Preparation method of device loaded with acid and alkali resistant long-acting slow-release type binary solid chlorine dioxide

Abstract

The application relates to the field of chlorine dioxide disinfecting materials, in particular to a preparation method of a device loaded with acid-alkali-resistant long-acting slow-release binary solid chlorine dioxide. The preparation of an acid-alkali-resistant long-acting slow-release chlorine dioxide solid preparation is as follows: cassava starch is used as a skeleton, polyvinyl alcohol is used as a soft segment, and quaternary ammonium carboxymethyl cellulose and chitin are added for modification, so that the acid resistance and alkali resistance of the hydrogel are improved; then sodium bicarbonate is introduced to increase the specific surface area of the hydrogel. The device is assembled by adsorbing sodium chlorite solution and citric acid solution through the three-dimensional network structure of the hydrogel, and long-term release of chlorine dioxide is realized through the coordination among raw materials, so that the shortcomings of solid chlorine dioxide, such as poor acid resistance and alkali resistance and poor mechanical property, are solved.

Description

Technical Field

[0001] This invention relates to the field of chlorine dioxide disinfection materials, specifically to a method for preparing a device loaded with acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide. Background Technology

[0002] Chlorine dioxide is a synthetic yellow-green gas that is readily soluble in water and sensitive to light and heat. It is highly effective at inactivating bacteria and viruses when used at low concentrations and over a wide pH range. Solid chlorine dioxide preparations are solid products that release chlorine dioxide gas under certain operating conditions. They offer advantages such as simple operation, high chlorine dioxide content, stable properties, and convenient transportation. They can slowly and quantitatively release low concentrations of chlorine dioxide disinfectant gas over a relatively long period.

[0003] Currently, long-lasting, slow-release binary solid chlorine dioxide products are relatively scarce in the market, and the chlorine dioxide production rate during release is unstable and varies considerably. During use, small molecules such as sodium chlorite, organic acids, and chlorine dioxide gas easily diffuse from the interior of polymer materials and migrate to the surface. However, biomass materials used in long-lasting, slow-release solid chlorine dioxide still suffer from easy collapse and disintegration in acidic and alkaline conditions, significantly reducing the slow-release time. Furthermore, most solid chlorine dioxide products have short release cycles, limited adsorption capacity, and difficulty in controlling the chlorine dioxide gas release rate. To address these issues, the resistance to acidic and alkaline solutions and the swelling rate can be improved by increasing the number of hydroxyl, carboxyl, and quaternary ammonium groups in the polymer carrier material, as well as increasing the porosity. Simultaneously, increasing the internal resistance of the material slows down the binding rate of chlorite and acidic activators, increases the diffusion resistance of chlorine dioxide gas, and prolongs the slow-release time.

[0004] Cassava starch, as a biodegradable biomass resource, can save on the application cost of chlorine dioxide slow release. By regulating the network structure, skeleton structure, and functional groups of hydrogels, and studying the chemical structure and cross-linking network molecular level of hydrogels, acid and alkali resistant long-lasting binary solid chlorine dioxide can be designed to improve the defects of existing materials and prepare low-cost chlorine dioxide carrier hydrogels with acid and alkali resistance. This is of positive significance for broadening the field of chlorine dioxide slow release, realizing the long-lasting release of chlorine dioxide, and solving the shortcomings of solid chlorine dioxide in acid and alkali solutions.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide, in order to solve the problem that slow-release biomass binary solid chlorine dioxide is prone to collapse and disintegration in acid and alkali environments.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] (1) Preparation of dry heat modified starch

[0009] By weight, 20 parts of distilled water were slowly added to 0.1 parts of xanthan gum while stirring continuously until the mixture was homogeneous. Then, 9.9 parts of tapioca starch were added and stirred evenly at room temperature. The pH of the mixture was adjusted to a certain value, and the mixture was placed in a petri dish and dried at 45 °C until the moisture content was less than 10%. The mixture was then pulverized and sieved, and then placed in a polytetrafluoroethylene petri dish and dried in an oven at 130 °C for 3 hours. Finally, the mixture was placed in a sample bottle to obtain the dry heat modified starch.

[0010] (2) Preparation of quaternized carboxymethyl cellulose

[0011] By weight, 2 parts of carboxymethyl cellulose were dissolved in 200 parts of distilled water. After complete dissolution, 0.5 parts of 2,3-epoxypropyltrimethylammonium chloride were added and mixed thoroughly at room temperature. The mixture was then placed in an oil bath at 60 °C for 24 h with the container sealed. After the reaction was complete, the product was precipitated with anhydrous ethanol. The precipitate was centrifuged, and the resulting substrate was precipitated with anhydrous ethanol. After repeated centrifugation and precipitation three times, the final centrifuged product was placed in a vacuum drying oven for vacuum drying. After vacuum drying, the sample was ground into powder using a mortar and pestle and then sealed and stored in a sample vial.

[0012] (3) Preparation of dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitosan / sodium bicarbonate hydrogel

[0013] ① Weigh out a certain amount of polyvinyl alcohol and dissolve it in distilled water.

[0014] ② After the polyvinyl alcohol has been fully dissolved, add a certain amount of dry heat modified starch, quaternized carboxymethyl cellulose, chitin, and sodium bicarbonate, and mix.

[0015] ③ After the mixture is evenly mixed, add sodium hydroxide at a mass-to-volume ratio of 6.0% (g / mL) of distilled water and stir.

[0016] ④ After stirring at room temperature for 2 hours, add the crosslinking agent epichlorohydrin and stir until the oil droplets disappear.

[0017] ⑤ Seal it and leave it at room temperature overnight until it crosslinks to form a hydrogel (a).

[0018] (4) Assemble an acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide device.

[0019] Weigh out hydrogels containing sodium chlorite solution and citric acid solution, and place them in a 100 mL tall beaker. The top layer should contain the hydrogel containing sodium chlorite solution, the middle layer the hydrogel containing citric acid solution, and the bottom layer the hydrogel containing sodium chlorite solution. By weight, the tall beaker contains 1 part sodium chlorite hydrogel and 1 part citric acid hydrogel, with 0.5 parts sodium chlorite hydrogel in each of the top and bottom layers. Separate the gels with filter membranes whose diameter matches the diameter of the tall beaker's opening. Place a filter membrane on top to prevent moisture evaporation. Prepare three parallel samples per group. Secure the samples tightly with braided thread around the mouth of the tall beaker. Quickly place this 100 mL tall beaker in this state into a 1000 mL wide-mouth bottle that has been purged with high-purity nitrogen for 5 min and has 10% potassium iodide solution, 2 mol / L H₂SO₄ solution, and 10% malonic acid solution added to the bottom. Tie a braided line to the mouth of a 100 mL tall beaker to control its balance, suspend it above the wide-mouth bottle, and seal the mouth of the wide-mouth bottle with PTFE tape.

[0020] Preferably, in step (3) ①, the mass ratio of polyvinyl alcohol to distilled water is 1.0% (g / mL).

[0021] Preferably, in step (3) ②, the mass ratio of dry heat modified starch to distilled water is 2.8% (g / mL), the mass ratio of quaternized carboxymethyl cellulose to distilled water is 0.8% (g / mL), the mass ratio of chitin to distilled water is 0.6% (g / mL), and the mass ratio of sodium bicarbonate to distilled water is 0.6% (g / mL).

[0022] Preferably, in step (3) ④, the volume ratio of epichlorohydrin to distilled water is 6.0% (mL / mL).

[0023] Preferably, in step (4) when assembling the acid and alkali resistant long-lasting slow-release binary solid chlorine dioxide device, the potassium iodide solution, H2SO4 solution and malonic acid solution are 25%, 25% and 2.5% of the sodium chlorite solution hydrogel, respectively, based on mL / g.

[0024] The present invention has the following beneficial technical effects compared with the prior art:

[0025] 1. Compared to hydrogels without added quaternized carboxymethyl cellulose and chitin, the dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitin hydrogel exhibits better mechanical properties in acidic and alkaline solutions. In alkaline solutions (sodium chlorite solution with pH=10), the tensile stress is 2.75 MPa and the compressive stress is 6.45 kPa; in acidic solutions (citric acid solution with pH=2), the tensile stress is 0.36 MPa and the compressive stress is 11.76 kPa.

[0026] 2. The optimized raw material ratio produces an acid and alkali resistant hydrogel that, within 24 hours, swells by more than 1300% in a 0.1% sodium chlorite solution and by more than 900% in a 0.1% citric acid solution, thus increasing the hydrogel's swelling performance in acid and alkali solutions (citric acid and sodium chlorite solutions).

[0027] 3. The lower the concentration of sodium chlorite solution and citric acid solution, the higher the swelling ratio of the acid and alkali resistant hydrogel.

[0028] 4. The gas release time of the acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide exceeds 30 days. Attached Figure Description

[0029] Figure 1 Curves showing the effect of the amount of each raw material added on the swelling rate and compressibility of the hydrogel.

[0030] Figure 2 Schematic diagram of acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide.

[0031] Figure 3 Figure 1 shows the test results for hydrogels 1-4.

[0032] Figure 4 A schematic diagram of the mechanism of acid and alkali resistant carrier hydrogels

[0033] Figure 5 Flowchart for acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide Detailed Implementation

[0034] The technical solution of this invention patent will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0035] (1) Preparation of dry heat modified starch

[0036] By weight, 20 parts of distilled water were slowly added to 0.1 parts of xanthan gum while stirring continuously until the mixture was homogeneous. Then, 9.9 parts of tapioca starch were added and stirred evenly at room temperature. The pH of the mixture was adjusted to a certain value, and the mixture was placed in a petri dish and dried at 45 °C until the moisture content was less than 10%. The mixture was then pulverized and sieved, and then placed in a polytetrafluoroethylene petri dish and dried in an oven at 130 °C for 3 hours. Finally, the mixture was placed in a sample bottle to obtain the dry heat modified starch.

[0037] (2) Preparation of quaternized carboxymethyl cellulose

[0038] By weight, 2 parts of carboxymethyl cellulose were dissolved in 200 parts of distilled water. After complete dissolution, 0.5 parts of 2,3-epoxypropyltrimethylammonium chloride were added and mixed thoroughly at room temperature. The mixture was then placed in an oil bath at 60 °C for 24 h with the container sealed. After the reaction was complete, the product was precipitated with anhydrous ethanol. The precipitate was centrifuged, and the resulting substrate was precipitated with anhydrous ethanol. After repeated centrifugation and precipitation three times, the final centrifuged product was placed in a vacuum drying oven for vacuum drying. After vacuum drying, the sample was ground into powder using a mortar and pestle and then sealed and stored in a sample vial.

[0039] (3) Preparation of dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitosan / sodium bicarbonate hydrogel

[0040] ① Weigh out a certain amount of polyvinyl alcohol and dissolve it in distilled water.

[0041] ② After the polyvinyl alcohol has been fully dissolved, add a certain amount of dry heat modified starch, quaternized carboxymethyl cellulose, chitin, and sodium bicarbonate, and mix.

[0042] ③ After the mixture is evenly mixed, add sodium hydroxide at a mass-to-volume ratio of 6.0% (g / mL) of distilled water and stir.

[0043] ④ After stirring at room temperature for 2 hours, add the crosslinking agent epichlorohydrin and stir until the oil droplets disappear.

[0044] ⑤ Seal it and leave it at room temperature overnight until it crosslinks to form a hydrogel (a).

[0045] (4) Assemble an acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide device.

[0046] Weigh out hydrogels containing sodium chlorite solution and citric acid solution, and place them in a 100 mL tall beaker. The top layer should contain the hydrogel containing sodium chlorite solution, the middle layer the hydrogel containing citric acid solution, and the bottom layer the hydrogel containing sodium chlorite solution. By weight, the tall beaker contains 1 part sodium chlorite hydrogel and 1 part citric acid hydrogel, with 0.5 parts sodium chlorite hydrogel in each of the top and bottom layers. Separate the gels with filter membranes whose diameter matches the diameter of the tall beaker's opening. Place a filter membrane on top to prevent moisture evaporation. Prepare three parallel samples per group. Secure the samples tightly with braided thread around the mouth of the tall beaker. Quickly place this 100 mL tall beaker in this state into a 1000 mL wide-mouth bottle that has been purged with high-purity nitrogen for 5 min and has 10% potassium iodide solution, 2 mol / L H₂SO₄ solution, and 10% malonic acid solution added to the bottom. Tie a braided line to the mouth of a 100 mL tall beaker to control its balance, suspend it above the wide-mouth bottle, and seal the mouth of the wide-mouth bottle with PTFE tape.

[0047] Preferably, in step (3) ①, the mass ratio of polyvinyl alcohol to distilled water is 1.0% (g / mL).

[0048] Preferably, in step (3) ②, the mass ratio of dry heat modified starch to distilled water is 2.8% (g / mL), the mass ratio of quaternized carboxymethyl cellulose to distilled water is 0.8% (g / mL), the mass ratio of chitin to distilled water is 0.6% (g / mL), and the mass ratio of sodium bicarbonate to distilled water is 0.6% (g / mL).

[0049] Preferably, in step (3) ④, the volume ratio of epichlorohydrin to distilled water is 6.0% (mL / mL).

[0050] Preferably, when assembling the acid and alkali resistant long-lasting slow-release binary solid chlorine dioxide device, the potassium iodide solution, H2SO4 solution, and malonic acid solution are 25%, 25%, and 2.5% of the sodium chlorite solution hydrogel, respectively, based on mL / g.

[0051] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Single-factor experiments were conducted using the following experimental factors: the amount of dry-heat modified starch, the amount of quaternized carboxymethyl cellulose, the amount of chitin, the amount of epichlorohydrin, the amount of polyvinyl alcohol, and the amount of sodium bicarbonate.

[0053] Example 1

[0054] (1) Preparation of dry heat modified starch

[0055] 80 mL of distilled water was slowly added to 0.4 g of xanthan gum while stirring continuously. After the mixture was homogeneous, 39.6 g of tapioca starch was added and stirred at room temperature for 30 min. The pH of the mixture was adjusted to 6.6, and the mixture was placed in a petri dish and dried at 45 °C until the moisture content was less than 10% (drying for 12 h). The mixture was then pulverized and passed through an 80-mesh sieve, and then placed in a polytetrafluoroethylene petri dish and dried in an oven at 130 °C for 3 h. Finally, the mixture was placed in a sample bottle to obtain the dry heat modified starch.

[0056] (2) Quaternization of carboxymethyl cellulose

[0057] Weigh 2 g of carboxymethyl cellulose and dissolve it in 200 mL of distilled water. After complete dissolution, add 0.5 g of 2,3-epoxypropyltrimethylammonium chloride and mix thoroughly at room temperature. Then, place the mixture in an oil bath at 60 °C for 24 h with the container sealed. After the reaction is complete, precipitate the product with anhydrous ethanol. Centrifuge the precipitate at 6000 rpm, 10 °C for 10 min. Precipitate the substrate with anhydrous ethanol after centrifugation. Repeat the centrifugation and precipitation process three times. Place the final centrifuged product in a vacuum drying oven for vacuum drying. After vacuum drying, grind the sample into powder using a mortar and pestle, and store it in a sealed sample bottle.

[0058] (3) Preparation of dry heat modified starch / polyvinyl alcohol hydrogel

[0059] Weigh 0.25 g of polyvinyl alcohol and dissolve it in 25 mL of distilled water. After it is fully dissolved, add 0.70 g of dry heat modified starch. After the dry heat modified starch is mixed evenly, add 1.5 g of sodium hydroxide. Stir at room temperature for 2 h, then add 1.5 mL of crosslinking agent epichlorohydrin and stir evenly until the oil droplets disappear. Seal it and leave it at room temperature overnight until it crosslinks to form a modified starch / polyvinyl alcohol hydrogel, which is called hydrogel 1.

[0060] (4) Assemble the solid chlorine dioxide device

[0061] Weigh 40 g each of hydrogels containing sodium chlorite solution and citric acid solution, and place them in a 100 mL tall beaker. Place 20 g of hydrogel containing sodium chlorite solution on top, 40 g of hydrogel containing citric acid solution in the middle, and 20 g of hydrogel containing sodium chlorite solution at the bottom. Separate the gels with a 50 μm diameter filter membrane. Place another filter membrane on top to prevent moisture evaporation. Prepare three parallel samples per group. Secure the beaker tightly with braided thread at the mouth. Quickly place the 100 mL tall beaker in this state into a 1000 mL wide-mouth bottle that has been purged with high-purity nitrogen for 5 minutes and has 10 mL of 10% potassium iodide solution, 10 mL of 2 mol / L H₂SO₄ solution, and 1 mL of 10% malonic acid solution added to the bottom. Maintain balance using the braided thread used to secure the beaker to the top of the wide-mouth bottle, and seal the bottle mouth with PTFE tape. Simultaneously, conduct a blank control experiment. The apparatus is as follows: Figure 2 As shown in (b).

[0062] Example 2

[0063] Steps (1), (2) and (4) are the same as in Example 1.

[0064] (3) Preparation of dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose hydrogel

[0065] Weigh 0.25 g of polyvinyl alcohol and dissolve it in 25 mL of distilled water. After it is fully dissolved, add 0.70 g of dry heat modified starch and 0.20 g of quaternized carboxymethyl cellulose. After the three are mixed evenly, add 1.5 g of sodium hydroxide and stir at room temperature for 2 h. Then add 1.5 mL of crosslinking agent epichlorohydrin and stir evenly until the oil droplets disappear. Seal it and leave it at room temperature overnight until it crosslinks to form a modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose hydrogel, which is denoted as hydrogel 2.

[0066] Example 3

[0067] Steps (1), (2) and (4) are the same as in Example 1.

[0068] (3) Preparation of dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitin hydrogel

[0069] Weigh 0.15 g of chitin and add it to 25 mL of distilled water containing 1.5 g of sodium hydroxide. Then add 0.25 g of polyvinyl alcohol, 0.70 g of dry heat modified starch, and 0.20 g of quaternized carboxymethyl cellulose. Stir and mix evenly at room temperature. Then add 1.5 mL of crosslinking agent epichlorohydrin and stir evenly until the oil droplets disappear. Seal it and leave it at room temperature overnight until it crosslinks to form a modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitin hydrogel, which is denoted as hydrogel 3.

[0070] Example 4

[0071] Steps (1), (2) and (4) are the same as in Example 1.

[0072] (3) Preparation of dry heat modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitosan / sodium bicarbonate hydrogel

[0073] Weigh 0.15 g of chitosan and add it to 25 mL of distilled water containing 1.5 g of sodium hydroxide. Then add 0.25 g of polyvinyl alcohol, 0.70 g of dry heat modified starch, 0.20 g of quaternized carboxymethyl cellulose, and 0.15 g of sodium bicarbonate. Stir well at room temperature, then add 1.5 mL of crosslinking agent epichlorohydrin and stir until the oil droplets disappear. Seal the mixture and leave it at room temperature overnight until it crosslinks to form a modified starch / polyvinyl alcohol / quaternized carboxymethyl cellulose / chitosan / sodium bicarbonate hydrogel, which is denoted as hydrogel 4.

[0074] The effects of adding various raw materials on acid and alkali resistant, long-lasting, sustained-release binary solid chlorine dioxide were investigated. The test results for hydrogels 1-4 are as follows: Figure 3 As shown.

[0075] Combination Figure 3 (a) It can be seen that FTIR proves that the raw materials in the hydrogel, including quaternized carboxymethyl cellulose, chitin, and dry heat modified starch, have been successfully cross-linked.

[0076] Combination Figure 3As shown in (b)-(e), in sodium chlorite solution (pH=10), the tensile and compressive properties of the hydrogel show a trend of first increasing and then decreasing. Compared with the mechanical properties of other hydrogels in sodium chlorite solution, hydrogel 3 has better alkali resistance, with a tensile stress of 2.75 MPa at 64.45% tensile strain and a compressive stress of 6.45 kPa at 80.60% compressive strain. In citric acid solution (pH=2), the tensile and compressive properties of the hydrogel show a trend of first increasing and then decreasing. Combining the tensile and compressive properties of the hydrogel in citric acid solution, it is found that hydrogel 3 has better acid resistance, with a tensile stress of 0.36 MPa at 73.78% tensile strain and a compressive stress of 11.76 kPa at 84.37% compressive strain.

[0077] Combination Figure 3 (f) and (g) show that the swelling properties of the hydrogel in different concentrations of citric acid gradually decrease with increasing concentration, and the swelling properties of the hydrogel in different concentrations of sodium chlorite gradually decrease with increasing concentration. Furthermore, the swelling rate of the hydrogel in sodium chlorite solution is higher than that in citric acid solution.

[0078] Combination Figure 3 (h) and (i) show that the release trend of chlorine dioxide at all sodium chlorite concentrations is first increasing and then decreasing. The total release gradually increases with increasing concentration, and increasing sodium chlorite concentration accelerates the release of chlorine dioxide to its maximum value, but has little effect on the release time. Similarly, the release trend of chlorine dioxide at all citric acid concentrations is first increasing and then decreasing. Increasing citric acid concentration can accelerate the time it takes for chlorine dioxide release to reach its maximum value, but has no significant effect on the total release time.

[0079] In summary, this invention introduces quaternary ammonium groups into the entire hydrogel system. The nitrogen-base coordination of the quaternary ammonium groups enhances the selective adsorption of alkalis by the hydrogel, thereby improving its alkali resistance. Simultaneously, it introduces carboxyl and amino groups. In acidic pH, the amino groups are protonated, and the mutual repulsion between positively charged ions prevents a decrease in swelling in acidic solutions, thus improving its acid resistance. This results in the preparation of a biodegradable, low-cost, acid- and alkali-resistant chlorine dioxide carrier hydrogel. The crosslinking mechanism of the hydrogel is as follows: Figure 4 As shown in (a). Because the hydrogel possesses acid-resistant anionic groups and alkali-resistant cationic groups, the shortcomings of acid and alkali resistant long-lasting binary solid chlorine dioxide, such as corrosion and disintegration under acid and alkali conditions, poor mechanical properties, and short release period, are improved. The mechanism of hydrogel acid and alkali absorption is described in [reference needed]. Figure 4 (b) The entire process flow diagram of the acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide is as follows: Figure 5 As shown.

[0080] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a device for loading acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide, characterized in that, Includes the following steps: (1) Preparation of dry heat modified starch By weight, 20 parts of distilled water were slowly added to 0.1 parts of xanthan gum while stirring continuously. After mixing evenly, 9.9 parts of tapioca starch were added and stirred evenly at room temperature. The pH of the mixture was adjusted to 6.6, placed in a petri dish and dried at 45°C until the moisture content was less than 10%. The mixture was then pulverized and sieved, and placed in a polytetrafluoroethylene petri dish and dried in an oven at 130°C for 3 hours to obtain dry heat modified starch. (2) Preparation of quaternized carboxymethyl cellulose By weight, 2 parts of carboxymethyl cellulose were dissolved in 200 parts of distilled water. After complete dissolution, 0.5 parts of 2,3-epoxypropyltrimethylammonium chloride were added. The mixture was stirred evenly at room temperature, and the container was sealed and placed in an oil bath at 60°C for 24 h. After the reaction was completed, the product was precipitated with anhydrous ethanol, and the precipitate was collected by centrifugation. The precipitate was repeatedly precipitated and centrifuged three times with anhydrous ethanol, then vacuum dried and ground into powder to obtain quaternized carboxymethyl cellulose. (3) Preparation of hydrogels ① Weigh out polyvinyl alcohol at a mass-to-volume ratio of 1.0% (g / mL) and dissolve it in distilled water; ② After the polyvinyl alcohol is fully dissolved, add the dry heat-modified starch at a mass-to-volume ratio of 2.8% (g / mL) of the dry heat-modified starch, the quaternized carboxymethyl cellulose at a mass-to-volume ratio of 0.8% (g / mL) of the dry heat-modified starch, the chitin at a mass-to-volume ratio of 0.6% (g / mL) of the chitin, and the sodium bicarbonate at a mass-to-volume ratio of 0.6% (g / mL) of the distilled water, and mix them together. ③ After the mixture is thoroughly mixed, add sodium hydroxide at a mass-to-volume ratio of 6.0% (g / mL) to distilled water, and stir. ④ After stirring at room temperature for 2 hours, add epichlorohydrin, a crosslinking agent, at a volume ratio of 6.0% (mL / mL) to distilled water, and stir until the oil droplets disappear. ⑤ Seal it and leave it at room temperature overnight until it crosslinks to form a hydrogel; (4) Assemble an acid and alkali resistant, long-lasting, slow-release binary solid chlorine dioxide device. Weigh the hydrogels containing sodium chlorite solution and citric acid solution prepared in step (3), and place them in a 100mL tall beaker. Place the hydrogel containing sodium chlorite solution in the upper layer, the hydrogel containing citric acid solution in the middle layer, and the hydrogel containing sodium chlorite solution in the lower layer. By weight, the tall beaker contains 1 part of sodium chlorite solution hydrogel and 1 part of citric acid solution hydrogel, with 0.5 parts of sodium chlorite solution hydrogel placed in each of the upper and lower layers. The layers of gel are separated by a filter membrane whose diameter matches the diameter of the mouth of the tall beaker. Place a filter membrane on the top of the tall beaker to prevent water evaporation, thereby obtaining a device loaded with acid and alkali resistant long-lasting slow-release binary solid chlorine dioxide.

2. The preparation method according to claim 1, characterized in that, In step (1), pulverizing and sieving means pulverizing and then passing the material through an 80-mesh sieve.

3. The preparation method according to claim 1, characterized in that, In step (2), the centrifugation parameters are 6000 rpm, 10℃, and centrifugation for 10 min.

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