WO2022146186A1

WO2022146186A1 - Method and device for the super high frequency plasma activation of water for hydrogen peroxide synthesis

Info

Publication number: WO2022146186A1
Application number: PCT/RU2021/000594
Authority: WO
Inventors: Константин Фёдорович СЕРГЕЙЧЕВ; Валерий Борисович ХАВАЕВ; Наталия Александровна ЛУКИНА
Original assignee: Общество С Ограниченной Ответственностью "Вандер Технолоджис"
Priority date: 2020-12-30
Filing date: 2021-12-27
Publication date: 2022-07-07
Also published as: RU2761437C1

Abstract

The invention relates to a method for producing chemically pure hydrogen peroxide in the form of an aqueous solution and to a device for carrying out same. The claimed method for the super high frequency plasma activation of water for the synthesis of hydrogen peroxide is based on the continuous generation of plasma by an electrodeless torch discharge created by a SHF plasmatron that generates, in a vapour-gas medium in a hermetically sealed chamber, a directed jet of low-temperature plasma of an inert gas for acting on water to be processed and on steam. With the aid of a steam generator, an additional flow of steam is created, which is fed to the SHF plasmatron coaxially with the directed flow of inert gas plasma; during the plasma activation of the water, the steam is condensed and the resulting condensate is sent to the hermetically sealed chamber containing water to be processed.

Description

METHOD AND DEVICE FOR MICROWAVE PLASMA WATER ACTIVATION FOR HYDROGEN PEROXIDE SYNTHESIS

The invention relates to electrophysical methods for producing chemically pure hydrogen peroxide (hereinafter referred to as PV, chemical formula H2O2) in the form of an aqueous solution, as a result of direct exposure of water to electrodeless microwave discharge plasma in an inert gas environment and water vapor at atmospheric pressure and can be used in healthcare , medicine, food industry, crop production and other fields of technology where reactive oxygen species (hereinafter referred to as ROS) are used that are safely stored in an aqueous solution.

A known method for producing active water or a solution using a physical effect on water, characterized in that the role of a physical factor using ultraviolet (UV) radiation generated by gas-discharge sources in quartz shells with a power flux density incident on the water surface> 0.4 W/ cm ² (Patent RU 2 151 742 C1). UV radiation forms OH* radicals in water, precursors to the formation of H2O2. UV radiation was created, for example, by a mercury arc lamp (ARL). The UV cutoff of this quartz-clad lamp is 170 nm, which provides an output of the 185 nm mercury line with an energy of < 6.7 eV. There are sources of radiation in the vacuum part of the UV spectrum (hereinafter referred to as VUV) with photon energies of 10-15 eV, which does not exit through the quartz shell of the lamps. Such VUV sources can be implemented in open space near the surface of the activated water.

A known method of plasma activation of water or aqueous solutions, developed at the Institute of General Physics. A.M. Prokhorov RAS [1], [2], which is carried out as follows: in the volume of an aqueous electrolyte solution (for example, saline) form an electrode plasma discharge with high-frequency pumping. Plasma discharge electrodes are a "hot" metal electrode immersed in a liquid and a liquid quasi-electrode at the plasma-electrolyte interface. Formation of liquid quasi-electrode around the surface of the metal electrode leads to the formation of a uniform thickness (~ 1.5-1 O' ⁴ m) plasma layer of water vapor with a constant current density. Plasma is excited by high-frequency current with a pulse repetition rate of 110 kHz at an amplitude value of the voltage on the metal electrode up to 300 V. To close the electrical circuit, a second metal electrode of a larger area, also immersed in liquid, is used. The short circuit of the current between the electrodes inside the liquid is carried out if the water contains dissolved salts, i.e. is an electrolyte. The interaction of free hot electrons (e) of water vapor plasma with water molecules leads to their dissociation with the formation of ions and radicals (H- and H*) and OH* hydroxyl radicals, which, as a result of plasma-chemical reactions, lead to the formation of hydrogen and hydrogen peroxide H2O2.

This method of plasma activation of water or aqueous solutions makes it possible to obtain activated water containing HP - an effective plant growth regulator, but since the activation is contact - both electrodes are immersed in the activated liquid, the dissolution of the electrode material in water is inevitable, which does not allow the widespread use of the resulting water, activated by plasma, for example, in medicine.

Also known is a method for the synthesis of H2O2 with direct exposure to argon plasma on the surface of water, disclosed in the article "Direct synthesis of hydrogen peroxide in the interaction of plasma with water" [3], in which atmospheric pressure plasma is ignited from a direct current source with a voltage of 500 V in a gap 3 mm wide between two vertical electrodes, one of which is a tungsten tube through which argon is supplied into the gap, and the second is a metal pipe with an end open at the top, through which water flows upward from the edge of the pipe. Water contains an admixture of salt and is a conductive electrolyte, due to which charge transfer occurs between the tungsten tube and water through the plasma and the plasma interface and the aqueous electrolyte. The synthesis of H2O2 is a consequence of charge transfer phenomena in water, including sputtering, electric field-induced emission of hydrated ions, and evaporation. The H2O2 productivity reaches ~ 1200 µmol/h when the liquid cathode is purified water or an aqueous solution of NaCl with an initial conductivity of 10500 μS.

This method of plasma activation of water or aqueous solutions makes it possible to obtain activated water containing HP, but since the activation is contact, since both electrodes are immersed in the activated liquid, the dissolution of the electrode metal with the formation of oxides in the resulting solution under the influence of HP, which become catalysts for the decomposition of HP itself, is inevitable. HP, which, however, does not prevent the use of the activated solution during the lifetime of HP in agriculture for seed treatment and watering plants.

Closest to the claimed method in terms of technical essence and the problem to be solved is the method of plasma activation of water or aqueous solutions, in which a direct effect on the water surface is carried out with a jet of low-temperature argon plasma obtained by an electrodeless torch microwave plasma torch at atmospheric pressure (Patent RU No. 2702594, publ. 08.10 .2019). In this case, the activation of water proceeds simultaneously in two ways - by the direct action of the plasma on the surface of the water and by plasma radiation containing VUV. Compared with other electrophysical methods for obtaining HP solutions with accompanying chemical products, given that water should initially be an electrolyte with electrical conductivity, the advantage of this activation method is that distilled water can be used to obtain pure HP, which does not have electrical conductivity, as it is a dielectric.

Closest to the claimed device is a device for plasma activation of water or aqueous solutions (Patent RU No. 2702594, publ. 08.10. 2019). The device is a microwave plasma torch, consisting of a magnetron, its power source, a waveguide system, a gas supply system: argon used as a plasma-forming gas, nitrogen used as a gas that stabilizes the combustion of the torch, and, finally, the coaxial "torch" of the plasma torch itself , which forms a directed jet of argon plasma in the open atmosphere. The plasma jet touches surface of the treated water (aqueous solution) and can be partially immersed in it. The power of a torch microwave plasma torch can be 1 kW or more. The dense core of the plasma jet has a diameter of 0.2–0.3 cm and a jet length of ~3 cm for a microwave frequency of 2.45 GHz. The temperature of the gas in the plasma reaches (4-g-5)x10 ^{3 0} C, and the electron temperature is <1.5 eV. The high rate of argon outflow from a narrow nozzle 1.5 mm in diameter at the end of the inner conductor of the coaxial “burner” does not allow the torch discharge, the front of which moves along the argon jet towards the flow, to reach the nozzle, due to which the nozzle is not heated by the plasma, which allows this type of torch discharge is considered electrodeless. The absence of nozzle material lines in the optical emission spectrum of the plasma characterizes the absence of plasma contamination by the nozzle material.

To isolate the working part of the plasma torch (hereinafter referred to as the burner) from the air, it is placed through a seal into a sealed stainless steel chamber, in which the operation of the plasma torch on an outflowing argon jet is stabilized by molecular gases, such as nitrogen, which is additionally introduced into the plasma torch.

These method and device make it possible to obtain sufficiently pure activated solutions of HP that do not contain impurities, such as, for example, metal oxides, which can be catalysts for the decomposition of HP. Pure HP solutions can be stored for a long time even without the addition of stabilizing additives - HP inhibitors.

However, the mentioned method and device (Patent RU No. 2702594), despite their inherent advantages, have the following disadvantages. Thus, when the microwave field is turned on without first creating an atmosphere of molecular gas around the argon jet flowing inside the quartz tube, an arc discharge can occur between the nozzle and the wall of the coaxial screen of the plasma torch, and not the expected ionization of the argon jet with the formation of a torch. And, despite the presence of water or other medium under the plasma torch, the plasma torch can burn out. Molecular gas is needed as a gas insulator around the plasma torch nozzle, acting as a stabilizing combustion factor to protect the plasma torch from breakdown, turning into an arc discharge. Molecular gases, due to dissociation around the flame, break up into atoms and carried away by the flow do not have time to ionize to provoke an arc discharge. In this case, steam is formed on the water surface in a steady-state torch discharge during stabilization with nitrogen in the process of plasma activation.

Meanwhile, the formation of steam on the water surface in the prototype is unstable, which does not guarantee reliable operation of the plasma torch without the use of nitrogen as a stabilizing factor.

Thus, for reliable operation of the device and stable "burning" of the discharge, nitrogen is required, which in a high-temperature argon jet, when interacting with water and steam, forms nitrogen oxides that dissolve in water in the form of nitrites and nitrates (NO _X ) simultaneously with the formation of HP. The resulting activated water containing PS and nitrogen oxides is used in crop production as a complex growth regulator due to its stimulating effect on plant growth and seed germination, synergism of PS and NOX _oxides . Meanwhile, it is equally important to obtain solutions of pure HP without any accompanying compounds, in order to use them not only in agriculture, but also in other areas - biology and medicine. In particular, pure solutions of HP are used in hyperoxygenation therapy of cancer in the form of injections [4].

Another disadvantage of the prototype in the implementation of plasma activation of water or aqueous solutions in the air is the loss of activated steam generated in the zone of interaction of hot plasma with water, since the steam is removed along with the exhaust gases into the ventilation, which reduces the efficiency of this method for obtaining activated water.

The main objective of the proposed method and device for microwave plasma activation of water or aqueous solutions for the synthesis of hydrogen peroxide is to obtain a pure solution of HP in a water-steam atmosphere using an inert gas (argon) plasma, excluding the appearance of nitrogen oxides or other impurities in the solution, as well as eliminating losses from the activated steam reactor.

The technical result of the claimed group of inventions is an increase in the degree of purity of an aqueous solution of HP by eliminating impurities of nitrates, and increasing the reliability of the device by stabilizing its operation with a steam flow instead of nitrogen, and, thereby, eliminating its failure.

Additionally, an increase in the efficiency and productivity of the device is achieved by completely eliminating losses from the activated steam reactor, as well as expanding the scope of the obtained PS, since the absence of nitrogen oxides and other impurities in it will allow the use of the PS solution not only in agriculture, but also in other areas - biology and medicine.

The technical result is achieved by the fact that in the known method of microwave - plasma activation of water for the synthesis of hydrogen peroxide, based on the continuous generation of plasma by an electrodeless torch discharge, which is created by a microwave plasma torch generating in a vapor-gas medium a directed jet of low-temperature inert gas plasma acting on the treated water and water steam resulting from the evaporation of the surface layer of water in a sealed chamber under the influence of a gas-plasma jet creates an additional flow of water vapor, which is fed into the microwave plasma torch to a coaxially directed flow of inert gas plasma, in the process of plasma activation of water, steam is condensed, and the resulting condensate is sent to a sealed treated water chamber.

Helium or argon is preferably used as the inert gas. A directed jet of low-temperature plasma is brought to the surface of water or an aqueous solution or partially immersed in it.

The flow of water vapor is passed through the plasma torch through the coaxial channel of the plasma torch, formed by a quartz or ceramic insulator tube.

The vapor condensation is preferably carried out in a condenser mounted vertically above a sealed chamber, with the resulting condensate being returned to the plasma-activated aqueous solution chamber.

It is optimal to regulate the rate of supply of inert gas, steam, the level of microwave power of the discharge and the rate of withdrawal of water with hydrogen peroxide using an automatic control system. It is preferable to remove the spent inert gas through a condenser.

The technical result is also achieved by the fact that in the known device for microwave plasma activation of water for the synthesis of hydrogen peroxide, containing a microwave plasma torch, including a magnetron, a rectangular waveguide and a coaxial waveguide containing a central conductor, and the working part of the microwave plasma torch is placed in a sealed chamber with treated water, and a compressed gas cylinder connected to the central conductor, a steam generator connected to the coaxial waveguide of the plasma torch, and a capacitor connected to the sealed chamber are additionally introduced.

It is preferable to install the condenser vertically above a sealed chamber connected to the condenser through a branch pipe.

The pipeline connecting the steam generator with the plasma torch is preferably provided with thermal insulation.

The central conductor of the coaxial waveguide can be made in the form of a copper tube containing a nozzle for forming a directed jet of plasma gas.

Optimally, the coaxial waveguide is hermetically isolated from the rectangular waveguide with a radio-transparent quartz insulator tube.

The condenser may have a shell-and-tube design, provided in the upper part with a valve for the release of inert gas into the atmosphere.

The sealed chamber contains an adjustable drain valve.

The device may further comprise a circulator with an absorbing load.

It is preferable to introduce an automatic control system into the device, which is configured to control the steam supply rate, the microwave power level of the discharge, and the treated water withdrawal rate to ensure a constant water level in the reactor.

The sealed chamber can be equipped with a water level sensor.

It is optimal to make a sealed chamber with optically transparent windows for monitoring the characteristics of a plasma torch using optical emission and absorption spectra recorded using spectrometers. The sealed chamber and condenser contain water cooling circuits.

The sealed chamber may further comprise a container for treated water.

The specified set of distinctive essential features of the proposed method and device provides reliable and stable operation of the microwave plasma torch due to the use of water vapor supplied to the plasma torch instead of nitrogen in connection with the following. The use of molecular gases of the chemical elements that make up water: oxygen or hydrogen for the same purpose is unsafe due to the problems generated by their chemical activity. Thus, argon plasma in an oxygen environment can provoke chemical combustion of the plasma torch nozzle, the transition of the torch discharge mode to an arc discharge with damage to all important parts of the plasma torch: the nozzle, the insulating quartz tube and the coaxial waveguide, which will lead to the complete failure of the plasma torch. Ignition of a discharge in a hydrogen atmosphere is explosive due to the possible presence of oxygen or air residues in the reactor chamber at the start. As a result, the most preferable option for solving the problem of torch discharge combustion stabilization is the use of water vapor, which is a product of combustion, but is safe at atmospheric pressure in combination with argon plasma. In the claimed invention, only water, water vapor and an inert gas, such as argon, are involved in the reactions. At the same time, the introduction of a steam generator makes it possible to additionally implement two functions, one of which is the preparation of steam to stabilize the burning of the torch, and the other is the continuous replenishment of the sealed chamber with water to maintain its level by condensing the steam and returning it from the condenser to the chamber. In the prototype, the water treatment process was not in-line (continuous), in which the chamber was filled with a given amount of water, which decreased during treatment due to water loss along with steam leaving with argon.

At the same time, in connection with the implementation of a practically continuous process for the production of hydrogen peroxide in the claimed device, an additional technical result arises - an increase in efficiency due to the elimination of steam losses from the reactor. In the technical solution for the prototype steam with exhaust argon is removed through ventilation, and in the inventive device, using a condenser installed above a sealed chamber, steam in the form of condensate is returned to the chamber, and exhaust argon is removed.

Thus, the use of an independent source of steam, which is created not in the chamber itself, but outside it, and is passed through a quartz tube, which acts as a vapor insulator that protects the plasma torch from arcing between the nozzle and the screen of the coaxial waveguide, makes it possible to ensure reliable operation of the plasma torch, due to creation of a stable torch burning mode.

This eliminates the need to use molecular gases, including the safest in terms of breakdown - nitrogen. The exclusion of nitrogen eliminates the presence of nitrogen oxides dissolved in water, the concentration of which can be many times higher than the concentration of hydrogen peroxide. In this case, argon, water, and water vapor from the steam generator remain as the main components of the interaction. As a result, a continuous production of high purity hydrogen peroxide is ensured.

Water vapor is difficult to ionize, since even a relatively small concentration of it is sufficient to ensure that the torch discharge does not go into the destructive arc discharge mode.

The use of water vapor instead of nitrogen to maintain stable combustion of the microwave flame allows you to achieve the following advantages: reliable stabilization of the combustion of the microwave flame; exclusion of diverse chemical reactions in combination with various chemical elements (except hydrogen and oxygen); organization of a continuous cycle of water replenishment with steam supply and selection of activated water (solution) without stopping the microwave treatment process.

The inventive method and device are illustrated by the following drawings.

In FIG. 1 schematically shows the design of the proposed device

In FIG. 2 shows a top view of the design of the proposed device The device for non-contact plasma activation of water or aqueous solutions contains a microwave plasma torch 1, including a magnetron generator 2, rectangular 3 and coaxial 4 waveguides. The internal volume of the coaxial waveguide 4 is hermetically sealed from the volume of the rectangular waveguide 3 by a quartz insulator tube 5 mounted on Viton sealing rings 6. The central conductor 7 of the coaxial waveguide 4 is a copper tube for supplying a plasma-forming inert gas, for example, argon or helium, coming from a cylinder 8 with compressed gas through a reducer 9. The central conductor 7 ends with a nozzle 10 with a hole, for example, 1.5 mm in diameter to form a directed jet of inert gas, in which, as a result of ionization under the action of a microwave field, a plasma jet 11 is formed. The plasma torch 1 is placed through a gland seal 12 made of Viton into a hermetic chamber 13 made of stainless steel with double walls 14 forming a water cooling circuit of the chamber filled with treated water or an aqueous solution. The sealed chamber can be equipped with an additional container (not shown in the drawing) in which the treated water can be placed. The pressure in the chamber 13 is maintained above atmospheric p>1 atm, while argon and part of the water vapor from the sealed chamber 13 exit through the outlet pipe 15, to which the condenser 16 is connected from above, having a shell-and-tube design, and the water cooling circuit 17. Steam, condenses in the hollow tubes of the condenser 16, the condensate flows into the chamber 13, and the plasma-forming gas through the valve 18 (figure 1) goes into the atmosphere, or can be used in the further operation of the device.

For efficient transfer of microwave power from magnetron 2 to the plasma torch, the adjustment of the matching of the microwave plasma torch by piston 19 is used (Fig. 2).

The protection of the magnetron 2 from the reflected wave when the plasma flame from the nozzle 10 is extinguished is provided by the circulator 20 with an absorbing load 21, which removes the energy of the reflected wave through the waveguide branch 22 to the load 21, which has its own water cooling circuit (not shown in the drawings). Sealed chamber 13 is filled with treated water (water solution) to a predetermined operating level, which is maintained unchanged, for example, using an automatic control system (hereinafter referred to as ACS) during the entire time of water treatment with a plasma torch. ACS maintains optimal conditions for water treatment (or aqueous solution) in the area of contact between the plasma torch and the water surface. The ACS is connected to a liquid level sensor 23 installed in the chamber 13. The level sensor 23 can be made in various versions. For example, it can be a float with a reed switch (hermetic contact) with a normally closed/open contact that operates near a magnet fixed on the wall of the chamber 13. For visual observation of the torch, optically transparent windows 24 can be made in the chamber 13, through which it is also possible to monitor the characteristics plasma torch 11 according to optical emission and absorption spectra recorded using a spectrometer 25.

To stabilize the operation of the microwave plasma torch with steam, it is fed into the plasma torch from the steam generator 26 through the pipeline 28 and the valve 27, creating a coaxial flow of water vapor around the nozzle and the burning plasma torch 11. To prevent steam condensation in pipeline 28 and valve 27, a thermal insulation layer (not shown in the drawings) is provided, due to which they are heated to an equilibrium temperature by the flow of the steam itself. When the discharge is stabilized by steam, the volume of water in the chamber 13 will increase due to water from the condensed steam, which can lead to excessive flooding of the plasma torch 11 and the termination of the stable operation of the plasma torch. Therefore, it is necessary to continuously maintain a balance between the supply of water with steam and the withdrawal of treated water through an adjustable drain valve 29. This balance can be maintained by the ACS, the control algorithm of which is based on maintaining a constant water level in the chamber 13, controlled by a level sensor 23. The ACS is connected to the system gas supply, represented by a cylinder of compressed gas 8 and a reducer 9, a steam generator 26, a water supply system (not shown in the drawings), a high-voltage magnetron power supply (not shown in the drawings), with a water level sensor 23 and an adjustable drain valve 29 for sampling water from sealed chamber 13. When the water level in the chamber 13 exceeds the set value, the signal from the sensor 23 is sent to the automatic control system to control the rate of water withdrawal or limit the supply of steam. When the water level in the chamber decreases, when the plasma torch I goes out of contact with water, as a result of which the efficiency of water treatment is sharply reduced, the sensor 23 sends a signal to the automatic control system, which accordingly sends a control signal to reduce the rate of water withdrawal or increase the steam flow in accordance with the specified algorithm. The function of controlling the selection of water or regulating the supply of steam is implemented using an adjustable valve 27 and an adjustable drain cock 29, controlled by ACS.

The condenser 16 has a shell-and-tube design and is a heat exchanger used to condense steam on the inner surface of thin stainless steel tubes, combined into a cassette enclosed inside the casing tube. The outer surface of the tubes of the condenser 16 is cooled by water inside the casing coming from the water cooling circuit 17. The total surface of the tubes is designed for complete condensation of the steam entering the refrigerator even at maximum steam generation modes. Steam does not reach the valve 18 of the condenser 16, turning into condensate on the way to it, which flows into the chamber 13 through the pipe 15. its contact with the torch plasma heated to 4000 K. The ratio of the intensity of steam generation by both sources can be controlled by changing the power of the external steam generator and varying the degree of contact between the flame plasma and water. At the same time, a change in the level of the microwave power of the discharge entails a change in the steam supply rate to stabilize the discharge and the rate of water withdrawal, according to a given algorithm, according to which the ACS operates, which controls the operation of the units and blocks of the device.

The power of the magnetron of the torch microwave plasma torch can be 700-6000 W. As a source of plasma in the proposed method of non-contact plasma activation of water or aqueous solutions, a torch microwave plasma torch 1 with capacitive coupling is used, which generates a jet of low-temperature plasma in a vapor-gas medium at atmospheric pressure, directed from above way down. The plasma column of the torch is formed in the jet of inert gas flowing out of the nozzle 10 as a result of its ionization. The microwave field of the surface electromagnetic wave is self-supported by the boundaries of the plasma column. The transverse dimensions of the plasma column are determined by the gas-dynamic characteristics of the nozzle. The length of the conductive plasma column is determined by the optimal length for an asymmetric radiating dipole antenna, equal to a quarter of the microwave wavelength in a vacuum.

The high speed of gas outflow from the narrow nozzle 10 does not allow the torch discharge 11, the front of which moves in the opposite direction towards the flow, to reach the nozzle, while the nozzle does not heat up, which allows this type of torch discharge to be considered electrodeless. When a liquid boundary appears on the path of the plasma jet, the gas-plasma jet squeezes out a pit in the form of a “meniscus” on the liquid surface and spreads to the sides and upwards symmetrically from the center of the meniscus along its surface in accordance with the laws of gas dynamics.

In the prior art, it is known to use a microwave torch-type plasma torch at atmospheric pressure in optical emission spectroscopy (OES) as a source of compressed brightly luminous pure plasma [5] used for processing, excitation and analysis of gaseous media [6]. Due to its small volume, the flame ignites and burns stably in an environment of molecular vapors and gases at atmospheric pressure, even at relatively low microwave power < 900 W, which can be obtained from commercially available magnetrons, for example, household microwave ovens. The self-compressed form of the plasma torch has a high specific density of absorbed microwave power < 10 ⁴ W/cm3, comparable to the specific density in the DC arc.

At a sufficiently high flow rate of the argon jet, the plasma torch is torn off from the nozzle, due to which the torch microwave discharge belongs to the category of electrodeless discharges.

The inventive device that implements the method of microwave - plasma activation of water works as follows.

The magnetron generator 2, which serves as a source of energy for the torch microwave plasma torch 1, operates in the continuous generation mode. In this case, a wave of the lowest type TEU is excited in the rectangular waveguide 3, which then it is converted into a TEM wave of the coaxial waveguide 4. The copper tube 7, which is the central conductor of the coaxial waveguide 4 and ends with a narrow nozzle 10, is supplied with plasma-forming gas (argon) from a compressed gas cylinder 8, the jet of which flows out of the nozzle 10 at a relatively high speed (flow rate argon is 3-5 liters per minute of a standard atmosphere), and as a result of ionization under the action of a microwave field, it turns into a plasma torch 11.

An inert gas, such as argon, entering through the nozzle 10 into the sealed volume of the chamber 13, flows out of it into the atmosphere through the outlet pipe 15, the condenser 16 and the valve 18. The microwave power of the magnetron 2 is transmitted to the plasma torch 11 through the coaxial waveguide 4 due to the capacitive coupling between the nozzle 10 at the end of the central conductor 7 and plasma of the torch 11. The plasma of the torch And is torn off from the nozzle 10 by the flow of the outflowing argon jet, the directed velocity of the outflow of which at the outlet of the nozzle is greater than the velocity of propagation of the ionization front moving in the torch towards the nozzle. The sealed chamber 13 is filled with water to the operating level determined by the position of the sensor 23 relative to the plasma torch And, which can be partially immersed in the liquid. The time of plasma exposure to the treated liquid is not limited. To monitor the characteristics of the plasma discharge by optical emission spectra in the wavelength range of 300-1000 nm, a spectrometer 25 is used, for example, of the AvaSpec-3648-USB2 type (13) with a resolution of 0.3 nm. Interaction with water of a low-temperature argon plasma with a temperature reaching 4000 K and containing a high concentration of metastablely excited Ar* atoms with an energy of 11.5-11.7 eV and a lifetime of >1.3 seconds is capable of activating chemical reactions in a double surface layer " water-steam" with the formation of a mixture of ions and radicals: H-, H ", OH" with their subsequent transformation into HP, as in the known method of contact plasma activation of water or aqueous solutions described above.

Below are examples of the implementation of the method using prototypes of the prototype device and the claimed device.

Example 1 A prototype device was tested according to the prototype with the stabilization of the plasma torch by a nitrogen flow.

We used a magnetron from a household microwave oven of the type OM 75 R (31), (frequency 2.45 GHz, wavelength 12.24 cm, power 900 W, rectangular waveguide with a cross section of 45x90 mm ² ). The pressure in the chamber was maintained above atmospheric p > 1 atm, while the spent argon was released into the exhaust ventilation.

At a microwave generation power of 0.9 kW, an argon flow rate of 4.0 l/min, and a nitrogen flow rate of 3 l/min, distilled water with a volume of 2.7 l was treated at a distance from the nozzle to the water surface of 2.5 cm for 3 hours. According to iodine titrimetry, hydrogen peroxide was obtained with a concentration of 2x10' ³ M, according to TDS-3 measurements, conductivity 240x10' ⁶ S/cm and pH = 6.0 at a water temperature of 20°C.

Example 2

A prototype of the proposed device was tested using the stabilization of the plasma torch with an additional source of steam.

A tank with a capacity of 12 liters filled with tap water with a volume of 6 liters was used as a steam generator. The tank was heated by an induction electric stove with adjustable power from 0 to 1800 W. A thermometer was installed on the steam outlet. The phase of water heating from 20° to 98° at the electric stove power of 1800 W lasted about 30 minutes, and was completed at the 40th minute with the release of steam at 100° C. To maintain the required steam flow, the power of the heating plate was switched to 1000 W, at which the volume of water turning into steam was 0.33 l/h (9 l/min). After 1 - 3 minutes, when the mode of stable vaporization was established, the tap was opened, supplying steam to the plasma torch. The reactor chamber was preliminarily filled with distilled water with a volume of 3.5 liters, the distance from the water surface to the nozzle was 2.5 cm. showed 100 ° C. At this moment, the plasma torch was prepared for work: the magnetron glow was turned on, in the nozzle was supplied with argon, the flow rate of which was -5.0 l/min. Then the high voltage source was turned on and a discharge occurred at a microwave generation power of 0.9 kW. Tests showed that the plasma jet burned stably, thanks to stabilization by the downward steam flow. Treatment of distilled water with plasma was carried out for 3 hours. To maintain the water in the chamber at the set level during the treatment, water was periodically sampled in a volume of 60 ml. According to iodine titrimetry, the concentration of hydrogen peroxide in a volume of 3.5 l was 3.1 IO' ³ M (mol/liter). The conductivity measured by TDS-3 in the cooled solution at a temperature of 20°C was 7x10' ⁶ S/cm, pH = 7.9.

A comparison was made of the data obtained during tests according to the presented examples, which showed that the concentration of hydrogen peroxide under comparable experimental conditions in the case of stabilization of the plasma torch with steam turned out to be higher.

At the same time, the conductivity of the treated aqueous solution during testing of a prototype according to the claimed invention decreased by 34 times, which means a significant decrease in NOx in the solution of nitrogen oxides, i.e. up to 3% relative to the content of nitrogen oxides when the plasma torch is stabilized with nitrogen.

The claimed method and device can be widely used in various fields of technology, because hydrogen peroxide purified from impurities obtained as a result of their implementation can be used in health care, medicine, food industry, crop production, etc. At the same time, the claimed group of inventions provides the following advantages compared to the solutions known in the prior art: reliable operation of the microwave plasma torch, exclusion of various chemical reactions in combination with other chemical elements, except for hydrogen and oxygen, high efficiency due to the organization of a continuous cycle of water supply with steam and the selection of activated water (solution) from the installation without stopping the process of microwave treatment, the collection of associated hydrogen released from the water when receiving a solution of activated water with hydrogen peroxide. Reference designations.

I. microwave plasma torch

2. Magnetron generator

3. Rectangular waveguide

4. Coaxial waveguide

5. Quartz insulator tube

6. Viton O-rings

7. Central conductor of the coaxial waveguide

8. Cylinder of compressed gas

9. Reducer

10. Nozzle

I I . Torch

12. Viton seal

13. Sealed chamber

14. Chamber water cooling circuit

15. Pipe

16. Capacitor

17. Condenser water cooling circuit

18. Valve

19. Piston

20. Circulator

21. Absorbing load

22. Waveguide branch 23. Liquid level sensor

24. Optically transparent window

25. Spectrometer

26. Steam generator

27. Adjustable valve

28. Pipeline

29. Adjustable drain valve

List of used scientific and technical literature.

1. N.V. Baburin, S.V. Belov et al. Heterogeneous recombination in water vapor plasma as a mechanism of action on biological tissues// Reports of the Academy of Sciences, Physics 2009, vol. 426, no. 4, p. 468-470/ MAIK Nauka, Moscow.

2. S.V. Belov, Yu.K. Danileiko et al. Features of low-temperature plasma generation in high-frequency plasma electrosurgical devices//M. Medical technology, No. 2, 2011, p. 26-32/MNTO instrument makers and metrologists, Moscow.

3. Liu, J. et al. Direct synthesis of hydrogen peroxide from plasma-water interactions. // Scientific Reports. 2016, 6, 38454; doi: 10.1038/srep38454 / Nature Publishing Group, England, London.

4. G Vilema-Enriquez, A Arroyo, M Grijalva, RI Amador-Zafra, J Camacho Molecular and Cellular Effects of Hydrogen Peroxide on Human Lung Cancer Cells: s // Potential Therapeutic Implications, Oxidative Medicine and Cellular Longevity, Special issue: Reactive Oxygen Species in Cancer Biology and Anticancer Therapy// V. 2016, Article ID 1908164, https://doi.org/10.1155/2016/1908164/Hindawi, United Kingdom, London. 5. Vlasov D.V., Sergeychev K.F., Sychev I.A. Application of plasma microwave torch in analytical spectroscopy // Plasma Physics, 2002, vol. 28, no. 5, p. 484-492/ MAIK Nauka, Moscow.

6. Lukina N.A., Sergeychev K.F. Emission of inversely populated levels of atomic oxygen in the plasma of an argon microwave flame, stimulated by the formation of ozone// Plasma Physics, 2008, vol. 34, no. 6. With. 567-572 / MAIK Nauka, Moscow.

Claims

Formula

1. The method of microwave plasma activation of water for the synthesis of hydrogen peroxide, based on the continuous generation of plasma by an electrodeless torch discharge, which is created by a microwave plasma torch that generates a directed jet of low-temperature inert gas plasma in the vapor-gas medium of a sealed chamber that acts on the treated water and water vapor that occurs in as a result of evaporation of the surface layer of water under the influence of a gas-plasma jet, characterized in that an additional flow of water vapor is created, which is fed into the microwave plasma torch to a coaxially directed flow of inert gas plasma, steam is condensed in the process of plasma activation of water, and the condensate is sent to a sealed chamber with treated water .

2. The method according to p. 1, characterized in that helium is used as an inert gas.

3. The method according to p. 1, characterized in that argon is used as an inert gas.

4. The method according to claim 1, characterized in that the directed jet of low-temperature plasma is brought to the surface of an aqueous solution or partially immersed in it.

5. Method according to and. 1, characterized in that the flow of water vapor is passed through the plasma torch through the coaxial channel of the plasma torch, formed by a quartz or ceramic insulator tube.

6. The method according to p. 1, characterized in that the steam is condensed in a condenser installed vertically above a sealed chamber.

7. The method according to claim 1, characterized in that the rate of supply of inert gas, steam, the level of microwave power of the discharge and the rate of withdrawal of treated water with hydrogen peroxide are controlled.

8. The method according to claim 1, characterized in that the spent inert gas is removed through a condenser.

9. A device for microwave plasma activation of water for the synthesis of hydrogen peroxide by the method according to claim 1, containing a microwave plasma torch, including a magnetron, a rectangular waveguide and a coaxial waveguide containing

twenty

SUBSTITUTE SHEET (RULE 26) a central conductor, wherein the working part of the microwave plasma torch is placed in a sealed chamber, and a compressed gas cylinder connected to the central conductor, characterized in that it contains a steam generator connected to the coaxial waveguide of the plasma torch, and a steam condenser connected to the sealed chamber.

10. The device according to claim 9, characterized in that the central conductor of the coaxial waveguide is made in the form of a copper tube containing a nozzle for forming a directed jet of plasma-forming gas.

11. The device according to claim 9, characterized in that the coaxial waveguide is hermetically isolated from the rectangular waveguide by a quartz insulator tube.

12. The device according to claim 9, characterized in that the condenser has a shell-and-tube design.

13. The device according to claim 9, characterized in that the condenser contains a valve for the release of inert gas into the atmosphere.

14. The device according to claim. 9, characterized in that the sealed chamber contains an adjustable drain valve.

15. The device according to claim 9, characterized in that it additionally contains a circulator with an absorbing load.

16. The device according to claim 9, characterized in that it contains an automatic control system configured to control the modes of steam supply rate, the level of microwave power of the discharge and the rate of withdrawal of treated water to ensure a constant water level in the sealed chamber.

17. The device according to claim. 9, characterized in that the sealed chamber contains a water level sensor.

18. The device according to claim 9, characterized in that the sealed chamber contains optically transparent windows for monitoring the characteristics of the plasma torch according to optical emission and absorption spectra recorded using spectrometers.

19. The device according to claim 9, characterized in that the sealed chamber and the condenser contain water cooling circuits.

21

SUBSTITUTE SHEET (RULE 26)