A detection device and method for benzene-based volatile organic compounds

Abstract

The present invention discloses a detection device for benzene-based volatile organic compounds, comprising a gas collection and supply unit, a gas rapid oxidation unit and a scattering and extinction characteristic measurement unit. An ozone generator, a gas sampling pump and a nitrogen oxide generator in the gas collection and supply unit are respectively connected to the oxidation flow reactor through provided pipelines. The gas rapid oxidation unit comprises an oxidation flow reactor with a built-in ultraviolet lamp. The scattering and extinction characteristic measurement unit comprises a smoke box and an optical characteristic measurement platform. The smoke box is located on the other side of the oxidation flow reactor, and the bottom of the smoke box is connected to the oxidation flow reactor through a provided pipeline. The present invention also relates to a detection method for the detection device for benzene-based volatile organic compounds, which realizes online detection of the scattering and extinction characteristics of benzene-based volatile organic compounds at two wavelengths in the ultraviolet and visible light regions.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric volatile organic compound detection, and in particular to a device and method for detecting benzene-based volatile organic compounds. Background Art

[0002] Volatile organic compounds, commonly referred to as VOCs, are a class of compounds commonly found in the atmosphere. They are mostly gaseous at room temperature and pressure and play a special role in the atmospheric oxidation process. The composition of atmospheric VOCs is complex and can be divided into compounds such as benzene, alkanes, alkenes, alkynes, halogenated hydrocarbons, aldehydes, esters, and ketones based on their chemical composition. Benzene-based volatile organic compounds are one of the important components of VOCs. They are mainly emitted from anthropogenic sources such as petrochemicals, motor vehicle exhaust, and organic solvents. They are important atmospheric pollutants commonly found in indoor and outdoor air and have an important influence on the formation of atmospheric pollution. Many benzene-based volatile organic compounds have varying degrees of toxicity to organisms and can directly endanger human health. Therefore, the detection of benzene-based volatile organic compounds is of great significance.

[0003] Since benzene-based volatile organic compounds have the characteristics of low concentration, high activity, volatility, and complex composition, the detection and analysis process must be simple, fast, efficient, and pollution-free. The current methods for determining benzene-based volatile organic compounds mainly include gas chromatography, gas chromatography-mass spectrometry, high-performance liquid chromatography, etc. Although they have high detection accuracy, the instruments are expensive, the operation is complicated and time-consuming, and it is not easy to achieve online detection, which is not convenient for real-time monitoring of air quality. For example, invention patents CN107764806A and CN113340882A use catalytic luminescence to detect total volatile organic compounds, and use plasma or microwave methods to activate ozone to promote the redox reaction, improve the sensitivity of catalytic luminescence detection, and realize rapid and sensitive detection of volatile organic compounds. This type of device can realize rapid detection of total volatile organic compounds, but it needs to be used in conjunction with a chromatographic separation device to distinguish different types of volatile organic compounds. Benzene-based volatile organic compounds are important precursors of secondary organic aerosols, which are often expressed as SOA. In the atmosphere, especially in the presence of nitrogen oxides and ozone, they can be oxidized to form brown carbon, whose absorption characteristics in the ultraviolet and visible regions are spectrally dependent. Therefore, online detection of benzene-based volatile organic compounds can be achieved by rapidly oxidizing benzene-based volatile organic compounds in the presence of nitrogen oxides and ozone to form secondary organic aerosols and detecting the multi-wavelength scattering and extinction characteristics of secondary organic aerosols. Summary of the invention

[0004] The purpose of the present invention is to provide a device and method for rapidly oxidizing benzene-based volatile organic compounds in the presence of nitrogen oxides and ozone to form secondary organic aerosols and detecting the multi-wavelength scattering and extinction characteristics of the secondary organic aerosols, so as to realize online detection of benzene-based volatile organic compounds.

[0005] To achieve the above-mentioned object, the present invention provides the following technical solutions: a detection device for benzene-based volatile organic compounds, comprising a gas collection and supply unit, a gas rapid oxidation unit, and a scattering and extinction characteristic measurement unit;

[0006] The gas collection and supply unit includes an ozone generator, a gas sampling pump and a nitrogen oxide generator; the gas rapid oxidation unit includes an oxidation flow reactor with a built-in ultraviolet lamp; the scattering and extinction characteristic measurement unit includes a smoke box and an optical characteristic measurement platform;

[0007] The ozone generator, gas sampling pump and nitrogen oxide generator are respectively connected to the oxidation flow reactor through the provided pipes, the smoke box is located on the other side of the oxidation flow reactor, and the bottom of the smoke box is connected to the oxidation flow reactor through the provided pipe, and the optical property measurement platform is placed in the center of the smoke box.

[0008] Preferably, the optical property measurement platform includes a laser, an aperture, a light detector, a filter, an annular guide rail and a nozzle, wherein the nozzle is located at the center of the optical property measurement platform and is connected to a pipe at a lower end, and the annular guide rail surrounds the optical property measurement platform, and the laser, the aperture, the light detector and the filter are located in a straight line, and the laser and the aperture are located on one side of the nozzle, and the light detector and the filter are located on the other side of the nozzle, and the laser, the aperture, the light detector and the filter all move around the annular guide rail.

[0009] Preferably, the laser includes a first laser light source with an emission wavelength in the ultraviolet region and a wavelength of λ1 and a second laser light source with an emission wavelength in the visible light region and a wavelength of λ2, the filter is a dual-band bandpass filter with wavelengths of λ1 and λ2, and the light detector is a photodiode or a photomultiplier tube.

[0010] Preferably, the aperture includes a first aperture and a second aperture, the light detector includes a first light detector and a second light detector, and the filter includes a first filter and a second filter.

[0011] Preferably, an exhaust pipe is provided at the upper end of the smoke box, and the reactants are sprayed out from the pipe at the lower end of the smoke box through the nozzle and discharged from the exhaust pipe.

[0012] A detection method of a benzene-based volatile organic compound detection device comprises the following steps:

[0013] S1. Using a gas sampling pump to collect gas samples containing benzene-based volatile organic compounds in real time, and using a nitrogen oxide generator and an ozone generator to respectively provide nitrogen oxides and ozone in real time for a rapid oxidation reaction of the benzene-based volatile organic compounds;

[0014] S2, the mixed gas of the sampled gas, nitrogen oxides and ozone undergoes a rapid oxidation reaction under the irradiation of the ultraviolet light emitted by the ultraviolet lamp in the oxidation flow reactor to form secondary organic aerosol;

[0015] S3. The secondary organic aerosol and gas mixture after the reaction enter the smoke box from the bottom through the pipeline, are sprayed out from the nozzle, enter the optical property measurement platform placed in the center of the smoke box, and then are discharged from the smoke box from the exhaust pipe at the top;

[0016] S4. On the optical property measurement platform, a set of light source-light detection devices is formed by a laser light source and a light detector located in the same straight line, and the set of light source-light detection devices is moved simultaneously on the circular guide rail to measure the extinction characteristics of the aerosol; the relative positions of the two sets of light source-light detection devices are adjusted within the range of 10°-170°, so as to measure the scattering characteristics of the aerosol at different angles;

[0017] S5. Finally, the detection of benzene-based volatile organic compounds is achieved based on the relationship between the scattering and extinction characteristics and the wavelength under the two wavelength laser light sources.

[0018] Preferably, one of the light source-light detection devices includes a set of light source lasers with a wavelength of λ1 emitted by the first laser light source, and the transmitted light after passing through the nozzle passes through a dual-band bandpass first filter with wavelengths of λ1 and λ2, and is detected by a first light detector located in the same straight line, and its scattered light passes through a dual-band bandpass second filter with wavelengths of λ1 and λ2 and is detected by another second light detector.

[0019] Preferably, another group of the light source-light detection device includes the second laser light source emitting a light source laser with a wavelength of λ2, and the transmitted light after passing through the nozzle passes through a second dual-band bandpass filter with wavelengths of λ1 and λ2 and is detected by a second light detector located in the same straight line, and its scattered light passes through a first dual-band bandpass filter with wavelengths of λ1 and λ2 and is detected by a first light detector.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. In the present invention, it is utilized that benzene-based volatile organic compounds can be oxidized to generate brown carbon with spectrally dependent absorption characteristics in the ultraviolet and visible light regions under the condition of the presence of nitrogen oxides and ozone in the atmosphere, and a dual-wavelength laser is used to simultaneously detect the aerosol scattering and extinction characteristics at two wavelengths, and the benzene-based volatile organic compounds that can be oxidized to generate aerosols with different scattering and extinction characteristics are distinguished according to the relationship between the scattering and extinction characteristics and the wavelength.

[0022] 2. In the present invention, the filter used in the light source-light detection device is a dual-band bandpass filter with wavelengths in the ultraviolet and visible light regions, which realizes the simultaneous detection of scattering and extinction characteristics at two wavelengths in the ultraviolet and visible light regions.

[0023] 3. The present invention can measure online, continuously and simultaneously the scattering and extinction characteristics of aerosols generated by rapid oxidation of a mixture of benzene-based volatile organic compounds with nitrogen oxides and ozone under ultraviolet light at different angles and their relationship with the wavelengths of ultraviolet and visible light, so as to distinguish different types of benzene-based volatile organic compounds. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0025] In the attached picture:

[0026] Figure 1 It is a schematic diagram of a detection device for benzene-based volatile organic compounds of the present invention;

[0027] Figure 2 It is a schematic diagram of an optical property measurement platform in the benzene-based volatile organic compound detection device of the present invention;

[0028] Numbers in the figure: 1. Ozone generator; 2. Gas sampling pump; 3. Nitrogen oxide generator; 4. Oxidation flow reactor; 41. Ultraviolet lamp; 5. Smoke box; 6. Optical property measurement platform; 60. Annular guide rail; 61. Nozzle; 62. First laser light source; 63. First aperture; 64. Second laser light source; 65. Second aperture; 66. First light detector; 67. First filter; 68. Second light detector; 69. Second filter. DETAILED DESCRIPTION

[0029] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0030] Example: Figure 1 and Figure 2As shown, a detection device for benzene-based volatile organic compounds includes a gas collection and supply unit, a gas rapid oxidation unit, and a scattering and extinction characteristic measurement unit;

[0031] The gas collection and supply unit includes an ozone generator 1, a gas sampling pump 2 and a nitrogen oxide generator 3. The gas rapid oxidation unit includes an oxidation flow reactor 4 with a built-in ultraviolet lamp 41. The scattering and extinction characteristic measurement unit includes a smoke box 5 and an optical characteristic measurement platform 6. The ozone generator 1, the gas sampling pump 2 and the nitrogen oxide generator 3 are respectively connected to the oxidation flow reactor 4 through provided pipes. The smoke box 5 is located on the other side of the oxidation flow reactor 4, and the bottom of the smoke box 5 is connected to the oxidation flow reactor 4 through a provided pipe. The optical characteristic measurement platform 6 is placed in the center of the smoke box 5. The optical characteristic measurement platform 6 includes a laser, an aperture, a light detector, a filter, a circular guide rail 60 and a nozzle 61. The laser includes a first laser light source 62 with an emission wavelength in the ultraviolet region and a wavelength of λ1 and a second laser light source 64 with an emission wavelength in the visible light region and a wavelength of λ2. The filter is a wavelength A dual-band bandpass filter with lengths of λ1 and λ2, the light detector is a photodiode or a photomultiplier tube, the aperture includes a first aperture 63 and a second aperture 65, the light detector includes a first light detector 66 and a second light detector 68, the filter includes a first filter 67 and a second filter 69, the nozzle 61 is located at the center of the optical property measurement platform 6, and the nozzle 61 is connected to the pipe at the lower end, an exhaust pipe is provided at the upper end of the smoke box 5, the reactant is sprayed out from the pipe at the lower end of the smoke box 5 through the nozzle 61, and is discharged from the exhaust pipe, the annular guide 60 surrounds the optical property measurement platform 6, the laser, the aperture, the light detector and the filter are located in a straight line, and the laser and the aperture are located on one side of the nozzle 61, and the light detector and the filter are located on the other side of the nozzle 61, and the laser, the aperture, the light detector and the filter all move around the annular guide 60.

[0032] A detection method of a benzene-based volatile organic compound detection device specifically comprises the following steps:

[0033] S1, using a gas sampling pump 2 to collect a gas sample containing benzene-based volatile organic compounds in real time, and using a nitrogen oxide generator 3 and an ozone generator 1 to respectively provide nitrogen oxides and ozone in real time for a rapid oxidation reaction of the benzene-based volatile organic compounds;

[0034] S2, the mixed gas of the sampled gas and nitrogen oxides and ozone undergoes a rapid oxidation reaction under the irradiation of the ultraviolet light emitted by the ultraviolet lamp tube 41 in the oxidation flow reactor 4 to form a secondary organic aerosol;

[0035] S3, the reacted secondary organic aerosol and gas mixture enter the smoke box 5 from the bottom through the pipeline, are ejected from the nozzle 61, enter the optical property measurement platform 6 placed in the center of the smoke box 5, and then are discharged from the smoke box 5 from the upper exhaust pipe;

[0036] S4. On the optical property measurement platform 6, one of the light source-light detection devices includes the first laser light source 62 emitting a light source laser with a wavelength of λ1, and the transmitted light after passing through the nozzle 61 passes through a first double-band bandpass filter 67 with wavelengths of λ1 and λ2, and is detected by a first light detector 66 located in the same straight line, and its scattered light passes through a second double-band bandpass filter 69 with wavelengths of λ1 and λ2 and is detected by another second light detector 68, wherein another group of the light source-light detection devices includes a second laser light source 64 emitting a light source laser with a wavelength of λ2, and the transmitted light after passing through the nozzle 61 passes through a first double-band bandpass filter 67 with wavelengths of λ1 and λ2, and is detected by another second light detector 68. The second double-band bandpass filter 69 with wavelengths of λ1 and λ2 is detected by the second light detector 68 located in the same straight line, and its scattered light passes through the first double-band bandpass filter 67 with wavelengths of λ1 and λ2 and is detected by the first light detector 66. The laser light source and the light detector located in the same straight line form a set of light source-light detection devices, and the formed set of light source-light detection devices are moved simultaneously on the circular guide rail 60 to measure the extinction characteristics of the aerosol; the relative positions of the two sets of light source-light detection devices are adjusted within the range of 10°-170°, so as to measure the scattering characteristics of the aerosol at different angles;

[0037] S5. Finally, the detection of benzene-based volatile organic compounds is achieved based on the relationship between the scattering and extinction characteristics and the wavelength under the two wavelength laser light sources.

[0038] Finally, it should be noted that the above description is only a preferred example of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A detection device for benzene-based volatile organic compounds, characterized in that: It includes a gas collection and supply unit, a gas rapid oxidation unit, and a scattering and extinction characteristic measurement unit; The gas collection and supply unit includes an ozone generator, a gas sampling pump and a nitrogen oxide generator; the gas rapid oxidation unit includes an oxidation flow reactor with a built-in ultraviolet lamp; the scattering and extinction characteristic measurement unit includes a smoke box and an optical characteristic measurement platform; The ozone generator, the gas sampling pump and the nitrogen oxide generator are respectively connected to the oxidation flow reactor through provided pipes, the smoke box is located at the other side of the oxidation flow reactor, and the bottom of the smoke box is connected to the oxidation flow reactor through a provided pipe, and the optical property measurement platform is placed in the center of the smoke box; The optical property measurement platform comprises a laser, an aperture, a light detector, a filter, an annular guide rail and a nozzle, wherein the nozzle is located at the center of the optical property measurement platform and is connected to a pipe at the lower end, and the annular guide rail surrounds the optical property measurement platform, wherein the laser, the aperture, the light detector and the filter are located in a straight line, and wherein the laser and the aperture are located on one side of the nozzle, and the light detector and the filter are located on the other side of the nozzle, and wherein the laser, the aperture, the light detector and the filter all move around the annular guide rail; The laser comprises a first laser light source with an emission wavelength in the ultraviolet region and a wavelength of λ1 and a second laser light source with an emission wavelength in the visible light region and a wavelength of λ2. The filter is a dual-band bandpass filter with wavelengths of λ1 and λ2, and the light detector is a photodiode or a photomultiplier tube.

2. The device for detecting benzene-based volatile organic compounds according to claim 1, characterized in that: The aperture includes a first aperture and a second aperture, the light detector includes a first light detector and a second light detector, and the filter includes a first filter and a second filter.

3. The device for detecting benzene-based volatile organic compounds according to claim 2, characterized in that: An exhaust pipe is arranged at the upper end of the smoke box, and the reactants are sprayed out from the pipe at the lower end of the smoke box through the nozzle and discharged from the exhaust pipe.

4. A detection method based on the detection device of benzene-based volatile organic compounds according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Using a gas sampling pump to collect gas samples containing benzene-based volatile organic compounds in real time, and using a nitrogen oxide generator and an ozone generator to respectively provide nitrogen oxides and ozone in real time for a rapid oxidation reaction of the benzene-based volatile organic compounds; S2, the mixed gas of the sampled gas, nitrogen oxides and ozone undergoes a rapid oxidation reaction under the irradiation of the ultraviolet light emitted by the ultraviolet lamp in the oxidation flow reactor to form secondary organic aerosol; S3. The secondary organic aerosol and gas mixture after the reaction enter the smoke box from the bottom through the pipeline, are sprayed out from the nozzle, enter the optical property measurement platform placed in the center of the smoke box, and then are discharged from the smoke box from the exhaust pipe at the top; S4. On the optical property measurement platform, a set of light source-light detection devices is formed by a laser light source and a light detector located in the same straight line, and the set of light source-light detection devices is moved simultaneously on the circular guide rail to measure the extinction characteristics of the aerosol; the relative positions of the two sets of light source-light detection devices are adjusted within the range of 10°-170°, so as to measure the scattering characteristics of the aerosol at different angles; S5. Finally, the detection of benzene-based volatile organic compounds is achieved based on the relationship between the scattering and extinction characteristics and the wavelength under the two wavelength laser light sources.

5. The detection method of a benzene-based volatile organic compound detection device according to claim 4, characterized in that: One of the light source-light detection devices includes a light source laser with a wavelength of λ1 emitted by the first laser light source, and the transmitted light after passing through the nozzle passes through a dual-band bandpass first filter with wavelengths of λ1 and λ2, and is detected by a first light detector located in the same straight line, and its scattered light passes through a dual-band bandpass second filter with wavelengths of λ1 and λ2 and is detected by another second light detector.

6. The detection method of a benzene-based volatile organic compound detection device according to claim 4, characterized in that: Another group of light source-light detection devices includes a second laser light source emitting a light source laser with a wavelength of λ2. The transmitted light after passing through the nozzle passes through a second dual-band bandpass filter with wavelengths of λ1 and λ2 and is detected by a second light detector located in the same straight line. The scattered light passes through a first dual-band bandpass filter with wavelengths of λ1 and λ2 and is detected by a first light detector.

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