Self-assembling gel capable of releasing gaseous disinfectant and method for producing the same

Abstract

A self-assembled gel capable of releasing a gaseous germicide, said gel comprising at least one moisture absorbing agent, at least one water absorbing agent, and at least one stable salt capable of releasing the gaseous germicide, and when sealed and stored, moisture in the air continues to release the germicide from the gel via hydrogen ions upon opening the seal.

Description

Technical Field

[0001] The present invention discloses a method for manufacturing a self-activated sustained-release bactericidal, antibacterial, and deodorizing gel and its preparation.

[0002] The growth of microorganisms is the most common cause of bad odors and allergens in the home. Prolonged exposure to bad odors can cause depression, nausea, and other mental health problems. Uncontrolled microbial growth can deteriorate household hygiene and may also cause detectable chronic diseases and discomfort. In addition to daily cleaning, gaseous disinfectants are excellent alternatives for solving the problem of microbial growth, and they may reach surfaces that are difficult to reach through the air. Aqueous chlorine dioxide has been well studied and is an effective disinfectant and is commonly used in water treatment. Gaseous chlorine dioxide is also a rapid and effective broad-spectrum disinfectant and can be used to combat biological weapons such as Bacillus anthracis. Since chlorine dioxide decomposes quickly and has a short half-life, large-scale gas use in unoccupied environments can be safely carried out with only 15 minutes of aeration, but chlorine dioxide is highly reactive, has a short half-life, and is highly toxic, which is also the reason why chlorine dioxide faces challenges in continuous disinfection. The continuous production of low-dose chlorine dioxide may be a solution to this problem. Kouji Ab et al. (US8603355B2, US20100086493A1, US8545898B[2) [1][2][3] reported that continuous generation of chlorine dioxide can be achieved by adding a pH adjuster. Then, the solution that continuously generates chlorine dioxide can be changed into various forms by blending a gelling agent or a foaming agent. However, the disadvantage of the above preparations is that it is necessary to separate chemical substances during transportation and storage. Since these components require the end user to mix the chemical substances at the final use site, it poses a work hazard to untrained workers. When the reaction starts after mixing, a large amount of chlorine dioxide is suddenly released, further endangering the end user. This invention solves this problem by generating a self-organizing, self-activating, and continuously released gaseous chlorine dioxide aerogel. It can be used to improve sanitary conditions in enclosed spaces and reduce odor problems. [Overview of the Initiative]

[0003] The present invention provides a gel that sustains the release of a gaseous disinfectant, the composition comprising at least one desiccant, at least one water absorbent, and at least one salt capable of releasing a gaseous disinfectant. An acidity regulator, i.e., a pH buffer salt, may be included in the composition to adjust the release rate of the gaseous disinfectant. This component composition should be stored in a sealed container until needed.

[0004] The specific details of this invention are as follows: A self-organizing gel capable of releasing a crystalline disinfectant, wherein the gel It comprises at least one desiccant, at least one water absorbent, and at least one stable salt capable of releasing a gaseous disinfectant, The composition consisting of the above components is stored in a sealed container. When using, the sealed container is opened, the desiccant absorbs moisture from the air, and after absorbing moisture, the desiccant dissolves a salt that releases a gaseous disinfectant. The salt that releases the gaseous disinfectant is activated by hydrogen ions in the solution and releases the disinfectant. Furthermore, the desiccant is one or more combinations selected from zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron chloride, potassium magnesium chloride, potassium carbonate, potassium phosphate, ammonium iron citrate, ammonium nitrate, potassium hydroxide, sodium hydroxide, and nanowater collection tubes. Furthermore, the water-absorbing agent is one or more combinations selected from sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene-maleic anhydride), carboxymethylcellulose, cross-linked carboxymethylcellulose, polyvinyl alcohol hydrogel, cross-linked polyethylene oxide, starch-grafted polyacrylonitrile hydrolysate, other metal-neutralized polyacrylic acid, and starch powder. Furthermore, the salts capable of releasing the gaseous disinfectant include sodium chlorite, other salts capable of inducing and releasing the gaseous disinfectant, and combinations thereof. Furthermore, it includes an acidity adjuster, a pH adjuster, a pH buffer, and / or a non-water-absorbing, inert spacer material. Furthermore, the acidity adjuster, pH adjuster, and pH buffer are one or more combinations selected from sodium citrate, citric acid, potassium dihydrogen phosphate, disodium hydrogen phosphate, disodium phosphate, sodium acetate, sodium dihydrogen phosphate, imidazole, sodium carbonate, sodium bicarbonate, sodium hydroxide, other acidic salts, and other basic salts. Furthermore, non-water-absorbing, inert spacer materials are selected from talcum powder, titanium powder, and combinations thereof. Furthermore, the gel is a single mixture, First, add a stable salt dry powder capable of releasing a gaseous disinfectant and a water absorbent and mix. Then, add a desiccant and mix. Furthermore, the gel is a single mixture, First, add and mix a stable salt dry powder capable of releasing a gaseous disinfectant, a water absorbent, an acidity adjuster, a pH adjuster, a pH buffer, and a non-water-absorbing, inert spacer material. Then, add and mix in the desiccant. Furthermore, the gel is At least the bottom layer containing a desiccant, An intermediate layer containing a stable salt capable of releasing a gaseous disinfectant, and It is divided into at least an uppermost layer containing an absorbent material, and Furthermore, the gel is At least the bottom layer containing a desiccant, An intermediate layer containing a stable salt capable of releasing a gaseous disinfectant, It is divided into at least an uppermost layer containing an absorbent, An acidity adjuster, pH adjuster, pH buffer, or non-water-absorbing, inert spacer material is added to any of the above layers. Furthermore, the gel is At least the bottom layer containing a desiccant, It is divided into an upper layer containing at least a mixture of a stable salt capable of releasing a gaseous disinfectant, an acidity regulator, a pH adjuster, a pH buffer, and a non-water-absorbing, inert spacer material.

[0005] When the sealed container is opened, the desiccant absorbs moisture from the air. The moisture is then absorbed by the desiccant, forming a hydrogel structure that simultaneously dissolves a salt or any other salt capable of releasing a gaseous disinfectant. Subsequently, the stable salt capable of releasing the gaseous disinfectant is activated by water molecules or hydrogen ions in the moisture collected by the desiccant. The balance between the desiccant's absorption and retention capacity ensures a slow, sustained release of the disinfectant by slowly supplying moisture or hydrogen ions. [Brief explanation of the drawing]

[0006] The present invention will be further described below with reference to the drawings. [Figure 1] This diagram shows an aerogel, with (a) the complete structure formed before moisture absorption and (b) the complete structure formed after moisture absorption. [Figure 2] (a) Examples of single-compound gels, (b) layer-by-layer composite gels, and (c) and (d) combinations of both preparation methods are shown. [Figure 3] This shows the duration of continuous release of the gel sample. [Figure 4] A schematic diagram of the sterilization testing apparatus is shown. [Modes for carrying out the invention]

[0007] This invention describes a self-assembling gel that releases a gaseous disinfectant. This invention allows for safe storage without activating the gel form until the sealed container is opened and moisture in the air is used as a reaction trigger, by adding dry chemicals to isolate them from moisture during transport and storage, and by introducing water into the system via a hygroscopic compound. While this invention describes a system that generates chlorine dioxide using sodium chlorite, this system is not limited to other biocides that can be activated with water or hydrogen ions.

[0008] Chlorine dioxide is a gaseous disinfectant that is effective against viruses [4] For bacteria, 0.05 ppm, [5] It is effective against [the target] at a low dose of 0.01 ppm. Chlorine dioxide exists in the form of a stable sodium chlorite salt and is activated to become chlorine dioxide gas by the following chemical reaction. 5NaClO2 + 4H + → 4ClO2 + 2H2O + 5NaCl Therefore, by controlling the supply of hydrogen ions, the release of gaseous chlorine dioxide can be controlled.

[0009] In this invention, the supply of hydrogen ions is controlled by first eliminating water within the system. Without moisture, the acidic and alkaline salts cannot ionize and provide hydrogen ions, preventing the activation of sodium chlorite, thus enabling safe storage and transport. (See Figure 1(a).) When using, the sealed container is opened, and the desiccant absorbs moisture from the air, activating the sodium chlorite and generating chlorine dioxide. Simultaneously, the absorbed moisture is absorbed by the water-absorbing agent, further hindering the supply of water to the sodium chlorite to activate chlorine dioxide generation, and forming a hydrogel structure. Once moisture is absorbed, the hydrogel structure expands and hardens, ensuring the structural integrity of the system and allowing it to remain fixed in the container even when inverted. (See Figure 1(b).)

[0010] The desiccant is the main reaction initiator of the chain reaction system. The moisture absorption rate from humid air can be controlled using one or more desiccants. The one or more desiccants can be selected from zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron(III) chloride, magnesium potassium chloride, potassium carbonate, potassium phosphate, ammonium iron citrate, ammonium nitrate, potassium hydroxide, sodium hydroxide, nano water collectors [6] , other metal nitrates, other metal chlorides, their anhydrous and hydrated forms, and any combination thereof.

[0011] When moisture is absorbed from the air, the absorbed water is retained by the absorbent or dissolves other substances in the system. The water absorbent is used to slow down the reaction rate of system activation and form a hydrogel to ensure the structural integrity of the system. The one or more water absorbents can be selected from the following substances: sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene - maleic anhydride), carboxymethyl cellulose, cross - linked carboxymethyl cellulose, polyvinyl alcohol hydrogel, cross - linked polyethylene oxide, starch - grafted polyacrylonitrile hydrolyzate, other metal - neutralized polyacrylic acid, starch powder.

[0012] Other components (such as pH adjusters and inert powders that do not absorb water) can be added to the system to further prevent the activation of sodium chlorite.

[0013] The gel can be prepared as a single mixture as shown in Figure 2(a), a layer - by - layer composite material as shown in Figure 2(b), or a water absorbent that combines both as shown in Figure 2(c), or, as shown in Figure 2(d), use a single mixture as the upper layer of the gel. Although a single mixture can already form a functional gel, it has been found that the layer - by - layer composite material is more excellent in terms of storage stability and sustained release.

[0014] When preparing a single-component gel, first, a stable salt capable of releasing a gaseous bactericide, a water absorbent, a pH adjuster (if present), and an inert spacer material (if present) are uniformly mixed, and then the desiccant is added and mixed uniformly. The desiccant must be added last, as adding it once can trigger a chain reaction and cause premature reactions. Examples 1 to 9 are examples of single-component mixtures prepared according to the above method.

[0015] When preparing a multilayer composite gel, it is necessary to place a desiccant at the bottom layer, a stable salt capable of releasing a gaseous disinfectant in the middle layer, and a water-absorbing agent at the top layer so that moisture can be removed from the entire system before use. If a pH adjuster is added, it can be incorporated into the lower or middle layer. If an inert spacer material is added, it can be mixed into the base layer or middle layer, or mixed between the base layer and the middle layer. To increase structural strength, a water-absorbing layer can also be added between the stable salt capable of releasing a gaseous disinfectant and the desiccant. Examples 10 to 12 are examples of four-layer multilayer composite gels prepared according to the above method.

[0016] The performance of the gel can be evaluated by its sustained release time. After opening the screw cap and exposing the gel to air, the bottle is held upright, and the gel is allowed to form a rigid structure within a certain time. In Examples 1 to 9, a rigid structure was obtained after 1 day. In Examples 10 to 13, a rigid structure was obtained after 3 days. Whether the formation of a rigid structure was successful was determined by inverting the bottle and confirming that the contents of the gel did not fall out within 1 minute. Once a rigid structure was obtained, the bottle was kept inverted throughout the observation period so that the chlorine dioxide gas, which is denser than air, could escape immediately.

[0017] Next, the presence of chlorine dioxide was measured using an ATI Porta Sens II gas detector and a 00-1004 probe. The gas detector was set to have a minimum detection limit of 0.01 ppm for chlorine dioxide. The detector inlet was located directly below the mouth of the container, and the number of days on which the detector detected chlorine dioxide was recorded.

[0018] Referring to Figure 3, the sustained release times of Examples 1 to 8 are compared. Comparing Example 1 with Examples 2 and 5, it can be seen that reducing the desiccant does not increase the sustained release time of the gaseous disinfectant. This is because, according to formulation method 1, if there is enough moisture to initiate the reaction, moisture is also generated throughout the entire activation process of sodium chlorite. Therefore, reducing or increasing the desiccant does not extend the duration of the gel.

[0019] Comparing Example 1 and Example 4, the results show that doubling the amount of gaseous disinfectant (i.e., sodium chlorite) can extend the durability of the gel to some extent and increase its consumption time. Comparing Example 1 with Examples 3, 6, 7, 8, and 9, it can be clearly observed that the more alkali salts present, i.e., the higher the pH, the longer the gel lasts. On the other hand, Example 9, which contained only alkali salts, achieved a maximum duration of 20 days compared to the previous examples.

[0020] Therefore, the release rate and duration of the disinfectant from the gel can be precisely controlled by selecting the content of different acidic and / or alkaline salts and the amount of gaseous disinfectant to be added.

[0021] Examples 10 to 12 were prepared in multilayer form, with their formulations similar to those of Example 9. The durability of all multilayer gels was significantly improved compared to the single-compound gels, extending by 33% from 3 weeks to 4 weeks. This is because, since the hygroscopic agent is separated from the stable salt that can release the gaseous disinfectant, water needs to travel a longer path to reach the disinfectant layer in order to fully initiate the activation of sodium chlorite. Another advantage of multilayer gels is that structural integrity is strongest in the outermost layer, providing the strongest support by ensuring that the outermost layer is absorbent.

[0022] According to research by Morin et al., chlorine dioxide at a concentration of 0.01 ppm can kill bacteria within 2-3 hours. [4]It can kill. Since the minimum detection value of the chlorine dioxide detector used for data collection in Figure 2 is 0.01 ppm, the gel sample in Figure 2 was able to kill bacteria throughout the entire release process. To evaluate whether the aerogel could be stored before activation and its performance after storage, Examples 13 to 17 were stored at room temperature for 36 days. Compared to Figure 2, the gel release time was longer. To prevent moisture from entering and activating the system, tightly close the bottle cap immediately after adding the material. After storage, remove the cap and allow sufficient time for air to circulate and activate the system (to release any chlorine dioxide that may have accumulated during storage).

[0023] After aeration and activation, the gels were placed individually in 35L airtight containers. A chlorine dioxide detector and agar plates pre-coated with E. coli were also placed in the containers to monitor chlorine dioxide levels and perform sterilization tests. For control, empty bottles were placed in the control container instead of aerogels.

[0024] Referring to Figure 4, after closing and sealing the container, leave the system for 10 minutes. Next, open the system again, remove the agar plate, and stop sterilization. Before turning on the system, record the chlorine dioxide concentration data. Then, incubate the agar plate for 1 day and count the following day.

[0025] Table 1 shows that Examples 13 to 17 are storable and can still achieve high bactericidal activity after activation. Example 17 also shows that the concentration of released chlorine dioxide can be controlled to a safe level (>0.3 ppm STEL and >0.1 ppm TWA) while maintaining a high sterilization rate. [Examples]

[0026] Example 1 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 2 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (0.5 g) was added to the mixture and further mixed using a vortex apparatus. Example 3 First, sodium polyacrylate (0.4 g), citric acid (0.5 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 4 First, sodium polyacrylate (0.4 g), citric acid (1 g), and sodium chlorite (3 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 5 First, sodium polyacrylate (0.8 g), citric acid (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 6 First, sodium polyacrylate (0.4 g), citric acid (0.32 g), sodium citrate dihydrate (0.68 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 7 First, sodium polyacrylate (0.4 g), citric acid (0.21 g), sodium citrate dihydrate (0.78 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 8 First, sodium polyacrylate (0.4 g), citric acid (0.12 g), sodium citrate dihydrate (0.88 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 9 First, sodium polyacrylate (0.4 g), sodium citrate dihydrate (1 g), and sodium chlorite (1.5 g) were mixed using a vortex apparatus. Next, copper nitrate trihydrate (1 g) was added to the mixture and further mixed using a vortex apparatus. Example 10 First, a pre-mixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Next, another pre-mixed mixture of sodium chlorite (1.5 g) and sodium polyacrylate (0.4 g) was added to the system as the second layer. Example 11 First, copper nitrate trihydrate (1 g) was added to the system as the bottom layer. Next, another pre-mixed mixture of sodium chlorite (1.5 g) and sodium citrate dihydrate (1 g) was added to the system as the second layer. Then, sodium polyacrylate (0.4 g) was added to the system as the top layer. Example 12 First, a pre-mixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Next, sodium polyacrylate (0.4 g) was added to the system as an intermediate layer. Then, a pre-mixed mixture of sodium chlorite (1.5 g) and sodium citrate dihydrate (1 g) was added to the system as the third layer. Finally, another layer of sodium polyacrylate (0.2 g) was added to the system as the top layer. Example 13 First, a pre-mixed mixture of copper nitrate trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Next, sodium chlorite (1.5 g) was added to the system as the second layer. After that, sodium polyacrylate (0.4 g) was added to the system as both the third and top layers. Example 14 First, a pre-mixed mixture of copper chloride trihydrate (1 g) and sodium citrate dihydrate (1 g) was added to the system as the bottom layer. Next, sodium chlorite (1.5 g) was added to the system as the second layer. Subsequently, sodium polyacrylate (0.4 g) was added to the system as both the third and top layers. Example 15 First, a pre-mixed mixture of copper chloride trihydrate (1g) and sodium bicarbonate (1g) was added to the system as the bottom layer. Next, sodium chlorite (1.5g) was added to the system as the second layer. Subsequently, sodium polyacrylate (0.4g) was added to the system as both the third and top layers. Example 16 First, a pre-mixed mixture of anhydrous copper chloride (1g) and sodium bicarbonate (1g) was added to the system as the bottom layer. Next, sodium chlorite (1.5g) was added to the system as the second layer. After that, sodium polyacrylate (0.4g) was added to the system as both the third and top layers. Example 17 First, a pre-mixed mixture of copper nitrate trihydrate (1g) and sodium bicarbonate (1g) was added to the system as the bottom layer. Next, sodium chlorite (1.5g) was added to the system as the second layer. Subsequently, sodium polyacrylate (0.4g) was added to the system as both the third and top layers.

[0027] References [1] K. Abe, "Composition for stabilizing chlorine dioxide", U.S. Patent US8603355B2, March 15, 2007. [2] K. Abe, "Pure Chlorine Dioxide Solution and Gel and Foaming Compositions Containing the Solution", U.S. Patent Application US20100086493A, March 15, 2007. [3] KATSToshiaki Fukuda, "Broad-spectrum antiviral composition with excellent storage stability", U.S. Patent US8545898B2, February 16, 2007. [4] TFTMTSHMorino, "Effects of low-concentration chlorine dioxide gas on bacteria and viruses on glass surfaces in humid environments", Journal of Applied Microbiology Letter, vol. 53, no. 6, pp. 628-634, 2011. [5] MFTMaTSHirofumiMorino, "Effects of very low concentrations of gaseous chlorine dioxide on Escherichia coli, Pseudomonas aeruginosa and Acinetobacter baumannii on the surface of a wet glass dish", BMCResNotes, Vol13, 2020. [6] L. Yingjian, "Water Extraction from Air Using Entrapped Titanium Dioxide Nanotubes", Hong Kong, Hong Kong University of Science and Technology, 2020.

Claims

1. A self-organizing gel capable of releasing a gaseous disinfectant, The aforementioned gel is The bottom layer contains a desiccant, An intermediate layer containing salt that can release a gaseous disinfectant, The top layer containing the water-absorbing agent, It is a multilayer gel containing, The gel is stored in a sealed container. The gel is characterized in that, when the sealed container is opened, a desiccant absorbs moisture from the air, and after the desiccant absorbs moisture, a salt capable of releasing a gaseous disinfectant is dissolved, and the salt capable of releasing a gaseous disinfectant is activated by hydrogen ions in the solution and releases the disinfectant.

2. The gel according to claim 1, characterized in that the desiccant is one or more combinations selected from zinc nitrate, copper nitrate, calcium chloride, magnesium chloride, zinc chloride, iron chloride, magnesium chloride-potassium chloride, potassium carbonate, potassium phosphate, ammonium iron citrate, ammonium nitrate, potassium hydroxide, and sodium hydroxide.

3. The gel according to claim 1, characterized in that the water-absorbing agent is one or more combinations selected from sodium polyacrylate, potassium polyacrylate, polyacrylamide copolymer, poly(ethylene-maleic anhydride), carboxymethylcellulose, cross-linked carboxymethylcellulose, polyvinyl alcohol hydrogel, cross-linked polyethylene oxide, starch-grafted polyacrylonitrile hydrolysate, other metal-neutralized polyacrylic acid, and starch powder.

4. The gel according to claim 1, characterized in that the salt capable of releasing the gaseous disinfectant is sodium chlorite, other salts capable of inducing and releasing the gaseous disinfectant, and combinations thereof.

5. The gel according to claim 1, further comprising an acidity adjuster, a pH adjuster, a pH buffer and / or a non-water-absorbing inert spacer material.

6. The gel according to claim 5, characterized in that the acidity adjuster, pH adjuster, and pH buffer are one or more combinations selected from sodium citrate, citric acid, potassium dihydrogen phosphate, disodium hydrogen phosphate, disodium phosphate, sodium acetate, sodium dihydrogen phosphate, imidazole, sodium carbonate, sodium bicarbonate, sodium hydroxide, other acidic salts, and other basic salts.

7. The gel according to claim 5, characterized in that the non-water-absorbing, inert spacer material is selected from talc powder, titanium powder, and combinations thereof.

8. The gel according to claim 5, A gel characterized in that an acidity adjuster, a pH adjuster, a pH buffer, and a non-water-absorbing, inert spacer material are included in any of the bottom layer, the middle layer, and the top layer.

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