A high-purity chlorine dioxide preparation apparatus and method

Abstract

A high-purity chlorine dioxide preparation device and method, belonging to the field of disinfection technology, uses sodium chlorite and sodium chloride as raw materials. The reaction is carried out in a specially structured electrolytic cell under catalytic conditions, and the generated chlorine dioxide is collected via low-temperature pure water or directly added for use through positive pressure aeration. The method for preparing chlorine dioxide provided by this invention features rapid reaction, high conversion rate, and low cost. Furthermore, the raw materials are readily available, and it does not use hazardous chemicals such as sulfuric acid and hydrochloric acid. This overcomes the drawbacks of traditional chlorine dioxide generators, such as high energy consumption, large size, and hazardous raw materials, thus expanding the application scenarios of chlorine dioxide.

Description

Technical Field

[0001] This invention belongs to the field of disinfection technology and relates to a device and method for preparing high-purity chlorine dioxide. Background Technology

[0002] Chlorine dioxide is a green disinfectant. Due to its oxidizing properties, it can remove various organic and inorganic pollutants and is widely used in environmental disinfection, aquaculture, livestock disease prevention, food processing, pulp bleaching, and industrial wastewater treatment. However, because chlorine dioxide is unstable and prone to disproportionation and decomposition, large-scale use requires on-site preparation. The main method for preparing chlorine dioxide is the chemical method, typically using CH3OH, H2O2, or SO2 as reducing agents to reduce NaClO3 in an acidic medium, or through the reaction of NaClO2 with acid. The chemical synthesis method has a long process flow, consumes a large amount of reagents, and leaves a large amount of acidic waste liquid after the reaction, which, if not properly treated, causes significant environmental harm. The chemical method also requires the use of hazardous chemicals such as hydrochloric acid and sulfuric acid, posing significant safety hazards. Furthermore, the preparation process requires heating, resulting in high energy consumption and undoubtedly increasing production costs. In contrast, the electrolytic method uses electricity as the driving force, which is powerful, efficient, safe, and produces a high-purity product. Currently, the most ideal methods for electrolytically preparing chlorine dioxide are mainly divided into the electrolysis of salt, the electrolysis of chlorate, and the electrolysis of chlorite. Domestically, there are chlorine dioxide generation processes using sodium chlorite as raw material and an electrolytic cell as the generator (invention patents CN110476962A and CN1216784A), which reduce the production cost and improve the efficiency of chlorine dioxide production. However, this method produces low yields of chlorine dioxide and the equipment cannot operate continuously and stably, making it unsuitable for large-scale production. There are also chlorine dioxide generation processes using a mixture of sodium chloride and sodium chlorite as raw material and a single electrolytic cell as the generator (CN101591786A), which have a simple structure, but this method produces chlorine gas, resulting in low purity chlorine dioxide, and the hydrogen produced in the reaction is not collected, leading to resource waste. These processes have many drawbacks; therefore, how to improve the yield, efficiency, and purity of chlorine dioxide, reduce production costs and resource waste, and ensure continuous and stable operation of the equipment has become an urgent technical problem to be solved. Summary of the Invention

[0003] To address the problems of high cost and pollution in existing technologies, the present invention aims to provide an efficient, energy-saving, and safe apparatus and method for preparing high-purity chlorine dioxide using the electrolysis of sodium chlorite. Specifically, the present invention uses an aqueous solution prepared from sodium chlorite and sodium chloride as raw material. The sodium chlorite solution is added to the anode chamber, and the sodium chloride solution is added to the cathode chamber. A catalyst composed of MnSO4, NaCl, NiSO4, CoSO4, and C3Cl2N3NaO3 is added to the sodium chlorite solution. Then, the current of the constant current power supply is adjusted to a specific value, and the preparation is carried out under the condition of an aeration intensity of 0.5–3 L / min in the aeration system. Compared with the blank group, this reaction can significantly improve the yield of chlorine dioxide under the action of the catalyst. The specific technical solution includes the following:

[0004] A high-purity chlorine dioxide preparation device mainly consists of four parts: a reaction system, an aeration system, a collection system, and a control system. The control system is connected to the reaction system, the aeration system, and the collection system respectively via wires. The aeration system is connected to the reaction system via a conduit. The collection system is connected to the reaction system via a conduit.

[0005] The control system controls parameters such as aeration rate, feed rate, acid feed rate, water feed rate, current magnitude, and the number of electrolytic cells in operation based on parameters such as temperature, liquid level, and chlorine dioxide concentration.

[0006] The reaction system consists of several electrolytic cells connected in parallel. The yield of a single electrolytic cell is controlled by controlling the electrodes and the amount of chemicals fed. A residual liquid collection outlet is provided at the bottom of the system, which serves as a discharge channel for the residual electrolyte. During the reaction, the residual electrolyte is continuously discharged into the residual liquid collection system. The discharge rate of the residual electrolyte is consistent with the addition rate of the sodium chlorite solution and the sodium chloride solution.

[0007] A single electrolytic cell is divided into an anode chamber and a cathode chamber by an ion exchange membrane, with residual liquid outlets located at the bottom of both chambers. The ruthenium-aluminum-cobalt oxide composite material (LiCo) is used. 1-x-y Ru x Al y O2 (0.0005≤x≤0.015, 0.0005≤y≤0.015) is used as the anode material connected to the positive electrode of the power supply, which is a novel electrode material with advantages of good catalytic effect and high safety. Ni-Fe alloy ceramic material is used as the cathode material connected to the negative electrode of the power supply, and has good catalytic activity and stability. The ion exchange membrane is an EPDM / PVDF cation exchange membrane, which is prepared using EPDM, PVDF, styrene and divinylbenzene as raw materials and concentrated sulfuric acid as sulfonating agent. It has an interpenetrating network structure and exhibits low resistance, low energy consumption and high current efficiency in electrodialysis, and is also oxidation resistant and has a long lifespan.

[0008] The top of the anode chamber of the electrolytic cell is equipped with a feed inlet A, an acid inlet A, a level gauge, and a chlorine dioxide flow pipe. The bottom is equipped with an outlet and a temperature sensor. The anode is located inside and connected to the positive terminal of the power supply. A pipe preheater is installed at the feed inlet A to preheat the anolyte. The feed inlet A is the feeding port for sodium chlorite solution and catalyst. The acid inlet A is the channel for the pickling solution to enter the anode chamber. The chlorine dioxide generated in the anode chamber enters the chlorine dioxide collection system through the chlorine dioxide flow pipe.

[0009] The top of the cathode chamber of the electrolytic cell is equipped with a feed inlet (B), an acid inlet (B), a pressure relief valve, and a level gauge. The bottom is equipped with an outlet and a temperature sensor. The cathode is located inside the cathode chamber and connected to the negative terminal of the power supply. A pipeline preheater is installed at feed inlet (B) to preheat the cathode solution. Feed inlet (B) is the inlet for adding sodium chloride solution, and acid inlet (B) is the channel for the pickling solution to enter the anode chamber. The pressure relief valve is used to release the gas generated at the cathode during the reaction, which is collected in a hydrogen storage tank via a hydrogen conduit. The pipeline preheater preheats the electrolyte at a temperature of 20–30°C.

[0010] The aeration system is connected to the anode and cathode chambers of the electrolytic cell in the reaction system via aeration conduits. A microporous aerator is connected to the bottom of the conduit. The microporous aerator aerates the anode and cathode chambers, thereby accelerating the reaction rate and blowing out the chlorine dioxide produced. The aeration intensity of the aeration system during operation is 0.5 to 3 L / min.

[0011] The collection system consists of two parts: a chlorine dioxide collection system and a hydrogen collection system. The chlorine dioxide collection system is a non-transparent container filled with pure water, with an inlet C at the top and an outlet C and a drain port at the bottom. Inside, there is a chlorine dioxide flow pipe, a chlorine dioxide concentration detector, a temperature sensor, and a level gauge to continuously monitor the concentration, temperature, and liquid level of the chlorine dioxide solution in the collection system. A microporous aerator is installed at the end of the chlorine dioxide flow pipe, ensuring the chlorine dioxide is fully absorbed. The inlet C serves as the inlet for the pure water, the outlet C serves as the outlet for the prepared chlorine dioxide solution, and the drain port serves as the discharge channel for residual liquid. The chlorine dioxide detector mainly consists of a 410nm wavelength LED lamp, a phototube, and a glass tube. The chlorine dioxide solution enters the glass tube, and under the illumination of the LED lamp, the phototube detects the real-time chlorine dioxide concentration. The hydrogen collection system includes a deoxygenation device, a hydrogen dryer, a hydrogen compressor, and a hydrogen storage tank. The gas generated at the cathode passes through the hydrogen flow pipeline in sequence through the deoxygenation device, the hydrogen dryer, and the hydrogen compressor, and is finally collected in the hydrogen storage tank.

[0012] The reaction system requires acid washing after 10 to 240 hours of operation, with the washing cycle adjusted according to water quality. During acid washing, first open the outlet at the bottom of the electrolytic cell to drain the accumulated brine from the pipes. Then open acid inlets A and B, and introduce 5-10% hydrochloric acid or 10-30% citric acid. Once the electrolytic cell is full, close acid inlets A and B, and allow the acid to soak in the cell for 1-2 hours before draining it.

[0013] A method for preparing high-purity chlorine dioxide, using the aforementioned chlorine dioxide preparation apparatus, specifically includes:

[0014] Analytical grade sodium chlorite and sodium chloride are used as raw materials. A 0.1–5.0 mol / L sodium chlorite solution is placed in the anode chamber as the electrolyte, and a 0.1–5.0 mol / L sodium chloride solution is placed in the cathode chamber as the electrolyte. A catalyst is added to the sodium chlorite solution. The catalyst is one of MnSO4, NaCl, NiSO4, CoSO4, and C3Cl2N3NaO3, or a mixture of these substances in any proportion. The total concentration of the added catalyst is 0.01–0.1 mol / L.

[0015] The operating cycle of the device is 10h to 240h. At the 0min, 0.1 to 5.0 mol / L sodium chlorite solution and 0.01 to 0.1 mol / L catalyst are added through inlet A, and 0.1 to 5.0 mol / L sodium chloride solution is added through inlet B. The addition rate of sodium chlorite solution and sodium chloride solution is 0.001 to 0.05 mol / (L·min).

[0016] The advantages of this invention are:

[0017] (1) Sodium chlorite and sodium chloride are used as raw materials, which are inexpensive, readily available and safe;

[0018] (2) Adding a catalyst significantly improves the yield of chlorine dioxide, and the purity of chlorine dioxide in the product is greater than 90%.

[0019] (3) The reaction is driven by electrical energy, the output is adjustable, and it can be started and stopped quickly. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the experimental setup;

[0021] Figure 2 It is a chlorine dioxide concentration detector. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] All raw materials used in this invention are products with a purity not lower than that of industrial grade.

[0024] Example 1:

[0025] A high-purity chlorine dioxide preparation device, such as Figure 1 As shown, it mainly consists of four parts: a reaction system, an aeration system, a collection system, and a control system. The control system is connected to the reaction system, the aeration system, and the collection system via wires; the aeration system is connected to the reaction system via conduits; and the collection system is connected to the reaction system via conduits.

[0026] The control system controls parameters such as aeration rate, feed rate, acid feed rate, water feed rate, current magnitude, and the number of electrolytic cells in operation based on parameters such as temperature, liquid level, and chlorine dioxide concentration.

[0027] The reaction system consists of several electrolytic cells connected in parallel. The yield of a single electrolytic cell is controlled by controlling the electrodes and the amount of chemicals fed. A residual liquid collection outlet is provided at the bottom of the system, which serves as a discharge channel for the residual electrolyte. During the reaction, the residual electrolyte is continuously discharged into the residual liquid collection system. The discharge rate of the residual electrolyte is consistent with the addition rate of the sodium chlorite solution and the sodium chloride solution.

[0028] A single electrolytic cell is divided into an anode chamber and a cathode chamber by an ion exchange membrane, with residual liquid outlets located at the bottom of both chambers. The ruthenium-aluminum-cobalt oxide composite material (LiCo) is used. 1-x-y Ru x Al y O2 (0.0005≤x≤0.015, 0.0005≤y≤0.015) is used as the anode material connected to the positive electrode of the power supply, which is a novel electrode material with advantages of good catalytic effect and high safety. Ni-Fe alloy ceramic material is used as the cathode material connected to the negative electrode of the power supply, and has good catalytic activity and stability. The ion exchange membrane is an EPDM / PVDF cation exchange membrane, which is prepared using EPDM, PVDF, styrene and divinylbenzene as raw materials and concentrated sulfuric acid as sulfonating agent to obtain a cation exchange membrane with an interpenetrating network structure. In the electrodialysis process, it exhibits the characteristics of low resistance, low energy consumption and high current efficiency, and is also oxidation resistant and has a long service life.

[0029] The top of the anode chamber of the electrolytic cell is equipped with inlet A, acid inlet A, a level gauge, and a chlorine dioxide pipeline. The bottom is equipped with an outlet and a temperature sensor. The anode is located inside and connected to the positive terminal of the power supply. A pipeline preheater is installed at inlet A to preheat the anolyte. Inlet A is the feeding port for sodium chlorite solution and catalyst. Acid inlet A is the channel for pickling solution to enter the anode chamber. The chlorine dioxide generated in the anode chamber enters the chlorine dioxide collection system through the chlorine dioxide flow pipeline.

[0030] The top of the cathode chamber of the electrolytic cell is equipped with a feed inlet (B), an acid inlet (B), a pressure relief valve, and a level gauge. The bottom is equipped with an outlet and a temperature sensor. The cathode is located inside the cathode chamber and connected to the negative terminal of the power supply. A pipeline preheater is installed at feed inlet (B) to preheat the cathode solution. Feed inlet (B) is the inlet for adding sodium chloride solution, and acid inlet (B) is the channel for the pickling solution to enter the anode chamber. The pressure relief valve is used to discharge the gas generated at the cathode during the reaction. This gas flows through a hydrogen pipeline, sequentially passing through a deoxygenation device, a hydrogen dryer, and a hydrogen compressor, finally being collected in a hydrogen storage tank. The pipeline preheater preheats the electrolyte at a temperature of 20–30°C.

[0031] The aeration system is connected to the anode chamber and cathode chamber of the electrolytic cell in the reaction system via aeration conduits. A microporous aerator is connected to the bottom of the conduit. The microporous aerator aerates the anode chamber and cathode chamber respectively, which can accelerate the reaction rate and blow out the chlorine dioxide produced. The aeration intensity of the aeration system is 0.5 to 3 L / min when it is running.

[0032] The collection system consists of two parts: a chlorine dioxide collection system and a hydrogen collection system. The chlorine dioxide collection system is a non-transparent container filled with pure water, with an inlet C at the top and an outlet C and an air vent at the bottom. Internally, it includes chlorine dioxide flow pipes and a chlorine dioxide concentration detector (e.g., [missing information]). Figure 2 The system includes a temperature sensor and a level gauge to continuously monitor the concentration, temperature, and liquid level of the chlorine dioxide solution. A microporous aerator is installed at the end of the chlorine dioxide flow pipe, ensuring thorough absorption of chlorine dioxide. Inlet C serves as the inlet for pure water, outlet C is the outlet for the prepared chlorine dioxide solution, and the vent serves as the discharge channel for residual liquid. The chlorine dioxide detector mainly consists of a 410nm wavelength LED, a phototube, and a glass tube. The chlorine dioxide solution enters the glass tube, and under the illumination of the LED, the phototube detects the real-time chlorine dioxide concentration. The hydrogen collection system includes a deoxygenation device, a hydrogen dryer, a hydrogen compressor, and a hydrogen storage tank. The gas generated at the cathode passes sequentially through the deoxygenation device, hydrogen dryer, and hydrogen compressor via the hydrogen flow pipe, and is finally collected in the hydrogen storage tank.

[0033] The method for preparing chlorine dioxide using the above-mentioned apparatus specifically includes:

[0034] 150 mL of a 1.0 mol / L sodium chlorite solution was placed in the anode chamber as the electrolyte, and 150 mL of a 1.0 mol / L sodium chloride solution was placed in the cathode chamber as the electrolyte. Six experimental groups were conducted. The blank group contained no catalyst added to the sodium chlorite electrolyte. Experimental group 1 contained 0.03 mol MnSO4 in the sodium chlorite solution; experimental group 2 contained 0.03 mol NaCl in the sodium chlorite solution; experimental group 3 contained 0.03 mol NiSO4 in the sodium chlorite solution; experimental group 4 contained 0.03 mol CoSO4 in the sodium chlorite solution; and experimental group 5 contained 0.015 mol C3Cl2N3NaO3 in the sodium chlorite solution. After running for 30 minutes under conditions of 3A current and 3L / min aeration, the purity of chlorine dioxide produced in all six experimental groups was greater than 90%, and the chlorine dioxide yields of the six experimental groups were 25.45%, 30.61%, 31.47%, 30.24%, 34.42%, and 44.26%, respectively. The chlorine dioxide yield of each experimental group was improved to varying degrees compared with the blank group.

[0035] Example 2:

[0036] A method for preparing chlorine dioxide, implemented using the apparatus of Example 1, specifically includes:

[0037] 150 mL of a 1.0 mol / L sodium chlorite solution was placed in the anode chamber as the electrolyte, and 150 mL of a 1.0 mol / L sodium chloride solution was placed in the cathode chamber as the electrolyte. Seven groups of experiments were conducted. The blank group contained no catalyst added to the sodium chlorite electrolyte. Experimental group 1 contained 0.03 mol MnSO4 in the sodium chlorite solution; experimental group 2 contained 0.03 mol NaCl in the sodium chlorite solution; experimental group 3 contained 0.03 mol NiSO4 in the sodium chlorite solution; experimental group 4 contained 0.03 mol CoSO4 in the sodium chlorite solution; and experimental group 5 contained 0.015 mol C3Cl2N3NaO3 in the sodium chlorite solution. After running for 30 minutes under the conditions of 4A current and 3L / min aeration, the chlorine dioxide yields of the six experimental groups were 38.23%, 42.78%, 45.73%, 47.7%, 46.59%, and 64.73%, respectively. The chlorine dioxide yields of each experimental group were all improved to varying degrees compared with the blank group.

Claims

1. A method for preparing high-purity chlorine dioxide, which is implemented by using a device for preparing high-purity chlorine dioxide, the device comprising a reaction system, an aeration system, a collection system and a control system, wherein: the control system is connected with the reaction system, the aeration system and the collection system through wires; the aeration system is connected with the reaction system through a conduit; the collection system is connected with the reaction system through a conduit; characterized in that 0.1-5.0 mol / L sodium chlorite solution is used as electrolyte in the anode chamber, 0.1-5.0 mol / L sodium chloride solution is used as electrolyte in the cathode chamber, and a catalyst is added in the anode chamber; the catalyst is one of MnSO4, NaCl, NiSO4, CoSO4 and sodium dichloroisocyanurate or a mixture of the above substances in any ratio, and the total concentration of the catalyst is 0.01-0.1 mol / L. The control system controls the parameters of the aeration amount, the feed amount, the water amount, the acid amount, the current size and the number of electrolytic cells according to the temperature, the liquid level, the chlorine dioxide concentration and the running time. The reaction system is composed of a plurality of electrolytic cells connected in parallel, the yield of a single electrolytic cell is controlled by controlling the electrode and the amount of medicine, and a residual liquid collection outlet is arranged at the bottom of the reaction system; the residual liquid outlet serves as a discharge channel for the electrolytic residual liquid, which is continuously discharged into the residual liquid collection system during the reaction, and the discharge speed of the electrolytic residual liquid is consistent with the addition speed of the sodium chlorite solution and the sodium chloride solution; The single electrolytic cell is divided into an anode chamber and a cathode chamber by an ion exchange membrane, and the bottom of the anode chamber and the cathode chamber is respectively provided with a residual liquid outlet; The reaction system comprises an electrolytic cell anode chamber, a cathode chamber and an ion exchange membrane, wherein the anode material in the electrolytic cell anode chamber is a ruthenium-aluminum-lithium cobalt oxide composite material, the chemical formula is LiCo 1-x-y Ru x Al y O2, wherein 0.0005≤x≤0.015, 0.0005≤y≤0.015; the cathode material in the cathode chamber is a Ni-Fe alloy ceramic material; and the ion exchange membrane is an EPDM / PVDF cation exchange membrane. The ion exchange membrane is a cation exchange membrane with interpenetrating network structure prepared by using EPDM, PVDF, styrene and divinylbenzene as raw materials and concentrated sulfuric acid as sulfonating agent; 2. The method of claim 1, wherein the chlorine dioxide is produced at a purity of 99.5% or more. The anode chamber is provided with a feed inlet A, an acid inlet A, a liquid level meter and a chlorine dioxide flow pipeline at the top, is provided with a liquid outlet and a temperature sensor at the bottom, and is provided with an anode inside and connected with the positive pole of a power supply; a pipeline preheater is arranged at the feed inlet A to preheat the anode liquid; the feed inlet A is the feed inlet for sodium chlorite solution and catalyst; the acid inlet A is the channel for the acid washing liquid to enter the anode chamber; 3. The method of claim 1, wherein the chlorine dioxide is produced at a purity of 99.9% or more. The anode chamber and the chlorine dioxide collection system are connected by a pipeline, and the chlorine dioxide generated by the anode chamber enters the chlorine dioxide collection system through the chlorine dioxide flow pipeline; the cathode chamber is provided with a feed inlet B, an acid inlet B and a pressure relief valve at the top, is provided with a liquid outlet and a temperature sensor at the bottom, and is provided with a cathode inside and connected with the negative pole of a power supply; a pipeline preheater is arranged at the feed inlet B to preheat the cathode liquid; The feed inlet B is the feed inlet for sodium chloride solution, and the acid inlet B is the channel for the acid washing liquid to enter the anode chamber; The pressure relief valve is used to discharge the gas generated by the cathode during the reaction, and the hydrogen gas flows through an oxygen removal device, a hydrogen gas dryer and a hydrogen gas compressor through a hydrogen gas flow pipeline and is collected into a hydrogen gas storage tank; the pipeline preheater is used to preheat the electrolyte, and the preheating temperature is 20-30℃. ​ ​ ​ ​ 4. The method of claim 1, wherein the chlorine dioxide is produced at a purity of 99.9% or more. The aeration system is connected with the anode chamber and the cathode chamber of the electrolytic cell in the reaction system through the pipes, and the microporous aerator is connected at the bottom of the pipes, so that the anode chamber and the cathode chamber are aerated through the microporous aerator, the reaction rate is accelerated, and the produced chlorine dioxide is blown out; the aeration intensity of the aeration system is 0.5-3 L / min during operation.

5. The method of claim 1, wherein the chlorine dioxide is produced at a purity of 99.5% or more. The collection system is divided into a chlorine dioxide collection system and a hydrogen gas collection system, the chlorine dioxide collection system is a non-transparent container filled with pure water, a liquid inlet C is arranged at the top of the container, a liquid outlet C and a emptying port are arranged at the bottom of the container, a chlorine dioxide flow pipeline, a chlorine dioxide concentration detector, a temperature sensor and a liquid level gauge are arranged in the container, and the concentration, temperature and liquid level of the chlorine dioxide solution in the collection system are detected at any time; the hydrogen gas collection system comprises an oxygen removal device, a hydrogen gas dryer, a hydrogen gas compressor and a hydrogen gas storage tank, and the gas generated by the cathode passes through the oxygen removal device, the hydrogen gas dryer and the hydrogen gas compressor in sequence through the hydrogen gas flow pipeline, and is finally collected into the hydrogen gas storage tank; The tail part of the chlorine dioxide flow pipeline is provided with a microporous aerator, and the chlorine dioxide is fully absorbed under the action of the microporous aerator. The liquid inlet C is the inlet of the pure water, the liquid outlet C is the outlet of the prepared chlorine dioxide solution, and the emptying port is the discharge channel of the residual liquid. The chlorine dioxide detector mainly comprises an LED lamp with a wavelength of 410 nm, a phototube and a glass tube, the chlorine dioxide solution enters the glass tube, the LED lamp irradiates, and the phototube detects the real-time chlorine dioxide concentration.

6. The method of claim 1, wherein the method is characterized by: The reaction system is subjected to acid pickling after 10-240 h of operation; during acid pickling, the liquid outlet at the bottom of the electrolytic cell is opened, the accumulated brine in the pipeline is discharged, then the acid inlet A and the acid inlet B are opened, and hydrochloric acid with a concentration of 5-10% or citric acid with a concentration of 10-30% is introduced; when the electrolytic cell is filled with liquid, the acid inlet A and the acid inlet B are closed, and after the acid water is soaked in the electrolytic cell for 1-2 h, the acid water is discharged.

7. The method of claim 1, wherein the chlorine dioxide is produced at a purity of 99.9% or more. At 0 min, 0.1-5.0 mol / L sodium chlorite solution and 0.01-0.1 mol / L catalyst are added through the feeding port A, and 0.1-5.0 mol / L sodium chloride solution is added through the feeding port B, and the adding speed of the sodium chlorite solution and the sodium chloride solution is 0.001-0.05 mol / (L·min).

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