Integrated atmospheric hydroxyl radical online luminescence detection device

Abstract

This invention relates to an integrated online chemiluminescence detection device for atmospheric hydroxyl radicals, comprising: a chassis and a collection module, a reaction detection module, a solution delivery module, and a control and data acquisition circuit disposed within the chassis; the collection module uses a composite scavenging agent solution to capture hydroxyl radicals in the ambient air to be tested, converting them into stable hydroxylation products; the solution delivery module, under the control of the control and data acquisition circuit, delivers the hydroxylation products, a pre-prepared strongly alkaline solution, and an oxidant solution to the reaction detection module for chemiluminescence reaction, and transmits the detection data to the control and data acquisition circuit; the control and data acquisition circuit controls the collection module, the reaction detection module, and the solution delivery module, and processes the detection data to obtain the online detection results of hydroxyl radicals in the ambient air to be tested. This invention can be widely applied in the field of trace ambient air detection technology.

Description

Technical Field

[0001] This invention belongs to the field of trace ambient air detection technology, and relates to online detection technology for gaseous pollutants, particularly to an integrated online luminescent detection device for atmospheric hydroxyl radicals. Background Technology

[0002] Hydroxyl radicals (·OH) are the most important oxidants in the troposphere, playing a crucial role in the oxidation and removal of many harmful atmospheric compounds. ·OH can eliminate most trace gases released into the troposphere, including greenhouse gases and harmful substances, and form various substances such as ozone and secondary organic compounds. Although the concentration of ·OH is extremely low, it determines the atmospheric lifetime of almost all pollutants and the photo-oxidation formation of secondary pollutants, earning it the title of "atmospheric cleaner." Therefore, real-time monitoring of ·OH concentration dynamics is crucial for a deeper understanding of atmospheric oxidation capacity, pollutant transformation mechanisms, and the development of effective control strategies. However, ·OH has an extremely short lifetime (microseconds) and extremely low concentration (average concentration approximately (10⁻⁶)). 5 molecules / cm 3 -10 7 molecules / cm 3 Its high reactivity and other characteristics pose a significant challenge to its detection.

[0003] Currently, the detection of ·OH is mainly divided into direct and indirect methods. Direct methods primarily utilize laser-induced fluorescence (LIF). While LIF technology offers rapid response and a low detection limit, its high purchase and maintenance costs limit its application. Indirect methods first use aromatic compounds (phenol, benzoic acid, salicylic acid, etc.) as trapping agents to react with ·OH, producing relatively stable hydroxylated products. These products can then be separated and measured using high-performance liquid chromatography (HPLC) combined with ultraviolet (UV) and fluorescence detection or mass spectrometry (MS). The core advantage of indirect methods lies in the variety of trapping agents, controllable costs, and potential for further optimization and system integration. Among these, chemiluminescence (CL) is an important indirect detection strategy, demonstrating promising application prospects for real-time ·OH detection due to its high sensitivity, rapid response, and ease of operation. Several ·OH detection devices based on chemiluminescence principles have been developed, but most methods are still limited to liquid-phase reaction systems, facing problems such as insufficient interference elimination and cumbersome pretreatment steps in practical applications, making it difficult to meet the requirements of continuous in-situ detection in the field. Summary of the Invention

[0004] To address the aforementioned problems, the purpose of this invention is to provide an integrated online luminescence detection device for atmospheric hydroxyl radicals that is highly integrated, has strong anti-interference capabilities, and is suitable for in-situ detection in the field. This device is based on wet chemical methods and chemiluminescence methods using gas diffusion absorption and capture to achieve real-time online detection of atmospheric hydroxyl radicals.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: An integrated online luminescent detection device for atmospheric hydroxyl radicals includes: The chassis and the collection module, reaction detection module, solution delivery module, and control and data acquisition circuit installed inside the chassis; The capture module uses a composite capture agent solution to capture hydroxyl radicals in the ambient air and convert them into stable hydroxylation products. The solution delivery module is used to deliver the hydroxylation product, the pre-prepared strong alkaline solution, and the oxidant solution to the reaction detection module for chemiluminescence reaction under the control of the control and data acquisition circuit, and transmit the detection data to the control and data acquisition circuit. The control and data acquisition circuit is used to control the trapping module, reaction detection module and solution delivery module, and to process the detection data to obtain the online detection results of hydroxyl radicals in the ambient air to be tested.

[0006] Furthermore, the trapping module includes a constant temperature vessel, a first trapping trap, and a second trapping trap; The thermostatic reactor is equipped with an air inlet channel and two independent cavities. The air inlet channel runs vertically through the center of the thermostatic reactor, and sampling holes connected to the two independent cavities are reserved at the same height on the side wall of the air inlet channel. This allows the ambient air to be tested to enter the thermostatic reactor through the air inlet at the top of the air inlet channel and simultaneously enter the first and second traps set in the two independent cavities through the sampling holes. This ensures that when conducting comparative experiments, the first and second traps collect ambient air samples of the same air mass at the same time. The first trap uses a trapping agent solution to capture hydroxyl radicals in the ambient air of the test environment, which serve as the detection sample for the test channel; After the second trap pre-treats the ambient air to be tested to remove hydroxyl radicals, it uses a trapping agent solution to capture the remaining interfering components in the ambient air to be tested, which serve as the detection sample for the background reference channel. The test samples from the test channel and the background reference channel are sequentially transported to the reaction detection module through the solution delivery module.

[0007] Furthermore, the first trap includes a first spiral tube and a first separation chamber; the first spiral tube is entirely enclosed inside the first separation chamber, and the air inlet and liquid inlet of the first spiral tube are simultaneously located at the top, so that the air inlet is connected to the side wall of the air inlet pipe, and the ambient air to be tested is immediately mixed with the trapping agent solution pumped in through the liquid inlet at the inlet; the liquid outlet of the first spiral tube is located at the bottom of the first spiral tube and is connected to the inside of the first separation chamber, so that the gas-liquid mixture after the reaction in the first spiral tube is separated into gas and liquid in the first separation chamber, and the liquid phase is discharged through the liquid phase outlets located at the bottom of the first and second separation chambers; The second trap includes a second spiral tube and a second separation chamber. The second spiral tube is entirely enclosed inside the second separation chamber, and the air inlet of the second spiral tube is located at the top. The second spiral tube includes a quenching section and a capturing section, and a liquid inlet is provided between the quenching section and the capturing section. The inner wall of the spiral tube of the quenching section is coated or filled with a hydroxyl radical selective quenching material. The capturing section has the same structure as the first spiral tube. The second separation chamber has the same structure as the first separation chamber.

[0008] Furthermore, the liquid phase outlets of the first and second separation chambers are respectively connected to a waste discharge peristaltic pump, which is used to discharge the residual liquid or cleaning fluid discharged from the cleaning flow path after the detection is completed; the upper part of the first and second separation chambers is provided with a waste gas outlet, which is connected to a vacuum diaphragm pump through an independent pipeline via a particulate filter and a flow controller.

[0009] Furthermore, the solution delivery module includes a three-channel peristaltic pump, first to fifth electromagnetic tees, first and second needle filters, first and second injection pumps, and a solution assembly; The solution group contains a pre-prepared solution, including water, an oxidant solution, an alkaline buffer solution, and a composite scavenging agent solution; The three input terminals of the three-channel peristaltic pump are respectively connected to the output terminals of the first to third electromagnetic tees, and the output terminal of the three-channel peristaltic pump is connected to the reaction detection module through a pipeline; The two input terminals of the first electromagnetic tee are connected to water and an oxidant solution, respectively. The two input terminals of the second electromagnetic tee are connected to water and an alkaline buffer solution, respectively; The two input terminals of the third electromagnetic tee are respectively connected to water and the output terminal of the fourth electromagnetic tee; The two input terminals of the fourth electromagnetic tee are respectively connected to the liquid output terminals of the first trap and the second trap, and the first needle filter and the second needle filter are respectively installed in front of the two input terminals of the fourth electromagnetic tee. The two input terminals of the fifth electromagnetic tee are connected to water and the composite capture agent, respectively, and the output terminal of the fifth electromagnetic tee is simultaneously connected to the input terminals of the first injection pump and the second injection pump. The output ends of the first and second injection pumps are connected to the first and second traps via pipelines for injecting a composite trapping agent solution into the first and second traps.

[0010] Furthermore, a buffer bottle is provided between the liquid phase outlet of the second trap and the input end of the fourth electromagnetic tee, for temporarily storing the detection sample output from the second trap when the detection sample output from the first trap undergoes a chemiluminescent reaction in the reaction detection module.

[0011] Furthermore, the composite trapping agent is a mixed solution composed of phthalohydrazide, a metal chelating agent, and an ozone quencher.

[0012] Furthermore, the reaction detection module includes a dark chamber and a mixing tank, a degassing device, a light counter, a temperature sensor, and a heating element disposed within the dark chamber; The mixing cell is used to receive the detection sample from the first trap or the second trap, and to realize the chemiluminescent reaction between the hydroxylation product and the oxidant in the detection sample under a strongly alkaline environment. The debubbling device is used to remove bubbles in the mixing pool to facilitate the detection of optical signals by the photon counter. The heating element is used to ensure that the mixing cell and the photon counter are at a preset temperature; The temperature sensor is used to detect the temperature inside the dark room; The photon counter is used to detect the optical signal generated by the mixing cell and transmit the detection data to the control and data acquisition circuit.

[0013] Furthermore, the constant temperature chamber controls the temperature of the reaction detection module at 45℃±0.5℃.

[0014] Furthermore, the control and data acquisition circuit includes a computer system and a data acquisition circuit; The data acquisition circuit is used to acquire the detection data of the reaction detection module; The computer system includes a data processing module and a control module. The data processing module is used to process the detection data in real time to obtain the concentration of hydroxyl radicals in the ambient air. The control module is used to control the temperature and flow rate of the collection module, reaction detection module, and solution delivery module according to the detection requirements. The present invention has the following advantages due to the adoption of the above technical solutions: 1. High system integration, enabling fully automated closed-loop monitoring throughout the entire process. This invention seamlessly integrates technologies such as gas sampling with particulate inertial separation, efficient gas-liquid mass transfer and capture, chemiluminescence reaction, photoelectric detection, and intelligent fluid control to construct an integrated, fully automated online measurement system. This system achieves fully automated closed-loop operation from ambient air sampling, efficient target object capture (capture efficiency >99%), sample transport, chemical reaction to signal acquisition and differential processing. It overcomes the drawbacks of traditional methods, such as fragmented processes and reliance on manual operation, significantly reducing maintenance complexity and making it suitable for long-term unattended continuous monitoring.

[0015] 2. Strong anti-interference ability, accurate and reliable measurement results. This invention innovatively employs a real-time differential detection mechanism and a multi-level collaborative anti-interference strategy. By setting up parallel test channels and background reference channels, and combining gas phase pretreatment and specific compound trapping agents, it can identify and subtract background signals caused by coexisting interfering substances (such as ozone, transition metal ions, etc.) online and synchronously. This significantly improves the selectivity and accuracy of hydroxyl radical measurement in complex atmospheric environments and effectively avoids false positive signals.

[0016] 3. High detection sensitivity and low detection limit. By employing an optimized conical microporous air inlet and a highly efficient mixing and mass transfer design with a spiral tube, combined with a highly sensitive chemiluminescence detection system, this method achieves a detection limit of 5.0 × 10⁻⁶ for atmospheric hydroxyl radicals under typical operating parameters (e.g., sampling flow rate of approximately 4 L / min, absorber flow rate of 0.45 mL / min, and collection temperature of 40-50 °C). 5 The molecular weight per centimeter (corresponding to 3 times the baseline noise standard deviation) is sufficient to meet the trace detection requirements of hydroxyl radicals under atmospheric background and typical pollution environments.

[0017] 4. Strong environmental adaptability and stable and reliable operation. The system's structural design fully considers the complexity of field applications. The isothermal reactor's conical top structure combines physical filtration (particulate matter removal rate >80%), rain and snow protection, and reduced wall wear. The constant temperature control of key modules (40-50℃ for collection, 35℃ for reaction) effectively suppresses errors and noise caused by temperature fluctuations. These design features ensure the system's long-term stable operation and data reliability in variable environments.

[0018] 5. The platform has strong versatility and scalability. This invention adopts a modular design concept, and its core sampling, flow path, and control platform possesses high flexibility and adaptability. By changing the functional coating within the trap, the capture agent formulation, and adjusting the corresponding reaction parameters, this platform can be rapidly expanded for the detection of other reactive substances in the atmosphere (such as nitrate radical NO3, ozone, etc.), and can also be adapted to the monitoring needs of different media such as water interfaces and soil gases, demonstrating excellent platform advantages and broad application potential.

[0019] The device of this invention features a simple structure, high integration, low operating cost, and convenient operation and maintenance, making it suitable for stable operation in field and long-term observation scenarios. Therefore, this invention can be widely applied in the field of trace ambient air detection technology. Attached Figure Description

[0020] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts. In the drawings: Figure 1 This is a schematic diagram of the integrated online luminescence detection device for atmospheric hydroxyl radicals provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the trap module structure provided in an embodiment of the present invention; The labels for the attached figures are as follows: 1. Collection module; 11. Thermostatic vessel; 111. Aluminum alloy inner layer; 112. Insulation layer; 113. Plastic outer layer; 12. First collection trap; 120. First spiral tube; 121. First separation chamber; 122. First air inlet; 123. First liquid inlet; 124. First liquid outlet; 125. First liquid phase outlet; 126. First independent pipeline; 127. Vacuum diaphragm pump; 128. First particulate filter; 129. First flow controller; 13. Second collection trap; 130. Second spiral tube; 131. Second separation chamber; 132. Second air inlet; 133. Second liquid inlet; 134. Second liquid outlet; 135. Second liquid phase outlet; 136. Second independent pipeline; 137. Second particle 1. Particulate filter; 138. Second flow controller; 14. Air inlet channel; 141. Sampling cone; 142. Main air inlet pipe; 143. Air inlet micro-hole; 144. Exhaust gas drainage device; 15. Independent cavity; 16. Sampling hole; 17. First waste peristaltic pump; 18. Second waste peristaltic pump; 19. Buffer bottle; 2. Reaction detection module; 21. Dark chamber; 22. Mixing tank; 23. Photon counter; 24. Temperature sensor and heating element; 3. Solution delivery module; 31. Three-channel peristaltic pump; 32. First electromagnetic tee; 33. Second electromagnetic tee; 34. Third electromagnetic tee; 35. Fourth electromagnetic tee; 36. Fifth electromagnetic tee; 37. First injection pump; 38. Second injection pump; 39. Solution group. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] In some embodiments of the present invention, an integrated online chemiluminescence detection device for atmospheric hydroxyl radicals is provided. By setting a test channel and a background reference channel, the difference between the luminescence signal values ​​obtained from the two channels is calculated to specifically obtain the chemiluminescence signal generated by hydroxyl radicals in the ambient air. The intensity of the chemiluminescence signal is proportional to the concentration of hydroxyl radicals, and the content of hydroxyl radicals in the test sample can be determined based on the chemiluminescence signal value. The device of the present invention not only effectively overcomes the limitation of traditional offline analysis in terms of continuous measurement, but also significantly reduces maintenance requirements due to the optimized design of the core trap and flow path, ultimately realizing in-situ online detection of ultra-low concentration hydroxyl radicals in ambient air.

[0024] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the invention and to fully convey the scope of the invention to those skilled in the art.

[0025] like Figure 1 As shown in the figure, this embodiment provides an integrated online chemiluminescence detection device for atmospheric hydroxyl radicals. Specifically, the device includes: a chassis (not shown in the figure) and a collection module 1, a reaction detection module 2, a solution delivery module 3, and a control and data acquisition circuit disposed within the chassis. The collection module 1 uses a composite capture agent solution to capture hydroxyl radicals in the ambient air to be tested and converts them into stable hydroxylation products. The solution delivery module 3, under the control of the control and data acquisition circuit, delivers the hydroxylation products, a pre-prepared strong alkaline solution, and an oxidant solution to the reaction detection module 2 for chemiluminescence reaction, and transmits the detection data to the control and data acquisition circuit. The control and data acquisition circuit controls the parameters of the collection module 1, the reaction detection module 2, and the solution delivery module 3, and processes the detection data to obtain the online detection result of the concentration of hydroxyl radicals in the ambient air to be tested.

[0026] Furthermore, such as Figure 2As shown, the collection module 1 includes a thermostatic vessel 11, a first collection trap 12, and a second collection trap 13. The thermostatic vessel 11 has an air inlet channel 14 and two independent cavities 15. The air inlet channel 14 vertically penetrates the center of the thermostatic vessel 11, and sampling holes 16 connected to the two independent cavities are reserved at the same height on the side wall of the air inlet channel 14. This allows the ambient air to enter the thermostatic vessel 11 through the air inlet at the top of the air inlet channel 14 and simultaneously enter the first collection trap 12 and the second collection trap 13 located in the two independent cavities 15 through the sampling holes 16. This ensures that during comparative experiments, the first collection trap 12 and the second collection trap 13 collect the same... At the same time, the exhaust gas of the ambient air sample to be tested from the same air mass is discharged from the bottom of the air inlet channel 14; the first trap 12 uses a composite trapping agent solution to capture hydroxyl radicals in the ambient air to be tested, which serves as the detection sample for the test channel; the second trap 13 pre-treats the ambient air to be tested to remove hydroxyl radicals, and then uses a trapping agent solution to capture the remaining interfering components in the ambient air to be tested, which serves as the detection sample for the background reference channel; the detection samples of the test channel and the background reference channel are successively transported to the reaction detection module 2 through the solution delivery module 3.

[0027] Furthermore, the top of the thermostatic vessel 11 is conical, and the vessel body adopts a three-layer composite structure, including an inner aluminum alloy layer 111, an insulation layer 112, and a plastic outer layer 113 arranged sequentially from the inside out. The inner aluminum alloy layer 111 has two independent cavities evenly distributed around the air inlet channel, and heating rods (not shown in the figure) are installed on the inner walls of the two independent cavities. These heating rods are connected to an external precision temperature control system, which maintains the internal temperature of the thermostatic vessel 11 within the range of 40°C to 50°C. The insulation layer 112 and the plastic outer layer 113 are fitted over the inner aluminum alloy layer 111. Pre-set positions on the insulation layer 112 and the plastic outer layer 113 have circular holes matching the first trap 12 and the second trap 13, used to connect the first trap 12 and the second trap 13 to the reaction detection module 2 and the solution delivery module 3. O-rings are installed at the connection points between each circular hole and each device.

[0028] In this embodiment, preferably, the aluminum alloy inner layer 111 adopts a split structure, including two half shells divided longitudinally along the thermostatic vessel 11, and the two half shells are fastened together by bolts, which facilitates the installation and use of the two traps; the insulation layer 112 and the plastic outer layer 113 adopt an integrated structure, and the insulation layer 112 adopts a high-efficiency insulation material to reduce heat loss; the plastic outer layer 113 is used to provide structural protection, and also has the advantages of being lightweight, corrosion resistant, and easy to deploy in the field.

[0029] Furthermore, the air intake channel 14 includes a sampling cone 141 and a cylindrical main air intake pipe 142. The upper end of the main air intake pipe 142 extends from the top of the constant temperature vessel 11 and is threadedly connected to the sampling cone 141. A micro-hole 143 is located at the center of the top of the sampling cone 141, serving as the air inlet of the air intake channel 14 for introducing ambient air under test through negative pressure. The lower end of the main air intake pipe 142 extends from the bottom of the constant temperature vessel 11 and is connected to the exhaust gas drainage device 144, used to continuously extract particulate-containing airflow that enters through the micro-hole 143 but does not enter the two traps from the constant temperature vessel 11. O-rings are provided at the connection points between the sampling cone 141 and the main air intake pipe 142. Sealing rings or sealing packing are provided at the connections between the upper and lower ends of the main air intake pipe 142 and the constant temperature vessel 11 to ensure the airtightness of the constant temperature vessel 11 and prevent heat loss.

[0030] In this embodiment, the sampling cone 141 and the air inlet pipe 142 are designed separately, and the sampling cone 141 protrudes above the conical top of the thermostatic vessel 11, which facilitates disassembly, cleaning or replacement of sampling cones 141 of different sizes and specifications to adapt to different sampling flow requirements and environmental conditions.

[0031] Meanwhile, the sampling cone 141, in conjunction with the conical top of the constant temperature vessel 11, also serves as a physical filter and protection function: As the ambient air enters the sampling cone 141, its flow direction changes from vertical downwards to horizontally entering the two traps; most of the particulate matter carried in the airflow (experimental tests show a removal rate of approximately 80%), due to its greater inertia, cannot complete this sharp turn, thus maintaining its original direction of motion and continuing downwards along the cylindrical air intake pipe, eventually being extracted from the constant temperature vessel system via the exhaust gas diversion device, preventing particulate matter deposition within the constant temperature vessel 11. The conical top structure of the sampling cone 141 and the constant temperature vessel 11 also effectively prevents rain and snow from directly entering the air intake channel 14, ensuring the dry and stable operation of the two traps inside.

[0032] Furthermore, the inner wall of the sampling cone 141 is coated with a fluorine coating. Because the fluorine coating has extremely low surface energy, it can significantly reduce the adsorption of hydroxyl radicals and particulate matter, while also facilitating cleaning and maintenance. Preferably, the fluorine coating can be a polytetrafluoroethylene (PTFE) coating.

[0033] Furthermore, the first trap 12 includes a first spiral tube 120 and a first separation chamber 121. The total extended length of the first spiral tube 120 is L1, and it completely covers the interior of the first separation chamber 121. The first air inlet 122 and the first liquid inlet 123 of the first spiral tube 120 are simultaneously located at the top, such that the first air inlet 122 is connected to the main air intake pipe 142, allowing the ambient air to be tested to immediately mix with the composite trapping agent solution pumped in through the first liquid inlet 123 at the inlet. The first drain outlet 124 of the first spiral tube 120 is located at the bottom of the first spiral tube 120 and is connected to the interior of the first separation chamber 121, allowing a reaction to occur within the first spiral tube 120. The gas-liquid mixture is separated in the first separation chamber 121. The test sample is discharged from the first liquid phase outlet 125 at the bottom of the first separation chamber 121 and enters the solution delivery module 3 for subsequent hydroxyl radical concentration detection. The residual gas is extracted by an external vacuum diaphragm pump 127 through the first independent pipeline 126 connected to the top of the first separation chamber 121. The first independent pipeline 126 can also be equipped with a first particulate filter 128 and a first flow controller 129 for filtering particulate matter and detecting and controlling the flow rate to maintain a stable negative pressure for gas extraction.

[0034] Furthermore, the structure of the second trap 13 is basically symmetrical to that of the first trap 12, except that the total unfolded length of the second spiral tube 130 in the second trap 13 is set to L2, and L2>L1.

[0035] Specifically, the second spiral tube 130 includes a quenching section and a capture section. The length of the quenching section is ΔL = L2 - L1. The inner wall of the quenching section spiral tube is coated or filled with a hydroxyl radical selective quenching material, forming a dedicated gas phase pretreatment section. The capture section has the same structure as the first spiral tube 120. The second air inlet 132 of the second spiral tube 130 is located at the top of the quenching section, and the second liquid inlet 133 is located between the quenching section and the capture section.

[0036] In this embodiment, because a quenching section is provided inside the second spiral tube 130, the hydroxyl radicals in the ambient air being tested are specifically removed when it flows through the quenching section, and undergo the same physical and chemical conditions in the subsequent "effective capture section". The quenched ambient air is then mixed with the capture agent solution, mainly capturing the remaining interfering components in the airflow, thereby outputting a background reference channel detection sample in the separation chamber that does not contain hydroxyl radical signals but contains signals of other interfering substances.

[0037] Through experimental optimization, the inner diameters of the first helical tube 120 and the second helical tube 130 range from 1.0 mm to 2.0 mm, preferably about 1.5 mm. This preferred size was determined through comparative experiments: under the premise of ensuring the formation of a stable gas-liquid two-phase flow and achieving sufficient mixing and mass transfer, a helical tube inner diameter of 1.5 mm can effectively reduce liquid retention and system dead volume, thereby optimizing reagent utilization and system response time. The total unfolded length L1 of the first helical tube 120 is preferably in the range of 100 mm to 300 mm, and can be adjusted according to detection requirements in practical applications; the length ΔL of the quenching section in the second helical tube 130 was experimentally optimized, and is preferably about 200 mm at a typical sampling flow rate (e.g., 4 L / min) to ensure a near 100% removal efficiency for hydroxyl radicals.

[0038] Furthermore, the first liquid phase outlet 125 of the first trap 12 is also connected to the first waste discharge peristaltic pump 17, and the second liquid phase outlet 135 of the second trap 13 is also connected to the second waste discharge peristaltic pump 18, so that after the detection is completed, the residual liquid or cleaning liquid discharged by the first waste discharge peristaltic pump 17 and the second waste discharge peristaltic pump 18 will be discharged to clean the flow path and trap.

[0039] Furthermore, the reaction detection module 2 includes a dark chamber 21 and a mixing cell 22, a degassing device (not shown in the figure), a photon counter 23, a temperature sensor, and a heating element 24 disposed within the dark chamber 21. The mixing cell 22 receives the detection sample from the first trap 12 or the second trap 13 delivered by the solution delivery module 3, enabling the detection of the chemiluminescent reaction between the hydroxylation product and the oxidant in the sample under a strongly alkaline environment. The degassing device removes air bubbles from the mixing cell 22 to facilitate the detection of the light signal by the photon counter 23. The heating element 24 ensures that the mixing cell 22 and the photon counter 23 are at a preset temperature. The photon counter 23 detects the light signal generated by the mixing cell 22 and transmits the detection data to the control and data acquisition circuit.

[0040] In this embodiment, the dark chamber 21 can ensure that the chemiluminescence reaction in the mixing cell 22 is not affected by the outside world, while reducing the detection error of the photon counter 23; the heating plate 24 can ensure that the photon counter 23 is in a preset constant temperature environment, while ensuring the reaction temperature of the chemiluminescence reaction.

[0041] Heating element 24 precisely controls the temperature of the reaction and detection module 2 at 45℃±0.5℃. This controlled temperature was determined through system conditional experimental optimization: it is well integrated with the constant temperature conditions (40-50℃) of the pre-collection module 1, avoiding the generation of bubbles or condensation of samples due to temperature changes during transport, and ensuring flow path stability. Experiments show that at this temperature, the chemiluminescent reaction of phthalohydrazide hydroxylation products with hydrogen peroxide has the best kinetic stability, achieving the optimal balance between luminescence signal intensity and repeatability; it provides a constant operating temperature environment for photon counter 23, effectively suppressing thermal noise drift caused by temperature fluctuations.

[0042] Furthermore, the solution delivery module 3 includes a three-channel peristaltic pump 31, first to fifth electromagnetic tees 32 to 36, first to second injection pumps 37 to 38, and a solution group 39. The solution group 39 contains a pre-prepared solution, including water, an oxidant solution, an alkaline buffer solution, and a composite trapping agent solution. The three input terminals of the three-channel peristaltic pump 31 are respectively connected to the output terminals of the first to third electromagnetic tees 32 to 34, and the output terminal of the three-channel peristaltic pump 31 is connected to the reaction detection module 2 via a pipeline. The two input terminals of the first electromagnetic tee 32 are respectively connected to water and the oxidant solution; the two input terminals of the second electromagnetic tee 33 are respectively connected to water and the alkaline buffer solution; the two input terminals of the third electromagnetic tee 34 are respectively connected to water and the output terminal of the fourth electromagnetic tee 35; the two input terminals of the fourth electromagnetic tee 35 are respectively connected to the first trapping trap 12 and... The first liquid outlet 125 and the second liquid outlet 135 of the second trap 13 are connected, and the first needle filter and the second needle filter are respectively provided before the two input ends of the fourth electromagnetic tee 35; the two input ends of the fifth electromagnetic tee 36 are respectively connected to water and composite trapping agent, and the output end of the fifth electromagnetic tee 36 is simultaneously connected to the input ends of the first injection pump 37 and the second injection pump 38; the output ends of the first injection pump 37 and the second injection pump 38 are respectively connected to the first liquid inlet 123 and the second liquid inlet 133 of the first trap 12 and the second trap 13 via pipelines, for injecting composite trapping agent solution into the first trap 12 and the second trap 13.

[0043] In this embodiment, the delivery flow rate of the three-channel peristaltic pump 31 was experimentally calibrated and set to a specific value that matches the liquid turnover rate during the capture phase. This matching relationship ensures the continuity of fluid flow between the capture and detection stages, thereby guaranteeing the overall response speed and time resolution of the system.

[0044] Furthermore, a buffer bottle 19 is provided between the liquid phase outlet 125 of the first trap 12 and the input end of the fourth electromagnetic tee 35, for temporarily storing the detection sample output from the first trap 12 when the detection sample output from the second trap 13 undergoes a chemiluminescence reaction in the reaction detection module 2.

[0045] In this embodiment, since the chemiluminescence reaction time of the detection sample in the mixing cell 22 is relatively long, in order to avoid errors caused by the reaction time, a buffer bottle is added after the first trap 12. This ensures that when the detection sample of the second trap 13 is transported to the mixing cell 22 for chemiluminescence reaction, the detection sample of the first trap 12 is simultaneously output to the buffer bottle 19. At the same time as the reaction of the detection sample in the second trap 13 is completed, the reaction of the detection sample in the first trap 12 is carried out according to the same process, so as to improve the detection resolution to half an hour or longer.

[0046] Furthermore, the composite trapping agent solution uses phthalohydrazide as the core functional component and achieves highly selective trapping through specific compounding. To eliminate potential interference in the environment, a metal chelating agent (such as diethylenetriaminepentaacetic acid, DTPA) and an ozone quencher (potassium iodide, KI) are added to the trapping agent solution. Among them, the metal chelating agent DTPA can effectively complex transition metal ions carried on the surface of particulate matter or in aerosols, inhibiting non-specific reactions caused by metal catalysis, thereby significantly reducing particulate matter interference. Experiments show that when the concentration of potassium iodide is in the range of 0.001 mM to 0.002 mM, the interference inhibition rate of ozone at typical environmental levels (such as 100 ppb) can reach more than 95%. The gas is dispersed in the composite trapping agent in the form of bubbles, and hydroxyl radicals are efficiently and specifically captured at the gas-liquid interface and converted into a stable, strongly chemiluminescent product—5-hydroxyphthalohydrazide.

[0047] A strong alkaline buffer solution can be a sodium carbonate solution, and an oxidizing agent solution can be a hydrogen peroxide solution. This invention is only using this as an example, but is not limited thereto.

[0048] Furthermore, the control and data acquisition circuit includes a computer system and a data acquisition circuit. The data acquisition circuit is used to acquire detection data from the first flow controller 129, the second flow controller 138, the photon counter 23, and the heating element 24. The computer system includes a data processing module and a control module. The data processing module processes the acquired data from the photon counter in real time to obtain the concentration of hydroxyl radicals in the ambient air. The control module precisely controls the gas or liquid flow rate or the temperature of the heating element from the three-channel peristaltic pump 31, the first to fifth electromagnetic tees 32 to 36, the first to second injection pumps 37 to 38, the first waste discharge peristaltic pump 17, and the second waste discharge peristaltic pump 18 based on flow rate and temperature data.

[0049] In this embodiment, the online detection process of atmospheric hydroxyl radicals in the ambient air to be tested can be divided into three parts: a collection process, a reaction process, and a detection process. Specifically, it includes: 1) Capture process: The ambient air to be tested is divided into two channels and introduced into the capture module as the test channel and the background reference channel, respectively. The composite capture agent solution is used to capture hydroxyl radicals and generate stable hydroxylation products.

[0050] Specifically, the operation method is as follows: The trapping agent solution is injected into the first trapping trap 12 and the second trapping trap 13 by controlling the first injection pump 37 and the second injection pump 38. The ambient air to be tested is divided into two paths using the exhaust gas diversion device 144. One path is directly introduced into the first trap 12 as the test channel, while the other path is used as a background reference channel after the hydroxyl radicals are specifically removed before capture by the pretreatment section of the second trap 13 with a built-in hydroxyl radical quenching section. The intake flow rate of the ambient air to be tested in the two channels is controlled by the first flow controller 129 and the second flow controller 138 to ensure the stability of the collection efficiency in the first trap 12 and the second trap 13. Inside the spiral tube, the gas and liquid phases flow downwards in parallel, achieving thorough mixing and mass transfer through the spiral path, ensuring that hydroxyl radicals in the gas phase are efficiently captured by the liquid phase scavenger.

[0051] 2) Reaction process: After waiting for a preset time, the hydroxylated products generated in the test channel and the background reference channel are successively introduced into the reaction module for photochemical reaction.

[0052] In this embodiment, hydrogen peroxide solution is used as the oxidant for 5-hydroxyphthalic acid hydrazide, and sodium carbonate solution is used as the strongly alkaline buffer medium for 5-hydroxyphthalic acid hydrazide. A three-channel peristaltic pump 31 transports the strongly chemiluminescent product generated in the collection module 1 to the mixing tank 22. Simultaneously, the strongly alkaline buffer medium sodium carbonate and the oxidant hydrogen peroxide are separately transported to the mixing tank 22 to mix with 5-hydroxyphthalic acid hydrazide. Under the strongly alkaline environment, 5-hydroxyphthalic acid hydrazide reacts with hydrogen peroxide to immediately generate chemiluminescence.

[0053] To achieve better measurement stability and detection limit, the mixing cell 22 is equipped with a temperature-adjustable heating element 24, which allows the chemiluminescent reaction in the mixing cell 22 to proceed at a specific temperature. At the same time, to avoid the influence of light on the reaction stability, the mixing cell 22 needs to be designed to avoid light, for example, by being placed in a dark chamber 21.

[0054] 3) Detection process: After the reaction has been preset for a certain time, the luminescence signal generated by the test sample output from the two channels is detected by the reaction detection module, and the online detection result of hydroxyl radicals in the ambient air is obtained by subtracting the signals.

[0055] The chemiluminescence reaction takes place in the mixing cell 22, and the emitted signal is detected by the photon counter 23 and transmitted to the computer terminal. The temperature during the detection process is kept constant by controlling the heating element 24, ensuring the stability of the light signal intensity detection. In addition, a bubble removal device is introduced at the front end of the mixing cell 22 to prevent bubbles from interfering with the subsequent optical detection.

[0056] To ensure detection accuracy, the detection device needs to be zeroed before detection. This involves capturing samples for the same amount of time using a composite trapping agent in both traps without introducing ambient air, and then transmitting the samples to the reaction detection module to obtain the zero-point optical signal intensity. The core purpose of the gas zeroing process is to measure and subtract the system's background signal to eliminate interference caused by reagent reactions, electronic noise, and optical background. This ensures that the final measured chemiluminescence signal specifically originates from hydroxyl radicals, thereby guaranteeing the accuracy and comparability of the data.

[0057] At the same time, the detection device needs to be calibrated at each preset period or according to actual needs. The calibration method can be a conventional method for those skilled in the art, and will not be described in detail in comparison to the present invention.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. An integrated online luminescent detection device for atmospheric hydroxyl radicals, characterized in that, include: The chassis and the collection module, reaction detection module, solution delivery module, and control and data acquisition circuit installed inside the chassis; The capture module uses a composite capture agent solution to capture hydroxyl radicals in the ambient air and convert them into stable hydroxylation products. The solution delivery module is used to deliver the hydroxylation product, the pre-prepared strong alkaline solution, and the oxidant solution to the reaction detection module for chemiluminescence reaction under the control of the control and data acquisition circuit, and transmit the detection data to the control and data acquisition circuit. The control and data acquisition circuit is used to control the trapping module, reaction detection module and solution delivery module, and to process the detection data to obtain the online detection results of hydroxyl radicals in the ambient air to be tested.

2. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 1, characterized in that, The trapping module includes a constant temperature vessel, a first trapping trap, and a second trapping trap; The thermostatic reactor is equipped with an air inlet channel and two independent cavities. The air inlet channel runs vertically through the center of the thermostatic reactor, and sampling holes connected to the two independent cavities are reserved at the same height on the side wall of the air inlet channel. This allows the ambient air to be tested to enter the thermostatic reactor through the air inlet at the top of the air inlet channel and simultaneously enter the first and second traps set in the two independent cavities through the sampling holes. This ensures that when conducting comparative experiments, the first and second traps collect ambient air samples of the same air mass at the same time. The first trap uses a trapping agent solution to capture hydroxyl radicals in the ambient air of the test environment, which serve as the detection sample for the test channel; After the second trap pre-treats the ambient air to be tested to remove hydroxyl radicals, it uses a trapping agent solution to capture the remaining interfering components in the ambient air to be tested, which serve as the detection sample for the background reference channel. The test samples from the test channel and the background reference channel are sequentially transported to the reaction detection module through the solution delivery module.

3. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 2, characterized in that, The first trap includes a first spiral tube and a first separation chamber. The first spiral tube is entirely enclosed inside the first separation chamber, and the air inlet and liquid inlet of the first spiral tube are simultaneously located at the top, so that the air inlet is connected to the side wall of the air inlet pipe, and the ambient air to be tested is immediately mixed with the trapping agent solution pumped in through the liquid inlet at the inlet. The liquid outlet of the first spiral tube is located at the bottom of the first spiral tube and is connected to the inside of the first separation chamber, so that the gas-liquid mixture after the reaction in the first spiral tube is separated into gas and liquid in the first separation chamber, and the liquid phase is discharged through the liquid phase outlets located at the bottom of the first and second separation chambers. The second trap includes a second spiral tube and a second separation chamber. The second spiral tube is entirely enclosed inside the second separation chamber, and the air inlet of the second spiral tube is located at the top. The second spiral tube includes a quenching section and a capturing section, and a liquid inlet is provided between the quenching section and the capturing section. The inner wall of the spiral tube of the quenching section is coated or filled with a hydroxyl radical selective quenching material. The capturing section has the same structure as the first spiral tube. The second separation chamber has the same structure as the first separation chamber.

4. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 3, characterized in that, The liquid phase outlets of the first and second separation chambers are also connected to a peristaltic pump for waste discharge, which is used to discharge the residual liquid or cleaning fluid discharged from the cleaning flow path after the detection is completed; the upper part of the first and second separation chambers is provided with a waste gas outlet, which is connected to a vacuum diaphragm pump through an independent pipeline, a particulate filter and a flow controller.

5. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 3, characterized in that, The solution delivery module includes a three-channel peristaltic pump, first to fifth electromagnetic tees, first and second needle filters, first and second syringe pumps, and a solution assembly; The solution group contains a pre-prepared solution, including water, an oxidant solution, an alkaline buffer solution, and a composite scavenging agent solution; The three input terminals of the three-channel peristaltic pump are respectively connected to the output terminals of the first to third electromagnetic tees, and the output terminal of the three-channel peristaltic pump is connected to the reaction detection module through a pipeline; The two input terminals of the first electromagnetic tee are connected to water and an oxidant solution, respectively. The two input terminals of the second electromagnetic tee are connected to water and an alkaline buffer solution, respectively; The two input terminals of the third electromagnetic tee are respectively connected to water and the output terminal of the fourth electromagnetic tee; The two input terminals of the fourth electromagnetic tee are respectively connected to the liquid output terminals of the first trap and the second trap, and the first needle filter and the second needle filter are respectively installed in front of the two input terminals of the fourth electromagnetic tee. The two input terminals of the fifth electromagnetic tee are connected to water and the composite capture agent, respectively, and the output terminal of the fifth electromagnetic tee is simultaneously connected to the input terminals of the first injection pump and the second injection pump. The output ends of the first and second injection pumps are connected to the first and second traps via pipelines for injecting a composite trapping agent solution into the first and second traps.

6. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 5, characterized in that, A buffer bottle is also provided between the liquid phase outlet of the second trap and the input end of the fourth electromagnetic tee, for temporarily storing the detection sample output from the second trap when the detection sample output from the first trap undergoes a chemiluminescent reaction in the reaction detection module.

7. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 1, characterized in that, The composite trapping agent is a mixed solution composed of phthalohydrazide, metal chelating agent and ozone quencher.

8. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 1, characterized in that, The reaction detection module includes a dark chamber and a mixing tank, a degassing device, a light counter, a temperature sensor, and a heating element disposed within the dark chamber. The mixing cell is used to receive the detection sample from the first trap or the second trap, and to realize the chemiluminescent reaction between the hydroxylation product and the oxidant in the detection sample under a strongly alkaline environment. The debubbling device is used to remove bubbles in the mixing pool to facilitate the detection of optical signals by the photon counter. The heating element is used to ensure that the mixing cell and the photon counter are at a preset temperature; The temperature sensor is used to detect the temperature inside the dark room; The photon counter is used to detect the optical signal generated by the mixing cell and transmit the detection data to the control and data acquisition circuit.

9. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 8, characterized in that, The constant temperature chamber controls the temperature of the reaction detection module at 45℃±0.5℃.

10. The integrated online luminescence detection device for atmospheric hydroxyl radicals as described in claim 1, characterized in that, The control and data acquisition circuit includes a computer system and a data acquisition circuit. The data acquisition circuit is used to acquire the detection data of the reaction detection module; The computer system includes a data processing module and a control module. The data processing module is used to process the detection data in real time to obtain the concentration of hydroxyl radicals in the ambient air. The control module is used to control the temperature and flow rate of the collection module, reaction detection module, and solution delivery module according to the detection requirements.

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