Separation device and system for separating impurity ions from hypochlorous acid water

Abstract

The present invention relates to a separation apparatus or system using a separation membrane, said separation apparatus or system serving as a means for separating ions of impurities other than hypochlorous acid from an aqueous solution that is mainly composed of hypochlorous acid; and the present invention provides a solution which is mainly composed of hypochlorous acid, and which has more excellent storage stability.

Description

[Technical Field]

[0001] The present disclosure relates to a separation device or system capable of separating contaminating ions other than hypochlorous acid from an aqueous solution containing hypochlorous acid as a main component and providing an aqueous solution containing hypochlorous acid as a main component and having excellent storage stability. [Background technology]

[0002] Traditionally, sodium hypochlorite, a chlorine-based halogenated chemical, has demonstrated rapid bactericidal activity against bacteria at very low concentrations. It is also the most reliable disinfectant in terms of its effectiveness against viruses such as HIV and HBV, and has been widely used in various fields, including public health, food, and medical care, for disinfecting and sterilizing daily life. In particular, non-enveloped viruses, such as Caliciviridae viruses such as norovirus and SLV (sapovirus), and rotavirus, cannot be disinfected with alcohol disinfectants, making hypochlorous acid disinfection and sterilization the first choice. Specifically, aqueous solutions containing sodium hypochlorite are used in spray form in homes and medical settings to disinfect and sterilize various items and environments, including clothing, tableware, glass containers, and plastic containers. Powdered formulations are also used to disinfect water and sewage systems and pools. Sodium hypochlorite can also be used for hand disinfection at very low concentrations in the form of an aqueous solution or wet wipes soaked in the aqueous solution. However, an aqueous solution of sodium hypochlorite in which sodium hypochlorite salt is dissolved in water is strongly alkaline, and its diluted solution is also alkaline, so using it for hand disinfection can cause rough hands (Patent Document 1).

[0003] On the other hand, hypochlorous acid produced by electrolysis using sodium chloride or other substances is said to have bactericidal and antiviral effects more than 80 times stronger than sodium hypochlorite. However, unlike alkaline sodium hypochlorite aqueous solutions, this hypochlorous acid water is acidic and prone to corrosion of metals due to its low pH. Furthermore, under acidic conditions, the amount of chlorine ions increases, making it more likely to produce chlorine gas and hydrogen chloride gas, which causes hypochlorous acid to decompose and fall below the indicated concentration within a short period of time. Furthermore, when hydrogen chloride dissolves in water, it becomes hydrochloric acid, making the aqueous solution acidic.

[0004] In contrast to this, Patent Document 2 describes the production of hypochlorous acid water that is substantially free of contaminating ions other than hypochlorous acid, using a two-diaphragm three-compartment electrolytic cell in which an anode chamber, a cathode chamber, and an intermediate chamber that is provided between the anode chamber and the cathode chamber and contains an electrolyte are separated by diaphragms. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-229833 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-72755 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the method of Patent Document 2, when the concentration of hypochlorous acid is increased, the pH decreases, resulting in an aqueous solution with a high total amount of chloride ions, which causes a problem that the concentration of hypochlorous acid decreases during storage. In addition, when the amount of hydrogen chloride in the aqueous solution is reduced by neutralizing it with sodium hydroxide or sodium bicarbonate, the amount of undecomposed chlorides such as NaCl increases.

[0007] Therefore, an object of the present disclosure is to provide an aqueous solution containing hypochlorous acid as a main component and having better storage stability. [Means for solving the problem]

[0008] As a result of studying the above problems, the present inventors have found that contaminating ions other than hypochlorous acid can be separated from an aqueous solution containing hypochlorous acid as a main component using a separation membrane, thereby providing a more stable aqueous solution containing hypochlorous acid as a main component.

[0009] That is, the present disclosure: [1] A separation device or system using a separation membrane as a method for separating contaminating ions other than hypochlorous acid from an aqueous solution mainly composed of hypochlorous acid; [2] Add a large molecular weight alkaline substance to an aqueous solution whose main component is hypochlorous acid. (i) making the molecular weight of the chloride in said aqueous solution larger than that of hypochlorous acid, and / or (ii) Neutralizing the aqueous solution increases the size of the hydrate of the ion to be separated. The separation device or system according to [1] above, which separates using a separation membrane; [3] The separation device or system according to [1] or [2] above, wherein the degree of separation is controlled by using a charged membrane and / or a separation membrane having a predetermined pore size. [4] The separation device or system according to any one of [1] to [3] above, wherein an RO membrane, an NF membrane, and / or an UF membrane is used as the separation membrane. [5] The separation device or system according to any one of [1] to [4] above, wherein the separation membrane is made of at least one material selected from the group consisting of polymers, ceramics, and metals. [6] The separation device or system according to [5] above, wherein the polymer is at least one selected from polysulfone, polyethersulfone, polypropylene, polyethylene, triacetate, diacetate, nylon-based polymers, and PMMA (polymethyl methacrylate); [7] The separation device or system according to any one of [1] to [6] above, wherein the aqueous solution containing hypochlorous acid as a main component is produced by electrolysis or ion exchange. [8] The separation device or system according to any one of [1] to [7] above, which uses an electric field or a magnetic field to assist in separating contaminating ions other than hypochlorous acid from an aqueous solution containing hypochlorous acid as a main component; [9] The separation device or system according to any one of [3] to [6] above, which separates chlorides produced in hypochlorous acid water produced by neutralizing sodium hypochlorite with an acid, removing sodium by electrodialysis, or replacing Na ions with H ions by ion exchange. Regarding. [Effects of the Invention]

[0010] According to the present disclosure, in an aqueous solution containing hypochlorous acid as a main component, by reducing the amount of contaminating ions other than hypochlorous acid in the aqueous solution, an aqueous solution that is less likely to be deactivated and has better storage stability can be obtained, and rust on metals can be suppressed when the aqueous solution containing hypochlorous acid as a main component is sprayed into the air. DETAILED DESCRIPTION OF THE INVENTION

[0011] As used in this specification, "mainly composed of hypochlorous acid" means that hypochlorous acid is contained as a representative component other than water as a solvent, and does not mean that hypochlorous acid accounts for the majority of components or that hypochlorous acid is the most abundant component among components other than water.In contrast, conventional hypochlorous acid water contains a large amount of undecomposed sodium chloride and hydrochloric acid, which is a component of pH, and the proportion of hypochlorous acid is lower than that of the solution according to the first embodiment of the present disclosure, which will be described later.

[0012] As used herein, " contaminating ion other than hypochlorous acid " refers to the ion that is contained in other than hypochlorous acid.Specifically, the contaminating ion other than hypochlorous acid can include chlorine ion, sodium ion etc., which can be separated from the aqueous solution that is mainly composed of hypochlorous acid as it is or as other compounds.

[0013] According to the first embodiment of the present disclosure, a separation device and system are provided that separate contaminating ions other than hypochlorous acid from an aqueous solution containing hypochlorous acid as a main component using a separation membrane. By separating contaminating ions other than hypochlorous acid from the aqueous solution, it is possible to bring the pH of the aqueous solution as close to neutral as possible, and it is believed that an aqueous solution containing hypochlorous acid as a main component with excellent storage stability can be obtained. Furthermore, the aqueous solution obtained in this manner has low concerns about metal corrosion and resin deterioration.

[0014] In the aqueous solution containing hypochlorous acid as the main component according to the first embodiment, the pH of the aqueous solution after separation is preferably 4.0 or higher, more preferably 5.0 or higher, and particularly preferably 6.0 or higher, due to the separation of contaminating ions other than hypochlorous acid in the aqueous solution by the separation membrane. If the aqueous solution contains a large amount of contaminating ions, particularly chloride ions, the pH of the aqueous solution will be low, resulting in an acidic aqueous solution. If the aqueous solution is acidic, damage such as irritation and corrosion will tend to be greater.

[0015] When preparing the aqueous solution containing hypochlorous acid as the main component to be applied to the device or system according to the first embodiment, it is preferable to use pure water (e.g., RO water), purified water, ion-exchanged water, etc., in order to prevent the inclusion of unexpected components, such as metal ions and organic matter contained in tap water.

[0016] As the separation membrane used in the separation treatment, for example, a backfiltration membrane (RO membrane, NF membrane) or an ultrafiltration membrane (UF membrane) can be used.

[0017] It is preferable to use a hydrophobic membrane with a charged surface as the separation membrane. By using a membrane with a charged surface, the membrane charge acts, making it difficult for charged ionized substances in the aqueous solution to pass through the membrane, thereby increasing separation efficiency. In other words, separation is achieved by utilizing the relationship between the charge state of the substance to be separated and the charge state of the membrane used. It is also possible to generate an electric field and a magnetic field to adjust the charge on the membrane surface and increase the proportion of substances to be separated.

[0018] Furthermore, by using a separation membrane with a predetermined pore size, it is possible to select substances that pass through the membrane depending on the size of the pores in the separation membrane. The pore size of the separation membrane is not particularly limited, but is preferably 50 nm or less, more preferably 5 nm or less. Furthermore, it is preferable to use a membrane with a charged surface and a predetermined pore size as the separation membrane, which makes it possible to control the degree of separation, i.e., the degree of separation and the selection of substances to be separated.

[0019] The separation membrane may be made of known materials such as high molecular weight polymers, ceramics, and metals, either singly or in combination.

[0020] Of the materials constituting the separation membrane, at least one polymer selected from PSF (polysulfone), PES (polyethersulfone), PP (polypropylene), PE (polyethylene), CTA (triacetate), CDA (diacetate), PA (nylon-based polymer), and PMMA (polymethyl methacrylate) can be used.

[0021] The aqueous solution containing hypochlorous acid as its main component that is applied to the separation device or system according to the first embodiment is preferably electrolyzed water, and more specifically, it is preferably electrolyzed water containing hypochlorous acid as its main component that is obtained by electrolysis using hydrochloric acid or sodium chloride and potassium chloride as raw materials.

[0022] The pH of the aqueous solution containing hypochlorous acid as a main component obtained by the separation device or system according to the first embodiment is preferably 4.0 or higher, more preferably 5.0 or higher, even more preferably 5.5 or higher, and particularly preferably 6.0 or higher. By adjusting the pH of the aqueous solution containing hypochlorous acid as a main component to 4.0 or higher, corrosiveness tends to be reduced, making it suitable for a variety of applications. In particular, when using an aqueous solution containing hypochlorous acid as a main component in a humidifier or air purifier, corrosion and deterioration of components used in the device are a concern, so a pH of 5.5 or higher is preferred. By adjusting the pH to 5.5 or higher, the generation of chlorine gas (hydrogen chloride gas) can be further suppressed. Furthermore, it is preferable to adjust the pH of the aqueous solution containing hypochlorous acid as a main component to 5.5 or higher and 6.5 or lower, which reduces irritation to mucous membranes and ensures compliance with drinking water standards.

[0023] The aqueous solution containing hypochlorous acid as a main component obtained by the separation device or system according to the first embodiment has a not-too-low pH and strong bactericidal and antiviral properties, making it suitable for a variety of applications. For example, it can be widely used in various fields, such as public health, food, and medicine, for disinfecting and sterilizing daily life. It can be used effectively in homes and medical settings to disinfect and sterilize various items and environments, such as clothing, tableware, glass containers, and plastic containers, and is particularly suitable for skin cleansing and sterilization, such as hand washing (hand sterilization), and for sterilizing air. In particular, in embodiments that do not contain salt and have a not-too-low pH, there is little concern about corrosion. While tap water can cause mold and other fungi to grow in water storage tanks and disperse the bacteria, the highly bactericidal hypochlorous acid contained in the solution can maintain the hygiene of not only the device but also the air, making it preferable for use in place of tap water in humidifiers and air purifiers.

[0024] The aqueous solution containing hypochlorous acid as a main component and applicable to the separation device or system according to the first embodiment can be prepared by various methods. For example, first, electrolysis is performed in a two-diaphragm, three-compartment electrolytic cell using a sodium chloride aqueous solution as the electrolyte, and acidic hypochlorous acid water is obtained in the anode chamber. In this case, in electrolysis using sodium chloride and water, chloride ions typically migrate to the anode and sodium ions to the cathode. The migrated chloride ions react with water to produce hydrochloric acid (HCl) and hypochlorous acid (HClO), and oxygen gas is generated. At the cathode, sodium ions react with water to produce sodium hydroxide, which generates hydrogen gas. In the reaction between sodium chloride and water, the stoichiometric ratio of hypochlorous acid to hydrochloric acid is approximately 1:1 or less, as shown in the following formula. Therefore, the ratio of hypochlorous acid generated does not exceed that of hydrochloric acid. 2NaCl + H2O → 2NaOH + HCl + HClO Next, the obtained aqueous solution mainly composed of acidic hypochlorous acid is passed through a separation membrane, and the hydrochloric acid in the aqueous solution is separated, and the proportion of hypochlorous acid in the aqueous solution can be increased.By carrying out the treatment to increase the proportion of hypochlorous acid to hydrochloric acid, the pH can be shifted to neutral at the same time.In order to obtain the desired proportion of hypochlorous acid to hydrochloric acid and the desired pH, this treatment can be repeated as many times as necessary.

[0025] According to a second embodiment of the present disclosure, a separation device or system is provided that adds an alkaline substance with a large molecular weight to an aqueous solution containing hypochlorous acid as a primary component to (i) increase the molecular weight of chlorides in the solution relative to hypochlorous acid and / or (ii) neutralize the solution, thereby increasing the size of hydrates of ions to be separated (e.g., sodium ions and chloride ions), and then separates the hydrates using a separation membrane. In this second embodiment, an alkaline substance with a large molecular weight is added to the hypochlorous acid-based solution to adjust the pH to, for example, 6.0 to 6.5, and the solution is passed through a separation membrane to separate chlorides such as NaCl. The purpose of this neutralization treatment before separation is to neutralize HCl contained in the hypochlorous acid-based aqueous solution with an alkaline substance such as NaOH to convert it to NaCl, which has a larger molecular weight than HCl, thereby facilitating separation using a separation membrane. By maintaining a pH of 6.0 or higher after separation, the solution complies with drinking water standards. In the second embodiment, it is more preferable to adjust the pH of the hypochlorous acid-based aqueous solution after separation to 6.0 to 6.8. Here, various pH adjusters can be used as the alkaline substance having a large molecular weight. Specific examples include aqueous solutions of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium bicarbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate, or magnesium citrate, and among these, aqueous sodium hydroxide solutions are particularly preferred.

[0026] The aqueous solution obtained by the device or system according to the second embodiment has a pH of 5.0 to 7.0, which is neutral to slightly acidic, and is close to the pH of the skin, significantly reducing the occurrence of acid irritation and alkaline itching. Furthermore, by not leaning toward the alkaline side, the generation of trihalomethanes can also be suppressed. When sprayed indoors, the low concentrations of hydrogen chloride (HCl) and salt can minimize the impact on corrosion, particularly on electronic circuit boards. In addition to the uses of the aqueous solution according to the first embodiment, the solution can be used for a wide variety of purposes, including, for example, skin cleansing and disinfection, such as hand washing (hand disinfection), space disinfection, instrument disinfection, and bedsore disinfection.

[0027] The aqueous solution containing hypochlorous acid as a main component, obtained by the separation device or system according to the first or second embodiment of the present disclosure, can be used to cleanse, sterilize, or disinfect wounds that come into contact with blood, such as those caused by surgical or non-surgical means, or can be introduced into the lungs using a nebulizer to disinfect the lungs. Specific examples of the aqueous solution include general surgery, endoscopic surgery, robot-assisted laparoscopic surgery, oral surgery, graft surgery, implant surgery, transplant surgery, and other surgeries; cauterization, amputation, radiation, chemotherapy; burns; cuts, abrasions, scrapes, rashes, ulcers, puncture wounds, bedsores; and combinations thereof. It is preferably used for infection control, keloid prevention, and other applications.

[0028] In this specification, the matters described in the above first and second embodiments are also applicable to other embodiments as long as there is no contradiction.

[0029] Furthermore, the separation device or system described in the first and second embodiments can perform a separation process to remove the chlorides produced when hypochlorous acid water is produced by a method other than electrolysis as described above, thereby increasing the relative concentration of the hypochlorous acid. For example, hypochlorous acid water can be produced by neutralizing sodium hypochlorite by adding an acid, removing sodium from sodium hypochlorite by electrodialysis, or replacing Na ions with H ions by ion exchange of sodium hypochlorite, and the chlorides produced can be separated using a separation membrane.

[0030] Hereinafter, the present disclosure will be specifically described based on examples, but the present disclosure is not intended to be limited to these examples. In addition, the aqueous solution containing hypochlorous acid as a main component obtained in the present disclosure can be frozen and stored. [Example]

[0031] Example 1 Aqueous sodium chloride solution was used as the electrolyte and electrolyzed in a two-diaphragm, three-compartment electrolytic cell, yielding a strongly acidic hypochlorous acid solution from the anode side. The resulting strongly acidic hypochlorous acid solution was passed through an RO membrane (a polyamide RO membrane manufactured by Mitsubishi Chemical Aqua Solutions Co., Ltd.) to separate the hydrochloric acid in the solution, yielding an aqueous solution primarily composed of hypochlorous acid with an increased proportion of hypochlorous acid. The hypochlorous acid concentration of the resulting aqueous solution primarily composed of hypochlorous acid was measured using an absorption spectrophotometer (AQ-102, manufactured by Shibata Chemical Co., Ltd.). The pH was measured using a multi-water quality meter (MM-60, manufactured by DKK-TOA Corporation).

[0032] Comparative Example 1 Except for not performing separation treatment using a separation membrane (RO membrane), an aqueous solution containing hypochlorous acid as a main component was obtained in the same manner as in Example 1. The concentration of hypochlorous acid and other physical properties of the obtained aqueous solution containing hypochlorous acid as a main component were obtained in the same manner as in Example 1. The results are shown in Table 1.

[0033] [Table 1]

[0034] From Table 1, it can be seen that after membrane separation in Example 1, the pH is higher than in Comparative Example 1 and the conductivity is lower, so the relative concentration of hypochlorous acid is increased, and an aqueous solution containing hypochlorous acid as a main component and having excellent storage stability is obtained.

[0035] Example 2, Comparative Example 2 As in Example 1 and Comparative Example 1, sodium hydroxide was added to an aqueous solution containing hypochlorous acid as a main component obtained by electrolysis, and the pH was adjusted to around 5.5. In Example 2, the obtained aqueous solution was subjected to a separation treatment using an RO membrane (a cellulose membrane manufactured by Toyobo Co., Ltd.) as in Example 1 (no separation treatment was performed in Comparative Example 2). Measurements in Example 2 and Comparative Example 2 were performed in the same manner as in Example 1 and Comparative Example 1. The results are shown in Table 2.

[0036] [Table 2]

[0037] From Table 2, it can be seen that in Example 2, an increase in pH and a decrease in conductivity were confirmed compared to Comparative Example 2, and therefore the relative concentration of hypochlorous acid increased, and it was possible to obtain an aqueous solution containing hypochlorous acid as the main component, which was stable and had reduced corrosive action on metals, etc.

Claims

1. A separation device or system using a separation membrane as a method for separating contaminating ions containing at least chlorine ions other than hypochlorous acid from an aqueous solution mainly containing hypochlorous acid, The aqueous solution containing hypochlorous acid as a main component is hypochlorous acid water generated by electrolysis, An RO membrane is used as the separation membrane; and An alkaline substance selected from sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium bicarbonate, potassium bicarbonate, calcium bicarbonate, magnesium bicarbonate, sodium acetate, potassium acetate, calcium acetate, magnesium acetate, sodium citrate, potassium citrate, calcium citrate, and magnesium citrate is added to an aqueous solution containing hypochlorous acid as a main component, and the solution is separated using the separation membrane. Separation device or system.

2. 2. The separation device or system according to claim 1, wherein the degree of separation is controlled by using a charged membrane and / or a separation membrane having a predetermined pore size.

3. 3. The separation device or system according to claim 1, wherein the separation membrane is made of at least one material selected from the group consisting of high molecular weight polymers, ceramics, and metals.

4. 4. The separation device or system according to claim 3, wherein the high molecular weight polymer is at least one selected from the group consisting of polysulfone, polyethersulfone, polypropylene, polyethylene, triacetate, diacetate, nylon-based polymers, and PMMA (polymethyl methacrylate).

5. The separation device or system according to any one of claims 1 to 4, wherein an electric field or a magnetic field is used to assist in separating contaminating ions containing at least chlorine ions other than hypochlorous acid from an aqueous solution mainly containing hypochlorous acid.

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