83 results about "Nitrogen dioxide" patented technology

The invention relates to the technical field of automobile air purification, and particularly discloses a filtering material, a preparation method of the filtering material and a novel automobile air conditioner multi-effect catalytic formaldehyde removal filter. The filtering material comprises a PET (Polyethylene Terephthalate) supporting layer, a gas filtering layer and a PP (Polypropylene) electrostatic filtering layer which are arranged in sequence, the gas filtering layer is prepared from the following raw materials in parts by weight: 30 to 90 parts of activated carbon and 10 to 70 parts of manganese catalyst. The gas filtering layer composed of the activated carbon and the manganese catalyst is matched with the filtering material composed of the PET supporting layer and the PP electrostatic filtering layer, four gases of n-butane, methylbenzene, sulfur dioxide and nitrogen dioxide can be adsorbed, the manganese catalyst degrades formaldehyde at normal temperature, meanwhile, the reaction on the formaldehyde is a catalytic reaction, and the environment-friendly effect is achieved. Therefore, the filter material disclosed by the invention also has longer service life, so that a filter made of the filter material has a better formaldehyde removal effect and longer service life.

The utility model discloses a diesel generator flue gas purification mechanism for civil air defence engineering, including air inlet pipe and purification bin, the air inlet pipe one end is linked with diesel generator exhaust pipe in civil air defence engineering power generation room intercommunication, the other end of air inlet pipe is inserted into the purification bin and the opening direction is perpendicular to downward, the open end position of air inlet pipe in the purification bin is connected with the shunt joint, each interface of shunt joint all is connected with the jet pipe that the air hole of pipe body lateral wall is evenly set up, the utility model relates to civil air defence engineering technical field, utilize liquid supply booster pump and press into the spray subassembly in alkaline solution (15% magnesium hydroxide compound agent), and further via spray subassembly to the spray of filler layer, make the nitrogen monoxide, nitrogen dioxide, sulfur dioxide and particulate matter etc. in tail gas contact with the alkaline water mist in purification bin and filler layer, to the purification treatment of nitrogen monoxide, nitrogen dioxide, sulfur dioxide and particulate matter.

The invention relates to an austenitic stainless steel food-grade pipe welding spot cleaning passivator. The austenitic stainless steel food-grade pipe welding spot cleaning passivator comprises the following components in parts by mass: 0.2-1.2 parts of a complexing agent, 0.5-2.5 parts of a sealing agent, 9.5-18 parts of organic acid, 1-5 parts of an oxidizing agent, 1-5 parts of a coordination agent, 0.2-2 parts of a corrosion inhibitor, 0.4-1.5 parts of an active agent and 64.8-87.2 parts of water. Through compounding of the whole materials, after a stainless steel workpiece is cleaned and passivated, no heavy metal is left on the surface of the workpiece, the corrosion resistance of the surface of the workpiece can be improved, the service life of the workpiece is prolonged, harmful gas, acid mist and toxic substances are not generated in the process of cleaning and passivating the workpiece, and the service life of the workpiece is prolonged. The austenitic stainless steel cleaning and passivating agent is safe and environment-friendly to use, and solves the problems that in the process of cleaning and passivating austenitic stainless steel products by adopting a pickling and passivating method in the market, acid mist is formed, nitrogen dioxide polluting the atmosphere is generated, chromium compounds with high toxicity are generated, and the health of operators is harmed and the environment is polluted.

An internal combustion engine system is described herein. The system uses a NOx detector at the exhaust of an internal combustion engine to compensate for the effects of NO2 on the measurements of NOx detectors at other locations, such as the input and the output of an SCR system. A controller uses the difference in measured NOx volume fractions between the NOx detector at the exhaust and other NOx detectors to modify the operation of the combustion engine system as well as, in some examples, determine NO2 created by a device containing a precious metal catalyst, such as precious metal containing diesel particular filter (DPF) and / or a diesel oxidizing catalyst (DOC), that oxidizes a portion of the exhaust from NO to NO2.

The invention discloses a method for relieving and eliminating sewage anaerobic fermentation stink. The method comprises the following steps: mixing malodorous gas generated by anaerobic fermentation with nitrogen dioxide, and carrying out gas-phase oxidation reaction; the reacted gas is subjected to ultraviolet photolysis treatment, so that nitrogen dioxide is decomposed to generate ozone; and the generated ozone is utilized to continuously oxidize the malodorous substances. The method can also comprise a source sulfur fixation step: adding a sulfur fixation agent into the anaerobic fermentation system, and reducing the generation of hydrogen sulfide from the source. Nitrogen dioxide can be prepared from steel cylinder gas, industrial waste gas or on site, and the on-site preparation comprises an ammonia water / ammonium salt catalytic oxidation method and a nitric acid reduction method. Through multi-stage cooperation of'source sulfur fixation + NO2 gas-phase oxidation + UV ozone conversion + ozone continuous oxidation ', efficient removal of malodorous gas is achieved, an ozone generator does not need to be additionally arranged, nitrogen dioxide residues are thoroughly eliminated, secondary pollution is avoided, equipment is compact, and the operation cost is low.

The invention relates to the technical field of adsorbents, in particular to a multi-element gas adsorbent as well as a preparation method and application thereof. The preparation method of the multi-element gas adsorbent provided by the invention is simple, economic and environment-friendly, and is suitable for industrial large-scale production. The prepared adsorbent is regular in morphology and rich in various active sites, and sulfur dioxide, nitrogen dioxide and ammonia gas in air can be effectively adsorbed. Compared with the prior art, the CHO-SBA-PEI multi-element gas adsorbent prepared by the preparation method disclosed by the invention combines a mesoporous structure (high specific surface area and regular pore channels) of SBA-15, amino active sites of PEI and aldehyde groups modified in the pore channels of SBA-15, not only realizes multi-element absorption of SO2, NO2 and NH3, but also has high adsorption capacity, and can effectively purify gas entering a hydrogen energy fuel cell. The preparation process is simple and controllable, does not need special equipment, is easy for large-scale production, and is suitable for industrial application of the hydrogen energy fuel cell air filter.

This application provides a method, apparatus, device, and storage medium for monitoring carbon and nitrogen emission data of emission sources. The method acquires observed concentration data of carbon dioxide, nitrogen dioxide, and wind field data for a target emission source; it performs spatiotemporal alignment and correlation of the carbon dioxide and nitrogen dioxide concentration observation data to obtain multiple observation data pairs; if preset plume identification conditions are met, it fits the plume concentration distribution based on the multiple observation data pairs to obtain the linear density of carbon dioxide and the linear density of nitrogen dioxide; using a nitrogen dioxide concentration decay correction model characterizing the chemical change law of nitrogen dioxide during atmospheric transport, it corrects the nitrogen dioxide linear density to obtain the linear density of nitrogen oxides; and based on the carbon dioxide linear density and the nitrogen oxide linear density, it determines the carbon-nitrogen emission rate ratio of the target emission source. The embodiments of this application can improve the accuracy of the carbon-nitrogen emission rate ratio.

The application relates to the fine chemical technology field and discloses a method for synthesizing N,O-dimethyl-N'-nitroisourea, which specifically comprises the following steps: mixing urea and an imidazole ionic liquid, adding dimethyl carbonate drop by drop under temperature rising, performing heat preservation reaction, opening a vacuum, continuously removing low-boiling substances in a slow temperature rising process, cooling, stirring, adding fuming nitric acid drop by drop, stirring and temperature rising, performing heat preservation reaction, cooling and standing to separate layers, pumping the upper concentrated nitric acid into nitrogen dioxide and oxygen, waiting for reuse, adding 4-6 times of water into the lower ionic liquid and N,O-dimethyl-N'-nitroisourea mixture, stirring and temperature rising, separating layers, taking the upper layer of N,O-dimethyl-N'-nitroisourea-containing aqueous solution, slowly cooling, precipitating white solids, filtering, washing with ice water, drying, and obtaining N,O-dimethyl-N'-nitroisourea, so that the shortcomings of traditional synthesis methods, i.e. the necessity of using dimethyl sulfate and sulfuric acid to generate dangerous waste salt of sodium sulfate and waste mixed acid with high COD, are solved.

This invention relates to a method for preparing and applying a ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide, belonging to the field of gas sensor technology. The invention discloses a ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide and its application as a sensing material in a highly selective and sensitive flexible NO2 gas sensor. The invention utilizes a liquid-phase growth method, using SnSe2 nanosheets, ammonium tungstate, and diphenyldiselenoether as raw materials, and varying reaction conditions such as temperature, reaction time, and raw material content to prepare the ternary heterostructure nanosheet of tungsten diselenide / tin diselenide / tin monoselenide. Subsequently, these nanosheets are sprayed onto interdigitated electrodes and dried to form a film, thus preparing a chemielectric resistive gas sensor capable of detecting low concentrations of nitrogen dioxide gas at room temperature. It not only possesses high sensitivity and selectivity but can also be applied to flexible NO2 gas sensing.

The invention belongs to the technical field of gas sensing, and discloses a preparation method of an indium oxide gas-sensitive material based on a bamboo biological template, which comprises the following steps: taking natural bamboo as a biological structure template, introducing an indium source precursor into a template pore channel by a solution impregnation method, drying, and carrying out high-temperature calcination in an air atmosphere. According to the heat treatment process, thermal degradation and removal of the biological template are achieved, decomposition and oxidation of the precursor are synchronously induced, and finally the indium oxide material with the bamboo biological form and the high specific surface area is generated. The obtained material shows high response and recovery speed to nitrogen dioxide gas, the response value exceeds three thousand, meanwhile, precious metal and a traditional chemical preparation method do not need to be used in the preparation process, and the green chemical concept of saving energy and reducing pollution is achieved.

Title of the invention: Chimney for plume reduction in a CO2 capture installation. A chimney for venting gas from a CO2 capture installation comprises an elongated hollow body open upwards to the atmosphere and means for bringing the NO2-containing gas into the elongated hollow body, the body comprising means for diluting the gas by mixing it with atmospheric air. No figure

The invention discloses a ZnO / ZnS / ZnSO4 nano composite material and a gas sensor based on the ZnO / ZnS / ZnSO4 nano composite material, a ZnO / ZnS heterojunction composite material with rough spherical morphology is prepared by adopting a two-step method, part of ZnS in the ZnO / ZnS heterojunction composite material can be converted into ZnSO4 through subsequent controllable annealing treatment, so that a ZnO / ZnS / ZnSO4 three-layer composite material is obtained, and finally the ZnO / ZnS / ZnSO4 three-layer composite material is prepared into the gas sensor. And high-performance detection of NO2 gas is realized. The prepared sensor has the characteristics of high sensitivity, good selectivity and strong stability, has relatively high response (65) to 5 ppm NO2 at a relatively low working temperature (110 DEG C), can detect nitrogen dioxide gas with extremely low concentration, and has huge potential in the aspect of developing and detecting low-concentration nitrogen dioxide gas.

The invention belongs to the technical field of gas sensors, and discloses a visible light excitation type nitrogen dioxide gas sensor based on a Bi2S3 / SnS2 heterostructure and preparation and application thereof, and the gas sensor comprises a gas sensitive material, an interdigital electrode and an LED light source. The preparation method specifically comprises the following steps: preparing bismuth sulfide with the microstructure of a nanorod structure and tin disulfide with the microstructure of a micron sheet structure by adopting a hydrothermal method to form a heterostructure composite material, uniformly coating the gas sensitive material on the surface of an interdigital electrode taking an aluminum oxide substrate as a substrate, and vertically placing an LED light source right above the gas sensitive material. The invention has the advantages of low price, simple preparation process, compatibility with CMOS (Complementary Metal Oxide Semiconductor) process, easiness in microminiaturization and integration with other microelectronic devices and the like.

The present invention relates to a catalyst composition for suppressing the occurrence of yellow smoke caused by nitrogen dioxide discharged during incomplete combustion of a stationary source of pollution, a method for manufacturing the same, and a method for treating yellow smoke emission by applying a yellow smoke emission reduction catalyst comprising a mixture of a first component of vanadium / titanium dioxide and a second component of copper / zeolite, compared with vanadium-based selective catalytic reduction (V-SCR), the NO2 adsorption performance can be improved by about 4 times, and the low-temperature denitration (DeNOx) performance can be improved by about 40% p.

The present application relates to a method of manufacturing a perovskite solar cell and a perovskite solar cell manufactured by the method, and more particularly, to a method of manufacturing a perovskite solar cell and a perovskite solar cell manufactured by the method, the method including the steps of: (S1) performing a) oxidant treatment, or b) ultraviolet and ozone treatment, or c) oxygen plasma treatment, or d) nitrogen dioxide gas treatment on a hole transport layer (HTL) of a laminate sequentially layering a base layer, a first electrode layer, and the HTL containing a metal oxide, to oxidize the metal oxide; and (S2) sequentially layering a perovskite layer, an electron transport layer, and a second electrode layer on the HTL of the laminate.

1. Name of the product in this design: Multi-parameter sensor for mining. 2. Application of this design: This design is mainly used to measure the concentration of various gases such as methane, carbon monoxide, and oxygen in coal mines and environments where gas and coal dust explosions occur. It can also detect the concentration of gases such as carbon dioxide, nitrogen dioxide, ethylene, and acetylene by replacing the detection components, and realize data communication and audible and visual alarms. 3. The key design feature of this product is its shape. 4. The image or photograph that best illustrates the design's key points: 3D rendering 1.

An engine data processor for an internal combustion engine is structured and arranged for: receiving a geometric characteristic of an exhaust unit for discharging an exhaust gas composition, and determining from the geometric characteristic a smoke visibility limit value; receiving filter fill status information from an exhaust gas filter for filtering the exhaust gas composition; receiving a filter pressure value; establishing the filter fill status information at least in part from the filter pressure value; receiving a mean catalytic converter temperature of an exhaust gas catalytic converter for catalyzing the exhaust gas composition and determining a nitrogen dioxide conversion rate subject to the filter fill status information which has been received and the mean catalytic converter temperature; comparing the calculated nitrogen dioxide conversion rate with the smoke visibility limit value, and determining therefrom a control variable for the internal combustion engine so that the exhaust gas composition is invisible.

The application discloses a Pt-WS2@BP nanoflower composite material and a preparation method and application thereof, and relates to the field of semiconductor gas sensing.The material is prepared by a one-step hydrothermal method, raw materials of which include sodium tungstate, thiourea and oxalic acid, and then is mixed with BP nanosheets and ultrasonically mixed with chloroplatinic acid, and vacuum drying is performed to obtain a noble metal Pt-loaded WS2@BP nanocomposite material, wherein the WS2 three-dimensional flower-like nanospheres have a flaky nanoflower structure, and the BP nanosheets have a nanosheet layer structure.The preparation process is simple, and the prepared Pt-WS2@BP nanoflower composite material has good response and recovery characteristics and excellent selectivity to nitrogen dioxide gas at low temperature.The prepared composite material can be used in the field of semiconductor gas sensing.

The present application relates to a kind of dual optical path nitrogen dioxide measurement system and method based on blue laser, using dual-wavelength laser cavity enhanced absorption spectroscopy technology, carries out NO2 absorption measurement under 405nm and 410nm wavelength, and combined with high reflectivity optical resonator, improve detection precision and sensitivity.Through dual-wavelength comparison method, using dual-wavelength absorption spectroscopy analysis, calculate absorbance difference, to effectively eliminate the influence of environmental factors on measurement accuracy, improve measurement reliability.Using more than 99.9% high reflectivity mirror, to realize high reflectivity optical resonator enhancement technology, laser is reflected in resonator multiple times, optical path is extended hundreds of times, improve NO2 absorption signal intensity, realize ppb grade ultra-low concentration measurement.Compared with traditional optical method, the system has lower cost, higher accuracy and stronger environmental adaptability, provides an efficient, stable solution for atmospheric pollution monitoring.

A method for producing ammonium nitrate includes a nitrogen dioxide recovery step of bringing nitrogen dioxide in a cement exhaust gas into contact with water to obtain an NOx-containing solution, a reduction reaction step of producing ammonia by bringing a reducing catalyst into contact with the NOx-containing solution, an ammonia recovery step of vaporizing the ammonia with a waste heat gas, a solid-liquid separation step of separating a residue after the ammonia recovery into iron hydroxide and an unused residue of NOx, a neutralization step of bringing the separated nitrate / nitrite nitrogen-containing solution and the NOx-containing solution into contact with the ammonia vaporized and recovered to prepare ammonium nitrate, and a catalyst production step in which magnetite used in the reduction reaction step is obtained by reacting iron sulfate with a sodium hydroxide aqueous solution and separating the mixture into solid and liquid, the sodium sulfate aqueous solution in the solid-liquid separation is separated into sodium hydroxide and sulfuric acid by electrodialysis, and the sodium hydroxide is used in a circulatory manner for preparing the magnetite, where the nitrogen dioxide in the cement exhaust gas is treated simply and efficiently while reducing environmental burden.

The invention discloses an Au atom regulation and control indium oxide / zinc oxide heterojunction sensor for realizing bidirectional high-selectivity detection of nitrogen dioxide and sulfur dioxide and a preparation method of the Au atom regulation and control indium oxide / zinc oxide heterojunction sensor, and belongs to the technical field of metal oxide semiconductor gas sensors.The preparation method comprises the steps that S1, an In2O3 / ZnO material is obtained through a two-step hydrothermal method; s2, the In2O3 / ZnO material is prepared into an Au-In2O3 / ZnO material through an impregnation method and a high-temperature decomposition process; s3, respectively grinding the In2O3 / ZnO material obtained in the step S1 and the Au modified Au-In2O3 / ZnO material obtained in the step S2 into slurry, and respectively coating two sensor micro hot plates with the slurry; and S4, preparing the sensor substrate in the S3 into the sensor. The Au atom regulated In2O3 / ZnO heterojunction sensor prepared by the invention can realize bidirectional high-selectivity detection of NO2 and SO2, and is applied to the field of environmental pollution gas sensors.

The invention discloses a production process and device for preparing liquid nitrogen tetroxide by recycling nitric oxide. Nitrogen oxides in the tail gas are respectively absorbed by water and alkali liquor to prepare a nitric acid solution and a sodium nitrate-nitrous acid solution; a dilute nitric acid solution and a sodium nitrate and nitrite solution are respectively stored and then mixed to enter a nitric oxide generation tower for reaction to generate nitric oxide gas and a sodium nitrate aqueous solution. The nitric oxide gas is lightly oxidized by using oxygen in the nitric oxide generation tower, then enters the oxidation absorption tower and is heavily oxidized by using concentrated nitric acid, so that the nitric oxide gas is completely converted into nitrogen dioxide gas, and the concentrated nitric acid is used for absorption at the upper section of the oxidation absorption tower to form fuming nitric acid. Fuming nitric acid is heated by steam, and liquid nitrogen tetroxide is produced after condensation. The non-condensable gas contains a small amount of nitrogen oxides, and then passes through a denitration device. By adopting the device and the process, the nitrogen oxide in the recovered waste gas can be effectively ensured to be prepared into liquid nitrogen tetroxide, and the content of the nitrogen oxide in the waste gas outlet is reduced.

The application discloses a kind of nitrogen dioxide vapor detection devices for silver nitrate preparation and its detection method, the detection device includes reaction kettle, reaction kettle is connected with detection box, detection box is provided with the gas inlet pipe connected with the kettle cavity of reaction kettle, gas inlet pipe is provided with suction assembly at gas inlet, pneumatic check valve is arranged in gas inlet pipe, the detection bottle for containing detection liquid is arranged at the end of detection box away from gas inlet pipe, glass tube connected with gas inlet pipe is arranged in detection bottle, drainage pipe is arranged in the bottom of detection bottle, first plugging component is arranged in drainage pipe, and liquid inlet pipe is connected to the top of detection bottle. The detection device of the application is simple in structure, easy to operate, and low in cost. The nitrogen dioxide content in the reaction kettle can be continuously and quickly detected, the nitrogen dioxide detection efficiency and detection effect are improved, and the silver nitrate preparation efficiency and preparation quality are ensured.

The invention provides a nitrogen dioxide gas sensor based on SnTe and In2S3 heterojunction, a preparation process and application, and belongs to the technical field of electronic components. According to the technical scheme, the gas sensor comprises a gold interdigital electrode and a gas sensitive material coated on the surface of the gold interdigital electrode, the gas sensitive material is a SnTe and In2S3 heterojunction composite nano material, and the SnTe and In2S3 heterojunction composite nano material is formed by attaching an In2S3 nanosheet on the surface of a layered block SnTe through a solvothermal method. The preparation method has the beneficial effects that a solvothermal method is adopted, the In2S3 nanosheet with one inclined side is attached to the surface of SnTe, the process is simple, and the cost is low; according to the heterojunction structure, the specific surface area is increased, gas adsorption and electron transfer are promoted, and the sensitivity, selectivity and stability of NO2 at room temperature are remarkably improved; the lower detection limit of the sensor reaches ppb level, the response recovery is fast, high-temperature aging is effectively avoided when the sensor works at room temperature, and the sensor is suitable for portable and wearable equipment.

A method for extracting copper from sulphide mineral ore, comprising the following steps: stacking the ore to form a pile (heap), a leaching step, irrigating the pile with a first irrigating solution containing an acidic nitrate solution and nitrite, thereby causing the oxidation of sulfide minerals inside the pile, oxidation of gaseous nitrogen oxide released during the oxidation of sulfide minerals inside the pile with oxygen to form nitrogen dioxide, and hydrolysis of nitrogen dioxide to form nitric acid and / or nitrous acid in the first irrigating solution inside the pile, to continue the leaching stage and reduce nitrogen oxide losses from the pile.

This invention proposes a palladium sulfide-molybdenum disulfide composite hierarchical nanostructure-based nitrogen dioxide sensor and its fabrication method, belonging to the fields of sensor technology and composite nanomaterials technology. The sensor of this invention includes a substrate and a gas-sensitive layer loaded on the substrate. The gas-sensitive layer is a palladium sulfide-molybdenum disulfide composite nanomaterial, in which PdS nanoparticle clusters are embedded on the surface of MoS2 nanoflowers. PdS and MoS2 form a heterojunction, improving the separation and transport rate of charge carriers, thereby enhancing the gas-sensitive performance of the nitrogen dioxide sensor. This results in a higher response value and faster response recovery time for NO2 concentrations at the ppm level.

The utility model relates to the field of carbon dioxide purification, and discloses a device for removing impurity gas in carbon dioxide, which comprises an impurity removal box, a carrier plate I provided with activated carbon, a carrier plate II provided with a photocatalyst, a carrier plate III provided with a polyimide film, an ultraviolet lamp and a steering assembly. The waste gas is introduced into an impurity removal box, activated carbon adsorbs all smoke dust, water molecules and part of impurity gases such as sulfur dioxide and nitrogen dioxide in the waste gas, and then a photocatalyst is irradiated by an ultraviolet lamp to promote volatile organic compounds, hydrocarbons and other impurities to be converted into carbon dioxide and water; meanwhile, impurities such as nitrogen dioxide and sulfur dioxide can be converted into nitrate, sulfate and the like, finally, the carbon dioxide is discharged out of the impurity removal box to be collected through the selection effect of the polyimide film on the carbon dioxide, and pure carbon dioxide is obtained. The device has the advantages and effects that the illumination intensity of the photocatalyst is uniform, the impurity removal efficiency is high, and the process is simple.

The utility model relates to a kind of industrial silicon furnace high-temperature flue gas backflow technology high-efficiency heat utilization device, including waste heat boiler, waste heat boiler is connected with the flue gas outlet of ore-heating furnace by pipeline, for recycling the heat in flue gas;Mixed reaction device, the air inlet of mixed reaction device is connected with the gas outlet of waste heat boiler by pipeline, for mixing and reacting the component in flue gas;Dust collector, the air inlet of dust collector is connected with the gas outlet of waste heat boiler by pipeline, for removing particulate matter in flue gas;Absorption tower, the air inlet of absorption tower is connected with the gas outlet of dust collector by pipeline, for removing sulfur oxide and nitrogen oxide in flue gas;Discharge pipeline, discharge pipeline is connected with the gas outlet of absorption tower, for flue gas after processing is discharged to atmosphere, the utility model is optimized flue gas treatment by adjusting oxygen content and back retention flue gas, effectively inhibit the emission of harmful gas such as nitrogen dioxide, while back retention flue gas utilizes waste heat, improve energy efficiency and reduce energy consumption.

The invention discloses a method for removing amorphous carbon in a single-walled carbon nanotube. Comprising the following steps: heating a crude single-walled carbon nanotube containing amorphous carbon impurities in mixed gas to a temperature I for roasting I, then reducing the temperature to a temperature II for continuously roasting II, and thus obtaining the purified single-walled carbon nanotube, the temperature I ranges from 350 DEG C to 500 DEG C; the temperature II ranges from 200 DEG C to 300 DEG C; the mixed gas comprises at least two of air, carbon dioxide, nitrogen dioxide or nitrous oxide. According to the method, the specific mixed gas is adopted, the temperature is firstly heated to the temperature I for roasting I, then the temperature is reduced to the temperature II for continuously roasting II, the amorphous carbon is selectively oxidized in the oxidation process, the single-walled carbon nanotubes are not damaged, and the method is simple in process, high in amorphous carbon removal rate and capable of being used for industrial large-scale production.

The utility model relates to the technical field of power electronics, in particular to a harmful gas detection circuit based on SMT32. Comprising a main control chip, a display chip, a buzzer, a chlorine gas sensor, a sulfur dioxide gas sensor, a hydrogen sulfide gas sensor, a nitrogen dioxide gas sensor, a resistor, a slide rheostat, a capacitor, a crystal oscillator, a light emitting diode, a triode, a 3V3 power supply, a 5V power supply and a terminal. The gas sensor converts concentration parameters of chlorine, sulfur dioxide, hydrogen sulfide and nitrogen dioxide into digital signals, the STM32 chip realizes protocol conversion and data acquisition, and gas data passes through the LCD display screen and the buzzer, so that data display and early warning functions are realized, and the convenience of environment testing is improved.