Device for preparing plasma activating solution on large scale and application of device in food sterilization

Abstract

The invention discloses a device for preparing a plasma activating solution on a large scale and application of the device in food sterilization. The device comprises a power supply, a gas supply system, a water tank and at least one mixed plasma reactor, the hybrid plasma reactor is arranged in the water tank and comprises a medium pipe, a rod-shaped grounding electrode, a first high-voltage electrode and a second high-voltage electrode; the rod-shaped grounding electrode, the first high-voltage electrode and the second high-voltage electrode are fixed in the dielectric tube; the first high-voltage electrode is a metal tube and sleeves the rod-shaped grounding electrode, and the rod-shaped grounding electrode is located in the center of the first high-voltage electrode; a dielectric layer is arranged on the inner surface of the first high-voltage electrode; the second high-voltage electrode is arranged below the first high-voltage electrode and sleeved outside the rod-shaped grounding electrode, and the rod-shaped grounding electrode is located at the center of the second high-voltage electrode. According to the invention, the variety and concentration of active ingredients in the plasma activating solution are improved, high-level food sterilization application is realized, and the device has spectral antibacterial property, is simple, energy-saving and extensible, and can be suitable for various food sterilization scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of non-thermal technology sterilization, and particularly to a device for large-scale preparation of plasma-activated solution and its application in food sterilization. Background Art

[0002] Atmospheric pressure non-thermal plasma and its derivative form - plasma-activated solution both have strong sterilization ability and are expected to become green reagents for eliminating pathogens. Plasma-activated solution is a solution produced by the interaction of atmospheric pressure non-thermal plasma and liquid medium, which is generated by direct plasma discharge in water or plasma discharge on the water surface. The biochemical activity of plasma-activated solution is related to the concentration of highly reactive oxygen / nitrogen species in water, such as hydrogen peroxide, hydroxyl radicals, and peroxynitrite. The synergistic effect of these active substances and low pH value plays a key role in the oxidative stress of bacterial cells and the destruction of intracellular DNA.

[0003] However, when plasma-activated solution moves from the laboratory to industrial applications, several technical problems still need to be solved: (1) The preparation scale of plasma-activated solution is small and the efficiency is low; (2) The plasma source required for the preparation method of plasma-activated solution is large in volume and high in energy consumption; (3) The loading of reactive substances and the activity of particles generated by the interaction between plasma and water are poor. Summary of the Invention

[0004] In order to overcome the above-mentioned disadvantages and deficiencies of the prior art, the purpose of the present invention is to provide a device for large-scale preparation of plasma-activated solution, which introduces two discharge schemes of dielectric barrier discharge and sliding arc discharge, improves the types and concentrations of active components in the plasma-activated solution, realizes high-level food sterilization applications, has spectral antibacterial properties, effectively removes harmful bacteria on the surfaces of food, food packaging materials, and processing equipment, and the device for large-scale preparation of plasma-activated solution has a simple structure, energy-saving, and scalable, and can be applied to a variety of application scenarios.

[0005] Another purpose of the present invention is to provide the application of the above-mentioned device for large-scale preparation of plasma-activated solution in food sterilization.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] The present invention provides a device for large-scale preparation of plasma-activated solution, which includes a power supply, a gas supply system, a water tank, and at least one hybrid plasma reactor; the hybrid plasma reactor is arranged in the water tank;

[0008] The hybrid plasma reactor includes a dielectric tube, a rod-shaped grounded electrode, a first high-voltage electrode, and a second high-voltage electrode; the rod-shaped grounded electrode, the first high-voltage electrode, and the second high-voltage electrode are fixed inside the dielectric tube;

[0009] The first high-voltage electrode is a metal tube sleeved outside the rod-shaped grounding electrode, and the rod-shaped grounding electrode is located at the center of the first high-voltage electrode; a dielectric layer is provided on the inner surface of the first high-voltage electrode;

[0010] The second high-voltage electrode is arranged below the first high-voltage electrode and sleeved outside the rod-shaped grounding electrode, and the rod-shaped grounding electrode is located at the center of the second high-voltage electrode;

[0011] The working gas in the gas supply system enters the dielectric tube through the air inlet at the top of the dielectric tube, and dielectric barrier discharge plasma is generated between the first high-voltage electrode and the rod-shaped grounding electrode; sliding arc discharge plasma is generated between the second high-voltage electrode and the rod-shaped grounding electrode; the dielectric barrier discharge plasma and the sliding arc discharge plasma form a mixed plasma, which is dispersed into the liquid in the water tank from the air outlet at the lower part of the dielectric tube to obtain a plasma-activated liquid.

[0012] Preferably, the working gas enters the dielectric tube at a flow rate of 5-15 L / min.

[0013] Preferably, the second high-voltage electrode has a spiral structure, and its radius increases successively from top to bottom.

[0014] Preferably, the second high-voltage electrode is welded to the lower end of the first high-voltage electrode.

[0015] Preferably, a plurality of microporous aerators are provided at the air outlet below the dielectric tube; a Pall ring is provided outside the microporous aerator.

[0016] Preferably, a surfactant is added to the liquid in the water tank; the mixed plasma forms bubbles with a particle size of 50 nm - 1 μm in the liquid; the surfactant is fatty alcohol polyoxyethylene ether, polyethylene glycol fatty acid ester or polyvinyl alcohol.

[0017] Preferably, the dielectric layer is borosilicate and covers the inner surface of the first high-voltage electrode.

[0018] Preferably, there are two mixed plasma reactors, one of which is connected to the positive pole of the power supply and the other is connected to the negative pole of the power supply.

[0019] Preferably, the device for large-scale preparation of plasma-activated liquid further includes a humidifying device for humidifying the working gas. Preferably, the device for large-scale preparation of plasma-activated liquid further includes a solar plasma generator system, which specifically includes a foldable solar panel power generation system, a plasma power supply, and a high-voltage transformer, and can use power or solar power to drive the mixed plasma generation system.

[0020] Preferably, a radiator is further provided on the outer layer of the dielectric tube, and the radiator is closely attached to the outer layer of the quartz dielectric tube.

[0021] Preferably, the grounding electrode lead of the device for large-scale preparation of plasma-activated liquid needs to be installed below the liquid level, and can be installed at the bottom, side of the water tank or suspended in the water.

[0022] Preferably, the second high-voltage electrode can also adopt other structures to form, such as the sliding arc discharge jet mode, and generate sliding arc discharge through the vortex air flow. Specifically, the sliding arc discharge jet mode uses a vortex air flow generating device to make the plasma air flow form a vortex motion inside the reactor, so as to generate a dynamic sliding arc discharge between the high-voltage electrode and the grounding electrode. Through this sliding arc discharge jet mode, the hybrid plasma reactor can adapt to different water treatment requirements, and can flexibly adjust the plasma generation method without significantly changing the existing structure to achieve a more efficient water treatment effect.

[0023] Preferably, the plasma power supply of the present invention can provide high-voltage pulses up to 10 - 80 kV (V p-p ), a repetitive pulse frequency of 100 - 3000 Hz, and the gas supply system can provide a working gas with a flow rate of 5 - 15 L / min. Two discharge modes can be switched or coexist through different voltage or gas flow rate ranges.

[0024] Preferably, the working gas can be different mixed gases or a single gas, and the working gas is humidified by washing the gas source and then pumped into the hybrid plasma generation system.

[0025] The present invention also provides the application of the above-mentioned device for large-scale preparation of plasma-activated liquid in food sterilization. The plasma-activated liquid prepared by the device for large-scale preparation of plasma-activated liquid is used for killing Escherichia coli, mold, Staphylococcus aureus, Salmonella, Listeria monocytogenes and Clostridium botulinum in food, food packaging and food processing equipment; the killing methods include at least one of flushing, spraying, soaking, wiping, dropping and coating; the materials of the food packaging and food processing equipment include at least one of quartz, metal, glass, stainless steel, plastic and paper.

[0026] Based on the method for large-scale preparation of plasma-activated liquid using the above-mentioned device for large-scale preparation of plasma-activated liquid, it includes the following treatment steps:

[0027] S1: Introduce the aqueous solution to be treated into the water tank, and add a surfactant to the aqueous solution to be treated;

[0028] S2: Turn on the gas supply system, introduce the humidified working gas into the hybrid plasma reactor, and then turn on the solar plasma generator system to generate hybrid plasma activation gas in the hybrid plasma reactor simultaneously.

[0029] S3: The hybrid plasma reaches the microporous aerator at the bottom of the quartz tube dielectric tube along with the gas flow, and the hybrid plasma activation gas forms ultra-fine nano-bubbles through the micropores and disperses into the liquid flow.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] (1) The device for large-scale preparation of plasma-activated liquid in the present invention introduces two discharge schemes of dielectric barrier discharge and sliding arc discharge. The dielectric barrier discharge region focuses on generating highly loaded reactive oxygen species, while the sliding arc discharge region focuses on generating highly reactive reactive nitrogen species. Moreover, the solubility of the hybrid plasma active gas generated by the two in water will be greatly improved, and a large amount of high-valent nitrogen oxides that play a key role in sterilization will be generated, thereby realizing high-level food sterilization applications and having spectral antibacterial properties.

[0032] (2) The device for large-scale preparation of plasma-activated liquid in the present invention implements a dual-reactor configuration (one connected to the positive terminal and the other connected to the negative terminal) within an AC circuit, greatly reducing the energy loss of the negative electrode (unused micro-discharge) in the single-reactor configuration, and significantly improving the generation of high-valent nitrogen oxide species and energy efficiency.

[0033] (3) The device for large-scale preparation of plasma-activated liquid in the present invention integrates plasma discharge and bubbles. The plasma bubble technology and bubble dynamics control (Pall ring) are designed to provide a large surface area for gas-liquid interaction, and improve mass transfer and residence time, greatly enhancing the efficiency of plasma activation. In addition, the addition of surfactants improves the particle size of ultra-fine bubbles and further enhances the efficiency of plasma activation, thereby realizing the large-scale preparation of plasma-activated liquid.

[0034] (4) The device for large-scale preparation of plasma-activated liquid in the present invention can achieve the switching or coexistence of two discharge modes through different voltage or gas flow ranges, and can activate various different liquid media (deionized water, physiological saline, cell culture medium or artificial seawater), showing great potential applications in the microbial disinfection of various scenarios (seawater aquaculture, medical treatment, cell and tissue engineering).

[0035] (5) In the device for large-scale preparation of plasma activation liquid of the present invention, the solar plasma generator system has a hybrid power supply mode of solar energy and traditional power supply, with the advantages of low carbon environmental protection, economy and energy saving, and is applicable to areas with power shortage and field environments, especially having significant advantages in remote areas or emergency situations. Description of the Drawings

[0036] Figure 1 It is a schematic structural diagram of the device for large-scale preparation of hybrid plasma activation liquid of the present invention.

[0037] Reference Signs: 1, water tank; 2, solar plasma generator system; 3, gas supply system; 4, grounding electrode lead; 5-1, first hybrid plasma reactor; 5-2, second hybrid plasma reactor; 6, water body inlet; 7, water body outlet; 8, foldable solar panel power generation system; 9, plasma power supply; 10, high-voltage transformer; 11, gas source; 12, air pump; 13, gas mixing tank; 14, flow controller; 15, switch valve; 16, second high-voltage electrode; 17, first high-voltage electrode; 18, radiator; 19, quartz dielectric tube; 20, microporous aerator; 21, Pall ring; 22, gas inlet; 23, stainless steel rod grounding electrode.

[0038] Figure 2 It is a schematic diagram of the second high-voltage electrode, the first high-voltage electrode and the stainless steel rod grounding electrode in the device for large-scale preparation of hybrid plasma activation liquid of the present invention.

[0039] Figure 3 It is the bactericidal effect of Escherichia coli with different volumes (10L, 15L, 20L and 30L) of plasma activation liquid in Example 1 of the present invention.

[0040] Figure 4 It is the bactericidal effect of the hybrid plasma activation liquid on different common foodborne pathogenic bacteria (Escherichia coli, mold, Staphylococcus aureus, Salmonella, Listeria monocytogenes and Clostridium botulinum) on the food surface in Example 2 of the present invention.

[0041] Figure 5 It is the bactericidal effect of the hybrid plasma activation liquid on Escherichia coli on the surfaces of food packaging and processing equipment made of different materials (quartz, metal, glass, stainless steel, plastic and paper) in Example 3 of the present invention.

[0042] Figure 6 It is a comparison chart of the concentrations of five typical gaseous reaction substances between the large-scale preparation equipment of the hybrid plasma activation liquid in Example 1 and Comparative Examples 1-2 of the present invention and other different comparative examples.

[0043] Figure 7This is a comparison chart of the bactericidal effects of the mixed plasma activation solutions prepared in Example 1, Comparative Examples 1-4, and Example 4 of the present invention against Escherichia coli. Detailed implementation manners

[0044] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0045] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific implementation manners of the specification of the present invention, which are obvious to those skilled in the art. Other implementation manners obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are only exemplary.

[0046] Regarding the use of "including", "provided with", etc. in this article, they are all open-ended terms, that is, they are meant to include but not limited to.

[0047] Example 1

[0048] Please refer to Figures 1 - 2 , the device for large-scale preparation of plasma activation solution of the present invention includes a water tank 1, a solar plasma generator system 2, a gas supply system 3, a grounding electrode lead 4, a mixed plasma reaction 5-1 and a mixed plasma reaction 5-2. The water tank 1 is used to hold the aqueous solution to be treated, and is provided with a water inlet 6 and a water outlet 7; the solar plasma generator system 2 includes a foldable solar panel power generation system 8, a plasma power supply 9, and a high-voltage transformer 10, which can use power or solar power to drive the mixed plasma generation system 5; the gas supply system 3 includes a gas source 11, a gas pump 12, a gas mixing tank 13, a flow controller 14, and a switching valve 15. The gas source 11 provides the working gas, and the working gas enters the gas mixing tank 13 through the gas supply pipeline, and then supplies the working gas with a certain pressure and flow rate to the mixed plasma reaction 5-1 and the mixed plasma reaction 5-2 through the flow controller 14; the grounding electrode lead 4 needs to be installed below the liquid level, and can be installed at the bottom of the water tank, on the side or suspended in the water.

[0049] The structures of the hybrid plasma reactors 5-1 and 5-2 are exactly the same, and they are respectively connected to the positive and negative electrodes of the plasma power supply 9. The hybrid plasma reactor includes a quartz dielectric tube 19, a second high-voltage electrode 16, a first high-voltage electrode 17, a radiator 18, a stainless-steel rod grounding electrode 23, a microporous aerator 20, and Pall rings 21. The second high-voltage electrode 16, the first high-voltage electrode 17, and the stainless-steel rod grounding electrode 23 are fixed inside the quartz dielectric tube 19, and the second high-voltage electrode 16 is welded to the lower end of the first high-voltage electrode 17. The first high-voltage electrode 17 is a metal tube that sleeves the outside of the stainless-steel rod grounding electrode 23, and the stainless-steel rod grounding electrode 23 is located at the center of the first high-voltage electrode 17; a dielectric layer is provided on the inner surface of the first high-voltage electrode 17, and the dielectric layer is borosilicate and covers the inner surface of the first high-voltage electrode 17. The inner and outer layers of the quartz dielectric tube 19 are covered with insulators, and a gas inlet 22 is installed at the upper end. The microporous aerator 20 is evenly distributed around the bottom of the quartz tube dielectric tube 19, and the number is set to be multiple. The Pall rings 21 can be placed as fillers outside the microporous aerator 20. The radiator 18 is closely attached to the outer layer of the quartz dielectric tube 19 to ensure that the temperature generated by the plasma discharge does not affect the normal operation of the hybrid plasma reactor.

[0050] The working gas enters the quartz dielectric tube from the gas inlet at the top of the quartz dielectric tube, and dielectric barrier discharge plasma is generated between the first high-voltage electrode 17 and the stainless-steel rod grounding electrode 23; sliding arc discharge plasma is generated between the second high-voltage electrode 16 and the stainless-steel rod grounding electrode 23; the dielectric barrier discharge plasma and the sliding arc discharge plasma form hybrid plasma and are dispersed into the water body in the water tank from the gas outlet below the dielectric tube. The water body can be deionized water, physiological saline, cell culture medium or artificial seawater. The water body is added with a surfactant so that the plasma gas forms ultra-fine nano-bubbles in the liquid containing the surfactant. The diameter of the ultra-fine nano-bubbles is 50 nm - 1 μm. In this embodiment, the surfactant can be fatty alcohol polyoxyethylene ether (such as surfactant AI-600), polyethylene glycol fatty acid ester (such as Tween series), polyvinyl alcohol (PVA), etc. These non-ionic surfactants have stable chemical properties and low sensitivity to pH, and are suitable for a variety of water body environments. In addition, these surfactants can significantly reduce the surface tension and promote the formation of ultra-fine nano-bubbles.

[0051] In this embodiment, the above-mentioned working gas can be different mixed gases or single gases. The working gas is humidified by washing the gas source and then pumped into the hybrid plasma reaction 5-1 and the hybrid plasma reaction 5-2.

[0052] In this embodiment, the above-mentioned plasma power supply 9 can provide up to 10 - 80 kV (Vp-p ) high-voltage pulses with a repetition pulse frequency of 100 - 3000 Hz. The gas supply system 3 can provide a working gas with a flow rate of 5 - 15 L / min, and two discharge modes can be switched or coexist by different voltage or gas flow rate ranges. Specifically, the voltage range for the single dielectric barrier discharge mode is 10 - 30 kV (V p-p ), the frequency is 100 - 500 Hz, and the gas flow rate is 5 - 10 L / min; while the voltage range for the single sliding arc discharge mode is 20 - 40 kV (V p-p ), the frequency is 500 - 3000 Hz, and the gas flow rate is 10 - 15 L / min. If two discharge modes need to coexist, the voltage can be controlled at 20 - 30 kV (V p-p ), the frequency is controlled at 300 - 1000 Hz, and the gas flow rate is controlled at 8 - 12 L / min.

[0053] Inoculate a single Escherichia coli colony into Luria - Bertani broth containing 3% NaCl at 37 °C and incubate at 37 °C for 24 h. The bacterial concentration is approximately 1.0×10 8 CFU / mL. Take 10.0 mL of the cultured Escherichia coli suspension, centrifuge at 5000 rpm for 10 min, and resuspend it in the pre - prepared aqueous solution to be treated (10 L, 15 L, 20 L, and 30 L). The final concentrations are 1.0×10 6 CFU / mL for subsequent water body microbial disinfection experiments.

[0054] Select the prepared bacterial suspension as the test water body and process it through the device for large - scale preparation of plasma activation solution. The processing steps are as follows:

[0055] S1: Pass the aqueous solutions to be treated with different volumes (10 L, 15 L, 20 L, and 30 L) into the water tank through the water inlet, and add a surfactant to the aqueous solution to be treated;

[0056] S2: Turn on the gas supply system, pass compressed air with a humidified flow rate of 10 L / min into the hybrid plasma reactor, then turn on the solar plasma generator system, and generate hybrid plasma in the first hybrid plasma reactor and the second hybrid plasma reactor under the conditions of a discharge voltage of 30 kV, an excitation frequency of 1000 Hz, and an ultra - fine nanobubble particle size of 150 nm for 1 min.

[0057] S3: The hybrid plasma reaches the microporous aerator at the bottom of the quartz tube dielectric tube along with the gas flow, and the hybrid plasma activation gas forms ultra - fine nanobubbles through the micropores and is dispersed into the liquid flow.

[0058] The standard spread plate method is used to determine the number of bacterial colonies. Through Figure 3It can be concluded that within a short discharge time (1 min), the large-scale preparation equipment for the hybrid plasma activation solution can efficiently generate an effective hybrid plasma activation solution, thereby reducing the Escherichia coli colonies by at least 6 logarithmic orders. In addition, the large-scale preparation equipment for the hybrid plasma activation solution can improve the energy efficiency of the hybrid plasma activation solution while increasing the liquid volume (from 10 L to 30 L). Even when the aqueous solution volume reaches 30 L, a hybrid plasma activation solution that can reduce the Escherichia coli colonies by 5.2 logarithmic orders can still be prepared within 1 min. This is because industrial applications require the production of a larger amount of effective plasma activation solution while minimizing energy consumption.

[0059] Example 2

[0060] The device for large-scale preparation of plasma activation solution in Example 1 was used to kill bacteria in food.

[0061] The preparation process of the hybrid plasma activation solution is as follows:

[0062] S1: The aqueous solution to be treated is introduced into the water tank through the water inlet, and a surfactant is added to the aqueous solution to be treated;

[0063] S2: The air supply system is turned on, and humidified compressed air with a flow rate of 10 L / min is introduced into the hybrid plasma reactor. Then, the solar plasma generator system is turned on, and hybrid plasma is generated in the first hybrid plasma reactor and the second hybrid plasma reactor under the conditions of a discharge voltage of 50 kV, an excitation frequency of 1000 Hz, and an ultra-fine nano-bubble diameter of 150 nm for 1 min to obtain the hybrid plasma activation solution.

[0064] The hybrid plasma activation solution prepared in this example was applied to the surface of food inoculated with different strain colonies (bacterial concentration of about 1.0×10 6 CFU / mL) by spraying, and the test results are as Figure 4 shown. It can be Figure 4 concluded that the six most common foodborne pathogenic bacteria in food sterilization applications, namely Escherichia coli, mold, Staphylococcus aureus, Salmonella, Listeria monocytogenes, and Clostridium botulinum, were completely inactivated. In addition, any mode of action (rinsing, spraying, soaking, wiping, dripping, and coating) can achieve complete inactivation, which also means that the present invention can be adapted to different food processing scenarios (such as large-scale production lines, small-scale manual operations, retail packaging, etc.).

[0065] Example 3

[0066] The device for large-scale preparation of plasma activation solution in Example 1 was used to kill bacteria in food.

[0067] The preparation process of the mixed plasma activation liquid is as follows:

[0068] S1: Pass the aqueous solution to be treated into the water tank through the water inlet of the water body, and add a surfactant to the aqueous solution to be treated;

[0069] S2: Turn on the gas supply system, pass compressed air with a humidified flow rate of 10 L / min into the hybrid plasma reactor, then turn on the solar plasma generator system, and generate hybrid plasma in the first hybrid plasma reactor and the second hybrid plasma reactor under the conditions of a discharge voltage of 50 kV, an excitation frequency of 1000 Hz, and an ultra-fine nano-bubble diameter of 150 nm for 1 min to obtain the mixed plasma activation liquid.

[0070] The mixed plasma activation liquid prepared in this example was applied by spraying onto the surfaces of different food packaging materials and processing equipment (quartz, metal, glass, stainless steel, plastic, and paper) inoculated with Escherichia coli (bacterial concentration of about 1.0×10 6 CFU / mL), and the test results are as Figure 4 shown. It can be Figure 4 seen that Escherichia coli on the surfaces of six different materials of food packaging and processing equipment all achieved good sterilization efficiency. According to the surface properties, reactivity, and interaction with plasma of different materials, there are slight variations in the sterilization efficiency among materials, but overall, it can meet the sterilization requirements for the surfaces of food packaging materials and processing equipment.

[0071] Comparative Example 1

[0072] Select 20 L of the prepared bacterial suspension as the test water body. The device for preparing the mixed plasma activation liquid is compared with that in Example 1, and only the spiral electrode at the lower end of the high-voltage electrode of the mixed plasma reactor is removed, but the dual-reactor configuration in an AC circuit is still maintained (one is connected to the positive terminal, and the other is connected to the negative terminal). The prepared bacterial suspension was subjected to dielectric barrier discharge plasma treatment for 1 min under the conditions of a discharge voltage of 30 kV, an excitation frequency of 500 Hz, an ultra-fine nano-bubble diameter of 100 nm, and compressed air with a flow rate of 5 L / min as the working gas.

[0073] Comparative Example 2

[0074] Select 20 L of the prepared bacterial suspension as the test water body. The device for preparing the mixed plasma activating solution is compared with that of Example 1. Only the first high-voltage electrode of the mixed plasma reactor is removed, but a dual-reactor configuration within an AC circuit is still maintained (one connected to the positive terminal and the other connected to the negative terminal). The prepared bacterial suspension is subjected to sliding arc discharge plasma treatment for 1 min under the conditions of a discharge voltage of 40 kV, an excitation frequency of 2000 Hz, an ultra-fine nano-bubble size of 200 nm, and compressed air as the working gas at a flow rate of 15 L / min.

[0075] Comparative Example 3

[0076] Select 20 L of the prepared bacterial suspension as the test water body. The device for preparing the mixed plasma activating solution is compared with that of Example 1. The helical electrode at the lower end of the high-voltage electrode in the mixed plasma reactor is removed, and a single mixed plasma reactor configuration is adopted, that is, the circuit is completed by connecting the negative electrode to the stainless steel rod grounding electrode in the plasma bubble reactor. The prepared bacterial suspension is subjected to dielectric barrier discharge plasma treatment for 1 min under the conditions of a discharge voltage of 30 kV, an excitation frequency of 500 Hz, an ultra-fine nano-bubble size of 100 nm, and compressed air as the working gas at a flow rate of 5 L / min.

[0077] Comparative Example 4

[0078] Select 20 L of the prepared bacterial suspension as the test water body. The device for preparing the mixed plasma activating solution is compared with that of Example 1. Only the first high-voltage electrode of the mixed plasma reactor is removed, and a single plasma bubble reactor configuration is adopted, that is, the circuit is completed by connecting the negative electrode to the stainless steel rod grounding electrode in the plasma bubble reactor. The prepared bacterial suspension is subjected to sliding arc discharge plasma treatment for 1 min under the conditions of a discharge voltage of 40 kV, an excitation frequency of 2000 Hz, an ultra-fine nano-bubble size of 200 nm, and compressed air as the working gas at a flow rate of 15 L / min.

[0079] Example 4

[0080] Select 20 L of the prepared bacterial suspension as the test water body. Use the same large-scale preparation equipment for the mixed plasma activating solution as in Example 1, and only remove the Pall rings in the mixed plasma generation system. The prepared bacterial suspension is subjected to mixed plasma treatment for 1 min under the conditions of a discharge voltage of 30 kV, an excitation frequency of 1000 Hz, an ultra-fine nano-bubble size of 150 nm, and compressed air as the working gas at a flow rate of 10 L / min.

[0081] Figure 6Concentrations of five typical gaseous reaction substances in the mixed plasma activation liquid prepared by the large-scale preparation equipment for the mixed plasma activation liquid in Example 1 and Comparative Examples 1-2 of the present invention. It should be noted that the solubilities of O3, NO, and NO2 are very low. Therefore, neither dielectric barrier discharge mode nor sliding arc discharge mode of air plasma can effectively activate water. The Henry coefficient of NO2 is only 1.2×10 -4 MPa -1 , and the Henry coefficients of O3 and NO are even lower. In contrast, the main discharge products of the mixed plasma in Example 1 of the present invention are high-valence NO x (such as N2O5 and NO3). Therefore, the activation efficiency of water may be much higher. This is because high-valence nitrogen oxides are easily soluble in water through reaction absorption, and their oxidation reaction activity is also higher than that of NO and NO2, which is positively correlated with the sterilization effect.

[0082] Figure 7 Inactivation efficiency of Escherichia coli by the large-scale preparation equipment for the mixed plasma activation liquid in Example 1, Comparative Examples 1-4, and Example 4 of the present invention and other different comparative examples. In contrast, the large-scale preparation equipment for the mixed plasma activation liquid in Example 1 of the present invention has better sterilization efficiency, and the double reactor configuration has lower energy consumption.

[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the described embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. Apparatus for large-scale preparation of plasma activation liquid, characterized in that, It includes a power supply, a gas supply system, a water tank, and at least one hybrid plasma reactor; the hybrid plasma reactor is arranged in the water tank; The hybrid plasma reactor includes a dielectric tube, a rod-shaped grounded electrode, a first high-voltage electrode, and a second high-voltage electrode; the rod-shaped grounded electrode, the first high-voltage electrode, and the second high-voltage electrode are fixed inside the dielectric tube; The first high-voltage electrode is a metal tube that sleeves outside the rod-shaped grounded electrode, and the rod-shaped grounded electrode is located at the center of the first high-voltage electrode; a dielectric layer is provided on the inner surface of the first high-voltage electrode; The second high-voltage electrode is arranged below the first high-voltage electrode and sleeves outside the rod-shaped grounded electrode, and the rod-shaped grounded electrode is located at the center of the second high-voltage electrode; The working gas in the gas supply system enters the dielectric tube through the air inlet at the top of the dielectric tube, and dielectric barrier discharge plasma is generated between the first high-voltage electrode and the rod-shaped grounded electrode; Gliding arc discharge plasma is generated between the second high-voltage electrode and the rod-shaped grounded electrode; The dielectric barrier discharge plasma and the gliding arc discharge plasma form hybrid plasma and disperse into the liquid in the water tank from the air outlet below the dielectric tube to obtain plasma-activated liquid.

2. The apparatus for large-scale preparation of plasma activation liquid according to claim 1, wherein The working gas enters the dielectric tube at a flow rate of 5-15 L / min.

3. The apparatus for large-scale preparation of plasma activation liquid according to claim 1, characterized in that, The second high-voltage electrode has a spiral structure, and its radius increases sequentially from top to bottom.

4. The apparatus for large-scale preparation of plasma activation liquid according to claim 3, characterized in that, The second high-voltage electrode is welded to the lower end of the first high-voltage electrode.

5. The apparatus for large-scale preparation of plasma activation liquid according to claim 1, characterized in that, A plurality of microporous aerators are provided at the air outlet below the dielectric tube; a Pall ring is provided outside the microporous aerator.

6. The apparatus for large-scale preparation of plasma activation liquid according to claim 5, characterized in that, Surfactant is added to the liquid in the water tank; the hybrid plasma forms bubbles with a particle size of 50 nm - 1 μm in the liquid; the surfactant is fatty alcohol polyoxyethylene ether, polyethylene glycol fatty acid ester, or polyvinyl alcohol.

7. The device for large-scale preparation of plasma activation liquid according to claim 1, characterized in that The dielectric layer is borosilicate and covers the inner surface of the first high-voltage electrode.

8. The device for large-scale preparation of plasma activation liquid according to claim 1, characterized in that, There are two hybrid plasma reactors, one of which is connected to the positive pole of the power supply and the other is connected to the negative pole of the power supply.

9. The apparatus for large-scale preparation of plasma activation liquid according to claim 1, characterized in that It also includes a humidifying device for humidifying the working gas.

10. Use of the apparatus for large-scale preparation of plasma activation liquid according to claim 1 in food sterilization, characterized in that, The plasma-activated liquid prepared by the device for large-scale preparation of plasma-activated liquid is used for disinfection and killing of Escherichia coli, mold, Staphylococcus aureus, Salmonella, Listeria monocytogenes, and Clostridium botulinum in food, food packaging, and food processing equipment; the disinfection and killing methods include at least one of flushing, spraying, soaking, wiping, dripping, and coating; the materials of the food packaging and food processing equipment include at least one of quartz, metal, glass, stainless steel, plastic, and paper.

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