Chlorine dioxide solid sustained-release agent and preparation method thereof

Abstract

The present application relates to a kind of chlorine dioxide solid sustained-release agent and its preparation method, the preparation method includes: S1, zeolite, activated carbon fiber and water are mixed, stirring and then filtering dry, obtain activated carbon fiber modified zeolite;S2, the above activated carbon fiber modified zeolite is contacted with fluorine gas, and activated carbon fiber-fluorine gas modified zeolite is obtained;S3, the above activated carbon fiber-fluorine gas modified zeolite is soaked in chlorite solution, filter dry, and the chlorine dioxide solid sustained-release agent is obtained, the chlorine dioxide solid sustained-release agent obtained by the method has the advantages of large chlorite loading, chlorine dioxide release rate is fast, sustained-release period is long etc..

Description

Technical Field

[0001] This invention relates to the field of sustained-release disinfectant technology, specifically to a solid chlorine dioxide sustained-release agent and its preparation method. Background Technology

[0002] Chlorine dioxide is an internationally recognized highly effective disinfectant and sterilizer. Chlorine dioxide sustained-release tablets are particularly popular due to their strong bactericidal ability; they can kill all microorganisms, including vegetative bacteria, bacterial spores, fungi, mycobacteria, and viruses, without inducing antibiotic resistance. Chlorine dioxide has a strong adsorption and penetration ability into microbial cell walls, effectively oxidizing intracellular enzymes containing sulfhydryl groups and rapidly inhibiting microbial protein synthesis, thus destroying microorganisms. Its lack of harm to humans and animals and its absence of secondary environmental pollution make it highly favored, and it has wide applications in sterilization, food preservation, and deodorization.

[0003] To better utilize the disinfection effect of chlorine dioxide, existing technologies have developed solid-loaded chlorine dioxide products. Commonly used solid carriers include zeolite, silica gel, calcium silicate, diatomaceous earth, talc, molecular sieves, activated carbon, superabsorbent polyacrylic acid resin, agar, super-adsorbent resin, and carboxymethyl cellulose. However, these generally suffer from low sodium chlorite loading, short chlorine dioxide release cycles, and low chlorine dioxide release rates, thus failing to effectively sterilize or purify the air. Summary of the Invention

[0004] The purpose of this invention is to overcome the deficiencies in the prior art. To this end, this invention provides a method for preparing a solid chlorine dioxide sustained-release agent and the solid chlorine dioxide sustained-release agent obtained by the method.

[0005] On one hand, the present invention provides a method for preparing a solid chlorine dioxide sustained-release agent, comprising the following steps:

[0006] S1. Mix zeolite, activated carbon fiber and water, stir and then filter and dry to obtain activated carbon fiber modified zeolite.

[0007] S2. The above-mentioned activated carbon fiber modified zeolite is contacted with fluorine gas to obtain activated carbon fiber-fluorine gas modified zeolite.

[0008] S3. The above-mentioned activated carbon fiber-fluorine modified zeolite is soaked in chlorite solution, filtered and dried to obtain the chlorine dioxide solid slow-release agent.

[0009] Activated carbon fiber (ACF) is a type of carbon fiber that has been activated at high temperatures and has a large specific surface area (1000-3000 m²). 2It has a large adsorption capacity and fast adsorption kinetics, and is resistant to acids and alkalis, high temperatures, and has strong adaptability. It also has excellent redox properties.

[0010] The core of preparing a solid chlorine dioxide sustained-release agent lies in the modification of zeolite. Traditional modification methods include acid modification, alkali modification, and high-temperature modification. These methods essentially remove internal impurities from the zeolite and reduce its porosity, but their effects are limited and do not significantly affect its loading capacity. This invention introduces nanoscale activated carbon fibers into the traditional modification process. Loading these activated carbon fibers onto the zeolite increases its specific surface area. Then, fluorination of the activated carbon fiber-modified zeolite with fluorine gas significantly increases the porosity of the zeolite due to the corrosiveness of the fluorine. Under the influence of fluorine, the carbon in the activated carbon fibers and the silicon in the zeolite form FC and F-Si bonds, improving the stability of the pores and preventing pore structure collapse during chlorite adsorption, thereby increasing the chlorite loading capacity. Simultaneously, the activated carbon fibers possess excellent redox capabilities, increasing the decomposition rate of chlorite. This results in a solid chlorine dioxide sustained-release agent with advantages such as rapid release rate and long sustained-release period.

[0011] Furthermore, the particle size of the activated carbon fiber is less than 10 nm.

[0012] Furthermore, the particle size of the activated carbon fiber is 1-10 nm, preferably 1-5 nm.

[0013] In a specific embodiment of the present invention, the particle size of the activated carbon fiber is 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, etc.

[0014] If the particle size of activated carbon fibers is too large, the specific surface area is small, the redox performance is reduced, the release of chlorine dioxide is reduced, and it is not easily adsorbed into the interior by zeolite. If the particle size of activated carbon fibers is too small, the surface area is large, the redox performance is improved, the decomposition rate of sodium chlorite is increased, and the product's slow-release cycle is shortened.

[0015] Furthermore, the activated carbon fiber is one or more of phenolic activated carbon fiber, polyacrylonitrile activated carbon fiber, viscose activated carbon fiber, and pitch-based activated carbon fiber.

[0016] Furthermore, the zeolite is one or more of clinoptilolite, mordenite, calcareous zeolite, flaky zeolite, and calcium cruciform zeolite.

[0017] Furthermore, the particle size of the zeolite is 0.1-1 mm, preferably 0.1-0.2 mm.

[0018] Furthermore, the zeolite undergoes acid-base modification treatment before use. The specific steps of the acid-base modification treatment are as follows:

[0019] The zeolite was soaked in an acid solution for 1.5-2.5 hours, then filtered and washed until the pH of the filtrate was 7, dried until constant weight, and then soaked in an alkaline solution for 1.5-2.5 hours. The zeolite was then filtered and washed until the pH of the filtrate was 7, dried until constant weight, and then calcined at high temperature in a muffle furnace to obtain acid-base modified zeolite.

[0020] The acid solution is one or a mixture of hydrochloric acid, sulfuric acid, and nitric acid; the alkali solution is one or a mixture of two of NaOH and KOH; the concentration of the acid solution or alkali solution is 1-2 mol / L, preferably 1.1 mol / L; the volume ratio of the acid solution or alkali solution to the mass of the zeolite is (1-2) L:1 kg, preferably 1.2 L:1 kg; the high-temperature calcination temperature in the muffle furnace is 400-600℃ and the time is 2-5 h, preferably calcination at 600℃ for 3 h.

[0021] Further, in step S1, the mass of activated carbon fiber in 1L of water is 1-20g, and the mass of zeolite is 0.5-1kg; the stirring time is 1-12h, preferably 10-12h. The activated carbon fiber used in this application is nanoscale, and the zeolite has a porous structure and a certain adsorption capacity. The zeolite can adsorb the activated carbon fiber in its pores.

[0022] In this invention, to avoid introducing impurities, the water is preferably deionized water.

[0023] Further, in step S1, the drying process includes: first drying at 80-120℃ for 2-6 hours to constant weight, and then drying at 150-200℃ for 3-5 hours under nitrogen protection to constant weight. The two drying stages are to prevent rapid dehydration of the zeolite due to high temperatures, avoid cracking of the zeolite caused by water vapor bubbles, and prevent rapid drying from causing the zeolite to clump together.

[0024] Furthermore, step S2 is carried out in a Monel reactor, and the fluorine gas is a mixture containing a protective gas, with a volume fraction of 10-20% in the mixture. Because fluorine gas is corrosive, a Monel reactor is chosen.

[0025] Furthermore, the protective gas is one or more of nitrogen, argon, and helium.

[0026] Furthermore, the mixed gas is introduced into the Monel reactor at a rate of 100-200 mL / min for 5-12 h. Within this range, the amount of fluorine gas allows the zeolite to be fully fluorinated. On the one hand, this forms corrosive pores; on the other hand, the F in the fluorine gas forms F-C bonds with the C in the activated carbon fibers and the Si in the zeolite, respectively, and the fluorine gas acts as a bridge, more firmly loading the activated carbon fibers onto the zeolite. This improves the stability of the pores within the zeolite, preventing the pore structure from collapsing during subsequent adsorption of chlorite solution, thereby increasing the chlorite loading.

[0027] In a specific embodiment of the present invention, the rate at which the mixed gas is introduced into the Monel reactor is 100 mL / min, 120 mL / min, 140 mL / min, 150 mL / min, 160 mL / min, 180 mL / min, 200 mL / min, etc.

[0028] In a specific embodiment of the present invention, the mixed gas is introduced at times of 5h, 5.5h, 6h, 7h, 8h, 9h, 10h, 10.5h, 11h, 12h, etc.

[0029] Further, in step S3, the mass fraction of the chlorite solution is 30-46%, and the soaking time is 0.1-1h.

[0030] In a specific embodiment of the present invention, the mass fraction of the chlorite is 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, etc.

[0031] In a specific embodiment of the present invention, the soaking time of the zeolite in the chlorite solution is 0.1h, 0.2h, 0.3h, 0.4h, 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, etc.

[0032] In this invention, the solvent for the chlorite solution is water.

[0033] Further, the chlorite is one or more of sodium chlorite, calcium chlorite, magnesium chlorite, potassium chlorite, and barium chlorite.

[0034] Furthermore, in step S3, the drying temperature is 60-100℃ and the drying time is 3-5h.

[0035] On the other hand, the present invention provides a solid chlorine dioxide sustained-release agent obtained by the above preparation method.

[0036] Furthermore, the loading of chlorite in the chlorine dioxide solid slow-release agent is 15-30%.

[0037] In a specific embodiment of the present invention, the loading of chlorite in the solid chlorine dioxide slow-release agent is 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, etc.

[0038] In this invention, the loading of chlorite refers to the proportion of the mass of chlorite to the total mass of the chlorine dioxide solid slow-release agent.

[0039] Thirdly, the present invention provides the application of the above-mentioned chlorine dioxide solid slow-release agent in the fields of air purification, food preservation and surface disinfection, which has the advantages of fast chlorine dioxide release rate and long slow release period, and can achieve the purpose of long-term and efficient disinfection and sterilization.

[0040] The beneficial effects of this invention are as follows:

[0041] (1) Introducing nano-activated carbon fibers into zeolite fills the large pores inside the zeolite, increases the specific surface area of ​​the zeolite, thereby increasing the adsorption capacity of the zeolite and improving the loading of chlorite.

[0042] (2) The introduction of fluorine gas can corrode the zeolite to form more dense pores. At the same time, the F in the fluorine gas can form FC bonds with the C in the activated carbon fiber and F-Si bonds with the Si in the zeolite. The fluorine gas acts as a bridge, which can more firmly load the activated carbon fiber onto the zeolite, making the pores inside the zeolite more stable.

[0043] (3) Activated carbon fiber has excellent redox properties, which can increase the decomposition rate of chlorite and make the release rate of chlorine dioxide high, thus playing a role in efficient sterilization and air purification.

[0044] (4) Compared with existing solid chlorine dioxide slow-release agents, the slow-release agent of the present invention has the advantages of large chlorite loading, high chlorine dioxide slow-release rate and long release cycle.

[0045] Terminology Definition

[0046] Unless explicitly stated otherwise, all scopes referenced in this invention include end values.

[0047] All figures in this invention are approximate values, regardless of whether words such as "approximately" or "about" are used. The numerical values ​​may vary by 1%, 2%, 5%, 7%, 8%, 10%, etc. Whenever a number with a value of N is disclosed, any number having a value of N+ / -1%, N+ / -2%, N+ / -3%, N+ / -5%, N+ / -7%, N+ / -8%, or N+ / -10% will be explicitly disclosed, where "+ / -" indicates addition or subtraction, and the range between N-10% and N+10% is also disclosed.

[0048] Unless otherwise stated, the following definitions as used in this invention shall apply. For the purposes of this invention, chemical elements are consistent with the CAS version of the periodic table and the 75th edition of the *Handbook of Chemistry and Physics*, 1994. Furthermore, general principles of organic chemistry can be found in *Organic Chemistry*, Thomas Sorrell, University Science Books, Sausalito: 1999, and *March's Advanced Organic Chemistry* by Michael B. Smith and Jerry March, John Wiley & Sons, New York: 2007, the entire contents of which are incorporated herein by reference.

[0049] Unless otherwise defined, all technical terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Although similar or equivalent methods and materials may be used in the implementation or testing of embodiments of this invention, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned in this invention are incorporated herein by reference in their entirety, except where specific paragraphs are cited. In case of any conflict, this specification and its included definitions shall prevail. Furthermore, materials, methods, and examples are illustrative only and are not intended to be limiting. Attached Figure Description

[0050] Figure 1 The graph shows the change in chlorine dioxide concentration released by the solid chlorine dioxide slow-release agent in Example 3 and the comparative example of the present invention after being placed in a 10L sealed container for 90 days. Detailed Implementation

[0051] The following description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0052] Before use, the zeolite in this embodiment of the invention undergoes acid-base modification treatment in the following steps:

[0053] 1 kg of clinoptilolite with a particle size of 0.1 mm was soaked in 1.2 L of 1.1 mol / L hydrochloric acid solution for 2 h, then washed until the pH of the filtrate was 7, dried until constant weight, and then soaked in 1.2 L of 1.1 mol / L NaOH solution for 2 h, then washed until the pH of the filtrate was 7, dried until constant weight, and then calcined in a muffle furnace at 600 °C for 3 h to obtain acid-base modified zeolite.

[0054] Example 1

[0055] S1. 1g of polyacrylonitrile-based activated carbon fiber (purchased from Jiangsu Kejing Carbon Fiber Co., Ltd.) with a particle size of 1nm was placed in 1L of water and dispersed into a suspension by a vibration mill. Then, 1kg of the above-mentioned acid-base modified zeolite was added and shaken and soaked for 12h. After filtration, it was dried at 100℃ to constant weight and then placed in a muffle furnace and dried at 200℃ to constant weight under nitrogen protection to obtain activated carbon fiber modified zeolite.

[0056] S2. Place 1 kg of the above-mentioned activated carbon fiber modified zeolite into a Monel reactor, and introduce a mixture of fluorine and nitrogen gas (fluorine gas fraction of 20%) into the reactor at a rate of 100 mL / min for reaction. After continuous gas introduction for 10.5 h, activated carbon fiber-fluorine modified zeolite is obtained.

[0057] S3. The activated carbon fiber-fluorine modified zeolite was soaked in a 30wt% sodium chlorite solution for 0.5h; then filtered and dried in an 80℃ oven for 4h to obtain the chlorine dioxide solid slow-release agent.

[0058] Example 2

[0059] S1. Place 10g of polyacrylonitrile-based activated carbon fiber with a particle size of 5nm into 1L of water, disperse it into a suspension by vibration milling, then add 1kg of the above acid-base modified zeolite and shake and soak for 12h, then filter, dry at 100℃ to constant weight, and then put it into a muffle furnace and dry at 200℃ to constant weight under nitrogen protection to obtain activated carbon fiber modified zeolite.

[0060] S2. Place 1 kg of the above-mentioned activated carbon fiber modified zeolite into a Monel reactor, and introduce a mixture of fluorine and nitrogen gas (fluorine gas fraction of 20%) into the reactor at a rate of 100 mL / min for reaction. After continuous gas introduction for 10.5 h, activated carbon fiber-fluorine modified zeolite is obtained.

[0061] S3. The activated carbon fiber-fluorine modified zeolite was soaked in a 30wt% sodium chlorite solution for 0.5h; then filtered and dried in an 80℃ oven for 4h to obtain the chlorine dioxide solid slow-release agent.

[0062] Example 3

[0063] S1. Place 20g of polyacrylonitrile-based activated carbon fiber with a particle size of 5nm into 1L of water, disperse it into a suspension by vibration milling, then add 1kg of the above acid-base modified zeolite and shake and soak for 12h, then filter, dry at 100℃ to constant weight, and then put it into a muffle furnace and dry at 200℃ to constant weight under nitrogen protection to obtain activated carbon fiber modified zeolite.

[0064] S2. Place 1 kg of the above-mentioned activated carbon fiber modified zeolite into a Monel reactor, and introduce a mixture of fluorine and nitrogen gas (fluorine gas fraction of 20%) into the reactor at a rate of 100 mL / min for reaction. After continuous gas introduction for 10.5 h, activated carbon fiber-fluorine modified zeolite is obtained.

[0065] S3. The activated carbon fiber-fluorine modified zeolite was soaked in a 30wt% sodium chlorite solution for 0.5h; then filtered and dried in an 80℃ oven for 4h to obtain the chlorine dioxide solid slow-release agent.

[0066] Example 4

[0067] S1. Place 20g of polyacrylonitrile-based activated carbon fiber with a particle size of 5nm into 1L of water, disperse it into a suspension by vibration milling, then add 1kg of the above acid-base modified zeolite and shake and soak for 12h, then filter, dry at 100℃ to constant weight, and then put it into a muffle furnace and dry at 200℃ to constant weight under nitrogen protection to obtain activated carbon fiber modified zeolite.

[0068] S2. Place 1 kg of the above-mentioned activated carbon fiber modified zeolite into a Monel reactor, and introduce a mixture of fluorine and nitrogen gas (fluorine gas fraction of 20%) into the reactor at a rate of 200 mL / min for reaction. After continuous gas introduction for 5.5 h, activated carbon fiber-fluorine modified zeolite is obtained.

[0069] S3. The activated carbon fiber-fluorine modified zeolite was soaked in a 30wt% sodium chlorite solution for 0.5h; then filtered and dried in an 80℃ oven for 4h to obtain the chlorine dioxide solid slow-release agent.

[0070] Comparative Example

[0071] S1. Place 20g of polyacrylonitrile-based activated carbon fiber with a particle size of 5nm into 1L of water, disperse it into a suspension by vibration milling, then add 1kg of the above acid-base modified zeolite and shake and soak for 12h, then filter, dry at 100℃ to constant weight, and then put it into a muffle furnace and dry at 200℃ to constant weight under nitrogen protection to obtain activated carbon fiber modified zeolite.

[0072] S2. The zeolite modified with the above-mentioned activated carbon fiber was soaked in a 30wt% sodium chlorite solution for 0.5h; then filtered and dried in an 80℃ oven for 4h to obtain the chlorine dioxide solid slow-release agent.

[0073] Performance testing

[0074] The sodium chlorite loading, initial chlorine dioxide release rate, and release period of the chlorine dioxide solid slow-release agents obtained in Examples 1-4 and the comparative example were tested. The test results are shown in Table 1. The change in chlorine dioxide concentration released by the chlorine dioxide solid slow-release agents in Example 3 and the comparative example after being placed in a 10L sealed container for 90 days was also tested. The test results are shown in Table 1. Figure 1 .

[0075] (1) Sodium chlorite loading

[0076] The test method for sodium chlorite loading is based on GB / T 27803-2011 "Analytical Methods for Chlorine Dioxide Solid Release Agents".

[0077] (2) Initial release rate of chlorine dioxide

[0078] Take 5g of the chlorine dioxide solid slow-release agent from Examples 1-4 and the comparative example above, wrap it in non-woven fabric and suspend it in a 10L acrylic sealed container. Adjust the temperature in the container to 15-35℃ and the humidity to 30-60%. After 24 hours, measure the release concentration of chlorine dioxide in the container to obtain the initial release rate of chlorine dioxide.

[0079] In Examples 3 and 3 (Comparative Examples), the air inside the containers was replaced until the chlorine dioxide concentration was 0 ppm. The release concentration of chlorine dioxide inside the containers was tested every 24 hours. The test results are shown in [Figure Number]. Figure 1 .

[0080] (3) Sustained-release period

[0081] The number of days for stable release of chlorine dioxide was recorded, and the test results are shown in Table 1.

[0082] Table 1

[0083] Serial Number Sodium chlorite loading Initial release rate of chlorine dioxide / ppm Sustained-release cycle / day Example 1 10％ 10 60 Example 2 17％ 16 70 Example 3 22％ 24 90 Example 4 20％ 20 60 Comparative Example 5％ 15 30

[0084] The test results show that zeolite modified with activated carbon fibers and fluorine gas can significantly increase the loading of sodium chlorite, increase the release rate of chlorine dioxide, and simultaneously increase the stable release period and release stability. In the comparative example, the zeolite was not modified with fluorine gas, and the loading of sodium chlorite was significantly reduced. Although the release rate of chlorine dioxide increased, the release period decreased simultaneously. This indicates that fluorine gas can corrode the zeolite to form more pores, increasing the loading of sodium chlorite, and activated carbon fibers can increase the decomposition rate of chlorite, thereby promoting the release of chlorine dioxide.

[0085] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a solid chlorine dioxide sustained-release agent, characterized in that, Includes the following steps: S1. Zeolite, activated carbon fiber and water are mixed, stirred and then filtered and dried to obtain activated carbon fiber modified zeolite; wherein the particle size of the activated carbon fiber is less than 10 nm. S2. The zeolite modified with activated carbon fiber is contacted with fluorine gas to obtain activated carbon fiber-fluorine gas modified zeolite. Step S2 is carried out in a Monel reactor. The fluorine gas is a mixture containing a protective gas, and the volume fraction of fluorine gas in the mixture is 10-20%. The rate at which the mixture is introduced into the Monel reactor is 100-200 mL / min, and the introduction time of the mixture is 5-12 h. S3. Soak the above-mentioned activated carbon fiber-fluorine modified zeolite in chlorite solution, filter and dry to obtain the chlorine dioxide solid slow-release agent.

2. The preparation method according to claim 1, characterized in that, The activated carbon fiber is one or more of phenolic activated carbon fiber, polyacrylonitrile activated carbon fiber, viscose activated carbon fiber, and pitch-based activated carbon fiber.

3. The preparation method according to claim 1, characterized in that, The particle size of the zeolite is 0.1-1 mm.

4. The preparation method according to claim 1, characterized in that, The zeolite undergoes acid-base modification treatment before use.

5. The preparation method according to claim 1, characterized in that, In step S1, the mass of activated carbon fiber in 1 L of water is 1-20 g, and the mass of zeolite is 0.5-1 kg; the stirring time is 1-12 h.

6. The preparation method according to claim 1, characterized in that, In step S1, the drying process includes: first drying at 80-120℃ for 2-6 h, and then drying at 150-200℃ for 3-5 h under nitrogen protection until constant weight.

7. The preparation method according to claim 1, characterized in that, The protective gas is one or more of nitrogen, argon, and helium.

8. The preparation method according to claim 1, characterized in that, In step S3, the mass fraction of the chlorite solution is 30-46%, and the soaking time is 0.1-1 h.

9. The preparation method according to claim 1, characterized in that, The drying temperature is 60-100℃, and the drying time is 3-5 hours.

10. A solid slow-release agent for chlorine dioxide, characterized in that, It is prepared by the preparation method according to any one of claims 1-9.

11. The chlorine dioxide solid slow-release agent according to claim 10, characterized in that, The loading of chlorite is 15-30%.

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