Passive sampling equipment for persistent organic pollutants in atmosphere

Abstract

The invention relates to the technical field of atmospheric monitoring instruments, in particular to passive sampling equipment for persistent organic pollutants in atmosphere, which comprises a sampling shell, a barrel cap detachably connected to the top of the sampling shell, a sampling column core detachably connected to the bottom of the barrel cap, and a turbulent flow adjusting assembly arranged in the sampling shell. The turbulent flow adjusting assembly is positioned below the sampling column core; a wind speed sensing assembly used for responding according to the environment wind speed is fixedly connected to the bottom in the sampling shell, a conversion assembly is arranged between the wind speed sensing assembly and the turbulent flow assembly, and the conversion assembly converts the environment wind speed change into an adjusting instruction or drives and dynamically adjusts the turbulent flow adjusting assembly in real time so as to adjust the circulation path and drift diameter parameters in the sampling shell; the flow path and path of gas are adaptively changed in a mechanical or electric control mode, and active compensation of sampling efficiency along with wind speed fluctuation is realized, so that the environmental adaptability and data reliability of the passive sampler in a severe environment are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of atmospheric monitoring instrument technology, specifically to a passive sampling device for persistent organic pollutants in the atmosphere. Background Technology

[0002] Persistent organic pollutants (POPs) are a class of highly toxic, environmentally persistent, and bioaccumulative chemical substances, with typical examples including dioxins and polychlorinated biphenyls (PCBs). The choice of atmospheric POPs sampling technology depends on the physicochemical properties, concentration level, and analytical requirements of the target pollutant, and is mainly divided into two categories: active sampling and passive sampling. Active sampling uses a powered system to extract air for collection, while passive sampling relies on the diffusion or infiltration of pollutant molecules. In addition, the choice of sampling medium (such as adsorbents and filter membranes) and equipment type (such as high-capacity samplers and individual samplers) also significantly affects sampling efficiency and result accuracy.

[0003] Based on passive sampling methods, such as the cylindrical XAD type atmospheric POPs passive sampler, the cylindrical sampler structure includes a top cap, a sampling column core, a shell with a bottom opening (i.e., the sampler body), and a coarse wire mesh fixed at the bottom of the shell. Organic pollutants in the atmosphere enter through the bottom opening of the shell, are initially filtered by the coarse wire mesh, and then diffuse to the sampling column core under the drive of the concentration gradient, where they are adsorbed and enriched by the XAD resin, thus completing passive sampling.

[0004] The research report "Improving Passive Atmospheric POPs Samplers to Make Them More Suitable for High Wind Speed ​​Environments," published by the Institute of Tibetan Plateau Research, Chinese Academy of Sciences, indicates that the sampling efficiency (PSR) of the cylindrical XAD-type passive atmospheric POPs sampler (XAD-PAS) is strongly affected by wind speed. Specifically, increased wind speed exacerbates airflow disturbances within the sampler, leading to an increase in the amount of air flowing through the sampling column core per unit time, thus causing a positive correlation increase in the PSR value. To address the PSR fluctuation problem under high wind speed conditions, the research team proposed an improved scheme by adding four rectifier plates to the bottom of the sampler casing. The flow field interference effect of the rectifier plates weakens the incident air kinetic energy, thereby reducing the change in wind speed gradient within the sampler and effectively suppressing the fluctuation amplitude of PSR with wind speed.

[0005] Given the limited accuracy of wind speed prediction in harsh environments, fixed-size rectifier structures struggle to match the dynamic changes in the flow field under sudden wind speeds, resulting in insufficient adaptability of passive samplers. Therefore, it is necessary to propose a passive sampling device for persistent organic pollutants in the atmosphere capable of sensing wind speed changes in real time and dynamically adjusting internal flow field parameters. Summary of the Invention

[0006] To address the aforementioned issues, this invention provides a passive sampling device for persistent organic pollutants in the atmosphere. By adaptively altering the gas flow path and trajectory through mechanical or electronic means, it achieves active compensation for sampling efficiency fluctuations with wind speed, thereby significantly improving the environmental adaptability and data reliability of the passive sampler in harsh environments.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A passive sampling device for persistent organic pollutants in the atmosphere includes a cylindrical sampling shell, a cap detachably connected to the top of the sampling shell, a sampling column core for adsorbing organic pollutants in the sampling gas detachably suspended at the bottom of the cap, a turbulence adjustment component that can adjust the gas flow path and flow diameter inside the sampling shell, the turbulence adjustment component being located below the sampling column core, and a wire mesh fixedly connected to the sampling shell being provided between the turbulence adjustment component and the sampling column core. A wind speed sensor is fixedly connected to the bottom of the sampling housing to respond to the ambient wind speed. A conversion component is provided between the wind speed sensor and the turbulence component. The conversion component converts the changes in ambient wind speed into adjustment commands or drives in real time, and dynamically adjusts the turbulence adjustment component to adjust the flow path and flow parameters inside the sampling housing.

[0008] The technical principle of the above scheme is as follows: When the sampling shell is fixed in the sampling environment for sampling, a dynamic response mechanism is formed by setting up a turbulence adjustment component, a wind speed sensing component and a conversion component inside the sampling shell. The wind speed sensing component monitors the changes in the ambient wind speed in real time, and the conversion component converts the wind speed signal into an adjustment command, which drives the turbulence adjustment component to dynamically change the flow path and parameters of the gas flow inside the sampling shell, so as to realize the adaptive control of the sampling efficiency according to the wind speed.

[0009] The above approach has the following beneficial effects: 1. This solution uses a wind speed sensing component to convert the ambient wind speed into a perceptible signal. The conversion component then identifies this signal and converts it into a drive for the turbulence adjustment component, enabling the wind speed signal to be captured. The turbulence adjustment component then adjusts the flow path and parameters of the gas flow inside the sampling housing in real time, forming a dynamic response mechanism between wind speed and the sampling flow field. Ultimately, this achieves adaptive compensation of sampling efficiency as wind speed changes, ensuring the stability and accuracy of sampling data under different wind speed conditions.

[0010] 2. This solution reduces the positive correlation between airflow disturbance and sampling efficiency at high wind speeds by dynamically adjusting the flow path and flow diameter, while avoiding insufficient sampling caused by airflow stagnation at low wind speeds. This improves sampling stability under different wind speed conditions and solves the impact of wind speed fluctuations on sampling efficiency.

[0011] Furthermore, the turbulence adjustment component includes a limiting cylinder and a rotating ring cylinder. The limiting cylinder is fixedly connected to the inner wall of the sampling shell. Several elastic turbulence spiral blades are slidably fitted to the outer wall of the limiting cylinder along its circumference. The bottom of each turbulence spiral blade is fixedly connected to the limiting cylinder. The rotating ring cylinder is located inside the limiting cylinder, and the rotating ring cylinder is rotatably connected to the inner wall of the sampling shell. The top of the interference flow spiral blades is fixedly connected to the bottom of the rotating ring frame.

[0012] Beneficial effects: The combination of the limiting cylinder and the rotating ring cylinder allows the turbulence-inducing spiral blades, which have elastic characteristics, to undergo elastic deformation as the rotating ring cylinder rotates, thereby achieving mechanical adjustment of the flow diameter and path and improving the accuracy and response speed of flow field control.

[0013] Furthermore, several ventilation channels are provided along the circumference of the inner side wall of the cap, and all ventilation channels are connected to the interior of the cap.

[0014] Beneficial effects: The ventilation channel design on the side wall of the cap promotes air exchange between the inside and outside of the sampling shell, enhances the driving force of gas flow, and helps maintain a stable sampling environment.

[0015] Furthermore, an adjustable screen with a corresponding wire mesh aperture is fixedly connected to the top of the rotating ring cylinder.

[0016] Beneficial effects: By rotating the top of the ring cylinder to adjust the misalignment between the screen and the fixed wire screen, the effective sieve aperture can be dynamically changed when adjusting the turbulence spiral blades, thus achieving a balance between impurity filtration efficiency and airflow resistance under different wind speeds.

[0017] Furthermore, the wind speed sensing component includes a wind turbine located at the bottom of the sampling housing, the wind turbine being rotatably connected to the inner wall of the sampling housing, and the shaft of the wind turbine extending into the rotating ring cylinder.

[0018] Beneficial effects: This design uses a wind turbine to convert ambient wind speed into a mechanical rotation signal, providing passive drive for turbulence regulation, and is suitable for outdoor environments without power supply.

[0019] Furthermore, the conversion component includes centrifugal rods symmetrically hinged to the rotating shaft and a drive cylinder vertically slidably connected to the rotating shaft. One end of each centrifugal rod is fixedly connected to a counterweight ball. The end of each centrifugal rod away from the counterweight ball is hinged to a transmission rod for driving the vertical displacement of the drive cylinder according to the centrifugal effect of the counterweight ball. The end of each transmission rod away from the centrifugal rod is hinged to the drive cylinder. Above the drive cylinder is a transmission component for transmitting the movement of the drive cylinder to the rotation of the rotating ring cylinder.

[0020] Beneficial effects: This design utilizes the centrifugal effect to drive the vertical displacement of the drive cylinder through the centrifugal rod and transmission rod assembly, converting the wind turbine speed signal into linear displacement, and realizing the mechanical coupling of wind speed and adjustment action.

[0021] Furthermore, the transmission assembly includes a transmission cylinder rotatably fitted to the top of the drive cylinder, a wedge block is fixedly connected to the outer wall of the transmission cylinder, and a wedge-shaped groove corresponding to the wedge block is opened on the inner wall of the rotating ring cylinder, with the wedge block slidingly fitted in the wedge-shaped groove.

[0022] Beneficial effects: Through the inclined plane transmission of the wedge block and the wedge groove, the vertical displacement of the drive cylinder is converted into the circumferential rotation of the rotating ring cylinder, realizing the direction conversion and efficient transmission of mechanical energy.

[0023] Furthermore, the wedge-shaped groove is an inclined groove that converts the vertical displacement of the transmission cylinder into the circumferential rotation of the rotating ring cylinder.

[0024] Beneficial effects: The inclined groove structure design of the wedge-shaped groove ensures a linear correlation between the vertical displacement of the transmission cylinder and the rotation angle of the rotating ring cylinder, thus improving the adjustment accuracy.

[0025] Furthermore, the wind speed sensing component may also include a wind speed sensor located at the bottom of the inner wall of the sampling housing, and the wind speed sensor signal is connected to a controller.

[0026] Beneficial effects: It is an equivalent replacement for the electronic detection scheme using wind speed sensors and controllers, realizing the digital acquisition and analysis of wind speed signals, and improving the sensitivity of wind speed response and the accuracy of threshold judgment.

[0027] Furthermore, the conversion component includes a bracket fixedly connected inside the sampling housing, on which a servo motor coinciding with the axis of the sampling housing is fixedly connected. The output end of the servo motor is fixedly connected to the inner wall of the rotating ring cylinder, and the servo motor is signal-connected to the controller.

[0028] Beneficial effects: By directly driving the rotating cylinder with a servo motor and combining it with the closed-loop control algorithm of the controller, precise electronic control adjustment of turbulence parameters can be achieved, expanding the equipment's adaptability to complex wind speed environments.

[0029] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of Embodiment 1 of the passive sampling device for persistent organic pollutants in the atmosphere of the present invention; Figure 2 This is an isometric sectional view of the sampling casing in Embodiment 1 of the passive sampling device for persistent organic pollutants in the atmosphere of the present invention; Figure 3 This is a schematic diagram of the arrangement of the limiting cylinder and the rotating ring cylinder in Embodiment 1 of the passive sampling device for persistent organic pollutants in the atmosphere of the present invention; Figure 4This is an isometric schematic diagram of the conversion component in Embodiment 1 of the passive sampling device for persistent organic pollutants in the atmosphere of the present invention; Figure 5 This is an isometric sectional view of the sampling casing in Embodiment 2 of the passive sampling device for persistent organic pollutants in the atmosphere of the present invention.

[0031] The reference numerals in the accompanying drawings of the instruction manual include: 1. Sampling shell; 2. Cap; 3. Sampling core; 4. Limiting cylinder; 5. Rotating ring cylinder; 6. First extension frame; 7. Turbulence spiral blade; 8. Second extension frame; 9. Rotary groove; 10. Wind turbine; 101. Support ring frame; 102. Turbine blade; 103. Rotating shaft; 11. Centrifugal rod; 12. Drive cylinder; 13. Counterweight ball; 14. First connecting rod; 15. Second connecting rod; 16. Transmission cylinder; 17. Wedge block; 18. Wedge groove; 19. Wire mesh; 20. Adjusting screen; 201. Screen plate; 22. Wind speed sensor; 23. Support; 24. Servo motor. Detailed Implementation

[0032] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] The following detailed description illustrates the specific implementation method: Example 1: This example provides a passive sampling device for persistent organic pollutants in the atmosphere, specifically as follows: Figure 1 and Figure 2 As shown, the device includes a cylindrical sampling shell 1, with a detachable cap 2 at the top. A sampling column 3, used for adsorbing organic pollutants from the sampled gas, is detachably suspended from the bottom of the cap 2 via a hook. During sampling, ambient air flows naturally through the bottom of the sampling shell 1 and upwards through the sampling column 3 driven by a concentration gradient. The high specific surface area adsorption medium (such as PUF or activated carbon) filled inside the sampling column 3 captures organic pollutants in the gas through molecular diffusion and physical adsorption, achieving passive sampling. The detachable design of the cap 2 and the sampling shell 1 facilitates quick replacement of the sampling column 3 after sampling, ensuring sample integrity.

[0036] Specifically, the bottom of the sampling column core 3 is equipped with a turbulence adjustment component that can adjust the gas flow diameter and flow path inside the sampling housing 1, specifically combined with... Figure 2 and Figure 3 As shown, the turbulence adjustment assembly includes a limiting cylinder 4 and a rotating ring cylinder 5. Several first extension frames 6 are integrally formed on the bottom of the limiting cylinder 4 along its circumference. The ends of the first extension frames 6 away from the limiting cylinder 4 are welded to the inner wall of the sampling shell 1. Several elastic turbulence spiral blades 7 are fitted and slidably fitted on the outer wall of the limiting cylinder 4 along its circumference. Figure 2 The bottom of the turbulence-disrupting spiral blade 7 is fused to the top surface of the first extension frame 6; the rotating ring cylinder 5 is located inside the limiting cylinder 4, and the top of the rotating ring cylinder 5 is integrally formed with several second extension frames 8 along its circumference. The inner side wall of the sampling shell 1 is provided with an annular groove 9 corresponding to the top of the rotating ring cylinder 5. The end of the second extension frame 8 away from the rotating ring cylinder 5 extends into the groove 9 and slides with the groove 9. The top of the turbulence-disrupting spiral blade 7 is fused to the bottom surface of the corresponding second extension frame 8. In this design, by rotating the rotating ring cylinder 5, the second extension frame 8 is driven to move circumferentially along the groove 9, so that the top of the turbulence-disrupting spiral blade 7 generates a circumferential traction force. Because the bottom of the turbulence spiral blade 7 is rigidly connected to the fixed first extension frame 6, and due to the elastic nature of the turbulence spiral blade 7, its body will deform as the top rotates, forming a dynamic adjustment of the spiral arc. That is, when the rotating ring cylinder 5 rotates relative to the limiting cylinder 4, the pitch of the turbulence spiral blade 7 decreases and the arc increases, extending the flow path of the gas to the sampling column core 3 and reducing the flow cross-sectional area; when rotating in the opposite direction, the pitch of the turbulence spiral blade 7 increases and the arc decreases, shortening the gas flow path and expanding the diameter, thereby realizing dynamic flow field control of the sampling airflow.

[0037] Based on the turbulence regulation of the gas flow inside the sampling housing 1, this embodiment designs a wind speed sensing component at the bottom of the sampling housing 1 for responding to ambient wind speed. Figure 2 and Figure 4As shown, the wind speed sensing component includes a wind turbine 10 located at the bottom of the sampling housing 1. The wind turbine 10 includes a support ring frame 101, the outer edge of which is fused to the inner wall of the sampling housing 1. A turbine blade 102 is rotatably connected to the top of the support ring frame 101 via a bearing. A rotating shaft 103 is integrally formed along the axial direction of the sampling housing 1. The end of the rotating shaft 103 away from the turbine blade 102 extends into the rotating ring cylinder 5. When the ambient airflow enters the bottom of the sampling housing 1, it drives the turbine blade 102 to rotate around the bearing. The rotational speed of the turbine blade 102 is positively correlated with the ambient wind speed. That is, when the wind speed increases, the impact force of the airflow on the turbine blade 102 increases, and the rotational speed of the rotating shaft 103 increases synchronously. When the wind speed decreases, the forced motion of the turbine blade 102 weakens, and the rotational speed of the rotating shaft 103 decreases accordingly. This design physically represents the magnitude of wind speed as the rotational motion of the turbine blade 102.

[0038] This embodiment links the wind speed response of the sampling environment with the flow control of the sampling airflow. A conversion component is incorporated between the wind speed sensing component and the turbulence control component. Figure 2 and Figure 4 As shown, the conversion assembly includes centrifugal rods 11 symmetrically hinged to a rotating shaft 103 and a drive cylinder 12 vertically slidably connected to the rotating shaft 103. One end of each centrifugal rod 11 has a counterweight ball 13 integrally formed. The end of each centrifugal rod 11 away from the counterweight ball 13 is hinged with a transmission rod for driving the drive cylinder 12 vertically according to the centrifugal effect of the counterweight ball 13. The transmission rod includes a first connecting rod 14 hinged to the centrifugal rod 11. The end of the first connecting rod 14 away from the centrifugal rod 11 is hinged with a second connecting rod 15. The end of the second connecting rod 15 away from the first connecting rod 14 is hinged to the bottom surface of the drive cylinder 12. A transmission rod is provided above the drive cylinder 12 for driving the drive cylinder 12. The motion is the transmission component that rotates the rotating ring cylinder 5. When the rotational speed of the rotating shaft 103 changes with the ambient wind speed, the counterweight ball 13 will generate a radial expansion force due to the centrifugal effect when the rotational speed of the rotating shaft 103 increases. That is, when the rotational speed of the rotating shaft 103 increases, the centrifugal force increases, causing the centrifugal rod 11 to swing outward around the hinge point through the counterweight ball 13. This pushes the second connecting rod 15 to undergo angular displacement through the first connecting rod 14, driving the drive cylinder 12 to slide downward along the axial direction of the rotating shaft 103. Conversely, when the rotational speed of the rotating shaft 103 decreases, the centrifugal force weakens, and the centrifugal rod 11 drives the first connecting rod 14 and the second connecting rod 15 to reset under the action of gravity, driving the drive cylinder 12 to reset upward. This conversion mechanism converts the rotational speed signal of the turbine blade 102 (wind speed representation) into the linear displacement of the drive cylinder 12, providing a precise displacement input for the subsequent transmission component to control the rotation angle of the rotating ring cylinder 5, realizing the dynamic mapping between wind speed and mechanical displacement.

[0039] Specifically, the transmission assembly includes a transmission cylinder 16 rotatably fitted to the top of the drive cylinder 12, such as... Figure 4As shown, a wedge block 17 is integrally formed on the outer wall of the transmission cylinder 16, and a wedge-shaped groove 18 corresponding to the wedge block 17 is opened on the inner wall of the rotating ring cylinder 5. The wedge block 17 slides in the wedge-shaped groove 18, which is an inclined groove that converts the vertical displacement of the transmission cylinder 16 into the circumferential rotation of the rotating ring cylinder 5. When the rotation speed of the rotating shaft 103 increases, the drive cylinder 12 slides vertically along the axial direction under the action of centrifugal effect, driving the top transmission cylinder 16 to move vertically in sync. At this time, the wedge block 17 on the outer side of the transmission cylinder 16 slides along the wedge-shaped groove 18 (spiral inclined groove) on the inner side of the rotating ring cylinder 5, and converts the vertical displacement into the circumferential rotation of the rotating ring cylinder 5 through the guiding effect of the inclined surface. The spiral helix angle design of the wedge-shaped groove 18 makes the rotation angle of the rotating ring cylinder 5 proportional to the vertical displacement of the drive cylinder 12, thereby driving the second extension frame 8 to drive the top of the turbulence spiral blade 7 to rotate synchronously, realizing the dynamic adjustment of the spiral arc and the flow diameter. This structure constructs a multi-stage transmission chain of wind speed, rotational speed of shaft 103, vertical displacement of transmission cylinder 16, and rotation angle of turbulence spiral blade 7, enabling the sampling device to have airflow regulation capability that adapts to environmental wind speed. It forms a negative feedback closed-loop control of wind speed and gas flow field inside the sampler, reducing the impact of wind speed changes on sampling efficiency fluctuations and improving the sampling stability of passive samplers under adverse weather conditions.

[0040] The key difference lies in the fact that, in conventional passive samplers, increased temperature reduces the adsorption capacity of the adsorbent. For example, in high-temperature, low-wind-speed environments, conventional samplers suffer from weak natural convection, leading to air stagnation and insufficient heat exchange efficiency. This results in the internal temperature of the sampler being 5-8°C higher than the ambient temperature, significantly reducing the adsorption efficiency of the sampling core 3 for VOCs. In contrast, this embodiment utilizes the design of turbine blades 102. The continuous rotation of the turbine blades 102 creates forced convection. Even when the ambient wind speed is below 0.5 m / s, the turbine can maintain a minimum rotation speed (≥15 r / min) through thermal buoyancy or residual airflow. This creates a top-down circulating airflow inside the sampling shell 1, with the airflow rate linearly correlated with the ambient wind speed at 0.3-0.8 times. This ensures that the airflow through the sampling chamber per unit time is ≥0.2 m³ / h. By enhancing convective heat transfer, the temperature difference between the inside and outside of the chamber is controlled within ±2°C, avoiding the negative impact of temperature increases on the adsorbent performance.

[0041] Furthermore, due to varying sampling environments, the amount of dust or other impurities in the air entering the sampling housing 1 differs. This embodiment is designed in conjunction with... Figure 2 and Figure 3As shown, a wire mesh 19, which is fused to the sampling shell 1, is provided between the top of the rotating ring cylinder 5 and the bottom of the sampling column core 3. The wire mesh 19 physically intercepts dust and impurities in the air through a metal mesh with a preset aperture. The top of the rotating ring cylinder 5 is also provided with an adjustable screen 20 corresponding to the aperture of the wire mesh 19. The adjustable screen 20 includes several screen pieces 201 located between adjacent second extension frames 8. Both ends of the screen pieces 201 are fused and fixed to the corresponding second extension frames 8. This design, firstly, forms a composite filter layer by staggering the screen pieces 201, increasing the probability of dust collision and interception, and significantly improving the screening efficiency of submicron particles. Secondly, when the ambient wind speed increases, the rotating ring cylinder 5 drives the screen plate 201 to rotate synchronously, so that the movable screen plate 201 and the mesh of the fixed wire screen 19 are misaligned and overlapped. The effective filtration aperture decreases linearly with the increase of overlap. At a wind speed of 15m / s, the initial 80μm aperture can be reduced to 30μm, that is, fine filtration under high wind speed is achieved. When the wind speed decreases, the aperture automatically recovers, avoiding excessive filtration resistance under low wind speed conditions that affects the sampling flow rate.

[0042] The following experiments were conducted using the passive sampling device described in this embodiment: Experimental objective: To verify whether the dynamic response mechanism for wind speed sensing, conversion, and turbulence regulation designed in this embodiment can solve the technical defects of traditional passive samplers, such as large fluctuations in sampling efficiency (PSR) under high wind speed conditions and the inability of fixed rectifier plates to adapt to sudden wind speed changes, and to achieve stable control of sampling efficiency under different wind speed conditions.

[0043] Experimental steps: 1. Experimental Materials and Equipment Experimental group: The passive sampling device described in this embodiment.

[0044] Control group: Traditional cylindrical XAD type passive sampler (no dynamic adjustment function, only the bottom rectifier plate is fixed).

[0045] Auxiliary equipment: wind tunnel laboratory (adjustable wind speed range 0-20m / s), air pollutant generator (target release: PCB28, initial concentration 10ng / m³), gas chromatography-mass spectrometry (GC-MS), thermometer, hygrometer.

[0046] 2. Experimental parameter settings Wind speed gradient: Set 5 wind speed levels (3m / s, 8m / s, 12m / s, 15m / s, 20m / s), and stabilize for 30 minutes under each wind speed condition.

[0047] Environmental conditions: Temperature (25±1℃) and relative humidity (50±5%) were kept constant throughout the process.

[0048] Sampling duration: 2 hours of sampling under each wind speed condition, with the experimental group and control group being sampled simultaneously.

[0049] 3. Experimental Procedure (1) Fix the samplers of the experimental group and the control group side by side in the wind tunnel experimental section, ensuring that the air inlets face the same direction and are 1.5m away from the air outlet of the pollutant generator.

[0050] (2) Start the pollutant generator and wait for the concentration of the target substance in the wind tunnel to stabilize (30 minutes as confirmed by the pre-experiment) before starting the wind tunnel and adjusting the wind speed according to the set wind speed gradient.

[0051] (3) After sampling under each wind speed condition, the sampling cores of the two samplers were immediately removed, the target analytes were extracted with hexane by ultrasonic extraction, the adsorption amount was determined by GC-MS, and the sampling efficiency was calculated (PSR = actual adsorption amount / theoretical diffusion amount × 100%).

[0052] (4) Repeat the experiment 3 times and take the average value as the final result.

[0053] Experimental data: Wind speed (m / s) Control group PSR (%) PSR (%) in the experimental group Control group PSR fluctuation range (%) Experimental group PSR fluctuation range (%) 3 68±3.2 72±2.1 - - 8 75±2.8 73±1.9 +10.3 +1.4 12 89±4.5 75±2.3 +30.9 +4.2 15 105±5.1 74±2.5 +54.4 +2.8 20 122±6.3 76±2.8 +79.4 +5.6 Experimental conclusions: The impact of wind speed fluctuations on sampling efficiency was significantly reduced: The PSR of the control group showed a linear increasing trend with increasing wind speed, increasing by 79.4% at 20 m / s compared to 3 m / s, with large fluctuations; while the PSR of the experimental group remained stable between 72% and 76%, with a maximum fluctuation of only 5.6%, verifying that the turbulence adjustment component effectively offset the positive correlation between airflow disturbances and sampling efficiency under high wind speeds by dynamically changing the flow path and flow channel.

[0054] Improved adaptability to sudden wind speed changes: When the wind speed suddenly increases from 3m / s to 15m / s (simulating sudden wind speed changes in a harsh environment), the PSR of the control group increases by 38% within 10 minutes, while the experimental group, through the real-time response of the wind speed sensing component and the conversion component, completes the adjustment of the turbulence parameters in only 2 minutes, and the PSR fluctuation is controlled within ±3%, which solves the defect that the traditional fixed rectifier plate cannot quickly adapt to sudden wind speed changes.

[0055] Long-term sampling stability verification: After continuous sampling for 8 hours at a wind speed of 15 m / s, the PSR of the experimental group remained at 74±3.1%, while the PSR of the control group continued to rise to 118±5.7%. This indicates that the proposed scheme achieves stable sampling efficiency under long-term high wind speed environment through mechanical / electrical control coordination, avoiding sampling deviation caused by flow field runaway in traditional equipment.

[0056] Example 2: The difference from Example 1 is that, specifically as follows... Figure 5As shown, in this embodiment, the wind speed sensing component includes a wind speed sensor 22 located at the bottom of the inner wall of the sampling housing 1. The wind speed sensor 22 is fixedly connected to the inner wall of the sampling housing 1 by screws, and the wind speed sensor 22 is connected to the controller. The wind speed sensor 22 is used to collect the ambient wind speed in real time. The controller converts the electrical signal of the wind speed sensor 22 into the actual wind speed value and compares it with the preset thresholds of 3m / s and 15m / s to form a three-level wind speed judgment signal.

[0057] In addition, compared to Embodiment 1, the conversion component is replaced by a bracket 23 fixedly connected inside the sampling housing 1. A servo motor 24, which is aligned with the axis of the sampling housing 1, is fixedly connected to the bracket 23 by bolts. The output end of the servo motor 24 is fixedly connected to the inner wall of the rotating ring cylinder 5, and the servo motor 24 is connected to the controller signal. The servo motor 24 achieves precise drive according to the drive signal output by the controller. When a low wind speed is detected, the controller outputs a positive pulse sequence to drive the servo motor 24 to rotate clockwise at an angular velocity of 1.2° / s. The output shaft of the servo motor 24 drives the rotating ring cylinder 5 to expand the turbulence spiral blades 7 to the maximum diameter. In the medium wind speed range, speed mode control is used, and the rotation speed of the servo motor 24 is linearly correlated with the wind speed by 0.8 times, maintaining the spiral blades in a dynamic adjustment range of 50%-80% of the diameter. In the high wind speed range, the torque mode is switched, and the servo motor 24 outputs a constant locking torque of 2.5 N·m to shrink the diameter and trigger mechanical limit protection.

[0058] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A passive sampling device for persistent organic pollutants in the atmosphere, comprising a cylindrical sampling shell (1), a cap (2) detachably connected to the top of the sampling shell (1), and a sampling core (3) for adsorbing organic pollutants in the sampled gas detachably suspended at the bottom of the cap (2), characterized in that, The sampling housing is equipped with a turbulence adjustment component that can adjust the gas flow path and flow diameter inside the sampling housing (1). The turbulence adjustment component is located below the sampling column core (3). A wire mesh (19) that is fixedly connected to the sampling housing (1) is provided between the turbulence adjustment component and the sampling column core (3). A wind speed sensing component is fixedly connected to the bottom of the sampling housing (1) for responding to the ambient wind speed. A conversion component is provided between the wind speed sensing component and the turbulence component. The conversion component converts the changes in ambient wind speed into adjustment commands or drives in real time, and dynamically adjusts the turbulence adjustment component to adjust the flow path and flow parameters inside the sampling housing (1).

2. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 1, characterized in that, The turbulence adjustment assembly includes a limiting cylinder (4) and a rotating ring cylinder (5). The limiting cylinder (4) is fixedly connected to the inner wall of the sampling shell (1). The outer wall of the limiting cylinder (4) is fitted with several elastic turbulence spiral blades (7) along its circumference. The bottom of each turbulence spiral blade (7) is fixedly connected to the limiting cylinder (4). The rotating ring cylinder (5) is located inside the limiting cylinder (4). The rotating ring cylinder (5) is rotatably connected to the inner wall of the sampling shell (1). The top of the interference flow spiral blade (7) is fixedly connected to the bottom of the rotating ring frame.

3. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 1, characterized in that, Several ventilation channels are provided along the circumference of the inner side wall of the cap (2), and all ventilation channels are connected to the interior of the cap (2).

4. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 2, characterized in that, The top of the rotating ring cylinder (5) is fixedly connected to an adjustable screen (20) with a corresponding wire mesh (19) aperture.

5. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 2, characterized in that, The wind speed sensing component includes a wind turbine (10) located at the bottom of the inside of the sampling housing (1). The wind turbine (10) is rotatably connected to the inner wall of the sampling housing (1), and the shaft (103) of the wind turbine (10) extends into the rotating ring cylinder (5).

6. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 5, characterized in that, The conversion assembly includes a centrifugal rod (11) symmetrically hinged to a rotating shaft (103) and a drive cylinder (12) vertically slidably connected to the rotating shaft (103). One end of the centrifugal rod (11) is fixedly connected to a counterweight ball (13). The end of the centrifugal rod (11) away from the counterweight ball (13) is hinged to a transmission rod for driving the vertical displacement of the drive cylinder (12) according to the centrifugal effect of the counterweight ball (13). The end of the transmission rod away from the centrifugal rod (11) is hinged to the drive cylinder (12). A transmission assembly is provided above the drive cylinder (12) for transmitting the movement of the drive cylinder (12) to the rotation of the rotating ring cylinder (5).

7. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 6, characterized in that, The transmission assembly includes a transmission cylinder (16) rotatably fitted to the top of the drive cylinder (12), a wedge block (17) is fixedly connected to the outer wall of the transmission cylinder (16), and a wedge groove (18) corresponding to the wedge block (17) is opened on the inner wall of the rotating ring cylinder (5), and the wedge block (17) is slidably fitted in the wedge groove (18).

8. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 7, characterized in that, The wedge groove (18) is an inclined groove for the vertical displacement of the transmission cylinder (16) and the circumferential rotation of the rotating ring cylinder (5).

9. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 2, characterized in that, The wind speed sensing assembly may also include a wind speed sensor (22) located at the bottom of the inner wall of the sampling housing (1), and the wind speed sensor (22) is connected to a controller.

10. The passive sampling device for persistent organic pollutants in the atmosphere according to claim 9, characterized in that, The conversion component includes a bracket (23) fixedly connected inside the sampling housing (1). A servo motor (24) that coincides with the axis of the sampling housing (1) is fixedly connected on the bracket (23). The output end of the servo motor (24) is fixedly connected to the inner wall of the rotating ring cylinder (5). The servo motor (24) is connected to the controller signal.

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