oven-dry material).

[0039] S5) The dried product is mixed with magnesium carbonate at a ratio of 1:150 (stirred at 300 rpm / min for 1 h), and sieved through a 30-200 mesh to obtain the potassium persulfate composite salt product. Example 3

[0040] S1) Add 350g of 115% sulfuric acid to 100g of 70% hydrogen peroxide solution, and control the temperature at around 0℃ to react and obtain an oxidizing solution.

[0041] S2) Add 2000g of mother liquor to the reactor and start stirring; add 290g of solid potassium carbonate simultaneously through 6 feed points, and control the temperature at about 5℃ during the feeding process; Nucleation begins 20 minutes after potassium carbonate is added, and ultrasound is applied at a frequency of 35 kHz, a power of 120 W, and a duration of 5 minutes. The growth period begins 60 minutes after the potassium carbonate is added. Ultrasound is applied at a frequency of 35 kHz, a power of 120 W, and a duration of 5 minutes, while 0.1 g of alkylphenol polyoxyethylene ether is added simultaneously.

[0042] S3) After the feeding is completed, the reaction slurry is heated to 5°C, kept at that temperature for 2 hours, and then cooled to 5°C.

[0043] S4) After centrifugation, the wet product is dried at 70°C, and the drying rate is controlled at 0.5 kg water / (h·kg oven-dry material).

[0044] S5) The dried product is mixed with magnesium carbonate at a ratio of 1:90 (stirred at 300 rpm / min for 1 h), and sieved through a 30-200 mesh to obtain the potassium persulfate composite salt product.

[0045] Existing technology comparison 97g of a 70% hydrogen peroxide solution was added to a 1000mL four-necked flask equipped with a stirrer and thermometer. The flask was cooled to 5°C using an ice-water bath. Then, 170g of a 65% fuming sulfuric acid solution was added dropwise, maintaining the system temperature at 10°C and the stirring speed at 300rpm / min. After adding the fuming sulfuric acid, 300g of a 45% potassium hydroxide solution was added dropwise, again maintaining the system temperature at 10°C. After neutralization, the reaction solution was further cooled at -5°C for 2 hours to crystallize, yielding potassium persulfate composite salt crystals. These crystals were then dried and mixed with magnesium carbonate to obtain the final product, the potassium persulfate composite salt.

[0046] The particle size distribution and bulk density properties of the potassium peroxymonosulfate composite salt products prepared in the above embodiments were tested compared with those prepared by the prior art. The test results are as follows: index Example 1 Example 2 Example 3 Comparative Example D50 / um 248.496 234.470 232.768 170.803 Particle size distribution width Span 0.885 0.766 0.737 1.716 Bulk density (g / cm3) 1.25 1.31 1.28 0.86 The bulk density of the product was determined in accordance with GB / T 23771-2009 "Determination of Bulk Density in Inorganic Chemical Products".

[0047] The average particle size was determined using an LS-909 laser particle size analyzer.

[0048] like Figure 1 As shown, compared with the existing technology comparative examples, the potassium persulfate composite salt crystals prepared in Example 1 are more regular.

[0049] like Figure 2 As shown, compared with the existing technology comparative examples, the potassium persulfate composite salt products prepared in Examples 1, 2 and 3 have a more uniform particle size distribution.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the concept 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 preparing a high-bulk-density potassium peroxymonosulfate composite salt, characterized in that... Includes the following steps: S1) Add sulfuric acid to hydrogen peroxide solution in a certain proportion and control the reaction temperature to obtain an oxidizing solution; S2) The oxidizing liquid and solid potassium carbonate are simultaneously added to water or centrifuged mother liquor for neutralization. During the neutralization process, potassium carbonate is added to the reactor through a multi-point feeding method. During the crystal nucleation period, 10-30 minutes after the addition of potassium carbonate, ultrasonic waves were applied for 3-5 minutes, with a frequency of 20-50 kHz and a power of 30-250 W. During the crystal growth period, 20 minutes to 5 hours after the addition of potassium carbonate, ultrasonic waves were applied for 3-5 minutes, with a frequency of 20-50 kHz and a power of 30-250 W. During the crystal growth period, one or more crystal guiding agents selected from sodium dodecylbenzenesulfonate, dodecylbenzenesulfonic acid, sodium α-alkenyl sulfonate, fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and perfluoroalkyl sulfonate are added, with the addition amount being 0.01%~0.2% of the mass of the oxidation solution; S3) After the feeding is completed, the formed crystal slurry is heated, kept warm, and then cooled before centrifugation. The heating range is 1~10℃, the holding time is 0.5~10h, and the temperature after cooling is consistent with the control temperature of the neutralization process. S4) The centrifuged wet product is dried, with the drying temperature controlled at 40~70℃ and the drying rate at 0.05~0.7 kg water / (h▪kg oven-dry material). S5) After mixing the anti-caking agent with the dried product evenly and sieving, a high-bulk-density potassium persulfate composite salt product is obtained.

2. The method for preparing a high bulk density potassium peroxymonosulfate composite salt according to claim 1, characterized in that: In step S1), concentrated sulfuric acid with a mass fraction of 90-100% and fuming sulfuric acid with a sulfur trioxide content of 20-65% are used, hydrogen peroxide with a mass fraction of 50-75% is used, the mass ratio of sulfuric acid to hydrogen peroxide is 2.5-4.2:1, and the reaction temperature is controlled within the range of -20-30℃.

3. The method for preparing a high bulk density potassium peroxymonosulfate composite salt according to claim 1, characterized in that: In step S2), the ratio of water or centrifugal mother liquor to oxidizing liquid is 3~6:1, the mass ratio of potassium carbonate to oxidizing liquid is 0.5~0.8, the temperature range of the neutralization process is controlled within -20~30℃, and potassium carbonate is added to the reactor through a multi-point feeding method, with the number of feeding points being 3~6.

4. The method for preparing a high bulk density potassium peroxymonosulfate composite salt according to claim 1, characterized in that: In step S2), the ultrasonic equipment used is an ultrasonic vibrating rod or an ultrasonic vibrating plate.

5. The method for preparing a high bulk density potassium peroxymonosulfate composite salt according to claim 1, characterized in that: In step S5), the anti-caking agent is magnesium carbonate. The anti-caking agent is mixed with the dried product at a mass ratio of 1:50~200. The stirring speed during mixing is 100~300 rpm / min, and the mixing time is 0.5~1.5 h. After mixing, the mixture is sieved, and the material with a mesh size of 30~200 is taken as the high bulk density potassium peroxymonosulfate composite salt product.

6. A method for preparing a high-bulk-density potassium peroxymonosulfate composite salt according to claim 1 or 5, characterized in that: In step S5), the bulk density of the high-bulk-density potassium persulfate composite salt product is ≥1.2 g / cm³. 3 .

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