Chlorine dioxide slow-release ball and method of making same

Abstract

This application relates to a chlorine dioxide slow-release ball, belonging to the technical field of environmental disinfection. It comprises, from the inside out, an activated alumina ball and an inorganic porous layer; wherein the activated alumina ball is loaded with sodium chlorite and a porous membrane, and the inorganic porous layer is loaded with a porous membrane. The chlorine dioxide slow-release ball of this application achieves the goals of high loading capacity, long release period, uniform release rate, and stable physical morphology.

Description

Technical Field

[0001] This application relates to the field of environmental protection and disinfection technology, and in particular to a chlorine dioxide slow-release ball and its preparation method. Background Technology

[0002] In recent years, chlorine dioxide has gained increasing attention as a safe and highly effective disinfectant, and has been applied in many fields such as water treatment, air purification, and food preservation. Chlorine dioxide is the fourth generation of chlorine-containing disinfectants, following chlorine gas, sodium hypochlorite, calcium hypochlorite, sodium dichloroisocyanurate, and trichloroisocyanuric acid. However, chlorine dioxide is highly reactive and easily degrades. To achieve sustained inhibition and killing of microorganisms, it needs to be released continuously and stably, maintaining a low concentration. Furthermore, chlorine dioxide is difficult to store stably for long periods and is generally stored in the form of chlorite, which is activated to produce chlorine dioxide upon use.

[0003] Currently, most commercially available chlorine dioxide slow-release products are slow-release powders, gels, and balls, with an effective chlorine dioxide content of 10-15 wt% of the total weight of the slow-release agent and a release period of 2-3 months. However, these products suffer from three major bottlenecks that severely limit their application effectiveness and scope: 1. A significant contradiction between loading efficiency and release period: Existing products have a low effective ingredient loading, resulting in insufficient effective action time per unit. Users need to frequently replace the slow-release agent, increasing usage costs and maintenance workload, and affecting the continuity of disinfection effects due to concentration fluctuations. 2. Poor release kinetic control: Many products exhibit an initial "burst release" phenomenon, with an excessively fast release rate and excessively high peak concentration. This may pose safety risks to specific application environments (such as enclosed spaces) and also leads to rapid depletion of the effective ingredient, shortening the overall lifespan. Some products rely on the addition of acidic activators to initiate the reaction, further accelerating the consumption process. 3. Insufficient stability of carrier structure and morphology: Especially for spherical sustained-release agents, the technology often remains at the stage of simple physical adsorption, which is to load sodium chlorite onto carriers such as activated alumina. This structure lacks an effective sustained-release control layer, which makes the active ingredients prone to premature decomposition or loss during processing (such as drying) and storage. At the same time, the product is prone to problems such as powdering and clumping, and the morphology is unstable, which affects the user experience and safety. Moreover, it is difficult to further increase the proportion of active ingredients per unit mass.

[0004] In summary, existing chlorine dioxide sustained-release technologies, due to inherent defects in carrier structure design, release control mechanisms, and morphological stability, cannot achieve continuous, stable, and controllable release of chlorine dioxide. This has become a key technological barrier hindering the wider application of this highly efficient disinfectant. Therefore, there is an urgent need to develop a novel chlorine dioxide sustained-release sphere to fundamentally solve the above problems and achieve the goals of high load capacity, long cycle, uniform release, and stable physical morphology. Summary of the Invention

[0005] The purpose of this application is to provide a novel chlorine dioxide slow-release sphere, which adopts a unique "core-shell" multilayer structure design. From the inside out, it consists of: an activated alumina sphere loaded with sodium chlorite and a first porous film, and an inorganic porous layer covering the core, also loaded with a second porous film. This structure achieves precise control of the chlorine dioxide release rate through a combination of physical barriers and chemical adsorption.

[0006] In a first aspect, this application provides a chlorine dioxide slow-release sphere, comprising, from the inside out: an activated alumina sphere and an inorganic porous layer; wherein, the activated alumina sphere is loaded with sodium chlorite and a porous film, and the inorganic porous layer is loaded with a porous film.

[0007] Optionally, the porous membrane is composed of an aldehyde-free aqueous adhesive.

[0008] Optionally, the formaldehyde-free water-based adhesive is selected from one or more of acrylic adhesives, modified starch adhesives, and polyester adhesives.

[0009] Optionally, the inorganic porous layer is composed of one or more of attapulgite, sepiolite, bentonite, and diatomite.

[0010] Optionally, the loading of sodium chlorite is 4%-8% based on the mass of the activated alumina balls.

[0011] Optionally, based on the mass of the activated alumina balls, the loading of the formaldehyde-free water-based adhesive is 0.3%-0.9%.

[0012] Optionally, the thickness of the inorganic porous layer is 0.3-0.5 mm.

[0013] Secondly, this application provides a method for preparing chlorine dioxide slow-release spheres, comprising the following steps:

[0014] S1: Provides activated alumina spheres as the core carrier;

[0015] S2: Apply sodium chlorite solution to the activated alumina balls to allow them to absorb it;

[0016] S3: Apply a formaldehyde-free aqueous adhesive solution to the sphere treated in step S2 to form an inner porous film.

[0017] S4: In the rolling state of the sphere, add inorganic porous layer material powder and spray water to granulate and coat until the predetermined thickness is reached;

[0018] S5: Apply formaldehyde-free water-based adhesive solution again during or after granulation to form an outer porous film;

[0019] S6: Dry the coated spheres to obtain the chlorine dioxide slow-release spheres.

[0020] Optionally, in step S4, the predetermined thickness is 0.3 mm to 0.5 mm more than the initial sphere diameter.

[0021] Optionally, in step S6, the drying temperature is 80°C to 100°C, and the spheres are dried until the moisture content is less than 5%.

[0022] In summary, this application includes at least one of the following beneficial technical effects:

[0023] 1. Controllable and stable release rate: Through the synergistic effect of the dual porous membrane of the core and shell and the inorganic porous layer, the initial "burst release" phenomenon is effectively avoided, and the slow and uniform release of chlorine dioxide is achieved, maintaining a long-term effective low-concentration sterilization environment.

[0024] 2. Significantly extended service life: The optimized loading capacity and physical barrier structure greatly reduce the loss of active ingredients during processing and use, and its release period can be extended to 6-12 months;

[0025] 3. Environmental friendliness and production safety: The entire preparation process uses water as a solvent, uses formaldehyde-free water-based adhesives, and has no waste discharge, meeting the requirements of green production;

[0026] 4. The product of this application has excellent physical properties: the obtained sustained-release spheres are regular in shape, dense in structure, and glossy on the surface, and are not easy to shed powder, making them easy to package, transport and use;

[0027] 5. The product of this application has demonstrated excellent antibacterial performance in real-world environmental testing and can be widely used for disinfection and deodorization in various scenarios. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the overall structure of the chlorine dioxide slow-release spheres in this application;

[0029] Figure 2 This is the result of the chlorine dioxide release amount of the chlorine dioxide slow-release spheres in this application;

[0030] Figure 3 This is the antibacterial result of the chlorine dioxide slow-release balls in this application. Detailed Implementation

[0031] To provide a clearer understanding of the technical features, objectives, and beneficial effects of this application, the technical solution of the present invention will now be described in detail with reference to the following specific embodiments and accompanying drawings. However, this should not be construed as limiting the scope of implementation of the present invention.

[0032] Example 1

[0033] The following process is carried out on a small granulator.

[0034] 90g of activated alumina balls are placed in a granulator at 60rpm, with a ball diameter of 2-3mm. A 12g solution of 30% sodium chlorite is prepared and sprayed onto the activated alumina balls for instant absorption. Polyester adhesive is diluted 10 times with water, and 5g is sprayed onto the alumina balls. The heat generated by friction during particle rotation will allow the adhesive to initially form a film, reducing the loss of the active ingredient, sodium chlorite, in subsequent operations. Attapulgite powder (200 mesh, viscosity 1200cps) is added to the granulator in multiple batches, spraying water during granulation. When the diameter increases to 0.5mm, 5g of acrylic resin adhesive is sprayed in, and the mixture is stirred evenly. The mixture is then dried in an oven to obtain chlorine dioxide slow-release balls. The drying temperature is 90℃, and the granules are dried until the moisture content is below 5%.

[0035] Example 2

[0036] 90g of activated alumina balls are placed in a granulator at 60rpm, with a ball diameter of 2-3mm. A 12g solution of 30% sodium chlorite is prepared and sprayed onto the activated alumina balls for instant absorption. 3g of acrylic resin is diluted 10 times with water and sprayed onto the alumina balls. The heat generated by friction during particle rotation will allow the adhesive to initially form a film, reducing the loss of the active ingredient, sodium chlorite, in subsequent processes. Attapulgite powder is added to the granulator in multiple batches, spraying water during granulation. When the diameter increases to 0.3mm, another 3g of acrylic resin is sprayed in, and the mixture is stirred evenly. The granules are then dried in an oven at 90℃ until the moisture content is below 5%.

[0037] Example 3

[0038] 90g of activated alumina balls are placed in a granulator at 60rpm, with a diameter of 2-3mm. Prepare 24g of a 30% sodium chlorite solution and spray it onto the activated alumina balls for instant absorption. Dilute polyester adhesive 10 times with water and spray 9g onto the alumina balls. The heat generated by friction during granulation will allow the adhesive to initially form a film, reducing the loss of the active ingredient, sodium chlorite, in subsequent processes. Add attapulgite powder to the granulator in multiple batches, spraying water during granulation. When the diameter reaches 0.5mm, spray in 9g of acrylic resin adhesive, stir thoroughly, and then dry in an oven to obtain chlorine dioxide slow-release balls. The drying temperature is 90℃, and the granules are dried until the moisture content is below 5%.

[0039] Example 4

[0040] 90g of activated alumina balls are placed in a granulator at 60rpm, with a ball diameter of 2-3mm. Prepare 24g of a 30% sodium chlorite solution and spray it onto the activated alumina balls for instant absorption. Dilute polyester adhesive 10 times with water and spray 4g onto the alumina balls. The heat generated by friction during granulation will allow the adhesive to initially form a film, reducing the loss of the active ingredient, sodium chlorite, in subsequent processes. Add attapulgite powder to the granulator in multiple batches, spraying water during granulation. When the diameter reaches 0.3mm, spray in 4g of acrylic resin adhesive, stir thoroughly, and then dry in an oven to obtain chlorine dioxide slow-release balls. The drying temperature is 90℃, and the granules are dried until the moisture content is below 5%.

[0041] Comparative Example 1

[0042] 90g of activated alumina balls were placed in a granulator at 60rpm, with a ball diameter of 2-3mm. 12g of a 30% sodium chlorite solution was prepared and sprayed onto the activated alumina balls for instant absorption. After thorough mixing, the balls were dried in an oven to obtain slow-release chlorine dioxide balls. The drying temperature was 90℃, and the granules were dried until the moisture content was below 5%. During the drying process, a pungent odor was produced, indicating the formation of chlorine dioxide. A large amount of sodium chlorite was decomposed at this stage, affecting the assessment of the later service life and resulting in a shorter actual service life.

[0043] Comparative Example 2

[0044] 90g of activated alumina balls were placed in a granulator at 60 rpm, with a ball diameter of 2-3mm. A 12g solution of 30% sodium chlorite was prepared and sprayed onto the activated alumina balls for instant absorption. Attapulgite powder was added to the granulator in multiple batches, spraying water during the granulation process. Adding was stopped when the diameter reached 0.5mm. After thorough mixing, the granules were dried in an oven at 90℃ until the moisture content was below 5%.

[0045] Comparative Example 3

[0046] 90g of activated alumina balls were placed in a granulator at 60rpm, with a ball diameter of 2-3mm. A 30% sodium chlorite solution (12g by mass) was prepared and sprayed onto the activated alumina balls for instant absorption. 10g of a polyester adhesive (diluted 10 times with water) was sprayed onto the alumina balls. The balls were then dried in an oven at 90℃ to obtain slow-release chlorine dioxide balls.

[0047] Comparative Example 4

[0048] 90g of activated alumina balls are placed in a granulator at 60rpm, with a ball diameter of 2-3mm. A 12g solution of 30% sodium chlorite is prepared and sprayed onto the activated alumina balls for instant absorption. 1g of polyester adhesive, diluted 10 times with water, is sprayed onto the alumina balls. The heat generated by friction during granulation helps the adhesive form a preliminary film, reducing the loss of the active ingredient, sodium chlorite, in subsequent processes. Attapulgite powder is added to the granulator in multiple batches, spraying water during granulation. When the diameter reaches 0.6mm, 1g of acrylic resin is sprayed in, stirred thoroughly, and then placed in an oven to dry at 90℃ until the granule moisture content is below 5%.

[0049] Comparative Example 5

[0050] 90g of activated alumina balls are placed in a granulator at 60rpm, with a ball diameter of 2-3mm. A 12g solution of 30% sodium chlorite is prepared and sprayed onto the activated alumina balls for instant absorption. 2g of polyester adhesive, diluted 10 times with water, is sprayed onto the alumina balls. The heat generated by friction during granulation helps the adhesive form a preliminary film, reducing the loss of the active ingredient, sodium chlorite, in subsequent processes. Attapulgite powder is added to the granulator in multiple batches, spraying water during granulation. When the diameter reaches 0.15mm, 2g of acrylic resin is sprayed in, stirred thoroughly, and then placed in an oven to dry at 90℃ until the granule moisture content is below 5%.

[0051] Performance testing

[0052] Chlorine dioxide release test

[0053] The test method for chlorine dioxide release is as follows:

[0054] Experimental principle: The chlorine dioxide released from the sample can oxidize the I- in potassium iodide in the absorption solution to I2. Starch is used as an indicator for color development. The I2 is reduced by titration with sodium thiosulfate. The mass of absorbed chlorine dioxide is calculated based on the amount and concentration of sodium thiosulfate used.

[0055] Experimental procedure: Prepare potassium iodide absorption solution and place it in a 250ml Erlenmeyer flask. Weigh 5g of sample and fix it to the mouth of the flask with a breathable mesh bag, then seal the mouth of the flask with sealing film. After absorption for 5-10 hours (samples with low release require a longer time), titrate the absorption solution.

[0056] The theoretical lifespan is calculated based on the sodium chlorite loading and the actual measured release amount. Theoretical lifespan (days) = sodium chlorite loading / actual release amount / 24.

[0057] The experimental results are shown in Table 1.

[0058] Table 1

[0059] Sodium chlorite loading (%) Water-based adhesive (porous film) loading rate (%) Inorganic porous layer thickness (mm) Day 10 release (mg / h) Theoretical lifespan (days) Actual lifespan (days) Surface condition Comparative Example 1 4 / / 0.325 25 20 Rough and powdery Comparative Example 2 4 / 0.5 0.231 51 13 Rough and powdery Comparative Example 3 4 1.0 / 0.010 / / Smooth and doesn't shed powder Comparative Example 4 4 0.1 0.6 0.310 / 23 Rough and powdery Comparative Example 5 4 0.2 0.15 0.290 / 30 Roughness and slight powder shedding Example 1 4 0.5 0.5 0.05 167 186 Smooth and doesn't shed powder Example 2 4 0.3 0.3 0.08 104 120 Smooth and doesn't shed powder Example 3 8 0.9 0.5 0.05 334 350 Smooth and doesn't shed powder Example 4 8 0.4 0.3 0.110 167 190 Smooth and doesn't shed powder

[0060] In Comparative Example 1, a pungent odor was produced during the drying process, indicating the generation of chlorine dioxide. A large amount of sodium chlorite was decomposed at this stage, affecting the assessment of the later service life and resulting in a lower actual service life. In Comparative Example 2, a pungent odor was produced during the drying process, indicating the generation of chlorine dioxide. A large amount of sodium chlorite was decomposed at this stage, affecting the assessment of the later service life and resulting in a lower actual service life. In Comparative Example 3, a large amount of acrylic resin adhesive was added, causing the alumina balls to agglomerate. The adhesive could not be completely absorbed, and after drying, the chlorine dioxide slow-release balls clumped together and were difficult to disperse, with a chlorine dioxide release rate of only 0.010 mg / h. In Comparative Example 4, the amount of acrylic resin glue added was too small, insufficient to form a protective film to confine sodium chlorite within the alumina spheres. This would lead to its loss during the later granulation and drying processes, reducing the service life (chlorine dioxide release was 0.310 mg / h, and the service life was 23 days). In Comparative Example 5, both the amount of acrylic resin glue and attapulgite clay added were too small, insufficient to form a protective film to confine sodium chlorite within the alumina spheres. This would lead to its loss during the later granulation and drying processes, reducing the service life (chlorine dioxide release was 0.290 mg / h, and the service life was 30 days).

[0061] Antibacterial test

[0062] Natural colony test method:

[0063] Principle: Using naturally occurring bacteria in the environment (such as colonies on object surfaces and skin) as test subjects.

[0064] Procedure: Two 100L experimental chambers, No. 1 and No. 2. Chamber No. 1 was left untreated, while Chamber No. 2 was placed with the chlorine dioxide slow-release balls from Example 1 and treated for 4 hours.

[0065] Sampling (before processing): Select the bottom surface of the experimental chamber. Dip a sterile cotton swab in a small amount of sterile saline solution and vigorously spread it over a selected area (5cm x 5cm). Then, cut or place the swab tip into a test tube containing a small amount of sterile water or buffer solution. Shake to mix. Label them as No. 1 and No. 2.

[0066] Take 1 mL of liquid from each of test tubes "1" and "2" and add them to the center of each test strip. Label the tubes accordingly. Place the test strips in an incubator and incubate for 48 hours. Results are as follows: Figure 3 As shown, from Figure 3 It is understood that the product of this application can be applied to antibacterial and deodorizing applications in a variety of scenarios.

[0067] Of course, the above description is only a specific embodiment of this application and is not intended to limit the scope of the invention. All equivalent changes or modifications made in accordance with the features and principles described in the claims of this invention should be included in the claims of this invention.

Claims

1. A chlorine dioxide slow-release ball, characterized in that, It comprises, from the inside out: activated alumina spheres and an inorganic porous layer; wherein, the activated alumina spheres are loaded with sodium chlorite and a porous film, and the inorganic porous layer is loaded with a porous film; The porous film is formed by an formaldehyde-free water-based adhesive, which is a polyester adhesive or an acrylic resin adhesive. The inorganic porous layer is attapulgite clay; based on the mass of the activated alumina balls, the loading of the formaldehyde-free water-based adhesive is 0.3%-0.9%.

2. The chlorine dioxide slow-release ball according to claim 1, characterized in that, Based on the mass of the activated alumina balls, the loading of sodium chlorite is 4%-8%.

3. The chlorine dioxide slow-release ball according to claim 1, characterized in that, The thickness of the inorganic porous layer is 0.3mm-0.5mm.

4. A method for preparing chlorine dioxide slow-release spheres as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Provides activated alumina spheres as the core carrier; S2: Apply sodium chlorite solution to the activated alumina balls to allow them to absorb it; S3: Apply a formaldehyde-free aqueous adhesive solution to the sphere treated in step S2 to form an inner porous film. S4: In the rolling state of the sphere, add inorganic porous layer material powder and spray water to granulate and coat until the predetermined thickness is reached; S5: Apply formaldehyde-free water-based adhesive solution again during or after granulation to form an outer porous film; S6: Dry the coated spheres to obtain the chlorine dioxide slow-release spheres.

5. The preparation method according to claim 4, characterized in that, In step S4, the predetermined thickness is 0.3 mm to 0.5 mm more than the initial sphere diameter.

6. The preparation method according to claim 4, characterized in that, In step S6, the drying temperature is 80°C to 100°C, and the spheres are dried until the moisture content is less than 5%.

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