A pretreatment device for soil volatile organic compounds

Abstract

This utility model discloses a pretreatment device for soil volatile organic compounds (VOCs), belonging to the technical field of VOCs treatment devices. It includes a closed desorption mechanism, with a dehydration tube, a collection tube, and a verification tube respectively installed on the upper part of the mechanism. The closed desorption mechanism includes a base, with a tank threadedly connected to the upper part of the base. A porous gas distribution plate is installed inside the base. An inert gas storage tank is provided on the side of the closed desorption mechanism, and a first connecting pipe is fixedly connected to the upper part of the inert gas storage tank. The first connecting pipe is fixedly connected to the porous gas distribution plate. A heating component is installed on the surface of the tank. This utility model improves the extraction rate of phenolic and ketone VOCs by breaking the hydrogen bonds of VOCs through high temperature and combined with helium bubble disturbance. The dehydration tube effectively removes moisture, avoiding interference with the adsorption efficiency of the collection tube. Real-time monitoring of the verification tube ensures complete VOCs extraction, solving the problems of data distortion and poor reproducibility.

Description

Technical Field

[0001] This utility model relates to the technical field of volatile organic compound treatment devices, and in particular to a pretreatment device for soil volatile organic compounds. Background Technology

[0002] Accurate detection of volatile organic compounds (VOCs) in soil is a crucial step in assessing soil pollution and ensuring ecological and environmental safety. Soil VOC pretreatment devices, as the core equipment in this process, can effectively extract and enrich trace amounts of VOCs from complex soil matrices while removing interfering substances such as moisture and particulate matter. This provides pure, high-concentration samples for subsequent instrumental analysis such as gas chromatography and mass spectrometry. Their performance directly affects the accuracy and sensitivity of the detection results, thus occupying an irreplaceable position in the soil VOCs detection process.

[0003] For example, CN223005813U discloses a soil volatile organic compound pretreatment device, which includes a sample bottle, an air inlet pipe, an air outlet pipe, a dehydration tube, and a collection tube. Since the sample bottle, air inlet pipe, air outlet pipe, dehydration tube, and collection tube are all relatively small in size and easy to carry and assemble.

[0004] However, in existing technologies, when sampling humic and clay mineral soils, humic substances are rich in polar groups such as hydroxyl and carboxyl groups, which can form stable bonds with polar VOCs such as phenols and ketones through hydrogen bonds. The layered structure and surface charge of clay minerals can physically adsorb VOCs through van der Waals forces. This dual adsorption effect makes VOCs tightly attached to the soil matrix. Existing devices such as purge-and-trap rely on physical purging, which can only act on free VOCs. Although heating can increase the activity of VOCs, the temperature increase is limited and it is difficult to completely overcome the binding of hydrogen bonds and van der Waals forces. As a result, a large number of VOCs remain in the soil, which directly causes serious distortion of the detection results. It cannot accurately reflect the true content of VOCs in the soil, may underestimate the degree of pollution, affect the scientific nature of pollution assessment and treatment decisions, and may also lead to poor data reproducibility due to incomplete extraction of target substances, reducing the reliability of the detection method. Utility Model Content

[0005] The purpose of this invention is to solve the problems existing in the prior art by proposing a pretreatment device for volatile organic compounds in soil.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a pretreatment device for volatile organic compounds in soil, comprising a closed desorption mechanism, wherein a dehydration tube, a collection tube, and a verification tube are respectively installed on the upper part of the closed desorption mechanism, the closed desorption mechanism includes a base, a tank is threadedly connected to the upper part of the base, and a porous gas distribution plate is installed inside the base, an inert gas storage tank is provided on the side of the closed desorption mechanism, a No. 1 connecting pipe is fixedly connected to the upper part of the inert gas storage tank, the No. 1 connecting pipe is fixedly connected to the porous gas distribution plate, and a heating component is installed on the surface of the tank.

[0007] Preferably, a regulating valve is installed on the surface of the first connecting pipe, and one end of the regulating valve passes through the side wall of the base and is fixedly connected to the perforated air distribution plate.

[0008] Preferably, a sealing ring is installed on the surface of the base, and the bottom of the tank is in contact with the sealing ring.

[0009] Preferably, one end of the dehydration tube is fixedly connected to a No. 2 connecting pipe, and the other end of the dehydration tube is fixedly connected to a No. 3 connecting pipe. The No. 2 connecting pipe is fixedly connected to the top of the No. 2 control valve. One end of the No. 3 connecting pipe is fixedly connected to the collection tube. The end of the collection tube is fixedly connected to a No. 4 connecting pipe. One end of the No. 4 connecting pipe is fixedly connected to the verification tube.

[0010] Preferably, the end of the verification tube is fixedly connected to a No. 5 connecting pipe, and a No. 2 control valve is installed on the surface of the No. 5 connecting pipe.

[0011] Preferably, a No. 6 connecting pipe is fixedly connected to the end of the No. 2 control valve, a vacuum pump is installed at the end of the No. 6 connecting pipe, and a pressure gauge is installed on the upper part of the vacuum pump.

[0012] Compared with the prior art, the advantages and positive effects of this utility model are as follows: 1. In this utility model, the extraction rate of phenolic and ketone VOCs is improved by breaking the hydrogen bonding of VOCs at high temperature and combined with helium bubble disturbance. The dehydration tube effectively removes water and avoids interfering with the adsorption efficiency of the collection tube. Real-time monitoring of the verification tube ensures complete extraction of VOCs, solving the problems of data distortion and poor reproducibility.

[0013] 2. In this utility model, the vacuum pump is turned on, and the gas in the system is extracted through the No. 6 connecting pipe and the No. 2 control valve. The pressure gauge displays the pressure in the tank, which facilitates stable control of the pressure. Phenolic and ketone VOCs adsorbed by humus in the soil through hydrogen bonds are released from their binding under high temperature and helium bubble disturbance, and flow upward with the helium, entering the No. 2 connecting pipe through the top of the tank. Attached Figure Description

[0014] Figure 1 This utility model provides a first three-dimensional structural schematic diagram of a pretreatment device for soil volatile organic compounds; Figure 2 This utility model provides a second three-dimensional structural schematic diagram of a pretreatment device for soil volatile organic compounds; Figure 3 A side view of the pretreatment device for soil volatile organic compounds is provided for this utility model. Figure 4 This invention presents a cross-sectional side view of a closed desorption mechanism in a soil volatile organic compound pretreatment device.

[0015] Legend: 1. Closed desorption mechanism; 101. Base; 102. Tank body; 103. Heating component; 104. Porous gas distribution plate; 105. Sealing ring; 2. Inert gas storage tank; 3. Connecting pipe No. 1; 4. Regulating valve No. 1; 5. Connecting pipe No. 2; 6. Dehydration pipe body; 7. Connecting pipe No. 3; 8. Collection pipe body; 9. Connecting pipe No. 4; 10. Verification pipe body; 11. Connecting pipe No. 5; 12. Control valve No. 2; 13. Connecting pipe No. 6; 14. Vacuum pump; 15. Pressure gauge. Detailed Implementation

[0016] To better understand the above-mentioned objectives, features, and advantages of this utility model, the present utility model will be further described below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0017] Many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways than those described herein, and therefore the present invention is not limited to the specific embodiments disclosed in the following specification.

[0018] Example 1: As Figures 1-4 As shown, this utility model provides a pretreatment device for soil volatile organic compounds, including a closed desorption mechanism 1. The upper part of the closed desorption mechanism 1 is respectively equipped with a dehydration tube 6, a collection tube 8 and a verification tube 10. The closed desorption mechanism 1 includes a base 101. The upper part of the base 101 is threadedly connected to a tank 102, and a porous gas distribution plate 104 is installed inside the base 101. An inert gas storage tank 2 is provided on the side of the closed desorption mechanism 1. A first connecting pipe 3 is fixedly connected to the upper part of the inert gas storage tank 2. The first connecting pipe 3 is fixedly connected to the porous gas distribution plate 104. A heating component 103 is installed on the surface of the tank 102. A regulating valve 4 is installed on the surface of the first connecting pipe 3. One end of the regulating valve 4 passes through the side wall of the base 101 and is fixedly connected to the porous air distribution plate 104. A sealing ring 105 is installed on the surface of the base 101. The bottom of the tank 102 is in contact with the sealing ring 105. One end of the dehydration pipe 6 is fixedly connected to the second connecting pipe 5, and the other end of the dehydration pipe 6 is fixedly connected to the third connecting pipe 7. The second connecting pipe 5 is fixedly connected to the top of the second control valve 12. One end of the third connecting pipe 7 is fixedly connected to the collection pipe 8. The end of the collection pipe 8 is fixedly connected to the fourth connecting pipe 9. One end of the fourth connecting pipe 9 is fixedly connected to the verification pipe 10.

[0019] The specific setup and function of this embodiment are described below. Soil samples with high humus content or high clay mineral content are placed into the tank 102 of the sealed desorption mechanism 1, so that the samples are evenly spread on the upper part of the porous gas distribution plate 104. The tank 102 is rotated and threadedly connected to the base 101. The bottom of the tank 102 is tightly fitted with the sealing ring 105 to ensure that the tank 102 is sealed. The inert gas storage tank 2 is opened, and helium is introduced into the porous gas distribution plate 104 through the first connecting pipe 3. The first regulating valve 4 is adjusted to stabilize the gas flow. The helium forms microbubbles of a certain diameter in the soil through the micropores of the porous gas distribution plate 104. At the same time, the heating component 103 on the surface of the tank 102 is activated to raise the temperature and continue heating. The mixed gas first enters the dehydration tube 6 to trap water vapor; the dried VOCs enter the collection tube 8 through the third connecting tube 7 for enrichment; a small amount of gas enters the verification tube 10 through the fourth connecting tube 9 for detection using the testing equipment.

[0020] By breaking the hydrogen bonds of VOCs at high temperatures and combining this with helium bubble disturbance, the extraction rate of phenolic and ketone VOCs is improved. The dehydration tube 6 effectively removes moisture, avoiding interference with the adsorption efficiency of the collection tube 8. Real-time monitoring of the verification tube 10 ensures complete extraction of VOCs, solving the problems of data distortion and poor reproducibility.

[0021] Example 2: Figure 1 , Figure 2 and Figure 3 As shown, a No. 5 connecting pipe 11 is fixedly connected to the end of the verification tube 10. A No. 2 control valve 12 is installed on the surface of the No. 5 connecting pipe 11. A No. 6 connecting pipe 13 is fixedly connected to the end of the No. 2 control valve 12. A vacuum pump 14 is installed at the end of the No. 6 connecting pipe 13. A pressure gauge 15 is installed on the upper part of the vacuum pump 14.

[0022] The overall effect of this embodiment is that when the vacuum pump 14 is turned on, the gas in the system is extracted through the No. 6 connecting pipe 13 and the No. 2 control valve 12 (which is in a half-open state at this time). The pressure gauge 15 displays the pressure in the tank 102, which facilitates stable pressure control. Phenolic and ketone VOCs adsorbed by humus in the soil through hydrogen bonds are released from their binding under high temperature and helium bubble disturbance, and flow upward with the helium, entering the No. 2 connecting pipe 5 through the top of the tank 102.

[0023] The above are merely preferred embodiments of this utility model and are not intended to limit the utility model in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this utility model without departing from the technical solution of this utility model shall still fall within the protection scope of this utility model.

Claims

1. A pretreatment device for volatile organic compounds in soil, comprising a closed desorption mechanism (1), wherein a dehydration tube (6), a collection tube (8), and a verification tube (10) are respectively installed on the upper part of the closed desorption mechanism (1), characterized in that: The sealed desorption mechanism (1) includes a base (101), a tank (102) is threadedly connected to the upper part of the base (101), and a perforated gas distribution plate (104) is installed inside the base (101). An inert gas storage tank (2) is provided on the side of the sealed desorption mechanism (1). A first connecting pipe (3) is fixedly connected to the upper part of the inert gas storage tank (2). The first connecting pipe (3) is fixedly connected to the perforated gas distribution plate (104). A heating component (103) is installed on the surface of the tank (102).

2. The pretreatment device for soil volatile organic compounds according to claim 1, characterized in that: A regulating valve (4) is installed on the surface of the first connecting pipe (3). One end of the regulating valve (4) passes through the side wall of the base (101) and is fixedly connected to the porous air distribution plate (104).

3. The pretreatment device for soil volatile organic compounds according to claim 1, characterized in that: A sealing ring (105) is installed on the surface of the base (101), and the bottom of the tank (102) is in contact with the sealing ring (105).

4. The pretreatment device for soil volatile organic compounds according to claim 1, characterized in that: One end of the dehydration tube (6) is fixedly connected to a second connecting pipe (5), and the other end of the dehydration tube (6) is fixedly connected to a third connecting pipe (7). The second connecting pipe (5) is fixedly connected to the top of the second control valve (12). One end of the third connecting pipe (7) is fixedly connected to the collection tube (8). The end of the collection tube (8) is fixedly connected to a fourth connecting pipe (9). One end of the fourth connecting pipe (9) is fixedly connected to the verification tube (10).

5. The pretreatment device for soil volatile organic compounds according to claim 1, characterized in that: The end of the verification tube (10) is fixedly connected to a No. 5 connecting pipe (11), and a No. 2 control valve (12) is installed on the surface of the No. 5 connecting pipe (11).

6. The pretreatment device for soil volatile organic compounds according to claim 5, characterized in that: The end of the second control valve (12) is fixedly connected to the sixth connecting pipe (13), and the end of the sixth connecting pipe (13) is equipped with a vacuum pump (14), and the upper part of the vacuum pump (14) is equipped with a pressure gauge (15).

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