Sustained release preparation based on calcium peroxide wrapped by composite carrier, preparation method and application

Abstract

The invention discloses a sustained release preparation based on composite carrier coated calcium peroxide, a preparation method and application, and belongs to the technical field of aquaculture substrate improvement, and the preparation method comprises the following steps: S1, adding a layered silicate clay mineral into water, heating and stirring, then adding an organosilane modifier for reaction, standing at constant temperature for a certain time, and filtering to obtain a filter cake; filtering to obtain activated layered silicate clay minerals; s2, pouring the activated layered silicate clay mineral obtained in the step S1 into a mixed aqueous solution of sodium alginate and food-grade white granulated sugar, stirring to obtain an activated montmorillonite-sodium alginate composite carrier solution, then adding calcium peroxide, and performing secondary stirring for a certain time to obtain a calcium peroxide-carrier mixed solution; and then introducing into an injector, dripping into normal-temperature deionized water to prepare small balls with a certain size, freezing, and drying in stages to obtain the sustained release preparation based on calcium peroxide wrapped by the composite carrier. The calcium peroxide loading capacity can be improved, and the calcium peroxide release period can be prolonged.

Description

Technical Field

[0001] This invention relates to the field of aquaculture substrate improvement technology, and more specifically, to a high-load calcium peroxide aquaculture substrate improvement agent encapsulated in montmorillonite-sodium alginate composite, its preparation method, and its application. Background Technology

[0002] During aquaculture, organic matter such as uneaten feed, feces, and animal and plant remains continuously accumulate at the bottom of the pond. Under anaerobic conditions, these substances easily decompose to produce toxic substances such as ammonia nitrogen, hydrogen sulfide, and nitrite. This also causes a sharp drop in dissolved oxygen in the bottom mud (often <2mg / L), leading to typical diseases in shrimp and crabs such as "climbing to the edge (hypoxia stress behavior)" and "sudden death (death from chronic poisoning)," resulting in a decrease in survival rate.

[0003] Calcium peroxide (CaO2), as a green oxidant and oxygen release agent, reacts with water in the following way: 2CaO2 + 2H2O == 2Ca(OH)2 + O2↑. It has dual advantages: 1. Continuous oxygen release, 2. The product calcium hydroxide can moderately adjust the pH of the sediment. Therefore, CaO2 is considered one of the mainstream sediment conditioners.

[0004] However, there are two major problems with the direct application of calcium peroxide: 1. Calcium peroxide powder has a large specific surface area and reacts rapidly upon contact with water. Most of the oxygen escapes from the upper layer of the water, which not only fails to reach the bottom sediment to exert its effect, but also easily leads to the problem of oxygen-rich water and oxygen-deficient bottom sediment; 2. Calcium hydroxide generated by calcium peroxide is a strong electrolyte. Its application can easily lead to excessively high local concentrations, resulting in a sudden increase in the pH of the bottom sediment (up to 9.0 or above), which causes alkaline stress to shrimp and crab larvae (the suitable pH for shrimp and crab larvae is 7.6-8.6, and the critical tolerance upper limit is 8.8).

[0005] To address the aforementioned issues, existing technologies utilize modification techniques such as "carrier encapsulation" or "mineral composites" to optimize the application of calcium peroxide. However, all these approaches have significant drawbacks: Sodium alginate-encapsulated calcium peroxide technology: This technology uses sodium alginate as a gel mechanism, employing a gel network to block water and achieve the slow release of calcium peroxide and oxygen, with a release cycle of 5-7 days. However, in this technology, the calcium peroxide loading is only 15%-20% (excessive loading will cause gel rupture), requiring large-scale application to achieve the desired bottom improvement effect, increasing aquaculture costs. Furthermore, this method requires the introduction of a large amount of metal ions as cross-linking agents to ensure sufficient stability of the slow-release agent; however, after preparation, the metal ions used may remain on the surface of the microspheres, causing abnormal local ion concentrations in the bottom sediment.

[0006] The single montmorillonite adsorption technology for calcium peroxide: This technology uses aquaculture-grade bentonite as a carrier. It leverages the high density of montmorillonite (2.6-2.8 g / cm³) to accelerate particle settling (sinking within 1-2 minutes), while simultaneously delaying the calcium peroxide reaction through interlayer adsorption. However, in this technology, calcium peroxide only adheres to the surface and interlayer of montmorillonite through physical adsorption, resulting in a loading of ≤25%, and it easily detaches in the water, leading to excessively rapid oxygen release in the early stages and insufficient dissolved oxygen in the sediment later. Simultaneously, it generates a large amount of calcium hydroxide, causing the pH of the sediment to fluctuate beyond the suitable pH range for shrimp and crab larvae (7.6-8.6). To address these issues, a method for composite encapsulating calcium peroxide with bentonite and sodium alginate has emerged. However, this method requires the addition of multiple metal chloride solutions, and the effective component of calcium peroxide in this technology is low, failing to meet the requirements of aquaculture.

[0007] In summary, existing calcium peroxide substrate improvement technologies generally suffer from drawbacks such as low loading capacity, short slow-release period, weak pH buffering capacity, and poor carrier stability, making it difficult to simultaneously meet the aquaculture requirements of "efficient substrate improvement," "cost control," and "ecological safety." Therefore, developing a calcium peroxide compound formulation with high loading capacity, long-lasting slow release, precise pH buffering, and structural stability has become a technical problem that needs to be solved in this field. Summary of the Invention

[0008] To address the problems existing in the prior art, the present invention aims to provide a sustained-release formulation based on a composite carrier encapsulating calcium peroxide, its preparation method, and its application. The sustained-release formulation prepared by this method can reduce the reaction of calcium peroxide before it reaches the bottom of the water after being sprinkled in; buffer the pH; increase the calcium peroxide loading; and improve the calcium peroxide release cycle.

[0009] To solve the above problems, the present invention adopts the following technical solution.

[0010] A method for preparing a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier, the preparation steps of which are as follows: S1 Activation Treatment: Layered silicate clay minerals are added to water and heated and stirred. Then, organosilane modifiers are added and reacted for a certain period of time. After being kept at a constant temperature and allowed to stand, the activated layered silicate clay minerals are obtained by filtration. S2 Preparation of calcium peroxide-carrier mixture: The activated layered silicate clay minerals obtained in step S1 are poured into a mixed aqueous solution of sodium alginate and food-grade white sugar, heated and stirred to obtain an activated montmorillonite-sodium alginate composite carrier solution, then calcium peroxide is added, and after stirring for a certain period of time, a calcium peroxide-carrier mixture is obtained. S3 Post-processing: After the calcium peroxide-carrier mixture obtained in step S2 is introduced into a syringe, it is dropped into room temperature deionized water to form small balls of a certain size. Then, it is frozen and dried in stages to obtain a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier.

[0011] Furthermore, in step S1, the layered silicate clay mineral is palygorskite, vermiculite, or montmorillonite; preferably montmorillonite.

[0012] Furthermore, in step S1, the organosilane modifier is γ-aminopropyltriethoxysilane, and the amount added is 3-7% of the layered silicate clay mineral content, preferably 5%.

[0013] Furthermore, the amount of sodium alginate added in step S2 is 1-5 times the amount of layered silicate clay minerals, preferably 3 times.

[0014] Furthermore, in the mixed aqueous solution of sodium alginate and food-grade white sugar in step S2, the mass ratio of food-grade white sugar to sodium alginate is 1:1.

[0015] Furthermore, the preparation method of the mixed aqueous solution of sodium alginate and food-grade white sugar is as follows: First, mix equal masses of sodium alginate and food-grade white sugar, then add them to deionized water and heat and stir for a certain period of time.

[0016] Furthermore, during the process of adding sodium alginate and food-grade white sugar to deionized water, the stirring speed is 200-300 r / min and the stirring temperature is 70℃. After the addition is completed, the temperature is kept constant and the stirring speed is 600-800 r / min for 1-2 hours to obtain a uniformly mixed aqueous solution of sodium alginate and food-grade white sugar. After obtaining a uniformly mixed aqueous solution, the stirring speed is continued at 150-200 r / min.

[0017] Furthermore, in step S2, the amount of calcium peroxide added is 35-45% of the mass of the activated montmorillonite-sodium alginate composite carrier solution, preferably 40%.

[0018] Furthermore, the particle size of calcium peroxide is 100-200 mesh.

[0019] Furthermore, in step S3, the freezing temperature is -10 to -30 ℃, preferably -25 ℃, and the freezing time is 3-5 h, preferably 4 h; the specific operation of the segmented drying is as follows: after drying in a dryer with a vacuum degree of 0.09 MPa and a temperature of 25 ℃ for 3 h, the temperature is raised to 35 ℃, the vacuum degree is maintained at 0.09 MPa, and drying continues for 2 h.

[0020] Furthermore, in step S1, the stirring temperature for heating and stirring the layered silicate clay mineral is 200-400℃, preferably 200-250℃, the heating and stirring time is 1-2h, and the stirring speed is 100-400r / min; after adding the organosilane modifier, the temperature is lowered to 20-40℃ and reacted for 20-60min, followed by standing for 1-3h, preferably 1-2h. In step S2, the stirring speed is 500-700 r / min, preferably 600 r / min, and the stirring time is 60-90 min, preferably 75 min; the stirring temperature for the second stirring is 18-25℃, the stirring speed for the second stirring is 300-500 r / min, preferably 350-400 r / min, and the stirring time is 30-90 min, preferably 60-70 min; In step S3, the dropping rate is 1-4 mL / min, preferably 2 mL / min; the size of the ball is 2-4 mm.

[0021] The present invention also provides a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier, which is prepared by the above-mentioned method for preparing a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier.

[0022] The present invention also provides the application of the above-mentioned slow-release formulation based on calcium peroxide encapsulated by a composite carrier in the bottom sediment of shrimp or crab farming ponds.

[0023] Compared with the prior art, the advantages of this invention are: I. The slow-release formulation based on calcium peroxide encapsulated by the composite carrier prepared in this scheme not only significantly increases the calcium peroxide loading, but also effectively alleviates the strong alkalinity during the oxygen release process of calcium peroxide, and controls the pH fluctuation of the surrounding waters at a low level. This fundamentally alleviates the stress response of shrimp and crab larvae caused by sudden alkalinity in the environment, and provides a strong guarantee for the healthy growth of the larvae.

[0024] II. This method employs a freeze-segmented drying approach to create a porous structure in the prepared sustained-release formulation based on a composite carrier encapsulating calcium peroxide, thereby delaying water penetration and effectively extending the release period of calcium peroxide. Furthermore, this method also makes the microsphere structure of the sustained-release formulation more uniform and stable, thus effectively preserving the activity of calcium peroxide and achieving a balance between long-lasting and high-efficiency effects. Detailed Implementation

[0025] Example 1 (Montmorillonite:Sodium alginate mass ratio = 1:3): Step 1: Add 10g of montmorillonite to 90mL of deionized water, heat at a constant temperature for 1h, then add 0.5g of γ-aminopropyltriethoxysilane, heat to 30℃ and continue stirring for 30min, let stand for 1h and then filter to obtain "silane-modified activated montmorillonite".

[0026] Step 2: Mix 30g of sodium alginate and 30g of edible white sugar evenly, then add to 240g of deionized water to prepare a 10% sodium alginate mixed solution. The heating temperature is set to 70℃, and the stirring speed is set to 250 r / min during the initial addition, increasing to 700 r / min during the dissolution phase. After confirming dissolution, maintain the stirring speed at 150 r / min, add the silane-modified activated montmorillonite obtained in Step 1, and stir at 600 r / min for 75 min to obtain the activated montmorillonite-sodium alginate composite carrier solution.

[0027] Step 3: Calcium peroxide, which accounts for 40% of the total mass of the activated montmorillonite-sodium alginate composite carrier solution, is passed through a 150-mesh sieve and dried. Then, it is added to the activated montmorillonite-sodium alginate composite carrier solution prepared in Step 2. After heating to 20°C, it is stirred at 400 r / min for 60 min to obtain a calcium peroxide-carrier mixture.

[0028] Step 4: Finally, the calcium peroxide-carrier mixture was introduced into a syringe and added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm microspheres. The microspheres were then frozen at -25°C for 4 hours. The frozen microspheres were then placed in a desiccator and dried at 25°C under a vacuum of 0.09 MPa for 3 hours. The temperature was then increased to 35°C, and the vacuum was maintained at 0.09 MPa for another 2 hours to obtain the sustained-release formulation of calcium peroxide encapsulated by the target product composite carrier.

[0029] Comparative Example 1 without freeze-segmented drying: The difference between this comparative example and Example 1 is that in step four, the calcium-carrier mixture is introduced into a syringe and then added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm spheres, which are then dried at room temperature for 5 h to obtain a sustained-release formulation.

[0030] Comparative Example 2: Step 1, prepare sodium alginate solution: Weigh 1g of sodium alginate and dissolve it in 50mL of distilled water. Heat slowly until dissolved, and let it cool to room temperature before use. Step 2, Adding materials: First, add 50mg of 200-mesh calcium peroxide to the sodium alginate solution prepared in Step 1 to obtain the solution to be mixed. Then, add bentonite at a mass percentage of 2% of the solution to be mixed. After vigorous stirring, a mixed solution is prepared. Step 3, obtaining the initial product: The mixed solution obtained in step 2 was added dropwise to a CaCl2 solution with a concentration of 50 mmol / L using a peristaltic pump, and the initial product was obtained after crosslinking for 40 min; Step 4, Post-processing: The initial product is separated from the cation solution, dried at room temperature for 2 hours, and then washed multiple times with distilled water to obtain the slow-release oxygen cation crosslinking agent.

[0031] Experimental Example 1: The performance of the sustained-release formulations involved in Example 1 and Comparative Examples 1-3 was tested, and the test contents and methods are as follows: Determination of calcium peroxide loading: The prepared calcium peroxide was ground by titration. 0.2 g of the sustained-release preparation was weighed, placed in an Erlenmeyer flask, dissolved in 40 mL of sulfuric acid (sulfuric acid: water = 1:3), and then titrated with 0.1 mol / L potassium permanganate.

[0032] Determination of sustained-release period: Prepare a 1000mL beaker, add water to 1000mL, insert the dissolved oxygen meter, start the data acquisition device, record the initial DO value, add the same mass of supercalcium (5g) and continuously detect the DO concentration until the cumulative release reaches 90% of the total amount, and record the number of days at this time.

[0033] Determination of reaction conditions before settling: Water was added to the chromatography column to a height of 1m. The same mass (1g) of supercalcium was weighed and slowly added from the top of the chromatography column. The rate of bubble generation before supercalcium settling and the settling time were recorded using a high-speed camera and a timer.

[0034] The performance test results are shown in Table 1.

[0035] ; As shown in Table 1, the calcium overload of the sustained-release formulation prepared in Example 1 is significantly higher than that of Comparative Example 1 and Comparative Example 2. At the same time, the sustained-release period of this formulation is significantly longer than that of Comparative Example 1 and Comparative Example 2, and the settling time is also significantly shorter than that of Comparative Example 1 and Comparative Example 2. This indicates that the sustained-release formulation prepared by this method not only has a higher calcium overload, but its sustained-release period and settling time can also be effectively improved.

[0036] Experimental Example 2: After using the sustained-release formulations involved in Example 1 and Comparative Examples 1-2, the pH change of the sediment was detected. The detection content and methods are as follows: pH Buffering Measurement: Simulating the reaction scenario after CaO2 settles to the bottom in actual applications, the buffering capacity of the particles on the system's pH during the bottom reaction was quantified through dynamic pH monitoring. Sludge of equal mass and pH was added to 1000mL beakers, and water was added to 1000mL to simulate the aquaculture environment. A precision pH meter was inserted, connected to a data acquisition device, and the initial pH was recorded. 5g of the prepared supercalcium solution was added to the water containing sludge, and the pH of the bottom sediment was measured hourly. The maximum value of the day was taken as the pH value for that day. Monitoring was conducted continuously for 15 days, and the daily bottom sediment pH was recorded. The results are shown in Table 2.

[0037] ; As shown in Table 2, during use, the pH fluctuation range of Example 1 was 7.8-8.5, which is within the suitable pH range (7.6-8.6) for aquatic organisms (such as shrimp and crabs). In contrast, the pH fluctuation range of the sediment in Comparative Example 2, which used a metal crosslinking agent, was 7.8-9.3, significantly exceeding the suitable pH range for aquatic organisms. In conclusion, the slow-release formulation prepared in Example 1 effectively avoids alkaline stress that may occur in aquatic organisms during use.

[0038] Example 2:

[0039] Step 1: Add 10g of montmorillonite to 90mL of deionized water, heat at a constant temperature for 1h, then add 0.5g of γ-aminopropyltriethoxysilane, heat to 30℃ and continue stirring for 30min, let stand for 1h and then filter to obtain "silane-modified activated montmorillonite".

[0040] Step 2: Mix 10g of sodium alginate and 10g of edible white sugar evenly, then add to 80g of deionized water to prepare a 10% sodium alginate mixed solution. The heating temperature is set to 70℃, and the stirring speed is set to 250r / min during the initial addition, increasing to 700r / min during the dissolution phase. After confirming dissolution, maintain the stirring speed at 150r / min, add the silane-modified activated montmorillonite obtained in Step 1, and stir at 600r / min for 75 min to obtain the activated montmorillonite-sodium alginate composite carrier solution.

[0041] Step 3: Calcium peroxide, which accounts for 40% of the total mass of the activated montmorillonite-sodium alginate composite carrier solution, is passed through a 150-mesh sieve and dried. Then, it is added to the activated montmorillonite-sodium alginate composite carrier solution prepared in Step 2. After heating to 20°C, it is stirred at 400 r / min for 60 min to obtain a calcium peroxide-carrier mixture.

[0042] Step 4: Finally, the calcium peroxide-carrier mixture was introduced into a syringe and added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm microspheres. The microspheres were then frozen at -25°C for 4 hours. The frozen microspheres were then placed in a desiccator and dried at 25°C under a vacuum of 0.09 MPa for 3 hours. The temperature was then increased to 35°C, and the vacuum was maintained at 0.09 MPa for another 2 hours to obtain the sustained-release formulation of calcium peroxide encapsulated by the target product composite carrier.

[0043] Example 3:

[0044] Step 1: Add 10g of montmorillonite to 90mL of deionized water, heat at a constant temperature for 1h, then add 0.5g of γ-aminopropyltriethoxysilane, heat to 30℃ and continue stirring for 30min, let stand for 1h and then filter to obtain "silane-modified activated montmorillonite".

[0045] Step 2: Mix 20g sodium alginate and 20g edible white sugar evenly, then add to 160g deionized water to prepare a 10% sodium alginate solution. The heating temperature is set to 70℃, and the stirring speed is 250 r / min during the initial addition, increasing to 700 r / min during the dissolution phase. After confirming dissolution, maintain the stirring speed at 150 r / min, add the silane-modified activated montmorillonite obtained in Step 1, and stir at 600 r / min for 75 min to obtain the activated montmorillonite-sodium alginate composite carrier solution.

[0046] Step 3: Calcium peroxide, which accounts for 40% of the total mass of the activated montmorillonite-sodium alginate composite carrier solution, is passed through a 150-mesh sieve and dried. Then, it is added to the activated montmorillonite-sodium alginate composite carrier solution prepared in Step 2. After heating to 20°C, it is stirred at 400 r / min for 60 min to obtain a calcium peroxide-carrier mixture.

[0047] Step 4: Finally, the calcium peroxide-carrier mixture was introduced into a syringe and added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm microspheres. The microspheres were then frozen at -25°C for 4 hours. The frozen microspheres were then placed in a desiccator and dried at 25°C under a vacuum of 0.09 MPa for 3 hours. The temperature was then increased to 35°C, and the vacuum was maintained at 0.09 MPa for another 2 hours to obtain the sustained-release formulation of calcium peroxide encapsulated by the target product composite carrier.

[0048] Example 4:

[0049] Step 1: Add 10g of montmorillonite to 90mL of deionized water, heat at a constant temperature for 1h, then add 0.5g of γ-aminopropyltriethoxysilane, heat to 30℃ and continue stirring for 30min, let stand for 1h and then filter to obtain "silane-modified activated montmorillonite".

[0050] Step 2: Mix 40g of sodium alginate and 40g of edible white sugar evenly, then add them to 320g of deionized water to prepare a 10% sodium alginate mixed solution. The heating temperature is set to 70℃, and the stirring speed is set to 250 r / min during the initial addition, increasing to 700 r / min during the dissolution phase. After confirming dissolution, maintain the stirring speed at 150 r / min, add the silane-modified activated montmorillonite obtained in Step 1, and stir at 600 r / min for 75 min to obtain the activated montmorillonite-sodium alginate composite carrier solution.

[0051] Step 3: Calcium peroxide, which accounts for 40% of the total mass of the activated montmorillonite-sodium alginate composite carrier solution, is passed through a 150-mesh sieve and dried. Then, it is added to the activated montmorillonite-sodium alginate composite carrier solution prepared in Step 2. After heating to 20°C, it is stirred at 400 r / min for 60 min to obtain a calcium peroxide-carrier mixture.

[0052] Step 4: Finally, the calcium peroxide-carrier mixture was introduced into a syringe and added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm microspheres. The microspheres were then frozen at -25°C for 4 hours. The frozen microspheres were then placed in a desiccator and dried at 25°C under a vacuum of 0.09 MPa for 3 hours. The temperature was then increased to 35°C, and the vacuum was maintained at 0.09 MPa for another 2 hours to obtain the sustained-release formulation of calcium peroxide encapsulated by the target product composite carrier.

[0053] Example 5:

[0054] Step 1: Add 10g of montmorillonite to 90mL of deionized water, heat at a constant temperature for 1h, then add 0.5g of γ-aminopropyltriethoxysilane, heat to 30℃ and continue stirring for 30min, let stand for 1h and then filter to obtain "silane-modified activated montmorillonite".

[0055] Step 2: Mix 50g of sodium alginate and 50g of edible white sugar evenly, then add to 400g of deionized water to prepare a 10% sodium alginate mixed solution. The heating temperature is set to 70℃, and the stirring speed is set to 250 r / min during the initial addition, increasing to 700 r / min during the dissolution phase. After confirming dissolution, maintain the stirring speed at 150 r / min, add the silane-modified activated montmorillonite obtained in Step 1, and stir at 600 r / min for 75 min to obtain the activated montmorillonite-sodium alginate composite carrier solution.

[0056] Step 3: Calcium peroxide, which accounts for 40% of the total mass of the activated montmorillonite-sodium alginate composite carrier solution, is passed through a 150-mesh sieve and dried. Then, it is added to the activated montmorillonite-sodium alginate composite carrier solution prepared in Step 2. After heating to 20°C, it is stirred at 400 r / min for 60 min to obtain a calcium peroxide-carrier mixture.

[0057] Step 4: Finally, the calcium peroxide-carrier mixture was introduced into a syringe and added dropwise to 500 mL of room temperature deionized water at a rate of 2 mL / min to form 3 mm microspheres. The microspheres were then frozen at -25°C for 4 hours. The frozen microspheres were then placed in a desiccator and dried at 25°C under a vacuum of 0.09 MPa for 3 hours. The temperature was then increased to 35°C, and the vacuum was maintained at 0.09 MPa for another 2 hours to obtain the sustained-release formulation of calcium peroxide encapsulated by the target product composite carrier.

[0058] Example 6:

[0059] The difference between this embodiment and Embodiment 1 is that the layered silicate clay mineral is attapulgite, and the amount of γ-aminopropyltriethoxysilane added is 5% of the mass of attapulgite.

[0060] Experimental Example 2: The performance of the sustained-release formulations involved in Examples 1-6 was tested, and the test content and methods are as follows: Determination of calcium peroxide loading: The prepared calcium peroxide was ground by titration. 0.2 g of the sustained-release preparation was weighed, placed in an Erlenmeyer flask, dissolved in 40 mL of sulfuric acid (sulfuric acid: water = 1:3), and then titrated with 0.1 mol / L potassium permanganate.

[0061] Determination of sustained-release period: Prepare a 1000mL beaker, add water to 1000mL, insert the dissolved oxygen meter, start the data acquisition device, record the initial DO value, add the same mass of supercalcium (5g) and continuously detect the DO concentration until the cumulative release reaches 90% of the total amount, and record the number of days at this time.

[0062] Determination of reaction conditions before settling: Water was added to the chromatography column to a height of 1m. The same mass (1g) of supercalcium was weighed and slowly added from the top of the chromatography column. The rate of bubble generation before supercalcium settling and the settling time were recorded using a high-speed camera and a timer.

[0063] pH buffer range of sediment after slow-release preparation: pH value is continuously monitored daily, and the maximum value of the day is taken as the pH value of that day. The monitoring is carried out for 15 consecutive days to form the pH buffer range.

[0064] The test results are shown in Table 3.

[0065] ; As shown in Table 3, changing the mass ratio of layered silicate clay minerals to sodium alginate, the best overall effect of the sustained-release formulation in terms of calcium peroxide loading, pH buffering capacity, settling time, and sustained-release period is achieved when the amount of sodium alginate added is three times the amount of layered silicate clay minerals. Changing the type of layered silicate clay mineral significantly reduces the calcium peroxide loading and sustained-release period; therefore, montmorillonite is the preferred layered silicate clay mineral.

[0066] Comparative Example 3 without modified montmorillonite: The difference between this embodiment and Embodiment 1 is that: 30g of sodium alginate and 30g of food-grade white sugar are prepared into a 10% solution according to the steps in Embodiment 1, and 120g of the treated supercalcium is directly added. The remaining steps are the same as in Embodiment 1 to obtain a sustained-release formulation.

[0067] Comparative Example 4 using only montmorillonite: The difference between this embodiment and Example 1 is that calcium peroxide is directly added to silane-modified activated montmorillonite, while other steps and conditions remain unchanged, to obtain a sustained-release formulation.

[0068] Experimental Example 3: The performance of the sustained-release formulations involved in Example 1, Comparative Example 3, and Comparative Example 4 was tested. The test content and methods are as follows: Determination of calcium peroxide loading: The prepared calcium peroxide was ground by titration. 0.2 g of the sustained-release preparation was weighed, placed in an Erlenmeyer flask, dissolved in 40 mL of sulfuric acid (sulfuric acid: water = 1:3), and then titrated with 0.1 mol / L potassium permanganate.

[0069] Determination of reaction conditions before settling: Water was added to the chromatography column to a height of 1m. The same mass (1g) of supercalcium was weighed and slowly added from the top of the chromatography column. The rate of bubble generation before supercalcium settling and the settling time were recorded using a high-speed camera and a timer.

[0070] pH buffer range of sediment after slow-release preparation: The pH value is continuously monitored every day, and the maximum value of the day is taken as the daily pH value. The monitoring is carried out for 15 consecutive days to form the pH buffer range.

[0071] The test results are shown in Table 4.

[0072] ; As can be seen from Table 4, the sustained-release formulations prepared by simply encapsulating calcium with sodium alginate or montmorillonite have significantly weaker CaO2 loading, pH buffering capacity, and settling time than the composite method in this embodiment.

Claims

1. A method for preparing a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier, characterized in that: The preparation steps are as follows: S1 Activation Treatment: Layered silicate clay minerals are added to water and heated and stirred. Then, organosilane modifiers are added and reacted for a certain period of time. After being kept at a constant temperature and allowed to stand, the activated layered silicate clay minerals are obtained by filtration. S2 Preparation of calcium peroxide-carrier mixture: The activated layered silicate clay minerals obtained in step S1 are poured into a mixed aqueous solution of sodium alginate and food-grade white sugar, heated and stirred to obtain an activated montmorillonite-sodium alginate composite carrier solution, then calcium peroxide is added, and after stirring for a certain period of time, a calcium peroxide-carrier mixture is obtained. S3 Post-processing: After the calcium peroxide-carrier mixture obtained in step S2 is introduced into a syringe, it is dropped into room temperature deionized water to form small balls of a certain size. Then, it is frozen and dried in stages to obtain a sustained-release formulation based on calcium peroxide encapsulated by a composite carrier.

2. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In step S1, the layered silicate clay mineral is palygorskite, vermiculite, or montmorillonite.

3. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In step S1, the organosilane modifier is γ-aminopropyltriethoxysilane, and the amount added is 3-7% of the amount of layered silicate clay minerals.

4. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: The amount of sodium alginate added in step S2 is 1-5 times the amount of layered silicate clay minerals.

5. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In the S2 step, the mass ratio of food-grade white sugar to sodium alginate in the mixed aqueous solution is 1:

1.

6. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In step S2, the amount of calcium peroxide added is 35-45% of the mass of the activated montmorillonite-sodium alginate composite carrier solution.

7. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In step S3, the freezing temperature is -10 to -30 ℃, and the freezing time is 3-5 hours. The specific operation of the segmented drying is as follows: after drying in a dryer with a vacuum degree of 0.09 MPa and a temperature of 25 ℃ for 3 hours, the temperature is raised to 35 ℃, the vacuum degree is maintained at 0.09 MPa, and drying continues for 2 hours.

8. The method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide according to claim 1, characterized in that: In step S1, the stirring temperature for heating and stirring the layered silicate clay mineral is 200-400℃, the heating and stirring time is 1-2h, and the stirring speed is 100-400r / min; after adding the organosilane modifier, the temperature is lowered to 20-40℃ and reacted for 20-60min, then allowed to stand for 1-3h. In step S2, the stirring speed is 500-700 r / min and the stirring time is 60-90 min; the stirring temperature for the second stirring is 18-25℃, the stirring speed for the second stirring is 300-500 r / min, and the stirring time is 30-90 min. In step S3, the dropping rate is 1-4 mL / min, and the size of the ball is 2-4 mm.

9. A sustained-release formulation based on calcium peroxide encapsulated by a composite carrier, characterized in that: It is prepared by the method for preparing a sustained-release formulation based on a composite carrier encapsulating calcium peroxide as described in any one of claims 1-8.

10. The application of a slow-release formulation based on a composite carrier encapsulating calcium peroxide in the bottom sediment of shrimp or crab aquaculture ponds according to any one of claims 9.