A device and method for quantitatively detecting photocatalytic free radicals on particle surface

Abstract

The present invention discloses a quantitative detection device and method for photocatalytic free radicals on the surface of particulate matter, which relates to the field of atmospheric photochemistry. In the device, a light source module irradiates a photolysis beam or a simulated natural light beam into a reaction module; a gas distribution system passes a free radical precursor synthesis gas into the reaction module; the reaction module is a place where free radicals are generated, and a photolysis beam is used to photolyze the free radical precursor synthesis gas to generate free radicals, or a simulated natural light beam / sunlight is used to photocatalyze a particulate sample placed in the reaction module to generate free radicals; the free radicals in the reaction module enter a free radical detection module, and the free radical detection module uses a laser to excite the free radicals to generate fluorescence, and collects the fluorescence photon signal and the outgoing laser energy. The method is to first calibrate the device by photolyzing the free radicals generated by the free radical precursor synthesis gas of a known concentration, and after the calibration is completed, quantitatively measure the concentration of free radicals generated on the surface of the particulate matter under photocatalysis.

Description

Technical Field

[0001] The invention relates to the field of atmospheric photochemical technology, and in particular to a device and method for quantitatively detecting photocatalytic free radicals on the surface of particles. Background Art

[0002] In recent years, atmospheric fine particulate matter (PM2.5) pollution has become a major environmental problem that seriously affects human health. Nowadays, gaseous pollutants driven by atmospheric oxidants, such as SO 2 , NOx and volatile organic compounds (VOCs), which are rapidly converted into PM, such as sulfates, nitrates and secondary organic aerosols (SOAs), are considered to be the main driving forces for the rapid nucleation and growth of fine particles, which often lead to severe haze events. However, the currently identified oxidation pathways appear to be incomplete, as they cannot fully explain the extremely high levels of PM observed during severe haze events, suggesting that there may be other unidentified sources of atmospheric oxidants. Rapid economic development and industrialization have led to a rapid increase in the emission of soot particles, resulting in an increasing number of high PM2.5 haze events.

[0003] Free radicals are the most important oxidants in the atmosphere. Based on theoretical research, we propose that free radicals will be generated on the surface of atmospheric particles under photocatalysis. Therefore, measuring the types and concentrations of free radicals generated on the surface of particles under photocatalysis is crucial to further improve the atmospheric oxidation process.

[0004] Due to the high activity and low lifespan of free radicals, and the low concentration of free radicals generated on the surface of particles under light, free radicals can be easily lost or even quenched during the sampling and measurement process. The low lifespan of free radicals also determines that there is no standard gas source for them. Therefore, there is no suitable solution to accurately measure the types and specific concentrations of free radicals generated on the surface of particles under photocatalysis. Summary of the invention

[0005] In order to overcome the defects in the above-mentioned prior art, the present invention provides a device and method for quantitative detection of photocatalytic free radicals on the surface of particulate matter, aiming to ensure that the collision loss and life loss of free radicals are minimized as much as possible under specified light band and light intensity, and adopts a highly sensitive and quantitative detection method to accurately measure the types and specific concentrations of free radicals generated on the surface of particulate matter under photocatalysis.

[0006] To achieve the above object, the present invention adopts the following technical solutions, including:

[0007] A quantitative detection device for photocatalytic free radicals on the surface of particles, the device comprising: a light source module, a reaction module, a gas distribution system, a free radical detection module, and a control system;

[0008] The light source module is used to generate a photolysis beam or simulate a natural light beam, and irradiate the photolysis beam or simulated natural light beam into the reaction module; the photolysis beam is used to photolyze free radical precursors to generate free radicals; the simulated natural light beam is used to irradiate the surface of the particles, and photocatalyze the surface of the particles to generate free radicals;

[0009] The gas distribution system is connected to the reaction module and is used to pass the free radical precursor synthesis gas into the reaction module;

[0010] The reaction module is a place where free radicals are generated. The photolysis beam irradiated by the light source module is used to photolyze the free radical precursor synthesis gas to generate free radicals; or the simulated natural light beam irradiated by the light source module is used to photocatalyze the particulate matter sample placed in the reaction module to generate free radicals; or the sunlight is directly irradiated into the reaction module to photocatalyze the particulate matter sample placed in the reaction module to generate free radicals;

[0011] The reaction module is connected to the free radical detection module, and the free radicals generated in the reaction module enter the free radical detection module; the free radical detection module is used to emit laser to the free radicals and excite the free radicals to generate fluorescence, and to collect fluorescence photon signals and emitted laser energy;

[0012] The control system is used to receive various data collected in the device, control various controllable devices in the device, and perform related computing tasks.

[0013] Preferably, the light source module includes: a mercury lamp for generating photolysis light, a xenon lamp for generating natural light, a concave lens, a convex lens, a filter, a reflector arranged in sequence along the light propagation direction, a DC regulated power supply for supplying power to the mercury lamp and the xenon lamp, a photosensor for collecting light intensity, and a cage-type fixing frame for detachably fixing each optical device;

[0014] The photolysis light or natural light is first expanded and collimated by a concave lens and a convex lens to obtain a beam of parallel light, and then filtered out the redundant bands of the parallel light beam by a filter; the reflector is arranged at the center of the parallel light beam, the central light beam of the parallel light beam is irradiated by the reflector and then reflected to the photosensitive surface of the photosensor, and the outer ring light beam of the parallel light beam is irradiated into the reaction module;

[0015] The filter is a bandpass filter, and light beams of different bands are generated by replacing the filter; the distance between the concave lens and the convex lens is adjustable to adjust the parallel beam expansion of photolysis light or natural light.

[0016] Preferably, the gas distribution system comprises: a calibration gas cylinder, a wet gas flow meter, a dry gas flow meter, a water bottle, an anti-backflow bottle, a detection tube and a humidity sensor;

[0017] The calibration gas cylinder is used to store the free radical precursor synthesis gas; the output pipe of the calibration gas cylinder is respectively connected to the input end of the wet gas pipeline and the dry gas pipeline; the wet gas pipeline is provided with a wet gas flowmeter, and the dry gas pipeline is provided with a dry gas flowmeter; the output end of the dry gas pipeline is connected to the detection tube; after the wet gas pipeline passes through the anti-backflow bottle and the water bottle in sequence, the output end of the wet gas pipeline is also connected to the detection tube; the detection tube is connected to the reaction module, and is used to pass the free radical precursor synthesis gas into the reaction module;

[0018] The free radical precursor synthesis gas is introduced into the reaction module, on the one hand, to be photolyzed to generate free radicals, and on the other hand, to drive the free radicals generated by the photolysis of the free radical precursor synthesis gas in the reaction module into the free radical detection module;

[0019] The detection tube is provided with a humidity sensor for collecting the humidity of the gas in the detection tube;

[0020] If the gas introduced into the reaction module does not need to contain water vapor, only the dry gas flow meter is turned on, the wet gas flow meter is turned off, and the dry gas in the gas cylinder is introduced into the reaction module through the dry gas pipeline and the detection tube;

[0021] If the gas introduced into the reaction module needs to contain water vapor, turn on the wet gas flowmeter and the dry gas flowmeter at the same time. The dry gas in the gas cylinder is divided into two paths. One path is converted into wet gas after passing through the anti-backflow bottle and the water bottle on the wet gas pipeline and enters the detection tube. The other path directly enters the detection tube through the dry gas pipeline. The dry gas in the detection tube is mixed with the wet gas and then introduced into the reaction module.

[0022] By controlling the flow rate of the dry gas flow meter and the wet gas flow meter, the water vapor concentration in the gas is controlled so that the gas humidity in the detection tube collected by the humidity sensor reaches the set value.

[0023] Preferably, the gas distribution system also includes: a nitrogen cylinder for storing nitrogen; the output pipe of the nitrogen cylinder is connected to the output pipe of the calibration gas cylinder through a four-way, and the other two ports of the four-way are respectively connected to the input ends of the wet gas pipeline and the dry gas pipeline; the nitrogen is introduced into the reaction module to drive the free radicals generated by the photocatalysis of the particulate matter light sample in the reaction module into the free radical detection module.

[0024] Preferably, the reaction module comprises: a reactor body, a quartz window for sealing the reactor body and transmitting light, and a reaction panel for placing a particle sample;

[0025] A first through hole is provided in the reactor body along the light irradiation direction, and the first through hole is divided into an upper and lower section, namely an upper section through hole and a lower section through hole, and the hole diameter of the upper section through hole is larger than the hole diameter of the lower section through hole, forming an installation step for installing a reaction panel;

[0026] The reaction panel is placed on the mounting step, a second through hole aligned with the first through hole is opened in the middle of the reaction panel, the hole diameter of the second through hole is smaller than the upper surface of the first through hole, and an annular groove is opened on the outer ring of the second through hole, and the annular groove is used to place the particle sample;

[0027] A circular gap with a circular cross section is provided in the reactor body and along the outer ring of the upper through hole, the outer circumference of the circular gap is connected to the air inlet, and the air inlet is connected to the gas distribution system; a plurality of evenly distributed air outlets are provided on the inner circumference of the circular gap, which are connected to the upper through hole through the plurality of air outlets, and the airflow blown out of the air outlets is pushed flatly from all sides to the top of the reaction panel;

[0028] The inner wall of the upper through hole is provided with a trapezoidal groove along the circumferential direction, and the cross section of the trapezoidal groove is a trapezoid with an opening at the bottom edge and facing the upper through hole; the annular gap is located at the outer ring of the trapezoidal groove, and a plurality of air outlet holes lead to the trapezoidal groove along the center direction of the annular gap;

[0029] The quartz window is placed on the upper surface of the reactor body and is located above the upper through hole of the first through hole 703-5, and is used to seal the reactor body and transmit light;

[0030] The free radicals generated in the reaction module enter the free radical detection module along the lower through holes.

[0031] Preferably, a plurality of gas outlet grooves connected to the bottom of the lower through holes are provided at the bottom of the reactor body, so as to discharge the excess gas flow at the bottom of the lower through holes in the first through holes.

[0032] Preferably, the diameters of the several air outlet holes opened on the annular gap gradually increase in the direction from near to far from the air inlet; the materials of the reactor body and the reaction panel are both aluminum alloys with a layer of PFA film coated on the surface; the upper surface of the quartz window is coated with a layer of anti-reflection film; the quartz window is pressed and fixed to the upper surface of the reactor body by a window pressing plate, the window pressing plate is annular, and the hole diameter of the middle through hole of the window pressing plate is adapted to the outer diameter of the reaction panel; a second sealing ring is provided between the quartz window and the reactor body; a first sealing ring is provided between the reaction panel and the mounting step.

[0033] Preferably, the free radical detection module comprises: a sampling nozzle, a diffusion tube, a fluorescence chamber, an optical arm, a conical aperture, a window, a laser energy meter, a vacuum air pump, a laser, and an optical fiber;

[0034] The free radicals generated in the reaction module enter the fluorescence chamber through the sampling nozzle and the diffusion tube in sequence; the sampling nozzle is a conical nozzle installed on the top surface of the diffusion tube, with the cone mouth facing the reaction module and the cone bottom facing the top of the diffusion tube; the bottom of the diffusion tube is connected to the top of the fluorescence chamber; the left and right sides of the fluorescence chamber are respectively connected with an optical arm, which are the first optical arm and the second optical arm, respectively, the first optical arm and the second optical arm are perpendicularly intersected with the diffusion tube and connected to the fluorescence chamber, and the ends of the first optical arm and the second optical arm away from the fluorescence chamber are sealed by a window sheet;

[0035] The laser is used to generate and emit laser light through an optical fiber. The laser light is irradiated into a fluorescence chamber through a first optical arm to excite free radicals in the fluorescence chamber to generate fluorescence. The laser light is then irradiated into a laser energy meter through a second optical arm. The laser energy meter is used to collect the emitted laser energy. A photomultiplier tube is installed in the fluorescence chamber to perform photoelectric conversion on the excited fluorescence and collect fluorescence photon signals.

[0036] Conical diaphragms are installed inside the first optical arm and the second optical arm, and the cone tops of the conical diaphragms are facing the side away from the fluorescence chamber; the bottom of the fluorescence chamber is also connected to a vacuum air pump for evacuating the fluorescence chamber.

[0037] The present invention also provides a detection method of a device for quantitatively detecting photocatalytic free radicals on the surface of particles, comprising the following steps:

[0038] S1, first calibrate the device, as shown below:

[0039] S101, the light source module generates a photolysis beam and irradiates the reaction module, and simultaneously obtains the light intensity of the photolysis beam;

[0040] S102, the gas distribution system introduces a free radical precursor synthesis gas into a reaction module; the free radical precursor concentration and water vapor concentration in the free radical precursor synthesis gas are known;

[0041] The concentration of free radicals generated by the photolysis of the free radical precursor synthesis gas is calculated through the light intensity of the photolysis beam, the water vapor concentration, the concentration of the free radical precursor, and according to the free radical photolysis equation, i.e., the free radical calibration concentration Rt;

[0042] S103, a photolysis light beam photolyzes the free radical precursor synthesis gas introduced into the reaction module to generate free radicals, and the free radicals generated in the reaction module enter the fluorescence chamber of the free radical detection module;

[0043] S104, the free radical detection module emits laser light and irradiates it into the fluorescence chamber to excite the free radicals in the fluorescence chamber and generate fluorescence. At this time, the free radical detection module collects and obtains the calibration signal St of the fluorescence photons and the calibration energy Pt of the emitted laser light;

[0044] S2, after the device calibration is completed, the concentration of free radicals generated on the surface of the particle sample under photocatalysis is actually measured, as shown below:

[0045] S201, placing a particle sample in a reaction module;

[0046] S202, using a light source module to generate a simulated natural light beam and irradiating the reaction module, or using sunlight to irradiate the reaction module;

[0047] S203, simulating natural light beams or sunlight to irradiate the surface of the particle sample in the reaction module to generate free radicals by photocatalysis, and the free radicals generated in the reaction module enter the fluorescence chamber of the free radical detection module;

[0048] S204, the free radical detection module emits laser light and irradiates it into the fluorescence chamber to excite the free radicals in the fluorescence chamber and generate fluorescence. At this time, the free radical detection module collects the fluorescence photon signal S and the emitted laser energy P;

[0049] S205, based on the calibration signal St of the fluorescent photons, the calibration energy Pt of the emitted laser, the calibration concentration Rt of the free radicals obtained in the calibration process, and the fluorescent photon signal S and the emitted laser energy P obtained in the actual measurement process, the free radical concentration R generated on the surface of the particle sample under photocatalysis in the actual measurement process is calculated, R=Rt×[(S×Pt) / (St×P)].

[0050] Preferably, during the calibration process, by changing the type of free radical precursor introduced into the reaction module by the gas distribution system, and correspondingly changing the type and wavelength of the photolysis light beam, different types of free radicals are generated by photolysis; by changing the wavelength of the laser emitted by the free radical detection module, different types of free radicals are excited to generate fluorescence; based on different types of free radicals, the device is calibrated to obtain the calibration concentration Rt of different types of free radicals, as well as the calibration signal St of the fluorescence photons corresponding to different types of free radicals and the calibration energy Pt of the emitted laser;

[0051] In the actual measurement process, by changing the wavelength band of the laser emitted by the free radical detection module, different types of free radicals are excited to produce fluorescence; according to the calibration results of different types of free radicals, the concentrations of different types of free radicals generated on the surface of the particle sample under photocatalysis during the actual measurement process are calculated, thereby obtaining the types and specific concentrations of free radicals generated on the surface of the particle under photocatalysis.

[0052] The advantages of the present invention are:

[0053] (1) The device of the present invention can not only use a photolysis beam to photolyze a free radical precursor synthesis gas to generate free radicals, but also use a simulated natural light beam to irradiate a particulate sample to generate free radicals, and can also use sunlight to directly irradiate a particulate sample to generate free radicals. The device is first calibrated by photolyzing a free radical precursor synthesis gas of known concentration to generate free radicals. After the calibration is completed, the concentration of free radicals generated on the surface of the particulate matter under photocatalysis is quantitatively detected. Based on the structural design of the device of the present invention, the concentration of free radicals generated on the surface of the particulate matter under photocatalysis can be accurately measured.

[0054] (2) The light source module of the device of the present invention can generate parallel light beams with adjustable illumination intensity and illumination band, including parallel light beams close to the band of natural light, providing illumination conditions for indoor measurement, and also including mercury lamp light beams for photolysis of free radical precursors to generate free radicals, providing calibration conditions for quantitative measurement of the concentration of free radicals generated on the surface of particulate matter samples. The light source module adjusts the parallel beam expansion of photolysis light or natural light by adjusting the distance between the concave lens and the convex lens; the supply voltage of the mercury lamp and xenon is adjusted by a DC regulated power supply; the filter is a bandpass filter, and light beams of different bands can be generated by replacing the filter, so that quantitative detection can be performed under specified illumination bands and illumination intensities.

[0055] (3) The gas distribution system of the device of the present invention can produce humidity-controlled gas. The gas distribution system of the device of the present invention can not only provide free radical precursor synthesis gas and pass the free radical precursor synthesis gas into the reaction module, on the one hand, for photolysis to produce free radicals, and on the other hand, for driving the free radicals generated by the photolysis of the free radical precursor synthesis gas in the reaction module into the free radical detection module. The gas distribution system can also provide nitrogen and pass the nitrogen into the reaction module, for driving the free radicals generated by the surface of the particle sample under photocatalysis in the reaction module into the free radical detection module.

[0056] (4) The structural design of the reactor body of the device of the present invention can push the airflow blown out from the air outlet evenly from all sides to the top of the reaction panel, and blow the free radicals generated on the surface of the particle sample under photocatalysis downward to the vicinity of the sampling nozzle of the free radical detection module without dead angles. At the same time, it can ensure that the airflow above the particle sample can always maintain a laminar state, thereby avoiding the loss of free radicals caused by airflow dead zones and turbulence. The flow state of the airflow inside the reactor body is laminar flow without vortexes throughout the entire process, and the flow range covers the entire interior of the reaction body.

[0057] (5) An air outlet groove for removing excess airflow is provided at the bottom of the reactor body of the device of the present invention. Since the airflow in the lower through hole is also in laminar flow, excess airflow near the bottom wall of the lower through hole flows away from the air outlet groove, so that the airflow in the sampling nozzle entering the free radical detection module is a lossless airflow in the middle, thereby further reducing the loss of free radicals. The narrow strip design of the air outlet groove can also ensure that the airflow outside the reaction module will not affect the airflow inside the reaction module.

[0058] (6) The upper surface of the quartz window is coated with an anti-reflection film to increase the transmittance of the light beam; the materials of the reactor body and the reaction panel are both aluminum alloys coated with a PFA film on the surface to reduce the loss of free radicals; the diameter of the outlet holes gradually increases from near to far from the air inlet to ensure that the amount of gas blown out of each outlet hole is approximately equal.

[0059] (7) The light source module of the device of the present invention can generate a coarse parallel light beam that is sufficient to cover the surface of the particle sample. A reflector is installed above the quartz window and at the center of the parallel light beam. The reflector can reflect the center light beam of the parallel light beam to the photosensor, which can detect the optical cavity in real time and block the light directly shining on the sampling nozzle below, thereby avoiding the light entering from the small hole of the sampling nozzle from affecting the measurement of the free radical detection module.

[0060] (8) The free radical detection module of the device of the present invention is a fluorescence measurement under artificial low-pressure environment, which can accurately measure the concentration of free radicals while reducing the loss of free radical lifetime. Since the photomultiplier tube has a high sensitivity, it can accurately measure free radicals with very low concentrations.

[0061] (9) The device of the present invention replaces the xenon lamp in the simulated light source module with a mercury lamp, takes out the particle sample in the reaction module, closes the nitrogen bottle, and opens the calibration bottle, so that the detection device can be changed from the measurement state to the calibration state. By measuring the light intensity of the mercury lamp and the water vapor concentration combined with the photolysis equation of the free radical, the concentration of free radicals generated by the photolysis free radical precursor can be calculated, thereby obtaining free radicals of known concentration. Then the xenon lamp is replaced, the filter of the wavelength to be measured is replaced, the particle sample is placed in the reaction module, the calibration bottle is closed, and the nitrogen bottle is opened, so that the concentration of free radicals generated on the surface of the particle sample under the light of the specified wavelength can be measured.

[0062] (10) In the method of the present invention, a simulated light source is first used to emit a photolysis beam, and the device is calibrated by generating free radicals through the photolysis of a known concentration of a free radical precursor synthesis gas. After the calibration is completed, the simulated light source is used to emit a simulated natural light beam or directly use sunlight to quantitatively measure the concentration of free radicals generated on the surface of the particle under photocatalysis. Based on the device method of the present invention, the concentration of free radicals generated on the surface of the particle under photocatalysis can be accurately measured.

[0063] (11) Although the free radicals that may be generated on the particle surface under photocatalysis are unknown, different types of free radicals will excite fluorescence under laser irradiation of different wavelengths, that is, one wavelength will excite a corresponding free radical. Replacing the laser with a laser of the corresponding wavelength can generate a fluorescence signal, thereby exploring whether the particle surface will produce this type of free radical under photocatalysis and its specific concentration. At the same time, during calibration, the free radical precursor also needs to be replaced with the precursor of this type of free radical. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The present invention is a schematic diagram of the structure of a device for quantitatively detecting photocatalytic free radicals on the surface of particles.

[0065] Figure 2 It is a schematic diagram of the longitudinal cross-sectional structure of the reaction module.

[0066] Figure 3 It is a schematic diagram of the transverse cross-sectional structure of the reaction module.

[0067] Figure 4 It is a schematic diagram of the longitudinal cross-sectional structure of the reactor body.

[0068] Figure 5 This is a top-down structural diagram of the reactor body.

[0069] Figure 6 It is an axonometric view of the reactor body.

[0070] Figure 7 It is a schematic diagram of the longitudinal cross-sectional structure of the reaction panel.

[0071] The meanings of the reference numerals are as follows:

[0072] 1-light source, 2-concave lens, 3-cage mount, 4-convex lens, 5-filter, 6-reflector,

[0073] 7-reaction module, 701-quartz window, 702-window plate, 703-reactor body,

[0074] 704-first sealing ring, 705-second sealing ring, 706-reaction panel, 707-particle sample,

[0075] 703-1-air outlet, 703-2-installation step, 703-3-circular gap, 703-4-air outlet groove,

[0076] 703-5-first through hole, 703-6-air inlet, 703-7-stepped annular groove,

[0077] 706-1-annular groove, 706-2-second through hole, 706-3-inner groove,

[0078] 8-sampling nozzle, 9-diffusion tube, 10-fluorescence chamber, 11-optical arm, 12-laser energy meter,

[0079] 13-window, 14-conical aperture, 15-vacuum air pump, 16-optical fiber,

[0080] 17-host computer, 18-laser, 19-calibration gas cylinder, 20-nitrogen cylinder,

[0081] 21- Wet gas flow meter, 22- Dry gas flow meter,

[0082] 23-anti-sucking bottle, 24-water bottle, 25-single chip microcomputer, 26-humidity sensor, 27-detection tube,

[0083] 28-Photosensitive sensor, 29-DC regulated power supply DETAILED DESCRIPTION

[0084] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0085] Example 1

[0086] Depend on Figure 1 As shown, a device for quantitatively detecting photocatalytic free radicals on the surface of particles includes: a light source module, a gas distribution system, a reaction module 7, a free radical detection module, and a control system.

[0087] The light source module is used to generate a photolysis beam or simulate a natural beam, and irradiate the photolysis beam or simulated natural beam into the reaction module 7; the photolysis beam is used to photolyze free radical precursors to generate free radicals; the simulated natural beam is used to irradiate the surface of the particles, and photocatalyze the surface of the particles to generate free radicals;

[0088] The gas distribution system is connected to the reaction module 7 and is used to pass the free radical precursor synthesis gas into the reaction module 7;

[0089] The reaction module 7 is a place where free radicals are generated. The free radical precursor synthesis gas is photolyzed by the photolysis beam irradiated by the light source module to generate free radicals; or the particulate matter sample placed in the reaction module 7 is photocatalyzed to generate free radicals by the simulated natural light beam irradiated by the light source module; or the particulate matter sample placed in the reaction module 7 is photocatalyzed to generate free radicals by directly irradiating sunlight into the reaction module 7;

[0090] The reaction module 7 is connected to the free radical detection module, and the free radicals generated in the reaction module 7 enter the free radical detection module; the free radical detection module is used to emit laser to the free radicals and excite the free radicals to generate fluorescence, and to collect fluorescence photon signals and emitted laser energy;

[0091] The control system is used to receive various data collected in the device, control various controllable devices in the device, and perform related computing tasks.

[0092] The present invention first calibrates the device according to the concentration of free radicals generated by photolysis of a free radical precursor synthesis gas by a photolysis light beam, and then uses the device to measure the concentration of free radicals generated by irradiating a particle sample with a simulated natural light beam.

[0093] The light source module is used to generate a parallel light beam close to the natural light band, providing lighting conditions for indoor measurement, and can also emit a mercury lamp beam that photolyzes free radical precursors to generate free radicals, providing calibration conditions for quantitatively measuring the concentration of free radicals generated on the surface of the particle sample 707.

[0094] Depend on Figure 1 As shown, the light source module includes: a mercury lamp 101 for generating photolysis light, a xenon lamp 102 for simulating natural light, a concave lens 2, a convex lens 4, a filter 5, a reflector 6 arranged in sequence along the light propagation direction, and a DC regulated power supply 29 for supplying power to the mercury lamp 101 and the xenon lamp 102, a photosensor 28 for collecting light intensity, and a cage-type fixing frame 3 for detachably fixing various optical devices;

[0095] After the photolysis light or natural light is expanded and collimated by the concave lens 2 and the convex lens 4 to obtain a relatively thick parallel light beam, the redundant band of the parallel light beam is filtered out by the filter 5. The reflector 6 is set at the center of the parallel light beam, and the photosensor 28 is installed on the right side of the reflector 6 and fixed on the cage-type fixing frame 3. The central light beam of the parallel light beam is irradiated to the reflector 6 and then reflected to the photosensitive surface of the photosensor 28, and the outer ring light beam of the parallel light beam is irradiated to the reaction module 7;

[0096] The filter 5 is a bandpass filter, and light beams of different wavelengths can be generated by replacing the filter 5, aiming to achieve a specified illumination wavelength band and illumination intensity. The distance between the concave lens 2 and the convex lens 4 can be adjusted in a small range to adjust the parallel beam expansion of the photolysis light or natural light.

[0097] Depend on Figure 1 As shown, the gas distribution system includes: a calibration gas cylinder 19, a nitrogen cylinder 20, a wet gas flow meter 21, a dry gas flow meter 22, a water bottle 24, an anti-backflow bottle 23, a detection tube 27 and a humidity sensor 26.

[0098] The calibration gas cylinder 19 is used to store a free radical precursor synthesis gas of known concentration; the nitrogen cylinder 20 is used to store nitrogen; the output pipe of the nitrogen cylinder 20 is connected to the output pipe of the calibration gas cylinder 19 through a four-way connection, and the other two ports of the four-way connection are respectively connected to the input ends of the wet gas pipeline and the dry gas pipeline; the wet gas pipeline is provided with a wet gas flowmeter 21 for controlling the wet gas flow rate, and the dry gas pipeline is provided with a dry gas flowmeter 22 for controlling the dry gas flow rate; the output end of the dry gas pipeline is connected to the detection tube 27; after the wet gas pipeline passes through the anti-backflow bottle 23 and the water bottle 24 in sequence, the output end of the wet gas pipeline is also connected to the detection tube 27.

[0099] The detection tube 27 is connected to the reaction module 7 and is used to pass the free radical precursor synthesis gas or nitrogen into the reaction module 7;

[0100] The free radical precursor synthesis gas is introduced into the reaction module 7, on the one hand, to be photolyzed to generate free radicals, and on the other hand, to drive the free radicals generated by the photolysis of the free radical precursor synthesis gas in the reaction module 7 into the free radical detection module.

[0101] Nitrogen is introduced into the reaction module 7 to drive the free radicals generated on the surface of the particle sample in the reaction module 7 under photocatalysis to enter the free radical detection module.

[0102] The detection tube 27 is provided with a humidity sensor 26 for collecting the humidity of the gas in the detection tube 27;

[0103] If the gas introduced into the reaction module 7 does not need to contain water vapor, only the dry gas flowmeter 22 is turned on, and the wet gas flowmeter 21 is turned off, and the dry gas in the gas cylinder is introduced into the reaction module 7 through the dry gas pipeline and the detection tube 27; if the gas introduced into the reaction module 7 needs to contain water vapor, the wet gas flowmeter 21 and the dry gas flowmeter 22 are turned on at the same time, and the dry gas in the gas cylinder is divided into two paths, one of which is converted into wet gas after passing through the anti-backflow bottle 23 and the water bottle 24 on the wet gas pipeline and enters the detection tube 27, and the other path directly enters the detection tube 27 through the dry gas pipeline, and the dry gas and the wet gas in the detection tube 27 are mixed and introduced into the reaction module 7;

[0104] By controlling the opening of the dry gas flowmeter 22 and the wet gas flowmeter 21, the gas humidity in the detection tube 27 reaches a set value according to the water vapor concentration in the gas.

[0105] Depend on Figure 2As shown, the reaction module 7 includes: a quartz window 701 for sealing the reaction module 7 and transmitting light, a window pressing plate 702 for pressing and fixing the quartz window 701, a reaction panel 706 for containing a particulate sample 707, and a reactor body 703 for carrying the reaction panel 706 and evenly blowing the gas introduced by the gas distribution system to the sampling nozzle of the free radical detection module.

[0106] Depend on Figure 4 and Figure 3 As shown, the reactor body 703 is provided with a first through hole 703-5, and the first through hole 703-5 is divided into an upper through hole and a lower through hole, the diameter of the upper through hole is larger than the diameter of the lower through hole, forming an installation step 703-2 for installing the reaction panel 706;

[0107] A trapezoidal groove 703-7 is provided on the inner wall of the upper through hole along the circumferential direction, and the cross-section of the trapezoidal groove 703-7 is a trapezoid with an opening at the lower bottom edge and facing the upper through hole; a circular ring gap 703-3 with a circular cross-section is provided on the outer ring of the trapezoidal groove 703-7, and the circumferential outer side of the circular ring gap 703-3 is connected with the air inlet 703-6, and the air inlet 703-6 is connected with the gas distribution system, and a plurality of evenly distributed air outlet holes 703-1 are provided on the circumferential inner side of the circular ring gap 703-3; these plurality of air outlet holes 703-1 lead to the trapezoidal groove 703-7 along the center direction of the circle, and the hole diameters of these plurality of air outlet holes 703-1 gradually increase from near to far from the air inlet 703-6 to ensure that the air flow rate blown out by each air outlet hole 703-1 is approximately equal. In this embodiment, 32 air outlet holes 703-1 are provided inside the circumference of the annular gap 703-3. The structural design of the present invention can push the airflow blown out from the air outlet holes 703-1 evenly from all sides to the top of the reaction panel 706, and blow the free radicals generated by the particle sample 707 under photocatalysis downward to the vicinity of the sampling nozzle of the free radical detection module without dead angles, and at the same time can ensure that the airflow above the particle sample can always maintain a laminar state, thereby avoiding the loss of free radicals caused by airflow dead zones and turbulence.

[0108] Depend on Figure 2 and 4 As shown, the reaction panel 706 is placed on the installation step 703-2, and the upper surface of the reaction panel 706 is flush with the lower edge of the trapezoidal groove 703-7, which can avoid collision losses of free radicals flowing from the surroundings to the center on the upper part of the reaction panel 26; a first sealing ring 704 is provided between the reaction panel 706 and the installation step 703-2 to prevent part of the gas flowing out of the air outlet 703-1 from flowing to the lower part of the reaction panel 706.

[0109] Depend on Figure 7As shown, a second through hole 706-2 aligned with the first through hole 703-5 is provided in the middle of the reaction panel 706, and the hole diameter of the second through hole 706-2 is slightly smaller than the hole diameter of the lower section of the first through hole 703-5; an annular groove 706-1 is provided on the upper surface of the reaction panel 706 and on the outer ring of the second through hole 706-2, and the annular groove 706-1 is used to place the particle sample 707; an inner groove 706-3 is provided on the inner side of the annular groove 706-1, which is convenient for taking out the reaction panel 706 to replace or place the particle sample 707.

[0110] Depend on Figure 2 and 4 As shown, the quartz window 701 is placed on the upper surface of the reactor body 703 and located above the upper through hole of the first through hole 703-5, and is used to seal the reactor body 703 and transmit light; a second sealing ring 705 is provided between the quartz window 701 and the reactor body 703.

[0111] Depend on Figure 5 As shown, the free radicals generated in the reaction module 7 enter the free radical detection module through the lower through hole of the first through hole 703-5, and four air outlet grooves 703-4 distributed in a "cross" shape are opened at the bottom of the reactor body 703, which are used to discharge the excess airflow in the first through hole 703-5. Since the flow state of the airflow in the first through hole 703-5 is also laminar flow, the excess airflow near the wall of the first through hole 703-5 flows away from the four air outlet grooves 703-4, so that the airflow in the sampling nozzle 8 entering the free radical detection module is a lossless airflow in the middle, thereby further reducing the loss of free radicals. The narrow strip design of the air outlet groove 703-4 can also ensure that the airflow outside the reaction module 7 will not affect the airflow inside the reaction module 7.

[0112] Depend on Figure 2 As shown, the window plate 702 is annular, and the diameter of the middle through hole of the window plate 702 is matched with the outer diameter of the reaction panel 706 , so as to press the quartz window 701 and further seal the upper part of the reactor body 703 .

[0113] Depend on Figure 6 As shown, two arc-shaped grooves are provided on the upper part of the reactor body 703 to facilitate the removal of the quartz window 701.

[0114] The upper surface of the quartz window 701 is coated with an anti-reflection film to increase the transmittance of the light beam; the materials of the reactor body 703 and the reaction panel 706 are both aluminum alloys coated with a PFA film on the surface to reduce the loss of free radicals.

[0115] In the present invention, the flow state of the airflow inside the reaction module 7 is laminar flow without vortexes throughout the entire process, and the flow range covers the entire interior of the reaction body 703. A PFA film is coated on the metal surface that is in direct contact with the free radicals. The excess airflow near the wall flows away through the air outlet groove 703-4 without being disturbed by the external airflow, which can reduce the loss and blow the free radicals to the sampling nozzle 8 of the free radical detection module below without dead ends.

[0116] Depend on Figure 1 As shown, the free radical detection module includes: a sampling nozzle 8, a diffusion tube 9, a fluorescence chamber 10, an optical arm 11, a conical aperture 14, a window 13, a laser energy meter 12, a vacuum air pump 15, a laser 18 and an optical fiber 16.

[0117] The free radicals generated by the reaction module 7 enter the fluorescence chamber 10 through the sampling nozzle 8 and the diffusion tube 9 in sequence; the sampling nozzle 8 is a conical nozzle installed on the top surface of the diffusion tube 9, with the cone mouth facing the reaction module 7 and the cone bottom facing the diffusion tube 9; the bottom of the diffusion tube 9 is connected to the top of the fluorescence chamber 10; the left and right sides of the fluorescence chamber 10 are respectively connected with an optical arm 11, which are the first optical arm and the second optical arm, respectively, the first optical arm and the second optical arm are perpendicularly intersected with the diffusion tube 9 and connected to the fluorescence chamber 10, and the ends of the first optical arm and the second optical arm away from the fluorescence chamber 10 are sealed by a window sheet 13;

[0118] The laser 18 is used to generate and emit laser light through the optical fiber 16. The laser light is irradiated into the fluorescence chamber 10 through the first optical arm to excite the free radicals in the fluorescence chamber 10 to generate fluorescence, and then emitted to the laser energy meter 12 through the second optical arm. The laser energy meter 12 is used to collect the emitted laser energy; a photomultiplier tube is installed in the fluorescence chamber 10 to perform photoelectric conversion on the excited fluorescence and collect fluorescence photon signals;

[0119] Three conical apertures 14 are installed inside the first optical arm and the second optical arm, and the cone tops of the conical apertures 14 are all facing the side away from the fluorescent chamber 10, so as to reduce the stray light generated by the laser irradiating into the fluorescent chamber 10;

[0120] The bottom of the fluorescence chamber 10 is also connected to a vacuum air pump 15 for evacuating the fluorescence chamber 10 to generate low pressure in the fluorescence chamber. When the vacuum air pump 15 evacuates air, it will suck in the gas in the reaction module 7 and generate a downward high-speed jet airflow through the sampling nozzle 8.

[0121] The free radical detection module of the present invention is a fluorescence measurement in an artificially manufactured low-pressure environment, which can accurately measure the concentration of free radicals while reducing the loss of free radical life. Since the photomultiplier tube has a high sensitivity, it can accurately measure free radicals with very low concentrations.

[0122] Depend on Figure 1 and Figure 2 As shown, the reactor body 703 and the cage-type fixing frame 3 of the light source module are coaxially mounted on the top surface of the diffusion tube 9, and the sampling nozzle 8 penetrates into the lower section through hole of the first through hole 703-5 of the reactor body 703. The reflector 6 in the light source module is mounted on the upper surface of the reaction module 7, specifically mounted at the center of the upper surface of the quartz window 701 and at an angle of 45° with the quartz window 701, and the diameter of the reflector 6 is the same as the diameter of the lower section through hole in the first through hole 703-5 opened in the reactor body 3. The light source module of the present invention can generate a coarse parallel light beam with adjustable light intensity, which is sufficient to cover the upper surface of the particle sample. A small reflector 6 is installed at the center of the upper surface of 701, which can reflect the center of the light beam to the photosensor 28 on the right side, and shield the light directly irradiated to the sampling nozzle 8 below while detecting the light intensity in real time, thereby avoiding the light entering from the small hole of the sampling nozzle 8 from affecting the measurement of the free radical detection module.

[0123] Depend on Figure 1 As shown, the control system includes a single chip microcomputer 25 and a host computer 17. The single chip microcomputer 25 is used to receive signals from the temperature sensor 26 and the photosensor 28, and control the on / off and output voltage of the DC regulated power supply 29; the host computer 17 is used to receive signals from the photomultiplier tube and the laser energy meter 12 in the free radical detection module, control the on / off and flow of the wet gas flow meter 21 and the dry gas flow meter 22, and receive and control the signals from the single chip microcomputer 25.

[0124] Example 2

[0125] The method for measuring the concentration of free radicals generated on the surface of particles under photocatalysis using the device of the present invention has the following specific principles and steps:

[0126] S1, install the mercury lamp 101 and the filter 5 corresponding to the photolysis band on the light source module to filter out the interference band of photolysis, turn on the mercury lamp 101, and the photolysis light emitted by the mercury lamp 101 is expanded and collimated into a thicker parallel light beam through the concave lens 2 and the convex lens 4. The central beam of the parallel light beam is irradiated onto the reflector 6 on the quartz window 701 and then reflected onto the photosensitive surface of the light intensity sensor 28. The outer ring beam of the light beam is irradiated into the reaction module 7 through the quartz window 701.

[0127] S2, open the calibration gas cylinder 19,

[0128] When the free radical precursor to be photolyzed does not contain water vapor, only the dry gas flow meter 22 is turned on, and the wet gas flow meter 21 is turned off, so that the dry free radical precursor synthesis gas is passed from the gas inlet 703-6 into the reaction module 7 through the detection tube 27;

[0129] When the free radical precursor to be photolyzed contains water vapor, the wet gas flow meter 21 and the dry gas flow meter 22 are turned on at the same time, so that the dry free radical precursor synthesis gas passes through the wet gas flow meter 21, flows through the anti-backflow bottle 23 and the water bottle 24 to become the wet free radical precursor synthesis gas, and then mixes with the dry free radical precursor synthesis gas passing through the dry gas flow meter 22 to become the wet free radical precursor synthesis gas with adjustable water vapor ratio. The humidity sensor 26 in the detection tube 27 detects the water vapor concentration of the gas in real time, and processes the data through the single chip microcomputer 25 and transmits it to the host computer 17; When the water vapor concentration is higher than the set value, the upper computer 17 directly controls the on / off and flow rate of the wet gas flow meter 21 and the dry gas flow meter 22, reducing the flow rate of the wet gas flow meter 21 while increasing the flow rate of the dry gas flow meter 22, and vice versa, so that the water vapor concentration of the wet radical precursor synthesis gas is always maintained near the preset value when the total flow rate remains unchanged, thereby avoiding the loss of free radicals in the reaction module 7 due to the change of the air flow rate, and then the wet radical precursor synthesis gas is passed into the reaction module 7 from the air inlet 703-6 through the detection tube 27. Among them, the maintenance of the total air flow rate makes the air flow mixed with free radicals in the reaction module 7 maintain the highest flow rate in the laminar state, so as to reduce the loss caused by the end of the free radical life and turbulence.

[0130] The free radical precursor synthesis gas in the reaction module 7 undergoes photolysis under the irradiation of the mercury lamp 101 to produce free radicals. By measuring the light intensity and water vapor concentration of the mercury lamp 1 and the known concentration of the free radical precursor, and combining the photolysis equation of the free radical, the concentration of the free radicals produced by the photolysis, i.e., the calibrated concentration Rt of the free radicals, can be calculated.

[0131] S3, when the free radical precursor synthesis gas flows into the annular gap 703-3 from the air inlet 703-6, the free radical precursor synthesis gas will fill the entire annular gap 703-3, and then flow from the 32 outlet holes 703-1 to the center of the upper surface of the reaction panel 706. Since the air pressure at the outlet hole 703-1 farther from the air inlet 703-6 is lower, the diameter of the outlet hole 703-1 farther from the air inlet 703-6 is larger, so that the air flow can flow out of the 32 outlet holes 703-1 with almost equal flow. The air flow flowing out of the outlet hole 703-1 is decelerated by the trapezoidal groove 703-7 and flows to the center of the upper surface of the reaction panel 706. The free radical precursor synthesis gas in the reaction module 7 is photolyzed under the irradiation of the mercury lamp 1 to generate free radicals. At the same time, the airflow carries the free radicals generated by the reaction through the lower through holes of the first through holes 703 - 5 to the vicinity of the sampling nozzle 8 below the reactor body 703 .

[0132] S4, turn on the laser 18 and the vacuum air pump 15. The vacuum air pump 15 can generate a low pressure of only several hundred Pa in the fluorescence chamber 10, which greatly reduces the collision probability of gas molecules in the fluorescence chamber 10, thereby increasing the life of free radicals. The free radicals in the reaction module 7 are sucked into the fluorescence chamber 10 by the sampling nozzle 8 of the free radical detection module, and a downward jet airflow is generated. The laser emitted by the laser 18 passes through the optical fiber 16 and the window 13 and is emitted into the optical arm 11 on the right side of the fluorescence chamber 10, i.e., the first optical arm, and then enters the fluorescence chamber 10 after passing through the three conical apertures 14 in the first optical arm, and excites the free radicals in the fluorescence chamber 10 to generate fluorescence. The fluorescence is received by the photomultiplier tube installed at the rear of the fluorescence chamber 10 and photoelectrically converted to obtain a calibration signal St of the fluorescence photons, which is transmitted to the host computer 17. The laser is emitted from the fluorescence chamber 10 and then emitted through the second optical arm to the laser energy meter 12. The laser energy meter 12 collects the calibration energy Pt of the emitted laser and transmits it to the host computer 17.

[0133] S5, remove the window pressing plate 702 that presses the quartz window 701, take out the quartz window 701 and the reaction panel 706, place the particle sample 707 in the annular groove 706-1 on the reaction panel 706, and then put the reaction panel 706 back into the reactor body 703 and cover it with the quartz window 701, and use the window pressing plate 702 to press and seal the quartz window 701.

[0134] S6, close the calibration gas cylinder 19 and open the nitrogen gas cylinder 20;

[0135] When measuring indoors, the mercury lamp 101 is replaced with a xenon lamp 102, and the filter 5 of the wavelength band to be measured is replaced, and the xenon lamp 102 is turned on. The natural light simulated by the xenon lamp 102 is expanded and collimated into a thicker parallel light beam through the concave lens 2 and the convex lens 4. The central light beam of the parallel light beam is irradiated to the reflector 6 on the quartz window 701 and then reflected to the photosensitive surface of the light intensity sensor 28. The outer ring light beam of the parallel light beam passes through the quartz window 701 and irradiates the surface of the particle sample 707 on the reaction panel 706.

[0136] When measuring outdoors, the light source module is removed to allow sunlight to directly irradiate the surface of the particle sample 707 on the reaction panel 706 through the quartz window 701 .

[0137] S7, the free radicals generated on the surface of the particle sample 707 under light are carried by the nitrogen gas flow to the sampling nozzle 8 of the free radical detection module;

[0138] S8, turn on the laser 18 and the vacuum air pump 15, the nitrogen mixed with free radicals is sucked into the fluorescence chamber 10 by the sampling nozzle 8 of the free radical detection module, the laser emitted by the laser 18 enters the fluorescence chamber 10, excites the free radicals in the fluorescence chamber 10 to produce fluorescence, the fluorescence is received by the photomultiplier tube installed at the rear of the fluorescence chamber 10, and is converted into a fluorescence photon signal S through photoelectric conversion, and is transmitted to the host computer 17, the laser is emitted from the fluorescence chamber 10 and then emitted through the second optical arm to the laser energy meter 12, the laser energy meter 12 collects the emitted laser energy P and transmits it to the host computer 17.

[0139] According to the calibrated concentration Rt of free radicals obtained by photolysis, the calibrated signal St of fluorescent photons, the calibrated energy Pt of the emitted laser, and the fluorescent photon signal S and the emitted laser energy P obtained on the surface of the particle sample under photocatalysis, the free radical concentration R generated on the surface of the particle sample under photocatalysis is calculated.

[0140] R=Rt×[(S×Pt) / (St×P)].

[0141] During indoor measurement, filters 5 of different wavelengths may be replaced to obtain illumination of different wavelengths, thereby exploring the effects of illumination of different wavelengths on the types of free radicals produced and the corresponding concentrations.

[0142] During the operation of the method of the present invention, the single-chip microcomputer 25 obtains the signals of the humidity sensor 26 and the photosensor 28 in real time, and controls the output light intensity of the xenon lamp 102 by controlling the output power of the DC regulated power supply 29, and adjusts the humidity of the gas entering the reaction module 7 by controlling the flow rate of the humidified gas flowmeter 21 and the dry gas flowmeter 22, and finally connects to the host computer 17 through the serial port.

[0143] Although the free radicals that may be generated on the surface of the particles under photocatalysis are unknown, different types of free radicals will excite fluorescence under laser irradiation of different wavelengths, that is, one wavelength corresponds to one free radical. Replacing the laser 18 with a laser of the corresponding wavelength can generate a fluorescence signal, thereby exploring whether the particle surface will generate such free radicals under photocatalysis and how much is generated, such as: OH free radicals will generate fluorescence under 308nm laser irradiation, and CH free radicals can generate fluorescence under 430.8nm laser irradiation. Correspondingly, the free radical precursor used during calibration also needs to be replaced with the precursor of this free radical.

[0144] When the gas in the calibration gas cylinder 19 is replaced with other free radical precursor synthesis gas, the mercury lamp 101 and the filter 5 are replaced with the corresponding photolysis band, and the laser 18 is replaced with a laser of the corresponding band that can excite the free radical to produce fluorescence, the concentration of other free radicals generated by photocatalysis on the particle surface can be measured using the above principles and methods, thereby detecting the types and specific concentrations of free radicals generated on the particle surface under photocatalysis.

[0145] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for quantitatively detecting photocatalytic free radicals on the surface of particles, characterized in that: The device includes: Light source module, reaction module (7), gas distribution system, free radical detection module, control system; The light source module is used to generate a photolysis beam or simulated natural light beam, and irradiate the photolysis beam or simulated natural light beam into the reaction module (7); the photolysis beam is used to photolyze free radical precursors to generate free radicals; the simulated natural light beam is used to irradiate the surface of the particles, and photocatalyze the surface of the particles to generate free radicals; The gas distribution system is connected to the reaction module (7) and is used to pass the free radical precursor synthesis gas into the reaction module (7); The reaction module (7) is a place where free radicals are generated. The free radical precursor synthesis gas is photolyzed using the photolysis light beam irradiated by the light source module to generate free radicals; or the particulate matter sample placed in the reaction module (7) is photocatalyzed using the simulated natural light beam irradiated by the light source module to generate free radicals; or the particulate matter sample placed in the reaction module (7) is photocatalyzed directly using sunlight to irradiate into the reaction module (7) to generate free radicals; The reaction module (7) is connected to the free radical detection module, and the free radicals generated in the reaction module (7) enter the free radical detection module; the free radical detection module is used to emit laser light to the free radicals and excite the free radicals to generate fluorescence, and is used to collect fluorescence photon signals and emitted laser energy; The control system is used to receive various data collected in the device, control various controllable devices in the device, and perform related computing tasks; The reaction module (7) comprises: a reactor body (703), a quartz window (701) for sealing the reactor body (703) and transmitting light, and a reaction panel (706) for placing a particle sample (707); A first through hole (703-5) is provided in the reactor body (703) along the light irradiation direction, and the first through hole (703-5) is divided into an upper through hole and a lower through hole, the hole diameter of the upper through hole being larger than the hole diameter of the lower through hole, forming an installation step (703-2) for installing a reaction panel (706); The reaction panel (706) is placed on the installation step (703-2), and a second through hole (706-2) aligned with the first through hole (703-5) is opened in the middle of the reaction panel (706), and the hole diameter of the second through hole (706-2) is smaller than the hole diameter of the lower section of the first through hole (703-5); an annular groove (706-1) is opened on the upper surface of the reaction panel (706) and on the outer ring of the second through hole (706-2), and the annular groove (706-1) is used to place the particle sample (707); A circular annular gap (703-3) with a circular cross section is provided in the reactor body (703) and along the outer ring of the upper through hole, the outer circumferential side of the circular annular gap (703-3) is connected to the air inlet (703-6), and the air inlet (703-6) is connected to the gas distribution system; a plurality of evenly distributed air outlet holes (703-1) are provided on the inner circumference of the circular annular gap (703-3), which are connected to the upper through hole through the plurality of air outlet holes (703-1), and the air flow blown out of the air outlet holes (703-1) is pushed horizontally from all sides to the top of the reaction panel (706); The inner wall of the upper through hole is provided with a trapezoidal groove (703-7) along the circumferential direction, and the cross section of the trapezoidal groove (703-7) is a trapezoid with an opening at the bottom edge and facing the upper through hole; the annular gap (703-3) is located at the outer ring of the trapezoidal groove (703-7), and a plurality of air outlet holes (703-1) are connected to the trapezoidal groove (703-7) along the center direction of the annular gap (703-3); The quartz window (701) is placed on the upper surface of the reactor body (703) and is located above the upper through hole of the first through hole 703-5, and is used to seal the reactor body (703) and transmit light; The free radicals generated in the reaction module (7) enter the free radical detection module along the lower through holes.

2. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 1, characterized in that: The light source module comprises: a mercury lamp (101) for generating photolysis light, a xenon lamp (102) for generating natural light, a concave lens (2), a convex lens (4), a filter (5), and a reflector (6) arranged in sequence along the light propagation direction, a DC regulated power supply (29) for supplying power to the mercury lamp (101) and the xenon lamp (102), a photosensor (28) for collecting light intensity, and a cage-type fixing frame (3) for detachably fixing various optical devices; The photolysis light or natural light is first expanded and collimated by a concave lens (2) and a convex lens (4) to obtain a beam of parallel light, and then filtered out unnecessary wavelengths of the parallel light by a filter (5); the reflector (6) is arranged at the center of the parallel light beam, and the central light beam of the parallel light beam is irradiated by the reflector (6) and then reflected to the photosensitive surface of the photosensitive sensor (28), and the outer ring light beam of the parallel light beam is irradiated into the reaction module (7); The filter (5) is a bandpass filter, and light beams of different wavelength bands are generated by replacing the filter (5); the distance between the concave lens (2) and the convex lens (4) is adjustable to adjust the parallel beam expansion of photolysis light or natural light.

3. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 1, characterized in that: The gas distribution system comprises: a calibration gas cylinder (19), a wet gas flow meter (21), a dry gas flow meter (22), a water filter bottle (24), an anti-backflow bottle (23), a detection tube (27) and a humidity sensor (26); The calibration gas cylinder (19) is used to store the free radical precursor synthesis gas; the output pipe of the calibration gas cylinder (19) is respectively connected to the input ends of the wet gas pipeline and the dry gas pipeline; the wet gas pipeline is provided with a wet gas flow meter (21), and the dry gas pipeline is provided with a dry gas flow meter (22); the output end of the dry gas pipeline is connected to a detection tube (27); after the wet gas pipeline passes through the anti-backflow bottle (23) and the water bottle (24) in sequence, the output end of the wet gas pipeline is also connected to the detection tube (27); the detection tube (27) is connected to the reaction module (7) and is used to pass the free radical precursor synthesis gas into the reaction module (7); The free radical precursor synthesis gas is introduced into the reaction module (7) to be photolyzed to generate free radicals and to drive the free radicals generated by the photolysis of the free radical precursor synthesis gas in the reaction module (7) to enter the free radical detection module; The detection tube (27) is provided with a humidity sensor (26) for collecting the humidity of the gas in the detection tube (27); If the gas introduced into the reaction module (7) does not need to contain water vapor, only the dry gas flow meter (22) is turned on, the wet gas flow meter (21) is turned off, and the dry gas in the gas cylinder is introduced into the reaction module (7) through the dry gas pipeline and the detection tube (27); If the gas introduced into the reaction module (7) needs to contain water vapor, the wet gas flow meter (21) and the dry gas flow meter (22) are turned on at the same time, and the dry gas in the gas cylinder is divided into two paths, one of which is converted into wet gas after passing through the anti-backflow bottle (23) and the water bottle (24) on the wet gas pipeline and enters the detection tube (27), and the other is directly passed through the dry gas pipeline and enters the detection tube (27). The dry gas in the detection tube (27) is mixed with the wet gas and then introduced into the reaction module (7); By controlling the flow rates of the dry gas flow meter (22) and the wet gas flow meter (21), the water vapor concentration in the gas is controlled so that the gas humidity in the detection tube (27) collected by the humidity sensor (26) reaches a set value.

4. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 3, characterized in that: The gas distribution system further comprises: a nitrogen bottle (20) for storing nitrogen; an output pipe of the nitrogen bottle (20) is connected to an output pipe of a calibration gas bottle (19) via a four-way connection, and the other two ports of the four-way connection are respectively connected to input ends of a humidified gas pipeline and a dry gas pipeline; nitrogen is introduced into the reaction module (7) to drive free radicals generated by photocatalysis of the particulate matter light sample in the reaction module (7) into the free radical detection module.

5. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 1, characterized in that: The bottom of the reactor body (703) is provided with a plurality of gas outlet grooves (703-4) connected to the bottom of the lower through hole, for discharging excess airflow at the bottom of the lower through hole in the first through hole (703-5).

6. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 1, characterized in that: The diameters of the plurality of air outlet holes (703-1) provided on the annular gap (703-3) gradually increase from near to far from the air inlet (703-6); the materials of the reactor body (703) and the reaction panel (706) are both aluminum alloys coated with a layer of PFA film on the surface; the upper surface of the quartz window (701) is coated with a layer of anti-reflection film; the quartz window (701) is pressed and fixed on the upper surface of the reactor body (703) by a window pressing plate (702); the window pressing plate (702) is annular, and the diameter of the middle through hole of the window pressing plate (702) is matched with the outer diameter of the reaction panel (706); a second sealing ring (705) is provided between the quartz window (701) and the reactor body (703); and a first sealing ring (704) is provided between the reaction panel (706) and the mounting step (703-2).

7. The device for quantitatively detecting photocatalytic free radicals on the surface of particles according to claim 1, characterized in that: The free radical detection module comprises: a sampling nozzle (8), a diffusion tube (9), a fluorescence chamber (10), an optical arm (11), a conical aperture (14), a window sheet (13), a laser energy meter (12), a vacuum air pump (15), a laser (18), and an optical fiber (16); The free radicals generated in the reaction module (7) enter the fluorescence chamber (10) in sequence through the sampling nozzle (8) and the diffusion tube (9); the sampling nozzle (8) is a conical nozzle installed on the top surface of the diffusion tube (9), with the cone mouth facing the reaction module (7) and the cone bottom facing the top of the diffusion tube (9); the bottom of the diffusion tube (9) is connected to the top of the fluorescence chamber (10); the left and right sides of the fluorescence chamber (10) are respectively connected with an optical arm (11), which are a first optical arm and a second optical arm, respectively, the first optical arm and the second optical arm are respectively perpendicularly intersected with the diffusion tube (9) and connected to the fluorescence chamber (10), and the ends of the first optical arm and the second optical arm away from the fluorescence chamber (10) are sealed by a window sheet (13); The laser (18) is used to generate and emit laser light through an optical fiber (16); the laser light is irradiated into a fluorescence chamber (10) through a first optical arm to excite free radicals in the fluorescence chamber (10) to generate fluorescence; and then irradiated into a laser energy meter (12) through a second optical arm; the laser energy meter (12) is used to collect the emitted laser energy; a photomultiplier tube is installed in the fluorescence chamber (10) to perform photoelectric conversion on the excited fluorescence and collect fluorescence photon signals; Conical diaphragms (14) are installed inside the first optical arm and the second optical arm, and the cone tops of the conical diaphragms (14) are both facing the side away from the fluorescent chamber (10); the bottom of the fluorescent chamber (10) is also connected to a vacuum air pump (15) for evacuating air from the fluorescent chamber (10).

8. A detection method applicable to a device for quantitatively detecting photocatalytic free radicals on the surface of particles according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, first calibrate the device, as shown below: S101, the light source module generates a photolysis beam and irradiates the reaction module (7), and simultaneously obtains the light intensity of the photolysis beam; S102, the gas distribution system passes the free radical precursor synthesis gas into the reaction module (7); the free radical precursor concentration and water vapor concentration in the free radical precursor synthesis gas are known; The concentration of free radicals generated by the photolysis of the free radical precursor synthesis gas is calculated through the light intensity of the photolysis beam, the water vapor concentration, the concentration of the free radical precursor, and according to the free radical photolysis equation, i.e., the free radical calibration concentration Rt; S103, a photolysis light beam photolyzes the free radical precursor synthesis gas introduced into the reaction module (7) to generate free radicals, and the free radicals generated in the reaction module (7) enter the fluorescence chamber of the free radical detection module; S104, the free radical detection module emits laser light and irradiates it into the fluorescence chamber to excite the free radicals in the fluorescence chamber and generate fluorescence. At this time, the free radical detection module collects and obtains the calibration signal St of the fluorescence photons and the calibration energy Pt of the emitted laser light; S2, after the device calibration is completed, the concentration of free radicals generated on the surface of the particle sample under photocatalysis is actually measured, as shown below: S201, placing a particle sample in a reaction module (7); S202, using a light source module to generate a simulated natural light beam and irradiating the reaction module (7), or using sunlight to irradiate the reaction module (7); S203, simulating natural light beams or sunlight to irradiate the surface of the particle sample in the reaction module (7) to generate free radicals by photocatalysis, and the free radicals generated in the reaction module (7) enter the fluorescence chamber of the free radical detection module; S204, the free radical detection module emits laser light and irradiates it into the fluorescence chamber to excite the free radicals in the fluorescence chamber and generate fluorescence. At this time, the free radical detection module collects the fluorescence photon signal S and the emitted laser energy P; S205, based on the calibration signal St of the fluorescent photons, the calibration energy Pt of the emitted laser, the calibration concentration Rt of the free radicals obtained in the calibration process, and the fluorescent photon signal S and the emitted laser energy P obtained in the actual measurement process, the free radical concentration R generated on the surface of the particle sample under photocatalysis in the actual measurement process is calculated, R=Rt×[(S×Pt) / (St×P)].

9. The detection method according to claim 8, characterized in that: During the calibration process, the type of free radical precursor introduced into the reaction module (7) by the gas distribution system is changed, and the type and wavelength of the photolysis light beam are correspondingly changed, so that different types of free radicals are generated by photolysis; the wavelength of the laser emitted by the free radical detection module is changed, so that different types of free radicals are excited to generate fluorescence; the device is calibrated based on different types of free radicals to obtain the calibration concentration Rt of different types of free radicals, as well as the calibration signal St of the fluorescence photons corresponding to the different types of free radicals and the calibration energy Pt of the emitted laser; In the actual measurement process, by changing the wavelength band of the laser emitted by the free radical detection module, different types of free radicals are excited to produce fluorescence; according to the calibration results of different types of free radicals, the concentrations of different types of free radicals generated on the surface of the particle sample under photocatalysis during the actual measurement process are calculated, thereby obtaining the types and specific concentrations of free radicals generated on the surface of the particle under photocatalysis.

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