Active oxygen and preparation method and application thereof

Abstract

The invention relates to active oxygen and a preparation method and application thereof, and the preparation method comprises the following steps: introducing fine bubbles into an alkaline solution, then putting a three-electrode system into the alkaline solution into which the fine bubbles are introduced, and electrifying the three-electrode system to obtain the active oxygen. According to the active oxygen preparation method provided by the invention, the alkaline solution is used as an alkaline medium, fine bubbles are added into the alkaline solution, and a three-electrode system is introduced for electrifying, so that the reaction efficiency of electrolyzed water in the system can be enhanced, and meanwhile, the hydrogen evolution reaction in the electrolysis system is reduced; and the concentration and uniformity of dissolved oxygen in the electrolytic medium are improved, so that the specific active oxygen with high concentration and good stability is prepared, the used raw materials are low in cost, the process is simple, and large-scale application of the active oxygen is facilitated.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to active oxygen and a preparation method and application thereof. Background Art

[0002] Reactive oxygen species (ROS) refer to a class of oxygen-containing chemicals that are highly chemically reactive. They include hydrogen peroxide (H2O2), hydrogen peroxide ions (HO2 - ), superoxide anion (·O2 - ), hydroxyl radical (·OH), etc. Reactive oxygen species have high oxidizing properties and are easy to react with other molecules in chemical reactions, leading to a series of biochemical reactions. Therefore, they are often used in the removal of difficult-to-degrade pollutants, oxidation of heavy metal ions, and dissociation of low-valent metal minerals.

[0003] However, since the existence time of active oxygen under natural conditions is extremely short, it is necessary to continuously supplement chemical reagents or adopt specific means to maintain the active oxygen concentration at a high level. Common active oxygen regulation methods include Fenton / Fenton-like method and photocatalysis method. For example, CN118702234A discloses an electric-Fenton system of an electrically responsive cyclic catalytic electrode and a water treatment method thereof, wherein hydrogen peroxide is produced in situ by a hydrogen peroxide-producing cathode, and the circulating catalytic cathode is used as an electric-Fenton after power is turned on to continuously activate hydrogen peroxide to produce active oxygen species. CN113181060A discloses a composite nanomaterial with a sterilization effect, a preparation method and an application thereof, wherein a sonosensitizer is loaded after the mesoporous nanomaterial is amino-modified, and the surface is coated with divalent or / and trivalent iron ions. In the presence of hydrogen peroxide, a Fenton reaction occurs to produce active oxygen (ROS) to exert a bactericidal effect. CN107033886A discloses a fluorescent carbon dot with dual functions of catalysis and indication, and its preparation method and application. The fluorescent carbon dot has good fluorescence performance, good photostability and high quantum yield, can catalytically degrade hydrogen peroxide to produce active oxygen (·OH), and can monitor the level of active oxygen produced by the fluorescence change of the carbon dot. However, the concentration of active oxygen produced by the above-mentioned Fenton / Fenton-like method and photocatalysis method is low, and there are many problems such as consuming a large amount of chemical reagents and needing to prepare specific functional materials.

[0004] In the process of electrochemical generation of reactive oxygen, a large amount of hydrogen and oxygen are mainly produced through the electrolysis of water. Among them, the reduction or oxidation reaction of oxygen can generate a variety of reactive oxygen species (ROS). However, due to the large number of side reactions in the electrolysis process, specific catalysts are required, such as ruthenium oxide, platinum, gold, palladium and other materials. These materials can adjust the overpotential in the process of electrochemical oxygen production and reduce the occurrence of side reactions such as hydrogen evolution. However, these precious metals are expensive and have the risk of dissolution in strong acid or high temperature and high pressure environments, making them difficult to use on a large scale.

[0005] Therefore, providing a preparation method that can simultaneously have the advantages of simple process, low cost and ensure that the obtained active oxygen has a high concentration has become an urgent problem to be solved. Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide an active oxygen and a preparation method and application thereof. The preparation method of active oxygen provided by the present invention can prepare a specific type of active oxygen with high concentration and good stability by using an alkaline solution as an alkaline medium, adding fine bubbles to the alkaline solution, and combining the process of introducing a three-electrode system for power supply. The raw materials used are low in cost, the process is simple, and it is conducive to the large-scale application of active oxygen.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing active oxygen, the preparation method comprising the following steps:

[0009] Fine bubbles are introduced into an alkaline solution, and then a three-electrode system is placed in the alkaline solution after the fine bubbles are introduced, and the three-electrode system is energized to obtain the active oxygen.

[0010] In the present invention, the "fine bubbles" refer to bubbles having a diameter of 200 μm or less.

[0011] The method for preparing active oxygen provided by the present invention applies an appropriate oxidation / reduction potential to an alkaline solution into which fine bubbles are introduced through a three-electrode system, so that dissolved oxygen molecules, hydroxide ions, water molecules and other substances near the electrodes undergo electron transfer, thereby generating specific active oxygen species. The alkaline solution is used as a medium, and the strong tendency of hydroxide ions in the alkaline medium to release electrons and the high conductivity of the alkaline solution are utilized to enhance the reaction efficiency of water electrolysis in the three-electrode system, reduce the occurrence of hydrogen evolution reaction in the electrolysis system, and improve the selectivity of the oxidation reaction. At the same time, the alkaline environment also helps to stabilize the active oxygen of the oxidation reaction, superoxide anion (·O2 -) and other active oxygen species can also be used as intermediates for further reactions to produce other active oxygen species. Secondly, the addition of fine bubbles in the alkaline solution is intended to increase the concentration of dissolved oxygen in the three-electrode electrolytic medium, and provide sufficient raw materials for the subsequent three-electrode system to electrolyze water to generate active oxygen. In addition, the turbulence and mixing effects formed by the fine bubbles in the solution enhance the diffusion of dissolved oxygen. The efficient mixing and bubble dispersion allow oxygen to be quickly and evenly distributed in the liquid, avoiding problems such as insufficient dissolved oxygen content caused by the low efficiency of the three-electrode system to electrolyze water. Furthermore, the preparation method provided by the present invention does not require the addition of specific functional materials and precious metal catalysts, can reduce the preparation cost of active oxygen, and the process used is simple, which is conducive to the large-scale preparation of active oxygen.

[0012] The method for preparing active oxygen provided by the present invention uses an alkaline solution as an alkaline medium, adds fine bubbles to the alkaline solution, and combines a process of introducing a three-electrode system for energizing, thereby enhancing the reaction efficiency of water electrolysis in the system, reducing the occurrence of hydrogen evolution reaction in the electrolysis system, and improving the concentration and uniformity of dissolved oxygen in the electrolytic medium, thereby preparing specific active oxygen with high concentration and good stability. The raw materials used are low in cost, the process is simple, and it is conducive to the large-scale application of active oxygen.

[0013] Preferably, the concentration of the alkaline solution is 0.5wt% to 50wt%, for example, 0.5wt%, 1wt%, 5wt%, 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt% or 50wt%, etc., preferably 30wt% to 40wt%.

[0014] The concentration of the alkaline solution regulated by the present invention is beneficial to the preparation of high-concentration active oxygen while reducing the amount of alkaline substances added, which, on the one hand, reduces the cost and, on the other hand, can reduce the corrosion of the medium to the equipment.

[0015] Preferably, the alkaline substance in the alkaline solution includes any one of NaOH, KOH, Na2O, K2O, Na2CO3 or K2CO3, or a combination of at least two thereof.

[0016] Preferably, the diameter of the fine bubbles is 50 μm to 200 μm, for example, 50 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 160 μm, 180 μm or 200 μm.

[0017] The present invention adjusts the diameter size of the fine bubbles within a suitable range, which can provide a large amount of gas-liquid interface contact area, accelerate the dissolution of gas into liquid, and thus increase the concentration of dissolved oxygen in the alkaline solution. At the same time, the fine bubbles of suitable size can increase their turbulence and mixing effects in water, further enhance the diffusion of dissolved oxygen, and improve the efficiency of the electrolysis process and the content of dissolved oxygen in the medium.

[0018] Preferably, the fine bubbles include any one of oxygen bubbles or air bubbles.

[0019] In the present invention, there is no specific limitation on the method of introducing fine bubbles, including but not limited to mechanical stirring and shearing large bubbles or cutting microporous fine bubble lines, and those skilled in the art can select according to needs.

[0020] Optionally, the fine bubbles are obtained by introducing the alkaline solution through a fine bubble disperser.

[0021] Preferably, the alkaline solution is stirred during the process of introducing the fine bubbles.

[0022] Preferably, the stirring speed is 100 rpm to 800 rpm, for example, 100 rpm, 200 rpm, 300 rpm, 400 rpm, 500 rpm, 600 rpm, 700 rpm or 800 rpm.

[0023] The invention regulates the stirring speed to improve the dissolution of fine bubbles in the alkaline solution, improve the content of dissolved oxygen in the electrolytic medium and the uniformity of the dissolved oxygen distribution, thereby improving the concentration of the prepared active oxygen.

[0024] Preferably, the initial flow rate of the fine bubbles into the alkaline solution is 0.1L / min to 1.0L / min, for example, 0.1L / min, 0.2L / min, 0.3L / min, 0.4L / min, 0.5L / min, 0.6L / min, 0.7L / min, 0.8L / min, 0.9L / min or 1L / min, etc.

[0025] In the present invention, “the initial flow rate of the fine bubbles introduced into the alkaline solution” refers to the bubble flow rate at the outlet of the device for introducing fine bubbles when fine bubbles are introduced into the alkaline solution.

[0026] Preferably, during the process of introducing the fine bubbles, the temperature of the alkaline solution is 60°C to 130°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C or 130°C.

[0027] The present invention further regulates the flow rate of fine bubbles and the solution temperature during the process of introducing bubbles, and can control the saturated dissolved oxygen concentration in the alkaline solution, thereby increasing the generated concentration of active oxygen.

[0028] Preferably, after the fine bubbles are introduced, the concentration of dissolved oxygen in the alkaline solution is 0.5 mg / L to 35 mg / L, for example, 0.5 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, 15 mg / L, 20 mg / L, 25 mg / L, 30 mg / L or 35 mg / L.

[0029] Preferably, the three-electrode system comprises a reference electrode, a working electrode and a counter electrode.

[0030] In the present invention, the energizing refers to using the reference electrode as the standard electrode and applying voltage to the working electrode.

[0031] Preferably, the working electrode comprises any one of a graphite electrode and a stainless steel electrode.

[0032] Preferably, the counter electrode comprises any one of a platinum sheet, a platinum wire or a platinum mesh.

[0033] Preferably, the reference electrode comprises any one of a standard hydrogen electrode, an Ag / AgCl electrode or a saturated calomel electrode.

[0034] Preferably, during the power-on process, the temperature of the alkaline solution after the introduction of fine bubbles is 20°C to 150°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, etc.

[0035] In the process of electrochemically generating active oxygen, the present invention designs single-electron oxidation and double-electron oxidation reactions. By controlling the type of reference electrode and accurately regulating the potential of the corresponding energized electrode, the type of active oxygen generated in the alkaline solution medium can be controlled. In addition, during the energization process, the temperature change of the solution in which the three-electrode system is located will also have a slight effect on the electrode voltage required to prepare different active oxygen.

[0036] As a preferred technical solution of the present invention, the reference electrode is a standard hydrogen electrode. When the voltage of the power supply is (-1.4V) to (-1.6V), the active oxygen obtained includes superoxide anions, wherein the selection range of the power supply voltage is "(-1.4V) to (-1.6V)", for example, -1.4V, -1.45V, -1.5V, -1.55V or -1.6V, etc.

[0037] Preferably, the reference electrode is a standard hydrogen electrode. When the voltage of the power supply is (-1.7V) to (-1.9V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions, wherein the selection range of the power supply voltage is "(-1.7V) to (-1.9V)", for example, -1.7V, -1.75V, -1.8V, -1.85V or -1.9V, etc.

[0038] Preferably, the reference electrode is a standard hydrogen electrode, and when the powered voltage is 2.2V to 2.5V, the reactive oxygen species obtained include hydroxyl radicals, wherein the powered voltage is in the range of "2.2V to 2.5V", for example, 2.2V, 2.25V, 2.3V, 2.35V, 2.4V, 2.45V or 2.5V, etc.

[0039] In the present invention, a standard hydrogen electrode is used as the reference electrode of the three-electrode system. When the voltage applied to the three-electrode system is in the range of (-1.4V) to (-1.6V), the oxygen contained in the alkaline solution after the fine bubbles are introduced will gain electrons under the action of the voltage to generate superoxide anions, that is, When the voltage applied to the three-electrode system is in the range of (-1.7V) to (-1.9V), the oxygen contained in the alkaline solution after the introduction of fine bubbles will gain electrons under the action of the voltage to generate superoxide anions. At the same time, a higher voltage value will also cause the obtained superoxide anions to continue to gain electrons with the water in the solution as an intermediate product to generate hydrogen peroxide ions and hydroxide ions, which is When the voltage applied to the three-electrode system is in the range of 2.2V to 2.5V, the water molecules in the solution will lose electrons to obtain hydrogen ions and hydroxyl radicals, namely H2O-e - →H + +·OH. The present invention uses a standard hydrogen electrode as a reference electrode. In the process of electrochemically generating active oxygen, single-electron oxidation and double-electron oxidation reactions are involved. By precisely controlling the applied voltage, different types of active oxygen species can be generated.

[0040] As a preferred technical solution of the present invention, the reference electrode is an Ag / AgCl electrode. When the powered voltage is (-1.6V) to (-1.8V), the active oxygen obtained includes superoxide anions, wherein the powered voltage is selected in the range of "(-1.6V) to (-1.8V)", for example, -1.6V, -1.65V, -1.7V, -1.75V or -1.8V, etc.

[0041] Preferably, the reference electrode is an Ag / AgCl electrode, and when the powered voltage is (-1.9V) to (-2.1V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions, wherein the powered voltage is selected in the range of "(-1.9V) to (-2.1V)", for example, -1.9V, -1.95V, -2.0V, -2.05V or -2.1V, etc.

[0042] Preferably, the reference electrode is an Ag / AgCl electrode, and when the powered voltage is 2.0V to 2.3V, the reactive oxygen species obtained include hydroxyl radicals, wherein the powered voltage is in the range of "2.0V to 2.3V", for example, 2.0V, 2.05V, 2.1V, 2.25V, 2.2V, 2.25V or 2.3V, etc.

[0043] In the present invention, the Ag / AgCl electrode is used as the reference electrode of the three-electrode system. When the voltage applied to the three-electrode system is in the range of (-1.6V) to (-1.8V), the oxygen in the alkaline solution after the fine bubbles are introduced will obtain electrons under the action of the voltage to generate superoxide anions, that is, When the voltage applied to the three-electrode system is in the range of (-1.9V) to (-2.1V), the oxygen in the alkaline solution after the introduction of fine bubbles will gain electrons under the action of the voltage to generate superoxide anions. At the same time, a higher voltage value will also cause the obtained superoxide anions to continue to gain electrons with the water in the solution as an intermediate product to generate hydrogen peroxide ions and hydroxide ions, which is When the voltage on the three-electrode system is in the range of 2.0V to 2.3V, the water molecules in the solution will lose electrons to obtain hydrogen ions and hydroxyl radicals, namely H2O-e - →H + +·OH.

[0044] As a preferred technical solution of the present invention, the reference electrode is a saturated calomel electrode. When the voltage of the power supply is (-1.64V) to (-1.84V), the active oxygen obtained includes superoxide anions, wherein the selection range of the power supply voltage is "(-1.64V) to (-1.84V)", for example, -1.64V, -1.68V, -1.7V, -1.72V, -1.74V, -1.76V, -1.78V, -1.8V, -1.82V or -1.84V, etc.

[0045] Preferably, the reference electrode is a saturated calomel electrode, and when the powered voltage is (-1.9V) to (-2.14V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions, wherein the powered voltage is selected in the range of "(-1.9V) to (-2.14V)", for example, -1.9V, -1.92V, -1.94V, -1.96V, -1.98V, -2.0V, -2.02V, -2.04V, -2.06V, -2.08V, -2.1V, -2.12V or -2.14V, etc.

[0046] Preferably, the reference electrode is a saturated calomel electrode, and when the powered voltage is 1.96V to 2.26V, the reactive oxygen obtained includes hydroxyl radicals, wherein the powered voltage is in the range of "1.96V to 2.26V", for example, 1.96V, 2V, 2.04V, 2.08V, 2.08V, 2.12V, 2.16V, 2.2V, 2.24V or 2.26V, etc.

[0047] In the present invention, a saturated calomel electrode is used as the reference electrode of the three-electrode system. When the voltage applied to the three-electrode system is in the range of (-1.64V) to (-1.84V), oxygen in the alkaline solution after fine bubbles are introduced will gain electrons under the action of the voltage to generate superoxide anions, namely When the voltage applied to the three-electrode system is in the range of (-1.9V) to (-2.14V), the oxygen in the alkaline solution after the introduction of fine bubbles will obtain electrons under the action of the voltage to generate superoxide anions. At the same time, a higher voltage value will also cause the obtained superoxide anions to continue to obtain electrons with the water in the solution as an intermediate product to generate hydrogen peroxide ions and hydroxide ions, which is When the voltage applied to the three-electrode system is in the range of 1.96V to 2.26V, the water molecules in the solution will lose electrons and obtain hydrogen ions and hydroxyl radicals, namely H2O-e - →H + +·OH.

[0048] In a second aspect, the present invention provides an active oxygen, which is prepared by the preparation method described in the first aspect.

[0049] The active oxygen prepared by the specific preparation method of the present invention has high concentration and good stability, which is conducive to the application of advanced oxidation technology in the fields of wastewater treatment, heavy metal recovery or valuable metal leaching.

[0050] Preferably, the active oxygen includes any one of hydroxyl radicals, superoxide anions or hydrogen peroxide ions, or a combination of at least two thereof.

[0051] In a third aspect, the present invention provides an application of the active oxygen according to the second aspect, wherein the active oxygen is applied in the fields of wastewater treatment, heavy metal recovery or valuable metal leaching.

[0052] The active oxygen and the preparation and control methods thereof provided by the present invention can be applied to any application field that can be thought of by those skilled in the art.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects:

[0054] The method for preparing active oxygen provided by the present invention uses an alkaline solution as an alkaline medium, adds fine bubbles to the alkaline solution, and combines a process of introducing a three-electrode system for energizing, thereby enhancing the reaction efficiency of water electrolysis in the system, reducing the occurrence of hydrogen evolution reaction in the electrolysis system, and improving the concentration and uniformity of dissolved oxygen in the electrolytic medium, thereby preparing specific active oxygen with high concentration and good stability. The raw materials used are low in cost, the process is simple, and it is conducive to the large-scale application of active oxygen. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a graph of active oxygen intensity prepared in Example 1, Examples 12-16 and Comparative Example 5. DETAILED DESCRIPTION

[0056] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and through specific implementation methods. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0057] Example 1

[0058] This embodiment provides a method for preparing active oxygen, comprising the following steps:

[0059] (1) NaOH and deionized water are added to a reaction container and mixed to obtain a NaOH alkaline solution with a concentration of 30 wt %.

[0060] (2) introducing fine bubbles of oxygen bubbles into the NaOH alkaline solution obtained in step (1) for 20 minutes using a fine bubble disperser, and at the same time, stirring the NaOH alkaline solution at a rotation speed of 500 rpm, wherein the diameter of the fine bubbles is 100 μm, the initial flow rate of the fine bubbles into the NaOH alkaline solution is 0.5 L / min, and the temperature of the NaOH alkaline solution during the process of introducing oxygen bubbles is 120° C. After the fine bubbles are introduced, the concentration of dissolved oxygen in the solution is tested using a dissolved oxygen meter, and the concentration of dissolved oxygen in the NaOH alkaline solution reaches 19.06 mg / L.

[0061] (3) placing a three-electrode system in the NaOH alkaline solution obtained in step (2) after the oxygen bubbles are introduced, wherein the reference electrode is a standard hydrogen electrode, the working electrode is a stainless steel electrode, and the counter electrode is a platinum electrode. The three-electrode system is energized through an electrochemical workstation, and the temperature of the solution is maintained at 120° C. during the energization process. The electrode potential is set to 2.3 V. After 30 minutes of energization, active oxygen is obtained.

[0062] Example 2

[0063] This embodiment provides a method for preparing active oxygen, comprising the following steps:

[0064] (1) NaOH and deionized water are added to a reaction container and mixed to obtain a NaOH alkaline solution with a concentration of 40 wt %.

[0065] (2) introducing fine bubbles of oxygen bubbles for 15 minutes into the NaOH alkaline solution obtained in step (1) using a fine bubble disperser, and at the same time, stirring the NaOH alkaline solution at a rotation speed of 500 rpm, wherein the diameter of the fine bubbles is 100 μm, the initial flow rate of the fine bubbles into the NaOH alkaline solution is 0.5 L / min, and the temperature of the NaOH alkaline solution during the process of introducing oxygen bubbles is 130° C. After the fine bubbles are introduced, the concentration of dissolved oxygen in the solution is tested using a dissolved oxygen meter, and the concentration of dissolved oxygen in the NaOH alkaline solution reaches 15.30 mg / L.

[0066] (3) placing a three-electrode system in the NaOH alkaline solution obtained in step (2) after the oxygen bubbles are introduced, wherein the reference electrode is a standard hydrogen electrode, the working electrode is a stainless steel electrode, and the counter electrode is a platinum electrode. The three-electrode system is energized through an electrochemical workstation, and the temperature of the solution is maintained at 130° C. during the energization process. The electrode potential is set to -1.7 V. After 30 minutes of energization, active oxygen is obtained.

[0067] Example 3

[0068] This embodiment provides a method for preparing active oxygen, comprising the following steps:

[0069] (1) NaOH and deionized water are added to a reaction container and mixed to obtain a NaOH alkaline solution with a concentration of 50 wt %.

[0070] (2) Using a fine bubble disperser, fine bubbles of oxygen bubbles are introduced into the NaOH alkaline solution obtained in step (1) for 10 minutes. At the same time, the NaOH alkaline solution is stirred at a rotation speed of 500 rpm, wherein the diameter of the fine bubbles is 100 μm, the initial flow rate of the fine bubbles introduced into the NaOH alkaline solution is 0.5 L / min, and the temperature of the NaOH alkaline solution during the process of introducing oxygen bubbles is 120° C. After the fine bubbles are introduced, the concentration of dissolved oxygen in the solution is tested using a dissolved oxygen meter, and the concentration of dissolved oxygen in the NaOH alkaline solution reaches 12 mg / L.

[0071] (3) placing a three-electrode system in the NaOH alkaline solution obtained in step (2) after the oxygen bubbles are introduced, wherein the reference electrode is a standard hydrogen electrode, the working electrode is a stainless steel electrode, and the counter electrode is a platinum electrode. The three-electrode system is energized through an electrochemical workstation, and the temperature of the solution is maintained at 140° C. during the energization process. The electrode potential is set to -1.5 V. After 30 minutes of energization, active oxygen is obtained.

[0072] Example 4

[0073] This embodiment provides a method for preparing active oxygen, comprising the following steps:

[0074] (1) KOH and deionized water are added to a reaction container and mixed to obtain a KOH alkaline solution with a concentration of 40 wt %.

[0075] (2) A fine bubble disperser is used to introduce fine bubbles of oxygen bubbles into the KOH alkaline solution obtained in step (1) for 20 minutes. At the same time, the KOH alkaline solution is stirred at a rotation speed of 100 rpm, wherein the diameter of the fine bubbles is 200 μm, the initial flow rate of the fine bubbles introduced into the KOH alkaline solution is 1 L / min, and the temperature of the KOH alkaline solution during the process of introducing oxygen bubbles is 130° C. After the fine bubbles are introduced, the concentration of dissolved oxygen in the solution is tested using a dissolved oxygen meter, and the concentration of dissolved oxygen in the NaOH alkaline solution reaches 20 mg / L.

[0076] (3) placing a three-electrode system in the KOH alkaline solution obtained in step (2) after the oxygen bubbles are introduced, wherein the reference electrode is a standard hydrogen electrode, the working electrode is a stainless steel electrode, and the counter electrode is a platinum wire electrode. The three-electrode system is energized through an electrochemical workstation, and the temperature of the solution is maintained at 130° C. during the energization process. The potential of the energized electrodes is adjusted to 2.4 V. After energization for 30 minutes, active oxygen is obtained.

[0077] Example 5

[0078] This embodiment provides a method for preparing active oxygen, comprising the following steps:

[0079] (1) KOH and deionized water are added to a reaction container and mixed to obtain a KOH alkaline solution with a concentration of 40 wt %.

[0080] (2) Using a fine bubble disperser, fine bubbles of air bubbles are introduced into the KOH alkaline solution obtained in step (1) for 20 minutes. At the same time, the KOH alkaline solution is stirred at a rotation speed of 800 rpm, wherein the diameter of the fine bubbles is 50 μm, the initial flow rate of the fine bubbles introduced into the KOH alkaline solution is 0.3 L / min, and the temperature of the KOH alkaline solution during the process of introducing oxygen bubbles is 120° C. After the fine bubbles are introduced, the concentration of dissolved oxygen in the solution is tested using a dissolved oxygen meter. The concentration of dissolved oxygen in the KOH alkaline solution reaches 10 mg / L.

[0081] (3) placing a three-electrode system in the KOH alkaline solution obtained in step (2) after introducing air bubbles, wherein the reference electrode is a standard hydrogen electrode, the working electrode is a stainless steel electrode, and the counter electrode is a platinum mesh electrode. The three-electrode system is energized through an electrochemical workstation, and the temperature of the solution is maintained at 120° C. during the energization process. The potential of the energized electrodes is adjusted to 2.5 V. After energization for 30 minutes, active oxygen is obtained.

[0082] Example 6

[0083] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is an Ag / AgCl electrode, and the electrode potential is adjusted to -1.7 V. The rest of the contents are the same as those in embodiment 1.

[0084] Example 7

[0085] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is an Ag / AgCl electrode, and the electrode potential is adjusted to -2.0 V. The rest of the contents are the same as those in embodiment 1.

[0086] Example 8

[0087] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is an Ag / AgCl electrode, and the electrode potential is adjusted to 2.2 V. The rest of the contents are the same as those in embodiment 1.

[0088] Example 9

[0089] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is a saturated calomel electrode, and the electrode potential is adjusted to -1.74 V. The rest of the contents are the same as those in embodiment 1.

[0090] Example 10

[0091] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is a saturated calomel electrode, and the electrode potential is adjusted to -2.1 V. The rest of the contents are the same as those in embodiment 1.

[0092] Embodiment 11

[0093] The difference between this embodiment and embodiment 1 is that in step (3) of the method for preparing active oxygen provided in this embodiment, the reference electrode of the three-electrode system is a saturated calomel electrode, and the electrode potential is adjusted to 2.0 V. The rest of the contents are the same as those in embodiment 1.

[0094] Example 12

[0095] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 40 wt %. The rest of the contents are the same as those in embodiment 1.

[0096] Embodiment 13

[0097] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 20 wt %. The rest of the contents are the same as those in embodiment 1.

[0098] Embodiment 14

[0099] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 10 wt %. The rest of the contents are the same as those in embodiment 1.

[0100] Embodiment 15

[0101] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 5 wt %. The rest of the contents are the same as those in embodiment 1.

[0102] Example 16

[0103] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 1 wt %. The rest of the contents are the same as those in embodiment 1.

[0104] Embodiment 17

[0105] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the concentration of the NaOH alkaline solution in step (1) is 60 wt %. The rest of the contents are the same as those in embodiment 1.

[0106] Embodiment 18

[0107] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the stirring process is omitted in step (2). The rest of the contents are the same as those in embodiment 1.

[0108] Embodiment 19

[0109] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the diameter of the fine bubbles in step (2) is 30 μm. The rest of the contents are the same as those in embodiment 1.

[0110] Embodiment 20

[0111] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the diameter of the fine bubbles in step (2) is 220 μm. The rest of the contents are the same as those in embodiment 1.

[0112] Embodiment 21

[0113] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the temperature of the NaOH alkaline solution during the process of introducing oxygen bubbles in step (2) is 25° C. The rest of the contents are the same as those in embodiment 1.

[0114] Embodiment 22

[0115] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the initial flow rate of fine bubbles introduced into the NaOH alkaline solution in step (2) is 0.01 L / min. The rest of the contents are the same as those in embodiment 1.

[0116] Embodiment 23

[0117] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the electrode potential in step (3) is adjusted to 1.9 V. The rest of the contents are the same as those in embodiment 1.

[0118] Embodiment 24

[0119] The difference between this embodiment and embodiment 1 is that in the method for preparing active oxygen provided in this embodiment, the electrode potential in step (3) is adjusted to 2.8 V. The rest of the contents are the same as those in embodiment 1.

[0120] Comparative Example 1

[0121] The difference between this comparative example and Example 1 is that in the method for preparing active oxygen provided in this comparative example, the fine bubble disperser used in step (2) for introducing fine bubbles of oxygen bubbles into the NaOH alkaline solution obtained in step (1) is omitted. The rest of the contents are the same as those in Example 1.

[0122] Comparative Example 2

[0123] The difference between this comparative example and Example 1 is that in the method for preparing active oxygen provided in this comparative example, step (3) of applying electricity through an electrochemical workstation is omitted. The rest of the contents are the same as those in Example 1.

[0124] Comparative Example 3

[0125] The difference between this comparative example and Example 6 is that in the method for preparing active oxygen provided in this comparative example, step (3) of applying electricity through an electrochemical workstation is omitted. The rest of the contents are the same as those in Example 6.

[0126] Comparative Example 4

[0127] The difference between this comparative example and Example 9 is that in the method for preparing active oxygen provided in this comparative example, step (3) of applying electricity through an electrochemical workstation is omitted. The rest of the contents are the same as those of Example 9.

[0128] Comparative Example 5

[0129] The difference between this comparative example and Example 1 is that in the method for preparing active oxygen provided in this comparative example, ultrapure water is used as the electrolytic medium, and the step (1) of preparing the alkaline solution is omitted. The rest of the contents are the same as Example 1.

[0130] The active oxygen solutions prepared in Examples 1-24 and Comparative Examples 1-5 were tested for the types and concentrations of active oxygen in the solutions using an electron paramagnetic resonance spectrometer and an ultraviolet spectrophotometer. The test results are shown in Table 1.

[0131] Table 1

[0132]

[0133]

[0134] The test results show that:

[0135] (1) It can be seen from Examples 1 to 12 that the method for preparing active oxygen provided by the present invention can prepare a specific type of active oxygen with high concentration and good stability by using an alkaline solution as an alkaline medium, adding fine bubbles to the alkaline solution, and introducing a three-electrode system for energization. The raw materials used are low in cost and the process is simple, which is conducive to the large-scale application of active oxygen.

[0136] (2) By comparing Example 1 with Examples 13-17, it can be seen that if the concentration of the alkaline solution of the present invention is too low, the reaction efficiency of water electrolysis will be low and the concentration of active oxygen will be reduced; if the concentration of the alkaline solution is too high, the amount of alkaline substance added will be too high, the cost will increase, the alkaline solution will also corrode the equipment, and the generated active oxygen will be easily decomposed, resulting in an increase in side reactions.

[0137] (3) By comparing Example 1 and Example 18, it can be seen that the present invention omits the stirring process during the process of introducing fine bubbles into the alkaline solution, which will cause uneven gas dispersion and difficulty in contacting the electrode surface, thereby reducing the reaction efficiency and the active oxygen concentration.

[0138] (4) By comparing Example 1 with Examples 19-20, it can be seen that if the diameter of the fine bubbles in the present invention is too small, the bubbles will exist in the solution for a long time and will be difficult to break, resulting in increased solution impedance and reduced electrochemical efficiency; if the diameter of the fine bubbles is too large, the gas will stay in the solution for a short time, the dissolved oxygen concentration in the solution will be low, and thus the amount of active oxygen generated will be small.

[0139] (5) By comparing Example 1 and Example 21, it can be seen that if the temperature is controlled at room temperature during the process of introducing fine bubbles into the alkaline solution in the present invention, the viscosity of the solution will increase, hindering the dissolution of oxygen, and the concentration of dissolved oxygen in the solution will decrease, thereby reducing the amount of active oxygen generated.

[0140] (6) By comparing Example 1 and Example 22, it can be seen that if the flow rate of the fine bubbles in the present invention is too low, oxygen will not be able to effectively enter the solution, the dissolved oxygen concentration will be low, and it will be unfavorable for the subsequent generation of active oxygen.

[0141] (7) By comparing Example 1 with Examples 23-24, it can be seen that if the electrode potential used in step (3) of the present invention is too low, the electrode voltage of the obtained active oxygen cannot be reached, and thus active oxygen cannot be generated; if the electrode potential used in step (3) is too high, hydrogen evolution reaction will occur, resulting in a decrease in electrochemical efficiency, energy waste, and a lower concentration of the obtained active oxygen.

[0142] (8) By comparing Example 1 with Comparative Example 1, it can be seen that the introduction of fine bubbles in the present invention increases the concentration of active oxygen in the alkaline solution, providing sufficient reactants for electrochemical oxidation of dissolved oxygen. If there is no introduction of fine bubbles, the oxygen in the electrolysis process mainly comes from the decomposition of water, and the concentration of active oxygen obtained after power is turned on is low. In addition, if a higher concentration of active oxygen is desired, a higher oxidation potential is required. On the one hand, this will lead to higher reaction energy consumption. On the other hand, due to the strong hydrogen evolution side reaction, it is not easy to maintain a high concentration of active oxygen in the system.

[0143] (9) By comparing Example 1 with Comparative Example 2, Example 6 with Comparative Example 3, and Example 9 with Comparative Example 4, it can be seen that when the present invention lacks the power-on process, active oxygen cannot be generated.

[0144] (10) By comparing Example 1 with Comparative Example 5, it can be seen that if an alkaline solution is lacking in the preparation process of active oxygen in the present invention, the conductivity of the solution will decrease and the electrochemical efficiency will be low. At the same time, the active oxygen generated lacks an effective carrier and is difficult to exist for a long time.

[0145] Figure 1 The generation intensity of hydroxyl radicals prepared in Example 1, Examples 13-16 and Comparative Example 5 is given. It can be seen from the figure that in the alkaline solution range of 0-40wt%, as the concentration of the alkaline solution increases, the generation intensity of hydroxyl radicals in the active oxygen preparation process gradually increases.

[0146] In summary, the method for preparing active oxygen provided by the present invention uses an alkaline solution as an alkaline medium, adds fine bubbles to the alkaline solution, and combines the process of introducing a three-electrode system for electrification, which can enhance the reaction efficiency of water electrolysis in the system, reduce the occurrence of hydrogen evolution reaction in the electrolysis system, and improve the concentration and uniformity of dissolved oxygen in the electrolytic medium, thereby preparing specific active oxygen with high concentration and good stability. The raw materials used are low in cost and the process is simple, which is conducive to the large-scale application of active oxygen.

[0147] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing active oxygen, characterized in that: The preparation method comprises the following steps: Fine bubbles are introduced into an alkaline solution, and then a three-electrode system is placed in the alkaline solution after the fine bubbles are introduced, and the three-electrode system is energized to obtain the active oxygen.

2. The preparation method according to claim 1, characterized in that: The concentration of the alkaline solution is 0.5wt% to 50wt%, preferably 30wt% to 40wt%; Preferably, the alkaline substance in the alkaline solution includes any one or a combination of at least two of NaOH, KOH, Na2O, K2O, Na2CO3 or K2CO3; Preferably, the diameter of the fine bubbles is 50 μm to 200 μm; Preferably, the fine bubbles include any one of oxygen bubbles or air bubbles; Preferably, the alkaline solution is stirred during the process of introducing the fine bubbles; Preferably, the stirring speed is 100 rpm to 800 rpm.

3. The preparation method according to claim 1 or 2, characterized in that: The initial flow rate of the fine bubbles into the alkaline solution is 0.1L / min to 1.0L / min; Preferably, during the process of introducing the fine bubbles, the temperature of the alkaline solution is 60° C. to 130° C.; Preferably, after the fine bubbles are introduced, the concentration of dissolved oxygen in the alkaline solution is 0.5 mg / L to 35 mg / L.

4. The preparation method according to any one of claims 1 to 3, characterized in that: The three-electrode system includes a reference electrode, a working electrode and a counter electrode; Preferably, the working electrode comprises any one of a graphite electrode or a stainless steel electrode; Preferably, the counter electrode comprises any one of a platinum sheet, a platinum wire or a platinum mesh; Preferably, the reference electrode comprises any one of a standard hydrogen electrode, an Ag / AgCl electrode or a saturated calomel electrode; Preferably, during the power-on process, the temperature of the alkaline solution after the fine bubbles are introduced is 20° C. to 150° C.

5. The preparation method according to claim 4, characterized in that: The reference electrode is a standard hydrogen electrode, and when the voltage of the power supply is (-1.4V) to (-1.6V), the active oxygen obtained includes superoxide anions; Preferably, the reference electrode is a standard hydrogen electrode, and when the voltage of the power supply is (-1.7V) to (-1.9V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions; Preferably, the reference electrode is a standard hydrogen electrode, and when the voltage of the power supply is 2.2V to 2.5V, the active oxygen obtained includes hydroxyl radicals.

6. The preparation method according to claim 4, characterized in that: The reference electrode is an Ag / AgCl electrode, and when the voltage of the power supply is (-1.6V) to (-1.8V), the active oxygen obtained includes superoxide anions; Preferably, the reference electrode is an Ag / AgCl electrode, and when the voltage of the power supply is (-1.9V) to (-2.1V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions; Preferably, the reference electrode is an Ag / AgCl electrode, and when the voltage of the power supply is 2.0V to 2.3V, the obtained active oxygen includes hydroxyl radicals.

7. The preparation method according to claim 4, characterized in that: The reference electrode is a saturated calomel electrode, and when the voltage of the power supply is (-1.64V) to (-1.84V), the active oxygen obtained includes superoxide anions; Preferably, the reference electrode is a saturated calomel electrode, and when the voltage of the power supply is (-1.9V) to (-2.14V), the active oxygen obtained includes superoxide anions and hydrogen peroxide ions; Preferably, the reference electrode is a saturated calomel electrode, and when the voltage of the power supply is 1.96V to 2.26V, the active oxygen obtained includes hydroxyl radicals.

8. An active oxygen, characterized in that The active oxygen is prepared by the preparation method according to any one of claims 1 to 7.

9. The active oxygen according to claim 8, characterized in that The active oxygen includes any one of hydroxyl radicals, superoxide anions or hydrogen peroxide ions, or a combination of at least two of them.

10. A use of active oxygen according to claim 8 or 9, characterized in that: The active oxygen is applied in the fields of wastewater treatment, heavy metal recovery or valuable metal leaching.

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