Method and device for producing hydrogen peroxide solution

Abstract

Generates hydrogen peroxide without lowering the pH. [Solution] The hydrogen peroxide generator stores water in a glass water storage container 11, inside which a submerged electrode 15 is attached. Additionally, an air electrode 14 made of a tungsten rod with a diameter of approximately 1 mm is attached at a position a height H above the surface of the water 12. The air electrode 14 is enclosed within a cylindrical glass sealed container 13, thereby forming an enclosed space V around the air electrode 14. When a voltage is applied from an AC power source 16 to the air electrode 14 and the submerged electrode 15, plasma P is generated in the enclosed space V, and hydrogen peroxide is generated by this action. Because the air electrode 14 is covered by the sealed container 13, the generation of nitrate ions by nitrogen molecules in the air during the generation of hydrogen peroxide can be suppressed, making it possible to generate hydrogen peroxide water while suppressing a decrease in pH.

Description

[Technical Field]

[0001] The present invention relates to a technique for producing aqueous hydrogen peroxide without causing a decrease in pH. [Background technology]

[0002] Hydrogen peroxide is used for a variety of purposes, including disinfecting wounds, sterilizing objects, and oxidizing pollutants and industrial wastewater, so there is a growing demand for it to be easily produced. Conventionally, hydrogen peroxide has been produced industrially using anthraquinone, as well as by reacting plasma with water. For example, Patent Document 1 discloses a method of producing hydrogen peroxide by discharging an inert gas to generate plasma and injecting it into water. Patent Document 2 discloses a method of producing hydrogen peroxide by introducing water vapor into a flow pipe together with a carrier gas such as an inert gas, and irradiating the pipe with ultraviolet light to generate plasma. The plasma method has the advantage that it can be produced without requiring large-scale facilities, as compared to industrial production methods. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2018 / 37467 publication [Patent Document 2] Japanese Patent Application Publication No. 2019-135204 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when plasma is applied to water in an air atmosphere, nitrate ions are generated from nitrogen molecules in the air, which causes a problem of lowering the pH of the resulting hydrogen peroxide solution. Depending on its use, acidic hydrogen peroxide solution with a lowered pH may cause skin irritation or burns. To prevent the pH from dropping, it is possible to use plasma in an inert gas atmosphere instead of air, but this method requires the preparation of an inert gas and a mechanism for supplying it, making it undesirable from the perspective of easily generating hydrogen peroxide. In view of the above problem, an object of the present invention is to provide a technique for generating aqueous hydrogen peroxide without affecting the pH. [Means for solving the problem]

[0005] The present invention provides A method for producing hydrogen peroxide solution, comprising: (a) providing water; (b) providing a submerged electrode in the water; (c) providing an air electrode at a position spaced apart from the surface of the water; (d) sealing the part of the water surface and the air electrode with an insulating sealed container; (e) applying a voltage between the submerged electrode and the air electrode to generate plasma.

[0006] According to the present invention, plasma can be generated by applying a voltage between the submerged electrode and the air-borne electrode, and hydrogen peroxide solution can be produced by the action of the plasma on water. In this invention, the air-borne electrode is covered with a sealed container, and after the air in the sealed container is decomposed and eliminated by the plasma discharge, the water evaporates, and the inside of the sealed container becomes gaseous water plasma. In other words, nitrogen molecules have almost no effect, making it possible to produce hydrogen peroxide solution while suppressing a decrease in pH.

[0007] The present invention does not exclude purging the sealed container with an inert gas or the like. However, the significance of the present invention lies in the discovery that, if the area around the air electrode is sealed, even if nitrogen molecules remain in the air at the beginning of generation, their effect on the pH of the hydrogen peroxide solution is very small, and that hydrogen peroxide solution can be generated through plasma generation without constant purging with an inert gas. Therefore, if there is an advantage to purging with an inert gas, it is that it can also remove nitrogen molecules remaining in the sealed container at the beginning of generation. At least once hydrogen peroxide solution generation has begun, there is no need to introduce an inert gas into the sealed container.

[0008] It is also possible to avoid the effects of nitrogen molecules and suppress the decrease in pH by placing an air electrode in water and using plasma in the water. However, this method requires the generation of a discharge due to the dielectric breakdown of the water, which requires the application of a very high voltage. In contrast, the present invention has the advantage that a lower voltage is required compared to the above method because it uses an air electrode.

[0009] In addition to the embodiment of a method for producing hydrogen peroxide solution, the present invention also provides: A hydrogen peroxide water generating device for generating hydrogen peroxide water, A water storage container; a submerged electrode attached at a position that will be in the water when the water is stored; an air electrode attached at a position that should be separated from the water surface when the water is stored; an insulating sealed container that seals a portion of the water surface and the periphery of the air electrode when water is stored; The hydrogen peroxide generating device may also include a power supply that applies a voltage between the submerged electrode and the air electrode to generate plasma.

[0010] According to the hydrogen peroxide generating device of the present invention, as described above in the method for generating hydrogen peroxide, plasma can be generated in a sealed state around the air electrode, and hydrogen peroxide can be generated.

[0011] In the hydrogen peroxide generating device of the present invention, The sealed container may be made of glass.

[0012] In the process of generating hydrogen peroxide solution, the inside of the sealed container becomes very hot due to the generation of plasma, but glass has excellent heat resistance and can prevent the container from deforming. Another advantage is that the glass is transparent, allowing you to see what is happening inside the sealed container. However, the sealed container does not have to be made of glass, and various materials can be used that are insulating materials that do not allow gas to pass through and have heat resistance sufficient to withstand the heat generated by plasma generation. For example, in addition to glass such as quartz, various materials can be used, such as ceramics, heat-resistant resins, and metals.

[0013] The shape and dimensions of the sealed container can also be determined arbitrarily. However, since the present invention assumes that the amount of nitrogen molecules remaining in the sealed container at the beginning of production is small enough not to affect the pH of the hydrogen peroxide solution, it is preferable that the volume of the sealed container is sufficiently small compared to the volume of water stored in the water storage container. From this perspective, the volume of the sealed container is preferably 10% or less of the volume of the water, more preferably 5% or less, or even 1% or less. The shape of the sealed container can be determined arbitrarily, but from the viewpoint of isotropy, it is preferable that the side surface is cylindrical and that the air electrode is disposed at the center.

[0014] In the hydrogen peroxide generating device of the present invention, The air electrode can be made of a metal rod with a diameter of about 1 mm.

[0015] The shape of the air electrode can be determined arbitrarily, but using a relatively thin metal rod has the advantage of making it easier to generate plasma. However, 1 mm is just one example, and various dimensions that can generate plasma can be selected depending on the electrode conductivity, the applied voltage, the distance between the air electrode and the water surface, etc.

[0016] In the hydrogen peroxide generating device of the present invention, The air electrode may be made of one or more of tungsten, copper, gold, platinum, and molybdenum.

[0017] The air electrode can be made of various materials that have conductivity that allows plasma to be generated and a high melting point that does not cause melting due to the generation of plasma. The materials mentioned above are examples of materials that meet these requirements. Materials other than those mentioned above are not excluded.

[0018] Various shapes, sizes, and materials can also be used for the submerged electrodes, which may be the same as or different from the air-borne electrodes.

[0019] The present invention does not necessarily have to include all of the above-described features, and some of them may be omitted or combined as appropriate. The various features described for the hydrogen peroxide generating device can also be applied to the hydrogen peroxide generating method. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating the configuration of a hydrogen peroxide water generating device. DETAILED DESCRIPTION OF THE INVENTION

[0021] An embodiment of the present invention will be described below. 1 is an explanatory diagram showing a schematic configuration of an apparatus for generating hydrogen peroxide solution according to an embodiment of the present invention, which generates hydrogen peroxide solution by applying plasma to water.

[0022] The hydrogen peroxide generator has a water storage container 11 for storing water. The water storage container 11 can be made of various materials such as glass, resin, and metal, as long as it does not leak water and does not leach out of the material, and the shape can also be determined arbitrarily. In this example, a cylindrical glass container was used. Approximately 1 liter of water 12 is stored inside the water storage container 11.

[0023] A submerged electrode 15 is attached inside the water storage container 11 so as to be submerged in the water 12. In this example, a tungsten rod with a diameter of approximately 3 mm is used as the submerged electrode 15. Various metals such as copper, gold, platinum, and molybdenum can be used for the submerged electrode 15 as long as they are conductive and do not leach out of the material. The shape and dimensions can also be determined as desired. The submerged electrode 15 may be insulated so that the part protruding into the air does not conduct electricity.

[0024] An air electrode 14 is attached at a position a height H above the water surface of the water 12. In this embodiment, a tungsten rod with a diameter of about 1 mm is used as the air electrode 14. Various metals such as copper, gold, platinum, and molybdenum can be used for the air electrode 14 as long as they are conductive and do not leach out of the material. The shape and dimensions can also be determined arbitrarily. From the viewpoint of lowering the discharge voltage and making it easier to generate plasma, it is preferable that the air electrode 14 be a thin metal rod, and from this viewpoint the air electrode 14 is thinner than the underwater electrode 15. The height H of the air electrode 14 from the water surface can be determined arbitrarily, but in this embodiment it was set to about 5 mm.

[0025] The air electrode 14 is surrounded by a sealed container 13. In this embodiment, the sealed container 13 is made of glass, but various materials can be used as long as they are insulating materials that do not allow gas to pass through and have heat resistance sufficient to withstand the heat generated by plasma generation. For example, in addition to glass such as quartz, various materials can be used, such as ceramics, heat-resistant resins, and metals. The gap between the sealed container 13 and the air electrode 14 is sealed with glasswork, a sealing member, an adhesive, etc. As a result, a sealed space V is formed around the air electrode 14 by the sealed container 13 and the water surface.

[0026] The sealed container 13 has a cylindrical shape with an outer diameter d of 10 mm, an inner diameter of 8 mm, and a height h of 140 mm. The volume of the sealed container 13 is approximately 7 cc, which is approximately 0.7% of the 1 liter volume of the water 12. The shape and dimensions of the sealed container 13 can be determined arbitrarily, but it is preferable that the volume is sufficiently smaller than the volume of the water 12; for example, it is preferable that it is 10% or less, and more preferably 5% or less, or 1% or less.

[0027] The air electrode 14 and the underwater electrode 15 are connected to a power source 16. When a sufficient voltage is applied between the air electrode 14 and the underwater electrode 15 by the power source 16, a plasma P is generated in the enclosed space V. The power supply 16 can be a DC power supply, a pulse power supply, a low-frequency or high-frequency AC power supply, a microwave power supply, or any other power supply. In this embodiment, an inverter-type neon transformer with a 50 Hz or 60 Hz AC power supply as its primary voltage was used because it is relatively inexpensive and can easily provide high voltage. A wound neon transformer or other transformers may also be used. If sufficient voltage can be obtained from the AC power supply, the transformer may be omitted.

[0028] In the hydrogen peroxide generator described above, when power is applied to power source 16, plasma P is generated in sealed space V, and hydrogen peroxide is generated by this action. In the hydrogen peroxide generator of the embodiment, air electrode 14 is covered by sealed container 13, so after the air in sealed container 13 is decomposed and eliminated by plasma discharge, water 12 evaporates and the inside of sealed container 13 becomes gaseous water plasma. In other words, nitrogen molecules have almost no effect, making it possible to generate hydrogen peroxide while suppressing a decrease in pH.

[0029] Next, we will explain the results of hydrogen peroxide generation using the hydrogen peroxide generator of this example. An inverter-type neon transformer with a primary AC voltage of 80 V was used as the power source 16, and the pH and hydrogen peroxide concentration were measured over time. The hydrogen peroxide concentration was evaluated using a spectrophotometric method (Tokai Technical Center, a general incorporated foundation) that uses color development by adding a titanium compound. Hydrogen peroxide generation was also confirmed using a Pack Test Model WAH-H2O2 manufactured by Kyoritsu Scientific Research Institute, Ltd. The comparative example shows the measurement results when no sealed container 13 was used and current was passed through the air electrode 14 in a state where it was open to the atmosphere. The results of the above measurements are shown in Table 1.

[0030] [Table 1]

[0031] As shown in the examples in Table 1, the concentration of hydrogen peroxide increases with increasing current application time, confirming that hydrogen peroxide is being continuously generated. Accordingly, the pH only fluctuates slightly from 7.3 to 7.0, and it was confirmed that the hydrogen peroxide solution remains nearly neutral. On the other hand, in the comparative example, it was confirmed that hydrogen peroxide was produced after 60 minutes of current application. However, the amount produced was only about 70% of that in the example, which also required 60 minutes of current application. In addition, the pH dropped to 4.3, confirming that the produced hydrogen peroxide solution was weakly acidic.

[0032] The above experimental results confirmed that the hydrogen peroxide generation method using the hydrogen peroxide generation device of this embodiment can continuously generate hydrogen peroxide by applying electricity, without any significant change in pH. It was also confirmed that the efficiency of hydrogen peroxide generation is improved compared to when electricity is applied while the air electrode 14 is open to the atmosphere.

[0033] The various features described in the embodiments do not necessarily need to be provided in their entirety, and some of them may be omitted or combined as appropriate. The present invention can be configured in various modified forms in addition to those described in the embodiments. The hydrogen peroxide water generating device and hydrogen peroxide water generating method of the present invention may be incorporated into various hydrogen peroxide utilization devices and utilization methods. [Industrial Applicability]

[0034] The present invention can be used to generate aqueous hydrogen peroxide without causing a decrease in pH. [Explanation of symbols]

[0035] 11 Water storage container 12 water 13 Airtight containers 14 Air electrode 15 Submerged electrode 15 Underwater electrode 16 Power supply

Claims

1. A method for producing hydrogen peroxide solution, comprising: (a) providing water; (b) providing a submerged electrode in the water; (c) providing an air electrode at a position spaced apart from the surface of the water; (d) sealing the part of the water surface and the air electrode with an insulating sealed container; (e) A method for generating hydrogen peroxide solution, comprising the step of applying a voltage between the liquid electrode and the air electrode to generate plasma.

2. A hydrogen peroxide water generating device for generating hydrogen peroxide water, A water storage container; a submerged electrode attached at a position that will be in the water when the water is stored; an air electrode attached at a position that should be separated from the water surface when the water is stored; an insulating sealed container that seals a portion of the water surface and the periphery of the air electrode when water is stored; A hydrogen peroxide generating device comprising a power supply that applies a voltage between the submerged electrode and the air electrode to generate plasma.

3. 3. The hydrogen peroxide generating device according to claim 2, wherein the sealed container is made of glass.

4. 3. The hydrogen peroxide generating device according to claim 2, wherein the air electrode is made of a metal rod having a diameter of about 1 mm.

5. 3. The hydrogen peroxide generating device according to claim 2, wherein the air electrode is made of one or more of tungsten, copper, gold, platinum, and molybdenum.

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