Method for the preparation of solid hydrogen peroxide granules

Description

1 Method for the preparation of solid hydrogen peroxide granules Technical field The present invention belongs to the field of disinfection and sterilization techniques, and more specifically to a method for the preparation of solid hydrogen peroxide granules. State of the art Due to its strong oxidative capacity and broad sterilization power, hydrogen peroxide is widely used in fields such as industry, the medical sector, food processing and water treatment. However, hydrogen peroxide solutions are susceptible to degradation during storage and transport, especially under high temperature conditions, whereby the degradation rate increases significantly. This leads to a rapid decrease in the effective content,which seriously affects the results of use. To extend the storage life of hydrogen peroxide, researchers have proposed a technical route to solidify hydrogen peroxide.15 By converting hydrogen peroxide into solid granules, the degradation rate can be significantly reduced and storage stability improved. However, existing solid hydrogen peroxide granules still present many technical problems during preparation and use. First, the thermal stability of existing solid hydrogen peroxide granules is inadequate. Especially under higher temperature conditions, the degradation rate of hydrogen peroxide remains high, which leads to a decrease in effective content during storage and transport and makes it difficult to guarantee long-term stability. Second, the solubility of the granules is poor. During use, hydrogen peroxide cannot be released quickly, which affects usage efficiency in the industrial and medical sectors. Moreover, the mechanical strength of the granules is low.causing them to break and crumble easily during storage and transport. This affects not only the appearance of the product but can also reduce performance and effectiveness in use. To solve these problems, researchers have attempted to significantly improve the performance of solid hydrogen peroxide granules by adding stabilizers and improving the preparation technique. The addition of stabilizers can, for example, slow down the degradation of hydrogen peroxide to a certain extent, but the choice of stabilizers and the optimization of the mixing ratio in the existing technique are insufficient, meaning that the thermal stability of the granules still needs to be improved. At the same time, most existing preparation techniques use a simple drying method, making it difficult to form a uniform granule structure. Consequently, the granules perform poorly in terms of solubility and mechanical strength. Moreover, it is still a major problem in the state of the art to find a balance between thermal stability,solubility and mechanical strength during the preparation of the granules. Therefore, the development of a method that can significantly improve the stability, solubility, and mechanical strength of solid hydrogen peroxide granules is an urgent problem in the field.5 Subject of the invention In light of the above, the aim of the present invention is to propose a method for the preparation of solid hydrogen peroxide granules, in order to solve the problems of existing solid hydrogen peroxide granules, such as rapid degradation rate, poor solubility, and insufficient mechanical strength. Based on the above-mentioned objective, the present invention offers a method for the preparation of solid hydrogen peroxide granules, comprising the following steps: (1) adding alginate and chitos to deionized water, raising the temperature to 50-70°C, stirring for 20-40 minutes, then cooling to 8-12°C, adding hydrogen peroxide solution,sodium tripolyphosphate and phytic acid and stir for 2-4 hours to obtain a mixed hydrogen peroxide solution; (2) distribute the mixed hydrogen peroxide solution over freeze-drying dishes, place them in a pre-cooled chamber of a freeze dryer, cool at a rate of 1-10°C / min to -50±2°C, hold this temperature for 3-5 hours, activate the vacuum system to lower the pressure in the chamber to 8-12 Pa, increase the temperature at a rate of 0.4–0.6°C / min to -25±2°C, hold this temperature for 20-28 hours, and finally increase the temperature at a rate of 0.1–0.3°C / min to 25°C, hold this temperature for 10-14 hours to obtain a solid hydrogen peroxide block; (3) break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve through to obtain 80-120 sieves of solid hydrogen peroxide granules; where the weight ratio of alginate, chitosan, hydrogen peroxide solution, sodium tripophosphate and phytic acid in the sieve(1)1-2:1.4–2.8:40-60:500:0.2-1:0.1–0,amounts to 3. Preferably, the viscosity of the alginate in step(1) is 1.0-1.2 Pa·s.30 Preferably, the molecular weight of the chitosan in step(1) is 80-120 kDa and the degree of deacetylation is 95%. Preferably, the concentration of the hydrogen peroxide solution in step(1) is 30 wt.%. Preferably, the height of the liquid layer of the mixed hydrogen peroxide solution in the freeze-drying dishes in step(2) is 1-2 cm. Preferably, the freeze-dryer in step(2) is pre-cooled to -40 ± 2°C. BE2025 / 7122 3 Benefits of the invention The present invention provides excellent solid hydrogen peroxide granules through the precise mixing ratio of alginate, chitosan, sodium tripolyphosphate and phytic acid and the optimization of the freeze-drying technique, whereby the problems of the existing technique such as poor stability, insufficient solubility and low mechanical strength of the granules are solved. The present invention forms a gel network structure by the addition of alginate and chitosan, whereby hydrogen peroxide molecules are effectively enclosed,the heat tolerance of the granules is significantly improved and the risk of hydrogen peroxide degradation during storage and transport is reduced.10 The present invention further provides for improved stability of the granules through the synergistic effect of sodium tripolyphosphate and phytic acid, and for optimization of the internal structure of the granules, so that the granules can rapidly absorb water during dissolution and uniformly release hydrogen peroxide, thereby meeting the needs for faster reactions in industry, the medical sector and other fields.15 The present invention optimizes the freeze-drying technique, guarantees the forming effect and structural uniformity of the granules, significantly improves the mechanical strength of the granules, and increases the compressive strength of the granules during storage,transport and manipulation and reduces the losses of product performance due to breakage. The method for the preparation of solid hydrogen peroxide granules provided by the present invention shows clear advantages in terms of improving product stability, solution capacity and mechanical strength, and has broad industrial application value. Examples25 To clarify the objectives, technical solutions and benefits of the present invention, the present invention is explained in more detail below by means of examples. Example 1 (1) Add 1g galginate (viscosity 1.1 Pa·s) and 1.4g chitosan (molecular weight 100 kDa, degree of tylation 95%) to 40g deionized water, raise the temperature to 50°C, stir for 20 minutes, cool down to 8°C, add 500g hydrogen peroxide solution with a concentration of 30 wt.%, 0.2g sodium tripolyphosphate and 0,1g phytic acid to be stirred for 2 hours to obtain a mixed hydrogen peroxide solution; (2)Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays,35 where the height of the liquid layer per tray is 1 cm, place them in the chamber of a freeze dryer that has been pre-cooled to -42°C, cool down at a rate of 1°C / min to -52°C, BE2025 / 7122 4 hold this temperature for 3 hours, activate the vacuum system to lower the pressure in the chamber to 8 Pa, increase the temperature at a rate of 0.4°C / min to -27°C, hold this temperature for 20 hours, and finally increase the temperature at a rate of 0.1°C / min to 25°C, hold this temperature for 10 hours to obtain a solid hydrogen peroxide block;5 (3)Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of to obtain 80mes hom solid hydrogen peroxide granules. Example 2 (1) Add 1.5g galginate (viscosity 1.1 Pa·s) and 2g chitosan (molecular weight 100 kDa, degree of tylation 95%) to 50g deionized water, increase temperature to 60°C,stir for 30 minutes, cool to 10°C, add 500g hydrogen peroxide solution with a concentration of 30 wt.%, 0.5g sodium tripolyphosphate and 0.2g phytic acid, stir for 3 hours to obtain a mixed hydrogen peroxide solution; (2)Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays, 15 where the height of the liquid layer per tray is 1.5 cm, place them in the chamber of a freeze dryer pre-cooled to -40°C, cool down at a rate of 5°C / min to -50°C, hold this temperature for 4 hours, activate the vacuum system to lower the pressure in the chamber to 10 Pa, increase the temperature at a rate of 0.5°C / min to -25°C, hold this temperature for 24 hours, and finally increase the temperature at a rate of 0.2°C / min to 25°C, hold this temperature for 12 hours to obtain a solid hydrogen peroxide block; (3)Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 100 mesh solid hydrogen peroxide granules to obtain. 25 Example3 (1)Add 2 galginate (viscosity 1,Add 1 Pa·s) and 2.8 g chitosan (molecular weight 100 kDa, degree of acetylation 95%) to 60 g deionized water, raise the temperature to 70°C, stir for 40 minutes, cool down to 12°C, add 500 g hydrogen peroxide solution with a concentration of 30 wt.%, 1 g sodium tripolyphosphate and 0.3 g phytic acid, stir for 30 minutes to obtain a mixed hydrogen peroxide solution; (2)Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays, where the liquid level per tray is 2 cm, place them in the chamber of a freeze dryer that has been pre-cooled to -38°C, cool down at a rate of 10°C / min to -48°C, hold this temperature for 5 hours, activate the vacuum system to reduce the pressure in the chamber to 12 Pa, increase the temperature at a rate of 0.6°C / min to -23°C, hold this temperature for 28 hours, and finally increase the temperature BE2025 / 7122 5 at a rate of 0.3°C / min to 25°C,hold this temperature for 14 hours to obtain a solid hydrogen peroxide block; (3) Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 120 oz solid hydrogen peroxide granules to obtain. 5 Comparison Example 1 Comparison Example 1 differs from Example 2 in that no alginate has been added. The specific steps are as follows: (1) Add 3.5 g chitosan (molecular weight 100 kDa, degree of acetylation 95%) to 50 g ge- deionized water, raise the temperature to 60°C, stir for 30 minutes, cool down to 10°C, add 50 g hydrogen peroxide solution with a concentration of 30 wt.%, 0.5 g sodium tripolyphosphate and 0.2 g phytic acid and stir for 3 hours to obtain a mixed hydrogen peroxide solution; (2)Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays, where the height of the liquid layer per tray is 1.5 cm, place them in the chamber of a freeze dryer that has been pre-cooled to -40°C, cool down at a rate of 5°C / min to -50°C, and hold this temperature for 4 hours,activate the vacuum system to lower the pressure in the chamber to 10 Pa, increase the temperature at a rate of 0.5°C / min to -25°C, hold this temperature for 24 hours, and finally increase the temperature at a rate of 0.2°C / min to 25°C, hold this temperature for 12 hours to obtain a solid hydrogen peroxide block; (3) Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 100 oz solid hydrogen peroxide granules. Comparison example 2 differs from example 2 because no chitosan is added. The specific steps are as follows: (1) Add 3.5g galginate (viscosity 1.1Pa·s) to 50g deionized water, raise the temperature to 60°C, stir for 30 minutes, cool down to 10°C, add 500g hydrogen peroxide solution with a concentration of 30 wt.%, 0.5g sodium tripolyphosphate and 0.2g phytic acid and stir for 3 hours to obtain a mixed hydrogen peroxide solution; (2) Divide the mixed hydrogen peroxide solution over stainless steel freeze-drying dishes,where the height of the liquid layer per tray is 1.5 cm, place it in the chamber of a freeze dryer that is pre-cooled to -40°C, cool down at a rate of 5°C / min to -50°C, hold this temperature for 4 hours, activate the vacuum system to lower the pressure in the chamber to 10 Pa, increase the temperature at a rate of 0.5°C / min to 25°C, hold this temperature for 24 hours, and finally increase the temperature at a rate of 0.2°C / min to 25°C, hold this temperature for 12 hours to obtain a solid hydrogen peroxide block; (3) Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 100 oz solid hydrogen peroxide granules to obtain.5 Comparison example 3 Comparison example 3 differs from example 2 because no sodium tripolyphosphate has been added. The specific steps are as follows:10 (1) Add 1,5g galginate (viscosity 1,1 Pa·s) and 2g chitosan (molecular weight 100 kDa, degree of acetylation 95%) to 50mg deionized water, raise the temperature to 60°C, stir for 30 minutes, cool down to 10°C,add 500g hydrogen peroxide solution with a concentration of 30 wt.% and 0.7g phytic acid and stir for 3 hours to obtain a mixed hydrogen peroxide solution;15 (2)Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays, where the height of the liquid layer per tray is 1.5cm, place them in the chamber of a freeze dryer that has been pre-cooled to -40°C, cool down at a rate of 5°C / min to -50°C, hold this temperature for 4 hours, activate the vacuum system to reduce the pressure in the chamber to 10 Pa, increase the temperature at a rate of 0.5°C / min to 20-25°C, hold this temperature for 24 hours, and finally increase the temperature at a rate of 0.2°C / min to 25°C,hold this temperature for 12 hours to obtain a solid hydrogen peroxide block; (3) Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 100 oz solid hydrogen peroxide granules to obtain.25 Comparison Example 4 Comparison Example 4 differs from Example 2 because no phytic acid has been added. The specific steps are as follows: 30 (1) Add 1.5g galginate (viscosity 1.1 Pa·s) and 2g chitosan (molecular weight 100 kDa, degree of acetylation 95%) to 50g deionized water, raise the temperature to 60°C, stir for 30 minutes, cool down to 10°C, add 500g hydrogen peroxide solution with a concentration of 30 wt.% and 0.7g sodium tripolyphosphate and stir for 3 hours to obtain a mixed hydrogen peroxide solution; 35 (2) Distribute the mixed hydrogen peroxide solution over stainless steel freeze-drying trays, where the height of the liquid layer per tray is 1.5cm, place them in the chamber of a BE2025 / 7122 7 freeze dryer that has been pre-cooled to -40°C, cool down at a rate of 5°C / min to -50°C,hold this temperature for 4 hours, activate the vacuum system to lower the pressure in the room to 10 Pa, increase the temperature at a rate of 0.5°C / min to -25°C, hold this temperature for 24 hours, and finally increase the temperature at a rate of 0.2°C / min to 25°C, hold this temperature for 12 hours to obtain a solid hydrogen peroxide block; (3) Break the solid hydrogen peroxide block under a nitrogen atmosphere and sieve it through a sieve of 100 oz solid hydrogen peroxide granules to obtain. Performance tests: 10 Determination of effective content: Accurately weigh a 1.000g sample (accurate to 0.1mg), dissolve it in 100mL of deionized water, determine using potassium permanganate titration according to standard GB / T1616-2014, perform three parallel tests and take the mathematical mean. The results are shown in Table 1. Heat stability test: Pack the solid hydrogen peroxide granules prepared in the 15 forms and comparison forms in aluminium-plastic combined foil bags, place them in a Constant Warm Water Bath at 60°C,Take samples for determination of the effective content on days 7, 14, and 21, and calculate the degradation rate (degradation rate = [(initial content - content at test) / initial content] x 100%). The results are shown in Table 1. Solubility test: Pour 200 mL of deionized water into a beaker, keep the temperature constant at 25°C, take a 1.00 g sample and place it in a porous container, immerse it 1 cm below the liquid surface, stir at 300 rpm, start the timer from the addition of the sample, and record the mass change curve in real-time. Determine complete solution when the mass change ≤ 0.01 g for 10 consecutive seconds, record the dissolution time, perform three parallel tests, and take the average. The results are shown in Table 1. Grain strength test: Determine with a texture meter, probe model number P / 0.5, test speed 0.5 mm / s, trigger force 5 g, recorded maximum pressure value at grain breaking,perform three parallel tests and take the average. The results are shown in Table 1.30. Data analysis: From the data of examples 1-3 in Table 1 it can be seen that the difference between the effective content of the solid hydrogen peroxide granules prepared by the present invention and the theoretical effective content is less than 0.5%. This indicates that the freeze-drying technique of the present invention prevents hydrogen peroxide from degrading during preparation. The degradation rate after 21 days at 60°C is less than 1.2%, which indicates that it has excellent thermal stability, helps to reduce the risk of degradation during storage and transport, and thus extends the shelf life of the product. Furthermore, the solid hydrogen peroxide granules have a fast dissolution time and high grain strength. Dissolving time ensures efficient release during use, meeting the needs for faster reactions in industry, the medical sector, and other areas; the high grain strength improves the pressure resistance and stability of the product during storage,transports manipulate-5 times,and reducesthe lossesof performancedue to grain breakage. Table1Performance test results Theoretical effectiveness and hold / % Working efficiency and hold / % A fb ra a x ne lh e id b ij 60 °C / % - D ag 7 A f b ra a x ne l e id b ij 60 °C / % - D ag 7 A fb ra a x ne lh id b ij 6 0 °C / % A fb ra a x ne lh id b ij 60 °C ra a ks ne lh e id b ij 6 0 °C / % - D ag 2 1 Solution time d / s Corr e ls te rk te / N Example198.297.80.30.71.112612.7 Example297.397.10.20.50.812. Example396.196.00.10.40.711213.8 Comparative Example1 97.396.80.71.83.21438.1 Comparative Example2 97.396.90.92.13.91699.6 Comparative Example3 97.396.22.15.18.713212.4 Comparison example4 97.396.41.84.27.524511.1 Output data example2and comparison examples1-2inTable 1 sample2,where both alginateal chitosan was added,showed significant advantages in terms of heating rangefrom effective content,heat stability,solubility and granule strength. This is possible because alginate and chitosan form an elastic network structure in the system, whereby hydrogen peroxide molecules can be effectively enclosed, slowing down the degradation rate and significantly improving thermal stability. At the same time, chitosan, as a macro-15 molecular material, can further improve the dispersion of sodium tripolyphosphate and phytic acid in the solid granules by forming hydrogen bonds or other weak interactions with amino and hydroxyl groups in its molecular structure, thereby improving the effect of sodium tripolyphosphate and phytic acid in the solid hydrogen peroxide granules. Moreover, the synergistic effect of alginate and chitosan can optimize the internal pore structure of the granules, so that they can absorb water quickly during dissolution and be uniformly dispersed, whereby- by the dissolution time is significantly shortened. The combination of both can also improve the formation effect BE2025 / 7122 9 of the granules during freeze-drying,preventing the granules from collapsing or becoming uneven during drying, and thus improving the mechanical strength of the granules. These results demonstrate that the synergistic effect of alginate and chitosan is of great importance for improving the stability, solubility, and strength of the granules. From the data of example 2 and comparison example 3 in Table 1, it can be seen that the addition of sodium tripolyphosphate plays an important role in optimizing the performance of solid hydrogen peroxide granules. Sodium tripolyphosphate can significantly slow down the degradation rate of hydrogen peroxide, thereby improving the thermal stability of the granules. Moreover, sodium tripolyphosphate can play a role in regulating the crystal structure during the preparation of the granules, making the internal structure of the granules denser and more uniform.and thus the mechanical strength of the granules is significantly improved. In terms of solubility, sodium tripolyphosphate can promote contact and diffusion between the granules and water by altering the hydrophobicity of the granule surface, so that the granules can quickly absorb water and dissolve uniformly. These mechanisms of action show that sodium tripolyphosphate can improve not only the storage stability of the granules, but also the solubility and mechanical performance. From the data of example 2 and comparison example 4 in Table 1 it can be seen that the addition of phytic acid significantly improves the overall performance of solid hydrogen peroxide granules, especially in terms of thermal stability, solubility and granule strength. As a versatile chelating agent, phytic acid contains multiple phosphate groups in its molecular structure,whereby, via weak interactions with active oxygen, it can significantly reduce the degradation rate of hydrogen peroxide molecules and thus improve the thermal stability of the granules. Furthermore, phytic acid can improve the mechanical strength of the granules by regulating the microstructure of the granule, so that the internal pore distribution is more uniform. In terms of dissolvability, phytic acid can promote contact between the granules and water by improving the surface properties and hydrophobicity of the granules, so that the granules can quickly absorb water and dissolve uniformly, and the dissolution time can be significantly shortened. The professional shall understand that the description of the examples is intended solely as an explanation and not to indicate that the scope of the present invention is limited for that purpose; within the framework of the present invention, technical features of the above-mentioned examples or different examples may also be combined, the steps may be carried out in any arbitrary order,and there are many other variations on different aspects of the present invention as described above, which have not been included in detail for the sake of brevity.35 BE2025 / 7122,