Apparatus for measuring hydrogen sulfide with a vuv lamp ion mobility spectrometer

Abstract

The application discloses a device for measuring hydrogen sulfide by a VUV lamp ion mobility spectrometer, comprising an ion mobility spectrometer and a time-resolved dynamic dilution structure; the ion mobility spectrometer comprises an electrode ring and an insulating ring, the electrode ring and the insulating ring are coaxially and alternately arranged and extruded and sealed to form a hollow cavity, one end of the ion mobility spectrometer is provided with an ionization source, one side of an outer wall of the ion mobility spectrometer close to the ionization source is sequentially provided with a tail gas port, a carrier gas port and a sample inlet, the other end of the ion mobility spectrometer is provided with a drift gas port on an outer wall thereof, the drift gas port is sequentially connected with an ozone device I and a flow controller I, the carrier gas port is sequentially connected with a dopant cylinder and a flow controller II, and a grid is arranged on one side of the hollow cavity of the ion mobility spectrometer close to the drift gas port.

Description

Technical Field

[0001] This invention relates to the field of ion mobility spectrometry measurement technology, and in particular to a device for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer. Background Technology

[0002] Hydrogen sulfide (H2S), a colorless gas with a rotten egg smell, commonly known as stench, swamp gas, and manure gas, is a foul-smelling, highly corrosive, and toxic gas produced under anaerobic conditions. It has long been considered a toxic gas and environmental pollutant. The history of H2S as an environmental toxin dates back to 1700, when an Italian physician described it in his writings as "sewage gas," causing eye irritation and inflammation in workers. This gas was subsequently identified as H2S. H2S released into the atmosphere poses a threat to human health; even concentrations as low as 20 ppb are considered a public health hazard. In fact, the U.S. Occupational Safety and Health Administration has established an 8-hour exposure limit of 10 ppm for humans. Because a concentration of 700 ppm can cause immediate collapse within a minute, H2S is often referred to as a "knockout agent" toxic gas; this "knockout" effect makes H2S a toxic gas with an extremely low safety margin. In the workplace, H2S inhalation is the second leading cause of death, and H2S is present in a wide variety of environments, including industrial sectors such as petrochemical plants, steel mills, fertilizer plants, power plants, and wastewater treatment plants; coal mining; agriculture; construction; personal health; and the energy sector—all of which are closely related to human physical and mental health. Therefore, monitoring H2S concentrations is crucial.

[0003] In addition to posing serious health risks, H2S's acidity and the microorganisms it induces can corrode and damage the structure of sewage systems, leading to costly additional maintenance and replacement expenses. Therefore, real-time measurement of H2S in sewage systems and tracking its short-term changes are beneficial for the maintenance of sewage networks and have practical significance for public health.

[0004] Methods and techniques for detecting the harmful gas H2S include gas chromatography, iodometric titration, laser absorption spectroscopy, methylene blue spectrophotometry, and silver sulfide colorimetry. Among these, the methylene blue colorimetric method is the most widely used and sensitive, but H2S is extremely unstable when applied to atmospheric measurements. It is easily degraded by oxidation and sunlight during sampling and storage, and the composition of the absorbent must take into account the stability of the H2S sample. Gas chromatography-based methods are often called the "gold standard" for H2S quantification due to their significant measurement sensitivity, but their application in actual detection is often limited by complex sample pretreatment, cumbersome analytical procedures, large instrument size, and high equipment costs. Other analytical methods also share these common problems. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention discloses a device for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer, comprising: an ion mobility spectrometer and a time-resolved dynamic dilution structure;

[0006] The ion mobility spectrometer includes an electrode ring and an insulating ring. The electrode ring and the insulating ring are coaxially alternately arranged and squeezed and sealed to form a hollow cavity. An ionization source is provided at one end of the ion mobility spectrometer. On the outer wall of the ion mobility spectrometer, near the ionization source, a tail gas port, a carrier gas port, and a sample inlet are arranged in sequence. A drift gas port is provided on the outer wall of the other end of the ion mobility spectrometer. The drift gas port is connected in sequence to an ozone device I and a flow controller I. The carrier gas port is connected in sequence to a dopant cylinder and a flow controller II. A grid is provided on the side of the hollow cavity of the ion mobility spectrometer near the drift gas port.

[0007] The time-resolved dynamic dilution structure includes a three-way solenoid valve I, a three-way solenoid valve II, a three-way solenoid valve III, and a sampling ring. One end of the sampling ring is connected to the vacuum pump II, and the other end is connected to the gas sample treated by the ozone device II. The sample injection volume of the vacuum pump II is controlled by a flow controller IV.

[0008] Furthermore, after the gas sample is processed by the time-resolved dynamic dilution structure, it enters the ion mobility spectrometer through the injection port during the pretreatment process. Air enters the ozone device I under the control of flow controller I for oxidation and enters the ion mobility spectrometer through the purging gas port. Air purges the dopant molecules in the dopant tube under the control of flow controller II and enters the ion mobility spectrometer through the carrier gas port. The tail gas from the tail gas port is discharged freely.

[0009] The ion mobility spectrometer uses a vacuum ultraviolet lamp as its ionization source, operates in negative ion mode, has a carrier gas flow rate of 100–150 ml / min, a drift gas flow rate of 250–350 ml / min, and a migration tube temperature of 130–150 °C.

[0010] The dopant molecules inside the dopant tube are ionizable organic solvents, wherein the organic solvent is one of acetone, butanone, or ethanol.

[0011] The sample to be tested after passing through the ozone device is drawn into the sampling loop by the vacuum pump II via flow controller IV. The purge gas, controlled by flow controller V, directly enters the inlet of the ion mobility spectrometer. Then, the vacuum pump II stops, and three-way solenoid valves I, II, and III are switched to change the airflow direction. The purge gas then enters the sampling loop, sending the sample into the inlet. The product SO2 flowing into the ion mobility spectrometer from the sampling loop undergoes an ion-molecule reaction with the dopant molecules, and the product peak is located at the reagent ion peak O2. - (H2O) nBehind; dopant molecules are ionized by a non-radioactive ionization source to generate reactant ions CO3. - With O2 - (H2O) n Where n is any integer value, the two reagent ions are adjusted to make CO3 - With O2 - (H2O) n Peak intensity ratio greater than 6.

[0012] The detection limit of this device is less than 5 ppb, and the single detection cycle is less than 2 minutes.

[0013] By employing the aforementioned technical solution, this invention provides a device for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer. This device is based on ion mobility spectrometry (IMS), a technique known for its high sensitivity and fast response time. The advantage of this method lies in the elimination of the need for additional sample pre-separation. Utilizing the difference in retention capacity between sample molecules and water molecules within the tetrafluoroethylene sampling ring, temporal resolution of their concentrations can be achieved during sample introduction, thereby eliminating humidity interference and shortening the response time. This device has been applied to the real-time measurement of H2S from sewage sources, and the correlation between sewage H2S and residents' daily living habits has been studied, demonstrating broad application prospects. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a structural block diagram of the device of the present invention;

[0016] Figure 2 The spectrum of 200 ppb H2S at 36% humidity was obtained by TRDD before and after connecting to ozone device II (21).

[0017] Figure 3 The spectrum of 100 ppb H2S directly detected by IMS in a humidity range of 20%-80%.

[0018] Figure 4 The spectrum of 100ppb H2S was obtained by TRDD detection in a humidity range of 20%-80% after connecting to ozone device II (21).

[0019] Figure 5The standard curve for detecting H2S concentrations at a humidity of 46% using TRDD-IMS.

[0020] Figure 6 This serves as an application demonstration of H2S in the source discharge of sewage. Detailed Implementation

[0021] To make the technical solutions and advantages of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention:

[0022] Example 1

[0023] like Figure 1 The device shown is a VUV lamp ion mobility spectrometer for measuring hydrogen sulfide, comprising: an ion mobility spectrometer and a time-resolved dynamic dilution structure. The ion mobility spectrometer includes an electrode ring 5 and an insulating ring 6, and includes a hollow cavity formed by the coaxial alternating placement and compression sealing of the electrode ring 5 and the insulating ring 6. An ionization source is provided at one end of the ion mobility spectrometer, and a tail gas port 1, a carrier gas port 2, and a sample inlet 3 are sequentially provided on the outer wall of the ion mobility spectrometer near the ionization source. A drift gas port 8 is provided on the outer wall of the other end of the ion mobility spectrometer. The drift gas port 8 is sequentially connected to an ozone device I 9 and a flow controller I 10. The time-resolved dynamic dilution structure includes a three-way solenoid valve I 18, a three-way solenoid valve II 19, a three-way solenoid valve III 20, and a sampling ring 11. One end of the sampling ring is connected to a vacuum pump II 16, and the other end is connected to a gas sample.

[0024] Furthermore, the carrier gas port 2 is sequentially connected to the dopant cylinder 12 and the flow controller II 13; the hollow cavity of the ion mobility spectrometer is provided with a grid 7 on the side near the drift gas port 8.

[0025] Furthermore, the sampling ring 11 is connected to the vacuum pump II 16, and the sample injection volume is controlled by the flow controller IV 17; the sampling ring 11 is connected to the sample that has passed through the ozone device II 21.

[0026] Furthermore, after time-resolved dynamic dilution pretreatment, the gas sample enters the ion mobility spectrometer through inlet 3; air, controlled by flow controller I10, enters ozone device I9 for oxidation and then enters the ion mobility spectrometer through purging port 8; air, controlled by flow controller II13, purges dopant molecules in dopant cartridge 12 and enters the ion mobility spectrometer through carrier gas port 2; tail gas from tail gas port 1 is freely discharged. The dopant molecules, after being ionized by the ionization source to obtain reagent ions, react with the sample to form complex ions, which are detected by the Faraday disk. The resulting ion mobility spectra are obtained through signal amplifiers and signal acquisition and display equipment.

[0027] Example 2

[0028] like Figure 1 As shown, a VUV lamp ion mobility spectrometer (IMS) for measuring hydrogen sulfide is described. The IMS gas path includes a tail gas port 1, a carrier gas port 2, a sample inlet 3, and a drift gas port 8. The carrier gas port 2 is connected to a dopant cylinder 12, and its flow rate is controlled by a flow controller II 13. The drift gas port 8 is connected to an ozone device 9, and its flow rate is controlled by a flow controller I 10. The sample at the sample inlet 3 is introduced after pretreatment by the ozone device II 21 and TRDD. When 200 ppb of H2S is prepared to 36% RH and detected by TRDD-IMS, no obvious sample peak is observed. However, when the sample is oxidized to SO2 by the ozone device before being detected by TRDD-IMS, a clear sample peak appears on the spectrum. Figure 2 As shown.

[0029] Example 3

[0030] Using the apparatus described in Example 1 or Example 2, employing a novel radio frequency VUV lamp as the ionization source, with the migration zone voltage set to 600 V / cm, the drift gas flow rate set to 300 ml / min, the tail gas flow rate set to 700 ml / min, and the carrier gas flow rate set to 100 ml / min, the sampling volume is 400 ml / min. A standard gas of 100 ppb H2S with a humidity range of 20%-80% RH is prepared and directly detected using IMS. Figure 3 As shown, the signal strength decreases sharply with increasing humidity, which affects the sensitivity.

[0031] Example 4

[0032] Using the apparatus described in Example 1 or Example 2, a novel radio frequency VUV lamp was used as the ionization source. The migration region voltage was set to 600 V / cm, the drift gas flow rate to 300 ml / min, the carrier gas flow rate to 100 ml / min, the sampling volume to 100 ml / min, and the purge flow rate to 300 ml / min. A standard gas of 100 ppb H2S with a humidity range of 20%-80% RH was prepared. The sample gas was then analyzed using TRDD-IMS after passing through an ozone device. Figure 4 As shown, the RSD of the signal intensity change in the H2S sample was less than 5% when the humidity increased from 22% to 81%, indicating that the above sample introduction method can eliminate the influence of humidity changes on IMS detection of H2S.

[0033] Example 5

[0034] Using the apparatus described in Example 1 or Example 2, a novel radio frequency VUV lamp was used as the ionization source. The migration zone voltage was set to 600 V / cm, the drift gas flow rate to 300 ml / min, the carrier gas flow rate to 100 ml / min, the sampling volume to 100 ml / min, and the purge flow rate to 300 ml / min. A series of H2S concentration standard gases at 46% RH were prepared, and a standard curve was plotted. The H2S content was characterized by peak intensity, such as... Figure 5 As shown.

[0035] Example 6

[0036] Using the apparatus described in Example 1 or Example 2, a novel radio frequency VUV lamp was used as the ionization source. The migration zone voltage was set to 600 V / cm, the drift gas flow rate to 300 ml / min, the carrier gas flow rate to 100 ml / min, the sampling volume to 100 ml / min, and the purge flow rate to 300 ml / min. The above method was demonstrated in a heavy rainwater sewer system within the park, while simultaneously monitoring the atmospheric environment and obtaining comparative spectra, such as... Figure 6 As shown, a sample peak appeared at approximately 3.2 ms, and the calculated concentration of H2S in the sewer was approximately 800 ppb.

[0037] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A device for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer, characterized in that... include: Ion mobility spectrometry and time-resolved dynamic dilution structures; The ion mobility spectrometer includes an electrode ring (5) and an insulating ring (6). The electrode ring (5) and the insulating ring (6) are coaxially and alternately arranged and squeezed and sealed to form a hollow cavity. An ionization source is provided at one end of the ion mobility spectrometer. On the outer wall of the ion mobility spectrometer, near the ionization source, there are a tail gas port (1), a carrier gas port (2) and a sample inlet (3) in sequence. On the outer wall of the other end of the ion mobility spectrometer, there is a drift gas port (8). The drift gas port (8) is connected to an ozone device I (9) and a flow controller I (10) in sequence. The carrier gas port (2) is connected to a dopant cylinder (12) and a flow controller II (13) in sequence. A grid (7) is provided on the side of the hollow cavity of the ion mobility spectrometer near the drift gas port (8). The time-resolved dynamic dilution structure includes a three-way solenoid valve I (18), a three-way solenoid valve II (19), a three-way solenoid valve III (20), and a sampling ring (11). One end of the sampling ring (11) is connected to the vacuum pump II (16), and the other end is connected to the gas sample after being treated by the ozone device II (21). The flow controller IV (17) controls the injection volume of the vacuum pump II (16). After the gas sample is processed by the time-resolved dynamic dilution structure, it enters the ion mobility spectrometer through the injection port (3) during the pretreatment process. The air enters the ozone device I (9) under the control of the flow controller I (10) for oxidation and enters the ion mobility spectrometer through the bleaching port (8). The air purges the dopant molecules in the dopant tube (12) under the control of the flow controller II (13) and enters the ion mobility spectrometer through the carrier gas port (2). The tail gas from the tail gas port (1) is discharged freely. The sample to be tested by the ozone device is drawn into the sampling loop (11) by the pump II (16) through the flow controller IV (17). The purge gas controlled by the flow controller V directly enters the inlet (3) of the ion mobility spectrometer. Then the pump II (16) stops and switches the three-way solenoid valve I (18), three-way solenoid valve II (19), and three-way solenoid valve III (20) to change the direction of airflow. The purge gas enters the sampling loop (11) and sends the sample into the inlet (3). The product SO2 flowing into the ion mobility spectrometer through the sampling loop undergoes an ion-molecule reaction with the dopant molecules. The product peak is located at the reaction reagent ion peak O2. - (H2O) n Behind; dopant molecules are ionized by a non-radioactive ionization source to generate reactant ions CO3. - With O2 - (H2O) n Where n is any integer value, the two reagent ions are adjusted to make CO3 - With O2 - (H2O) n Peak intensity ratio greater than 6.

2. The apparatus for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer according to claim 1, characterized in that: The ion mobility spectrometer uses a vacuum ultraviolet lamp as its ionization source, operates in negative ion mode, has a carrier gas flow rate of 100-150 ml / min, a drift gas flow rate of 250-350 ml / min, and a migration tube temperature of 130-150℃.

3. The apparatus for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer according to claim 1, characterized in that: The dopant molecules inside the dopant tube (12) are ionizable organic solvents, wherein the organic solvent is one of acetone, butanone, or ethanol.

4. The apparatus for measuring hydrogen sulfide using a VUV lamp ion mobility spectrometer according to claim 1, characterized in that: The detection limit of this device is less than 5 ppb, and the single detection cycle is less than 2 minutes.

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